The genetics, nature and occurrence of self-and cross-incompatibility in four annual species of
Coreopsis L.
by Jagan Nath Sharma
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY in GENETICS
Montana State University
© Copyright by Jagan Nath Sharma (1971)
Abstract:
Four annual species of Coreopsis L. (Compositae: Heliantheae: Coreop-sidinae), C. bigelovii. (A.
Gray) H. M. Hall, C. calliopsidea (DC.) A. Gray, C. califomica (Nutt.) Sharsmith, and C. tinctoria
Nutt., were studied to determine the genetics of their self-incompatibility mechanisms. Diallel -cross,
backcross, and F2 studies revealed that these species have a sporo-phytic, multiple allelic, monogenic
system of self-incompatibility. C. tinctoria had 7 multiple alleles, while C. bigelovii and C. califomica
had 5 multiple alleles each. The number of multiple alleles could not be assigned to C. calliopsidea.
Cytological studies' revealed a strong correlation between the sporophytic system of
self-incompatibility and the stigma as the site of pollen inhibition. Meiotic chromosome numbers for all
four species were determined as n=12. Secondary associations between different bivalents were found
in all four species studied; these point toward some form of polyploidy associated with the genus.
Significant heterosis for horticultural traits was detected and a method of producing F1 hybrid cultivars
in Coreopsis tinctoria, using incompatibility as a technique, has been suggested. THE GENETICS, NATURE AND OCCURRENCE OF SELFAND CROSS-INCOMPATIBILITY IN FOUR ANNUAL SPECIES OF COREOPSIS L„
^
/
by
Jagan Nath Sharma
A thesis submitted to the Graduate Faculty in partial
fulfillment of the requirem ents for the degree
of
DOCTOR OF PHILOSOPHY
in
GENETICS
APPROVED:
Major Department
Co-chairman, Examining^Committee
Co-chairm an, Examining Qqmmittee
^7)
_________
Deqn, College of Grg^uate Studies
MONTANA STATE UNIVERSITY
Bozeman, Montana
December,..1971
- iii -
ACKNOWLEDGMENTS
The author would like to express his deepest appreciation to Professor H. N.
■Metcalf and D r. S. R. Chapman for their help and guidance during the course of
this investigation.
He would also like to express his appreciation to the staff of the Plant and,
Soil Science, Genetics Institote, for their help and encouragement, and to
Montana State University for the use of facilities and financial assistance
during the m ajor part of the studies .
A special thanks to my wife for h er long patience and understanding dur­
ing the past 3 1/2 years while caring for two children all alone, often in difficult
circum stances.
)
-iv -
TABLE OF CONTENTS
Page
V I T A .............................................................................................................
ii
ACKNOWLEDGEMENTS...................................................................
!Tii
TABLE OF CONTENTS
...........................................................
LIST OF TABLES....................................................
iv
vi
LIST OF F IG U R E S ............................................................................
x
ABSTRACT...................................................................' .....................
xiii
INTRODUCTION........................................
I
REVIEW OF LITERATURE ...............................................................
3
Incom patibility...................
The genus Coreopsis L .................................
3
17
RESEARCH PROCEDURES, METHODS, RESULTS
AND DISCUSSIONS ....................................
22
Plant m aterials (c u ltu re ).................................................
Confirming species identification ...........................................
Morphological variations in four annual species of
the genus Coreopsis L , ..........................
M aterials and Methods .............................................................
R e s u l t s .................................................
Discussion. ....................................................................................
Genetics and incompatibility mechanism operating
in four annual species of Coreopsis L ...............................'. .
M aterials and Methods.................................................................
R e s u lts ..................
D is c u s s io n ...................................................................................
Factors associated with "S" gene action .......................... .
M aterials and m eth o d s................................. ... . .....................
22
22
24
24
26
43
45
45
48
75
87
87
-V -
Table of Contents
(Continued)
Page
Results .....................................................
D is c u s s io n ................................
Hybrid vigor studies in Coreopsis tinctoria Nutt,
using self-incompatibility as a tool for producing Fj
h y b r id s .................... :................................ ................................
M aterials and m eth o d s..................
R e s u lts ............. .......................*
.....................
Production of Fi hybrid seed on a comm ercial scale . . .
Discussion
88
96
98
98
99
102
104
SUMMARY AND CONCLUSIONS .....................................................
HO
LITERATURE CITED ......................................................................
112
-V L -
LIST OF TABLES
Context Tables
N um ber
Page
I
Chromosome number reported for the genus Coreopsis L .
19
2
Coreopsis species and cultivars used in these investi­
gations with seed sources and notes on growth hab its. . .
23
Variability in inflorescence morphology and fertil­
ity ratings of ligulate and disc flowers of four
species of Coreopsis L .................................................. ...
28
Variation in quantitative traits: Summary of the
height and spread in four species of Coreopsis L ..............
29
Inter-group crossability behavior of the plants com­
prising the three compatibility groups studied in
Coreopsis tin c t o r i a ................................................................
50
Crossability behavior of the 4 plants of Coreopsis
tinctoria falling into incompatibility Group I ..................
51
Crossability behavior of the 2 plants of Coreopsis
tinctoria falling into compatibility Group II......................
52
Crossability behavior of the 3 plants of Coreopsis
tinctoria falling into compatibility Group III . . . . .
53
3
4
5
6
7
8
9
10
.
Inter group crossability behavior of the plants com­
prising three intra self cross-incom patible but
cross-com patible groups studied in Coreopsis
californica as measured by seed set success . . . . . .
55
Crossability behavior of the four plants of
Coreopsis californica falling into incompatibility .
Group I .................... ..............................................................
56
-v iiL lst of T ab les
Context Tables
(Continued)
Number
11
12
13
14
15
16
17
18
Page
Crossability behavior of the three plants of
Coreopsis califom ica falling into incompati­
bility Group II...................................................................
57
Crossability behavior of the three plants of
Coreopsis califom ica falling into incompati­
bility Group III............. ...
o .................... ...
58
Intergroup crossability behavior of the plants com­
prising the three incompatibility groups studied
in Coreopsis bigelovii as m easured by seed set
success . . . . . . . . . . . . . . . . . . . . . . . .
60
Crossability behavior of the two plants of
Coreopsis bigelovii falling into incompati­
bility Group I ........................................................ ...
61
Crossability behavior of the two plants of
Coreopsis bigelovii falling into incompati­
bility Group H........................................................
62
Crossability behavior of the three plants of
Coreopsis bigelovii falling into incompati­
bility Group III. . . .............................................................
63
Intergroup crossability behavior of the plants
comprising two, intra self and cross-incompatible
but inter cross-com patible groups studied in
Coreopsis calliopsidea as measured by seed
success ..................................... . . . . . . . . . . . .
65
Crossability behavior of the six plants of Coreopsis
callopsidea falling into incompatibility Group I. . . .
66
-v iiiL ist of T ab les
Context Tables
(Continued)
Number
19
Page
Crossability behavior of four plants of
Co calliopsidea falling into incompatibility
Group n . . . . . . . . . . . . . . . ..................
67
Results of the backcross in C . tinctoria
plants showing reciprocal differences in a
diallel c ro s s . Reciprocal cross I, plants
21
22
23
24
25
26
27
5 and 9 o o * . e . . o o e o o o o o o . o *
68
Results of the backcrosses in C . tinctoria
using plants showing reciprocal differences
in a diallel c ro s s . Plants chosen here are
N os. I and 4 ..................................... ........... .
69
Results of the backcross in C . califom ica
using plants showing reciprocal differences
in a diallel c ro s s . Plants 9 and I . . . . „ .
70
Results of the backcross in C. bigelovii
using plants showing reciprocal differences
in a diallel c ro s s . Plants 5 and 6 .................
72
Segregation in Fg generation of a cross
between self-incompatible and. self- compatible
mutant of C. tin cto ria. ............................................
73
Genotypes assigned to the 10 plants (G. tinctoria)
chosen for diallel c r os s . . . . . . . . . . . . . .
77
Genotypes assigned to the 10 plants chosen for
diallel cross in C . califo m ica.................
Genotypes assigned to 10 plants chosen for
diallel cross in C. bigelovii . . . . . . . . . . . . .
.
78
80
-ix L ist of T ab les
Context Tables
(Continued)
Number
' 28
29
Page
Results of the study of site of inhibition
of pollen germination in four se lf-incompati­
ble/compatible species of Coreopsis L. . . . . . .
Comparison of plant height, plant spread,
number of buds per plant, number of flowers
per plant and flower diam eter for four par­
ental lines of Coreopsis tinctoria with their
resultant Fj hybrids, Bozeman, Montana,
1968.................... ...........................................
94
100
-X -
LIST OF FIGURES
F igure
la
lb
2a
2b
4a
4b
5
6
7a
Page
Forms of ray p e ta ls. C . tinctoria upper row
from left to right flat, sem i-cactus lower
row from left to right cactus, flat, tubular . . . . .
27
Forms of ray petals, left to right C . californica
sem i-cactus, C . bigelovii flat, C. calliopsidea
f l a t ..................................................... ..............................
' 27
Plant height. C . tinctoria T all plant class
60-90 cm s. ...............................................
31
Plant height C_. tinctoria Nana plant class
37-75 cm s. . . ............... ....................................* . . .
31
Plant height C „ tinctoria Nana compacta class
15—
22 cm s . . . . . . . . . 0 0 0 . 0 . 0 6 . 0
32
Branching habit C. californica left erect branches,
right drooping branches . . . . . . . . . . . . . . .
34
Branching habit C . bigelovii left erect branches,
right drooping branches.................... ...
34
Branching habit C_. calliopsidea left erect branches,
right drooping b ra n c h e s ...............................................•
35
Achene morphology. Left C. tinctoria upper row
sm allest, middle row medium sized, lowest row
largest. Right C. californica one morphological
form dorsal and ventral view.............................. ...
38
Achene morphology C . bigelovii left, dorsal
and ventral view of ray achenes. Right, dorsal
and ventral view of disc achenes
39
-x i-
Llst of Figures
(Continued)
F ig u re
7b
8a
8b
9a
9b
10
Ila
lib
12a
12b
Page
Achene morphology C . calliopsidea left, dorsal
and ventral view of ray achenes. Right, dorsal
and ventral view of disc achenes. . . . . . . . . . .
39
Leaf form s C. tinctoria. Most common form
is the first group from l e f t ...........................................
40
Leaf forms C . californiea. Most common form is
the first one from l e f t ..................................................
40
Leaf forms C . bigelovii. Most common form is the
first one from l e f t ........................................... ...
42
Leaf forms C . calliopsidea. Most common form is
the first one from le ft................................................. .
42
Coreopsis . Individual flowers in a head. Left
only a few flowers of outer whorl have opened.
Right, almost all the flowers are open . .................
46
Meiotic studies C. tinctoria A P.M .C . Meta­
phase I with 12 bivalents . . . . . . . . . . . . . . .
89
Meiotic studies C. tinctoria A P.M .C . Dtafcinesis with 12 bivalents grouped in a group of
I four, I three and 2 twos. . . . . . . . . . . . . . .
89
Meiotic studies C. califom ica A P.M .C . Diafcinesis with 12 bivalents. ■One group of four biv­
alents ....................... . . . . . . . . . . . . . . . .
90
Meiotic studies C. bigelovii A P.M .C . F irst
anaphase M = 12............................................................
90
-x ii-
L ist of Figures
(Continued)
Figure
13
14a
14b
15
16
Page
Meiotic studies C . calliopsidea A P.M .C.
Metaphase I with 12 bivalents. 5 groups
of t w o s .........................................................................
91
Pollen studies C . tinctoria compatible pollination.
Pollen grains germinating after 48 h o u rs.................
93
Pollen studies C . tinctoria Incompatible pollinatio n . Pollen grains (a few in number) not
germinating 48 h r s ........................................... ... . . .
93
Hybrid Vigor in C. tinctoria. Fi hybrids
Petite Purple (female) x^Self-compatible mutant'
(male)
105
,>
/
Hybrid Vigor in C„ tin cto ria.CultivariPetite
106
17
18
Hybrid Vigor in C. tinctoria „Gultivart unnamed dwarf . . . . . . . . . . . . . . . . . . . . . .
107
Hybrid Vigor in C. tinctoria. Fi hybrid. Unnamed dwarf (female)x'Self-compatible mutant*
108
19
Hybrid Vigor in C. tin cto ria.Qultivarsself-cornpatible m utant.................... ..........................................
109
-X iii-
ABSTRACT
Four annual species of Coreopsis L. (Compositae: Heliantheae: Coreopsidinae), C . bigelovii. (A. Gray) H. M. Hall, C. calliopsidea (DC.) A. Gray,
C . califom ica (Nutt.) Sharsmith, and C. H nctoriaN utt., were studied to
determ ine the genetics of their self-incompatibility mechanisms. Diallel c ro ss, backeross, and Fg studies revealed that these species have a sporophytic, multiple allelic, monogenic system of self-incompatibility. C. ■
tinctoria had 7 multiple alleles, while C . bigelovii and C_. califom ica
had 5 multiple alleles each. The number of multiple alleles could not be
assigned to C. calliopsidea.
Cytological studies' revealed a strong correlation between the sporophytic
system of self-incompatibility and the stigma as the site of pollen inhibition.
Meiotic chromosome numbers for all four species were determined as vh=12.
Secondary associations between different bivalents were found in all four
species studied; these point toward some form of polyploidy associated with
the genus.
Significant heterosis for horticultural tra its was detected and a method
of producing F^ hybrid cultivars in Coreopsis tinctoria, using incompati­
bility as a technique, has been suggested.
INTRODUCTION
Four North American annual species distributed among three sections
of the genus Coreopsis were chosen for study. Coreopsis tinctoria is a
widely cultivated ornamental annual. Coreopsis californica, Coreopsis
bigelovii and Coreopsis calliopsidea are showy and attractive and may
have horticultural potential. The usefulness of these four species of Cor­
eopsis to breeders of ornamental plants could be better evaluated if their
genetic characteristics were well-documented.
Self-incompatibility has been used as a means of producing
hybrids which have, in many different crops , a yield advantage over
open pollinated or pure line varieties (Allard, 1960). In general this in­
volves the production of inbreds which are homozygous for "S" alleles.
Homozygous lines can be produced with the sporophytic system , but their
maintenance is a problem . Maintenance is possible in Brassica crops
where incompatibility is overcome by bud pollination (Odland & Noll, 1950).
It may be achieved in crops which can be multiplied vegetatively. It may
also be achieved in crops like alsike clover where the level of incompat­
ibility varies with the tem perature (Townsend, 1968).
Hybrid seed is produced by sowing together in isolation two inbreds
with different "S" a lle le s. Odland & Noll (1950) have, suggested the use
of a double cross in cabbage, yrtiile Thompson (1964) proposed that a triple
»2-
cross be used for maximum efficiency in seed production. Hermsen (1969)
has worked out a program of using "S" alleles for the production of hybrid
seeds in several species and varieties of cruciferous crops (Brassica,
Raphanus) .
According to him a large number of "S" alleles may hamper
the setting up of a practical program ..
Self-incompatibility as a tool for hybrid seed production is useful
only in the crops with high multiplication coefficients (Van Der Meer et
al, 1968). In crops with low multiplication coefficients (ration, of Kg
seed produced per acre/Kg seed sown per acre), like bean, some other
methods like .the use of male sterility may be used with better resu lts.
The following types of information must be obtained before effective
plant breeding program s can be initiated in C oreopsis.
(1) The breeding systems of various species must be investigated..
This involves genetical and cytological investigations to determine the nature
and the occurrence of self and cross-incom patibility because self-incompat­
ibility is an important and widely employed system which promotes out
crossing and tends to maintain heterozygosity.
(2) The nature and extent of variation within each species (within
cultivars of species where possible) must be evaluated for floristic tra its.
REVIEW OF LITERATURE
INCOMPATIBILITY
Self-incompatibility has been treated extensively in review papers by
Bateman (1952), Lewis (1954), and by Arasu (1968),• that by Arasu being
perhaps most comprehensive.
Self-incompatibility may be defined as "the inability of a plant pro­
ducing functional gametes to set seed when self-pollinated" (Brewbaker,
1957). It may be differentiated from the term "self-sterility” which is used
‘
in a wider sense to include sterility due to chromosomal abnorm alities,
the production of non-functional gametes and post-fertilization failure
(Crane and Brown, 1937; Crane and Lawrence, 1952 and Williams, 1964).
Self-incompatibility is widespread amongst flowering plants.. Every
y ear several genera and species are added to the list of plants known to ■
exhibit self-incom patibility. Oryza, until recently cited as an example
of a self-fertilized crop plant, has been added to the list of selfincom patible
sp e cie s. Oryza perennis ssp. barthii has been found to be self-incompatible
(Chu, et al, 1969). It is not intended here to list all the genera and species
reported to be self-incom patible. Suffice it to say it occurs in every major
phylogenetic lin e . It occurs not only in hermaphroditic species but also
in monoecious species with unisexual flowers on the same plant (Godley,
1955; Pandey, I960).
Systems of self-incompatibility: Self-incompatibility system s have
—4
“
been classified by various authors (A rasu, 1968; Bateman, 1953; Crowe,
1964; F isher and M ather, 1943; Tammisola et al, 1970; Lewis, 1944, 1954,
1949a; Linskens, 1965; Lundquist, 1965; Sears, 1937). Self-incompatibility
in flowering plants may be divided in two m ajor c la sse s.
(1) Self-incompatibility of homomorphic angiosperms.
(2) Self-incompatibility of heteromorphic angiosperm s.
Homomorphic Angiosperms: Self-incompatibility operating in homo­
morphic plants has always been classified according to the expression of
an "Sji' allele in the male gametophyte. This is commonly referred to as
the gametophytic system of s elf - incompatibility. In this system of self­
incompatibility "S" allele expression in pollen is not influenced by both
"S" alleles of the sporophyte. In the sporophytic form of self-incompat­
ibility "S" allele expression in a pollen grain is influenced by both "S"
alleles of the sporophyte. Thus, until recently two. major system s of self­
incompatibility (gametophytic and sporophystic) were reported in homo­
morphic flowering plants.
This system of classification does not take into account the relation­
ship of the two "S" alleles in the diploid stigm a, style and ovarian tissue
and one "S" allele in the haploid female gametophyte. Recently, Tammisola
and Ryynanen (1970) presented a new system of classification that takes
into account both the male gametophyte, the interverihg diploid tissue
. (sporophyte) and the female gametophyte. A modified form of classification
adapted from Tammisola et al (1970) is:
(A) Gametophytic-gam etophytic: self-incompatibility
(B) Gametophytic-sporophytic self-incompatibility
(C) Sporophytic-sporophytic. self-incompatibility
Gametophytic - gametophytic system of self-incompatibility: As the
name suggests, the "S" allele in pollen grains is controlled gametophyticalIy and is not influenced by the "S" alleles of the sporophyte; also, either
the male gametophyte does not come in contact with the female sporophyte,
or it is not influenced by the female sporophyte.
At least two types of gametophytic - gametophytic incompatibility
system s have been proposed. F irst is the type in which th e pollen tube
enters uninhibited into the ovule and sterilizes the egg cell if the two gametes
a re incompatible (Bateman, 1954). The second type is sim ilar to that pro­
posed by Glenk (1964) for Oenothera. Certain pollen tubes, depending upon
th eir genotypes, . fail to.reach certain ovules because of the lack ofchem otropic attraction. This system of self-incompatibility apparently operates
in N arcissus, H em erocallis, Lilium, G asteria, Ribes and Annona (Bateman,
1954; A rasu, 1968).
-(i-
/Gametophytlc - sporophyttc system of self-incompatibility: The
. self-incompatibility allele. ("S" allele) reaction in the pollen is controlled
gametophytically. In the female organ "S" alleles do act independently.
However, a portion of the male gametophyte (the pollen tube) has to come
into intimate contact with the female sporophyte; hence the name gametophytic-sporophytic system of self-incompatibility.
Genetically, both these forms of self-incompatibility (gametophyticgametophytic and gametophytic- sporophytic) can be explained by what was
firs t described by Prell (1921) as the hypothesis of oppositional factors and
la te r (1925) by East and Mangelsdorf as the gametophytic system of self­
incompatibility in interpreting their data on Nicotiana.
The basic concept of this hypothesis, which has stood the te st of time,
is that self-incompatibility is governed by an allelomorphic series of
alleles (SiSn) such that pollen tubes, having a particular "S" allele are in­
hibited in styles that c arry the same allele and are not inhibited in those
that do not. Thus, the progeny derived by crossing two self-incompatible
plants (S1S2 and S3S4) would consist of four types of individuals (SiSg1-SiS^
Sg^S’^S^.) in approximately equal num bers. All off spring would be selfx
■ .
incompatible. ■All crosses among individuals bearing the same pair of alleles
would be incompatible. C rosses among individuals that have alleles ' x ;
-7 -
not in common would be compatible.
P rell, Lehman,. F ilz e r, East and Mangelsdorf (cited by A rasu, 1968)
assuming that the "S" allele of the male gametophyte is not influenced by
the sporophyte, term ed this form of s elf - incompatibility gametophytic.
(C) Sporophytic - sporophytic system of self-incompatibility: The
self-incompatibility allele ("S" allele) in the pollen is influenced by the .
"S" alleles of the sporophyte. This leads to an expression of dominance
in pollen.
In the stigma and Style (diploid, m aternal tissue) however, "S" alleles
may act independently or show dominance, hi some cases dominance in
the stigma and style may be variable. This form of self-incompatibility
was separated from the gametophytic form , as a result of work- in Brassica
oleracea v ar capitata (Kakizaki, 1930), and Cardamine pratensis (Beatus,
1934). G erstel (1950) and Hughes and Babcock (1950),. working with Parthenium species and Crepis foetida respectively, propose dominance r e ­
lationships in pollen grains. Crowe (1954), working with Cosmos bipinnatus,
suggested variable dominance relationships between "S" alleles in the stigma
and style. The sporophytic influence of the "S" allele on the ovule was
demonstrated by Cope (1962) in Theobroma cacao. Studies by Im rie (1969)
in Carthamus flavescens and Martin (1965) in Ipomea helped in understanding
-8 -
this complex system of self-incom patibility.
Heteromorphic Angiosperms: A variation of this system of self-in­
compatibility is found in some heteromorphic species. Incompatibility
is controlled by a diallelic "S" locus, acting in conjunction with a locus
conditioning flower structure (Brewbaker, 1964; Fisher and M ather, 1943).
Number of alleles at one lociis:
Whereas the number of alleles at
a locus is generally very large with the gametophytic system , the number
identified in those species having a sporophytic system is generally less than
10 (Gerstel, 1960; Lewis, 1954; Pandey, 1960; Ramanamurthy, 1963; Sampson,
1967).
Mayo (1966), on the basis of computer simulation studies, estimated
a high rate of loss of self-incompatibility alleles from a population and
a consequent high mutation rate to maintain the system . This suggested.up
■to 40 alleles at one locus in the gametophytic system of self-incompatibility.
Wright (1964) estimated 7 alleles would be maintained in a population of
size 100 by a mutation rate I x 10 - 5 and in a population size of 55 by a
mutation rate of I x 10 - 4. This model has a closer approximation to the
situation pertaining to the 4 species of Coreopsis studied in this re se a rc h .
The maintenance of self-incompatibility despite the reproductive
advantage of self-compatibility has been discussed by Crowe, (1964) and
-9 -
Mayo, (1966). It was concluded that high levels of heterozygote advantage,
or heterosis, are a feature of those species in which the self-incompatibil­
ity system is maintained.
Anomalies in incompatibility system s: The genetic system in the
Gramineae differs from the commonly occurring form of the gametophytic
system in being controlled by two m ulti-allelic series of independent loci
which act in a complementary way (Lundquist, 1965). In Physalis ixocarpa
(Solanaceae) the system is under the control of two independently segregating
m ulti-allelic loci, though the pollen reaction is gametophytically determined
(Pandey, 1957). Pandey (1962!)} !reported a two locus gametophytic system
of self-incompatibility operational in Solanum pinnatisectum.
' A broad spectrum of patterns of inheritance is reported in the sporophytic system . In Iberis am ara, eight alleles were identified including
an allele for self-com patibility. C rosses between plants with strongly
differentiated "S" alleles gave a normal seed set; whereas, crosses between
plants with sim ilar "S" alleles resulted in a reduced seed set. The allele
Sf (for self-fertility) was dominant to one self-incompatibility allele and
recessive to the re s t (Bateman, 1954). Inheritance may be further com­
plicated by the action of modifying genes . Compatibility levels have been
changed, apparently by selection of modifying genes, in Cichorium intybus
-10-
(Pecauty 1962, cited by Im rie and Knowles, 1971) and-Helianthus annuus
(Luciano et al, 1965).
Distribution of types of self-incompatibility in Angiosperms: In
those families where self-incompatibility is known, only one system has
been found in any particular family. For example, the gametophytic system
is characteristic of the Solanaceae, and only the sporophytic system has
been found in the Cruciferae and Composltae (Lewis, 1954; Pandey,, 1960).
Pandey (1960) suggests that the gametophytic and sporophytic systems
of self-incompatibility may be found in the same family, depending on the
nature of cytokinesis.
Factors associated with "S” gene reaction; Pandey (I960,- 1970) h a s .
reviewed in detail the time and site of the "S" gene action, breeding system s,
pollen cytology and relationships in incompatibility. Genetic and cytological
studies have revealed that there is a correlation between floral morphology,
genetical control of self-incompatibility system , pollen cytology and site
of pollen inhibition.
Lewis (1949 and 1954) and Pandey (1957) reported a relationship be­
tween floral morphology and the genetics of self-incompatibility . All heteromorphic plants had a diallelic control (with one or two loci), hi homo­
morphic angiosperm s, self-incompatibility was controlled by a multiallelic system; the form er had a sporophytic system; whereas, the latter
-11-
had either gametophytic or a sporophytic system .
Lewis (1956) reported another relationship (in homomorphic plants
only) between site of pollen inhibition and system of self-incom patibility.
•In species with a gametophytic system , inhibition usually occurs in the style
o r ovary; in those with a sporophytic system it occurs in the stigma.
Brewbaker (1957) discovered that the number of nuclei in the pollen
grain at anthesis is related to the type of self-in compatibility system of
the parent plant: species with a gametophytic system have binucleate pollen
while those with a sporophytic system have trinucleate pollen. Thus, four
features of incompatibility, the genetic system of control, floral character­
istic s, pollen cytology and site of inhibition, were found to have interlock­
ing relationships.
It appears to be generally agreed that the; time of "S" gene action is
the critical factor in incompatibility relationships; however, a number of
exceptions have been cited (Cope, 1958, in Theobroma cacao; Hecht, 1964,
in Oenothera sp .).
It is suggested that m ajor exceptions are byproducts
of secondary evolution of incompatibility after the prim ary incompatibility
has been disturbed, or has broken down.
Physiology of "S" gene action: Studies after 1960 have devoted more
attention to resolving the phenomenon of the mode of "S" gene'action.
-12-
East (1926, 1929) was the first to suggest the sim ilarity of the in­
compatibility reaction to the immunity reaction in anim als. This concept
has been supported by various authors (Lewis, 1952, in Oenothera organensis
cited by A rasu, 1968; Linskens, 1960, in Petuniacited by A rasu, I960. Strong
support came from Nasrallah and Wallace (1967a, 1967b, 1970). They dem­
onstrated the presence of antigenic substances (proteins) that were specific
to each "S" genotype in the tissue of unpollinated pistils of Brassica sp.
T heir work suggests that the inhibition is the result of an antigen antibody
type of reaction. Using radioactive tra c e rs , Linskens (1958, 1959, 1960,
cited by A rasu, 1968) was able to show that the proteins of the pollen and
style formed a complex in selfed p is tils . The nature of these substances
is not yet known.
Pandey (1967) worked on the electrophoresis of stylar tissues and
suggested that each "S" allele is associated with a specific combination of
peroxidase isozymes; these could cause the inhibition of pollen tubes by
destroying the IAA present in them . Application of IAA in lanolin to lily
styles and ovaries has resulted in improved seed set with reduced tendency
for m aternal inheritance. (Emsweller and Stuart, 1948).
Safonov et al (1969) reported that non-identity of protein systems in
Malus may be an important factor underlying physiological incompatibility.
-13-
Different models have been proposed for "S" gene action. Lewis
(1965), in suggesting his dim er hypothesis of'gametophytic incompatibility,
stated "that (I) the "S" gene complex produces a polypeptide whose spec­
ificity, determined by the prim ary structure,is different Loru ,each allele.
Each allelic polypeptide is an identical molecule in pollen and sty le .
(2) The polypeptide polymerizes into a dim er in both pollen and style.
(3) the first step in the incompatible reaction is that the same dim ers in
pollen and style and only the sam e, combine to form a tetram er with the
aid of an allosteric molecule which may be glucose, a protein of"one of many
sm all m olecules. (4) The second step in the incompatible reaction is that
the tetram er acts on a genic regulator either to induce the synthesis of an
inhibitor o r to rep ress the sythesis of an auxin of pollen tube growth".
Ascher (1966) suggested a sim ilar model for "S" gene action: "The
. "S" alleles may be assumed to be regulators which produce monomers of
a dim er rep re sso r of a high rate of growth operoh in the pollen tube.
"Sim ilar monomers of pollen and style produce a functional dim er repressor
which inhibits this operon". Pandey (1967) suggested that the peroxidase
isozym es, characteristics of each "S" genotype, were equivalent to Lewis's
d im e rs. Ascher (1971) tried to correlate RNA synthesis in pollen and style
with the s elf-incompatibility reaction; he suggested that RNA synthesis is
required in the style for incompatibility reaction while it is the blockage
I
—
14of RNA synthesis in pollen that probably causes the incompatibility reaction.
Breakdown of self-incompatibility system: Most of the studies con­
cerning the breakdown of self-incompatibility seem to have been done in flower­
ing plants having the gametophytic form . Review of the available literature
reveals that four important mechanisms usually cause the breakdown. These
are (a) polyploidy, (b) mutation, (c) tem perature, and (d) mechanical methods.
Polyploidy: The effect of polyploidy on incompatibility has been studied
by a number of workers (Lewis, 1943, 1947; Atwood and Brewbaker, 1950;
Brewbaker, 1954). It has been shown that diploid pollen, carrying two "S"
alleles, can have one of three types of action:
(1) The two alleles function independently, so that an SjSg pollen
grain would fail on all styles carrying either Sj or Sg.
(2) One of the alleles dominant over the other (e . , g . SjSg). In
this case, SjSg pollen would function on all styles with SgSx genotype, but
fail on styles carrying the S] gene.
(3) The two alleles are competitively interacting or mutually weak­
ening.
.
Mutation: Arasu (1968) has summarized in detail the information
available on mutation (induced and spontaneous) and its effect on incompatibility.
Recently, DeNettancourt (1969) presented a brief review of the tem porary
■■11»UWvW1T-TV.IV.
and permanent effects which are usually observed after irradiation treatm ent
-15-
of s elf- incompatible plants . Irradiation treatm ent has only negative effects
on the self-incompatibility systems (inactivation of the incompatible reaction
and/or genetic losses at the S-locus). It is suggested that self-incompatible
plants may be equipped with a switch system , or a mutagenic mechanism,
which enables them to display a new specificity. This leads to an increase
in the level of genetic polymorphism in the population to which the plant be­
longs .
T em perature;
High tem perature has been reported to result in break­
down of self-incompatibility, at least in the genus Lilium , (Ascher, 1970).
Townsend (1966, 1968, 1970), while studying the breakdown of self-incompati­
bility in Trifolium hybridum, found another "T" gene which seem s to inactivate
the "S" allele. It seems probable that this T locus is influenced by poly­
genes .
Mechanical Methods; hi Brassica oleracea incompatibility was over­
come by applying pollen to cut stigmas . Incompatibility has also been over­
come by bud pollination in different genera, e . g . , Brassica (Thompson, 1957)
and Guizotia (Naik and Panda, 1969). Higuchi (1968) reported induction of
pseudo -fertility in Petunia by means of repeated pollinations. The under­
lying success of these methods has been attributed to the application of ripe
pollen before the time of "S" gene action in the stigma (Lundquist, 1965). It
-
16-
is assumed that^in the cases where these methods succeed,the evolution of
the incompatability system has resulted in the strongest b a rrie rs to fe r­
tilization occurring at the sam e tim e that the stigma is most receptive.
-17-
THE GENUS COREOPSIS L.
The genus coreopsis is a member of the plant family Compositae,
in the tribe Heliantheae, sub-tribe Eoreopsidinae (Hoffman, 1894). The
generic name is derived from the Greek Koris - a bug, and ops is - like;
in allusion to the shape of the achene. The genus is known by the common
name "tickseedV cultivated form s, notably in C. tinctoria N utt., are called
"calliopsis".
Sherff (1936, 1955) considered Coreopsis to be comprised of 116 species
in 11 sections. The genus is dispersed geographically in North America,
South Am erica, and A frica. A few species have become established as
adventives outside of their natural ranges.
■ Morphology:
Bi term s of growth habit. Coreopsis includes a wide
a rra y of fo rm s, including shrubs to three m eters tall, other frutescent and
suffrutescent form s, many perennial herbs of diverse form (including
tuberculate-rooted and succulent ones), and a number of annual herbs, a
few of which are specialized desert annuals (Sherff, 1936, 1955).
From various authorities (Sherff, 1936, 1955 and Munz and Keck,
1959), the m ajority of Coreopsis species can be characterized as having
yellow ligulate florets; however, seven North American species have hi- or p articolored ligulate flo re ts.
Among 55 species of the A m ericas, the ligulate
florets in i l are fertile and sterile in two. The fertility status of 47 is
-IS1™
unknown. The fertility of but one African species is known.
C. camporum
has fertile ligulate florets (Sherff, 19361955). Fertility of the ligulate
florets is an important taxonomic tr a i t .
The disc florets are reported to be bisexual and usually fertile (Bailey,
1949).
Cytology; Cytologically, the genus Coreopsis is incompletely described.
Chromosome numbers have been reported for only 17 of 55 North American
species. Reported species, chromosome numbers and authorities are given
in Table I. The modal chromosome number appears to be x =. 12; however,
there are conflicts in reported chromosome numbers for some species (for
example, see T urner, Powell and King, 1962 or Crawford, 1970). hi addition,
reported chromosome numbers include only six of ten North American
sections.
>
From an evolutionary point of view, cytological sim ilarities among
coreopsis and closely related genera are of in te re st. The sub-tribe Coreopsidinae is polybasic (Melchert, 1968). The modal haploid number appears to
be 12 and x ranges from 8 to 19.
Table I
Chromosome Numbers Reported for the Genus Coreopsis L.
Section and species
I.
c.
c.
c.
c.
c.
c.
mutica
mutica
mutica
mutica
mutica
mutica
c.
cuneifolia Greenman
var. mutica
var..Ieptomera Sherff
var. subvillosa DC.
var. carnosifolia Crawford
var. multiligulata Crawford
var. microcephala Crawford
cyclocarpa Blake
ca. 24, 26
ca. 24, 26
Turner, Powell
ca. 112
56
ca. 112
ca. 112
56
56
28
Crawford,
Crawford,
Crawford,
Crawford,
Crawford,
Crawford,
1970
1970
1970
1970
1970
1970
Crawford, 1970'
12
Powell & Turner, 1963
12
12
Sharma, hoc Ipc.
Sharma, hoc Ioc.
12
Sharma, hoc Ioc.
Pugiopappus (A. Gray) Blake
C. bigelovii (A. Gray) Voss
C. calliopsidea (DC.) A. Gray
5.
Authority
Anathysana Blake
C_.
4.
2n
Electra (DC.) Blake
c . mutica DC.
2.
n
Euleptosyne (A. Gray) Blake
C. californica (Nutt.) Sharsmith
Table I (continued)
Section and species
6.
Pseudo-Agarista
2n
n
Authority
A. Gray
C . petrophiloides Robins, et Greenm.
•
52
Crawford, 1971
Coreopsis Sherff
24, 48
C. lanceolate L.
C. pubescens Ell.
26
26
26
Gelin, 1937; Turner, 1960
Sharma, hoc Ioc.
Turner, 1960; Gelin, 1937
Turner, 1960; Gelin, 1937
26:
24
C . grand!flora Hogg ex Sweet
C . auriculata L.
C . nuecensis Heller"
C. tripteris L.
Bilquez, 1951
Snoad, 1952 (cited by
Darlington and Wylie)
Gelin, 1937
Bilquez, 1951 (cited by
Darlington and Wylie)
Turner, 1960
Gelin, 1937
28
9
Calliopsis (Reichenb.) Nutt.
C . tinctoria Nutt.
12
C. basalis (Dietr.) Blake
C. cafdaminefolia (DC.) T&C
12
12
Eublepharis Nutt.
C. Iinifolia Nutt.
13
.Turner, 1960
-
21 -
Horticultural aspects: Only a few of the 116 species of Coreopsis
are commonly cultivated. Bailey (1949) listed 12 species which are cultivated
in North Am erica. Chittenden and Synge (1956) listed 23 species cultivated
in Great Britain and Europe, where Coreopsis is more popular.
C. auriculata, C„ grandiflora, C. Ianceolata, and C. verticillata
are encountered in perennial b o rd ers. The form er two species a re perhaps
the most commonly encountered. Cultivated form s of these species are
term ed "coreopsis" by nurserym en.
Cultivated forms of annual species are classified as C . tinctoria;
however, Everett (1960) implied that they descended from three species,
C . neucensis, C . basalis, and C . tin cto ria. If this be the case, it re p ­
resents an instance of interspecific hybridization among species with dif­
ferent base chromosome num bers, since for C. neucensis (x T 9), for C .
basalis (x =. 13), and for C. tinctoria (x = 12).
Cultivated annuals may be
grouped into three classes by height: "Tall" plants vary from 60-90 cm,
"nana" plants range from 37-45 cm, and "nana compacta" types are 15-23
cm in height. The cultivated annuals are frequently misnamed "Calliopsis"
in comm ercial seed catalogues.
RESEARCH PROCEDURES, METHODS, RESULTS AND DISCUSSIONS
Plant M aterials (Culture):
Seeds of four species of Coreopsis were pro­
cured in 1967-68 from various sources for use in the present investigations.
Species and cultivar nam es, growth habit, and seed sources for these m ater­
ials are presented in Table 2.
Seedlings were raised in verm iculite under m ist in the greenhouse at
Bozeman, Montana.
Seedlings w ere transplanted into 2-inch Jiffy pots as soon as the first
true leaves appeared. Jiffy pots were either transplanted directly into the
field at Bozeman, or into 10-inch pots filled with a standard greenhouse
soil mixture for greenhouse cultures. Where field culture was employed,
the plants were spaced 18 inches apart, in rows 24 inches a p a rt.
All species and cultivars were transplanted in the field and in the green­
house. Thus data reported have been collected both from field-grown and green
house-grown plants during the period 1968-71.
Confirming species identification; Identity of the study m aterial as
to species was confirmed by comparison of random samples of 10 plants of
each taxon (5 plants from field cultures, 5 from greenhouse culture) with
keys and descriptions contained in the most recent monograph on the genus
Coreopsis (Sherff, 1955). Representative voucher specimens of each species
have been deposited in the Montana State University Herbarium.. The
Table 2. Coreopsis species and cultivars used in' these investigations with seed sources and motes on growth
habits..
'
Growth
Cultivar name if any habit
Source
Species
class
C . tinctoria Nutt.
'Petite Purple'"
'T iger Star"
nana compacta Geo. W. Park Seed Co.
Greenwood, S.C. 29646
11
Tl'
IT
nana compacta
"Yellow Star"
nana compacta
"Tall tubular"
ta li'
" "
"
"
nana
C . bigelovii (A. Gray) H.M. Hall
—
dwarf
C. calliopsidea (D.C.) A. Gray
-
dwarf
C . californica (Nutt.) Sharsmith
—
dwarf
' -
Indian Agricultural Research
Institute, Kulu Valley, India
"Compatible mutant" tall
"Unnamed dwarf"
.
i
Montana A gr. Exp.. Sta.
■■■-'
Bozeman, Mont. 59715
Rancho Santa Ana Botanic
.. ,
Garden, Claremont, Calif 91711
Rancho Santa Ana Botanic
"
Garden, Claremont, Calif 91711
Rancho Santa Ana Botanic ■
Garden, Claremont, Calif 91711
and
Botanic Garden, University of
California at Los Angeles,
Los Angeles, Calif. 90024
to
■'
-
21
-
numbers alloted are: C. bigeloyit MONT 65881, C. calliopsidea MONT 65882,
C. callfom lca MONT 65883, and C . tinctorla MONT 65884.
■ Morphological variations in four annual species'of the genus Coreopsis L.
Fam iliarity with the range of variation for various traits' is essential to under­
standing the nature of research m a teria ls. Prelim inary studies to determine
patterns of quantitative variation for several tra its were carried out from
1968-1971.
M aterials and Methods: Unless otherwise noted, studies w ere made on
10 unrelated plants of each species and/or cultivar Which were cultured as
described above. Five characters were m easured on each plant. Plants
were grown at random both under field conditions and in the greenhouse.
Measurements of variation in inflorescence morphology included determining
the relative fertility of disc and ray florets by microscopic examination to
determ ine the presence of functional pistils and by scoring seed set in
m ature flow ers. Mean number of ray flowers p e r head was based on counts
from two heads on each plant. The type of ray petal was scored as flat or
tubular vs s ta r shaped (cactus type). Mean number of involucral bracts
was counted on the same flowers for which number of ray flowers was
scored. Similarly the number of whorls of bracts was scored. Mean head
diam eter in cm was based on two heads/plant using three plants/species
and/or cultivar. Receptacle chaffiness, an important taxonomic tra it, was
-2 5 -
s cored as chaffy or non-chaffy based on m icroscopic observation of two
r eceptacles/plant for 10 plants.
Height and spread of plants were recorded in all the cultivars available
in C. Jdnctoria. Height in cm was m easured from the soil surface to the
tallest point of the m ature plant. Spread in cm was measured as the greatest
diam eter of the mature plant. In the other three species no named cultivars
w ere available, hence the characters under study were scored on ten unre­
lated randomly chosen plants in each sp ecies.
Variation in color range of ray flowers was. studied with the help of
the color chart published by the Royal Horticultural Society - London. Color
matching was done in all the cultivars and species on a sunny clear day at
noon tim e. Ten plants within each species and variety were scored.The range of variation in leaf form was studied by collecting the
firs t true leaves from m ore than forty plants within each species. Variation
was described in term s of deviation in leaf form from the form most common
to the cultivar and/or sp ecies. Representative samples of common and
deviant form s were photographed.
Following the procedures used in describing variation in leaf form,
morphological features of achenes from four species were compared with the
standard description given by Munz and Keck (1959) . Important form s were
photographed.
-2 6 -
R esults; The results of the study of quantitative variation in five
tra its are summarized in Tables 3 and 4. In C. tinctoria maximum v ar­
iability in inflorescence morphology was observed in the shape of the ray
petals . The most common shape was flat. Two more form s, one with thinpointed ligulate florets (termed "cactus" type), and another with tubular (Fig. la)
ligulate florets were observed. In C. califom ica no unusual variants were
■noted. The same was true of C. bigelovii and_C. caUiopsidea. (F ig. lb).
C . calliopsidea was extremely variable with regard to the fertility of the
ligulate flo re ts. Some of the plants had only 2-3 (out of 8) female fertile
ligulate flo rets, while in some others all 8 florets were fe rtile . On the other
hand, in some plants all 8 ligulate florets were ste rile ; One plant had no
■ray petals; only m ale-fertile disc florets were present. Habitwise, C . tinctoria can be separated into three c lasses. It stands .
distinct from the three other species studied in not having basal leaves.
It also has distinct branches. Variation in height and width within each
class of this species and the three other species studied is summarized
in Table 4.
Class A. T all.
Height, 60-90 cm. This group consists of plants
that are tall and need support to stand erect if planted alone. Branches,
shown distinctly, are either dichotomous or trichotom ous. .The branches
a re not hidden in the leav es. (Figure 2a)
-2 7 -
.
1
4
3
6
7
8
Fig. la.
Forms of ray petals. C . tinctoria upper row from
left to right flat, semi cactus,Lower row from left
to right cactus, flat, tubular
Fig. lb.
Form s of ray p etals. Jgft to right C . californica
sem i cactus, C. bigelovii flat, C. calliopsidea flat.
Table 3
Variability in Inforescence Morphology and Fertility Ratings of Ligulate
and Disc Flowers of Four Species of Coreopsis L.
Species or
cultivar
Floret fertility
Ray
Disc
florets florets
Mean no.
of ray
petals
Ray
petal
Whorls
of involucral
bracts
Mean no.
of involucral
bracts
Mean
head
diam.
em.
Nature
of receptable
C. tinctoria
'Petite Purple1’ sterile
fertile
7.6+0.43
flat
2
6.8+.62
3.8+.41
chaffy
'Tiger Star'
sterile
fertile
7.6±0.40
cactus
2
6.5+.32
3.8+.43
chaffy
"MSU selection"
sterile
fertile
7.4+0.15
flat
2
6.5+.87
3.9t.l2
chaffy
"Katrain self­
compatible
mutant"
sterile
fertile
7.3+0.14
cactus
2
6.0+.68
3.3+.13
chaffy
"Tall tubular"
sterile
fertile
7.6+0.52
tubular
2
6.8+.85
3.6+.47
chaffy
C. bigelovii
female
fertile
fertile
8.6+1.3
flat
2
6.0+.51
4.07+.36
chaffy
C. calliopsidea
highly
fertile
variable
8.0+3.3
flat
2
3.5+.89
3.2+.47
chaffy
C. californica
female
fertile
8.8±0.78
flat &
semicactus
2
4.0+.11
2.8+5.7
chaffy
fertile
Table 4
Variation in Quantitative Traits :■ Summary of the Height
and Spread in Four Species of Coreopsis L.
Species
C. tinctoria
Cultivar
Plant
height
cm.
"Tall tubular"
77.66*2.26
Not applicable
21.16+1.69
Pedicel
height
cm.
Plant
spread
cm.
I!
IT
'Petite Purple'
19.45tl.02
Not applicable
22.02+1.29
Il
Il
'’Tiger star'
26.55+1.67
Not applicable
21.77+2.19
Tl
Il
"Unnamed dwarf"
21.25+2.04
Not applicable
21.30+1.10
Tl
IT
"Compatible
mutant"
32.69+1.28
Not applicable
29.35+1.28
C . californica
Not applicable
11.91+1.44
34.58+1.37
14.58+1.16
C. bigelovii
Not applicable
10.41+1.37
34.66+0.49
15.08+1.67
C. calliopsidea
Not applicable
19.91*2.15
. 27.75+1.91
22.08+1.78
I
NO
3
V
I
-
30 -
Class B. Nana. Height, 37-45 cm. This group consists of plants that
are intermediate in height. These plants do not need any support to stand erect
if planted alone. Branching is dichotomous or trichotom ous. Leaves are
not basal, but the inflorescence and the leaves do not expose the branches.
(Figure 2b).
Class C. Nana Compacta. Height, 15-22 cm. This class consists of
true dwarf plants. Branches are hidden in the leaves and the inflorescence
tops the p lants. (Figure 3).
Study of growth habit variation in the available plants of C . cal ifom ica
revealed that they have bas ically one fo rm . The plant height ranged between
10 cm. and 14 cm. while spread ranged between 12 cm. and 16 cm. All the
plants had basal leaves and floral branches topped the plants (Figure 4a).
Two main types of branches were observed:
Type A. E rect floral branches and support not required.
Type B. Drooping floral branches and support needed.
As with C . californica, the plants of C . bigelovii had a common form .
(Figure 4b).
Variability for height and spread has been summarized in Table 3.
Height ranged between 7 cm . and 12 c m ., while the range in spread was
between 12 cm . and 18 cm .
Fig. 2a. Plant height. C. tin cto ria.
Tall plant class 60-90 cms.
Fig. 2b. Plant height. C. tin cto ria.
Nana plant class 37-75 cm s.
-3 2 -
-3 3 -
All the plants had basal leaves and floral branches topped the plants
(Figure 4).
Once again two main types of branches were observed.
Like C . califom ica, type A.
Like C. califom ica, type B.
As with C. bigelovii, the plants of CL calliopsidea had one basic form
(Figure 5).
Variability for height and spread has been summarized in Table 3.
Plant height ranged between 12 cm . and 23 cm ., while spread ranged
between 18 cm . and 23 cm „ All the plants had basal leaves and floral branches
topped the plant (Figure 5).
Once again, two main types of branches as described for_C. califom ica
w ere detected.
In summary C . califom ica, C. bigelovii and C. calliopsidea
had one basic fo rm . Leaves w ere almost basal and flowering branches topped
the plant growth habit variation within species is recorded in the table.
C . tinctoria differed entirely from these species in growth habit, having
dichotomous branches with leav es.
Only one morphological form of achePie type was found in C . tinctoria .
This matched the accepted description of achenes (Munz 1959). hi term s
of variability (not reported earlier) three size forms were found (Figure 6).
One unnamed cultivar selected at the Montana Agricultural Experiment
-3 4 -
Fig. 4a. Branching habit C . californicaf
left erect branches, right
drooping branches.
Fig. 4b. Branching habit C . bigelovii
left erect branches, right
drooping branches.
-3 5 -
Fig. 5. Branching habit C . Calliopsideaa
left erect branches, right drooping branches.
-3 6 -
Station. always had large se e d s. No such relationship was noticed in other
v a rie tie s.
Seed oil composition: A sample of the seed of a tubular-floreted
mutant form of C. tinctoria was submitted to the Industrial Crops Laboratory,
Northern Utilization Research & Development Division, ARS, USDA (Peoria,
111.) for determinations of seed oil content and composition. This seed sample
had been raised in the Netherlands by the Dutch seedhouse of Sluis en Groot.
In letters dated 19 June 1970 and 28 August 1970 respectively, F . R. Earle,
Head, New Crops Screening Investigations, NURDD, reported the following:
"The Coreopsis samples were received last week, and three portions
a re being analyzed now. There is no difference in the oil (24.3%) or protein
(24.5%) (as is). E sters have been made of these three (sam ples), but the
analysis of them is not com plete. A previous sample had essentially the same
composition (26% oil and 24% protein) and its oil was much like safflower
oil. It had a little less linoleic acid (73% vs. 80%) and a little more palmitic
(12% v s . 5%)."
"We analyzed the three portions mentioned in my June 19 le tte r and
this unintentional checkup speaks well for our analysis. The iodine values
w ere 148.8, 148.6, and 149.3. The amount of linoleic acid (as methyl ester
in mixed methyl esters) was 79.0, 79.2, and 79.9 percent."
-3 7 -
Thus, should agronomic comparisons prove favorable, coreopsis
might yield an oilseed competitive with safflower for end-uses.
Only one morphological form was found in C= califom ica sp ecies.
These matched the description of achenes by Munz (1959). No m ajor varia­
bility was observed in this species (Figure 6).
Seed dimorphism was observed in C_. bigelovii. The ray achenes
w ere morpholgically different from the disc achenes. No variability within ray
or disc achenes were observed (Figure 7a). Ray and disc achenes in this
species matched the accepted description of achenes (Munz 1959).
Two distinct form s, like those reported in C . bigelovii; were observed
in C . calliopsidea . AU the heads , depending upon, the fertility of the ray
flo rets, had ray achenes distinctly different from the disc achenes (Figure 7b).
Description of the variation in leaf form foHows Munz (1959). The
firs t true leaves were scored for variation. In C. tinctoria the commonest
form was found to be bipinnate with three linear divisions. The variations
observed were bipinnate with zero, one or two linear divisions (Figure 8a).
In C . .califom ica the most common leaf form was linear, the variations
observed were with one or two linear divisions present on ,the main linear
leaf blade (Figure 8b). Bi C. bigelovii the commonest form observed was
bipinnate with three linear divisions. It was ovate in outline. The
• 11
U »
38-
-
T
Achene morphologyw
Fig. 6. Left C . tinctorla upper row sm allest, middle row medium sized, lowest row largest.
Right C . califom ica One morphological form dorsal and ventral view.
IllllllllllIiniIIlTTT
Fig. 7a. Achene m o rp h o lo g ic, bigelovii.
Left, dorsal and ventral view of
ray achenes. Right, dorsal and
ventral view of disc achenes.
Fig. 7b. Achene morphology,C . calliopsidea.
Left, dorsal and ventral view of ray
achenes. Right dorsal and ventral
view of disc achenes.
-4 0 -
Fig. 8a. Leaf form SyC. tlnctoria.
Most common form is the
first group from le ft.
Fig. 8b. Leaf form ^C . californica.
Most common form is the
first one from left.
-41-
variations observed were bipinnate with four linear-divisions (Figure 9a),.
In C„ calliopsidea the commonest form of leaf was bipinnate with two linear
divisions. It was ovate in outline, the variations observed were simple
lin ear leaf and leaves with one division (Figure 9b).
A color range study done on cultivars of C . tinctoria revealed
that it has two basic colors - purple and yellow. Within purple, the follow­
ing variations were seen:
Dahlia Purple 931
Pansy Purple 928
Purple Madder 1028
Within yellow, the following colors were encountered:
Buttercup Yellow 5
Indian Yellow 6
Saffron Yellow 7
In the yellow group some varieties had ligulate florets with a dot of
purple. This dot could be as broad as 2.5 cm. In at least one cultivar,
T iger Starv, both yellow and purple w ere present in blotches.
C. califom ica, C_. bigelovii and C_. calliopsidea fall in one color range.
T heir basic color was yellow with the following range:
Buttercup Yellow 5
Indian Yellow 6
Saffron Yellow 7
-4 2 -
Fig. 9a. Leaf form s, C . bigelovii ,
Most common form is the
first one from left.
Fig. 9b. Leaf forms, C . calliopsidea,
Most common form is the first
one from left.
-4 3 -
Diseussion:
It is clear that the four species of the genus Coreopsis
studied are quite variable. Coreopsis tinctoria was found to have consider­
able variability with regard to the m ajor characters studied. This was
expected because of a wide collection of cultivars under study in this species „
Variability within each variety of C. tinctoria, as reflected by standard
d eviation^as considerably less than other species (Tables 3 and 4). This
may be due to constant selection practised by plant breeders to maintain
so-called purity within each cultivar. Achene size, as seen by gross morph­
ology, proved to be interesting in this species; only one cultivar (unnamed
dwarf selection made at the Montana A gr. Exp. Sta.) had large-sized seeds;
the others had sm all, medium and large se ed s. Color range and shape of
ra y floret was highly variable in this species. Coreopsis tinctoria was
found to be highly stable with regard to its having sterile ray petals; however,
one plant with female fertile ray petals was found. It may represent a
mutant form that could not be maintained.
C. californica, C. bigelovii and C. calliopsidea all had a common
pattern of plant form , plant height and width. One interesting variability
observed in all the three species was two form s of branching which bear
flow ers. Horticulturally, flowers and branches that drqpp down have a
distinct disadvantage over the erect ones.
-4 4 -
Color and form of ray petals did not' show a great range of variation
within and between these three species. The reason for this low variability
in form of ray petals may be the limited samples studied for these species .
Selection done by plant breeders does not seem to be a m ajor factor as these
species are not widely cultivated in gardens.
With regard to size of the capitulum and fertility status of the disc
and ray flo re ts, Coreopsis calliopsidea showed maximum variability. Two
plants without any ray petals were sco red . Fertility status of ray petals
was very variable in this species.
Dimorphic achenes were found in C . bigelovii
and in C. calliop­
sidea.
These studies exposed variation in important characters which were
previously not reported in these four species of Coreopsis .
A la rg e r collection covering diverse habitats is recommended in C .
californica, C. bigelovii and C . calliopsidea for unearthing further v ar­
iability in these interesting annual species.
-
45 -
Genetics and Incompatibility Mechanisms Operating in Four Annual
Species of Coreopsis L.
The phenomenon of self and cross - incompatibility is widely distributed
throughout higher plants. The inheritance of this phenomenon is of basic,
genetical interest and may be of practical significance to horticulturalists
in developing and maintaining hybrid seed and stock. The inheritance of selfand cross-incom patibility was studied in four annual species of Coreopsis L.
M aterials and Methods: Ten random plants of each species investigated
in the previous study were crossed in a diallel pattern in the field.
Each plant was enclosed in a muslin bag that was supported by a two
unit m etal fram e. Bagging was done as soon as the buds were about to open.
In C. tinctoria five cultivars were available, so two plants of each cultivar
were bagged; in the other three species all ten plants-were chosen at random .
Flowers of C oreopsis, as with other Compositae, are borne in what
is term ed a capitulum. Two photographs (Figure 10) show clearly the pattern
in which the individual florets of the capitulum open. The best tim e for pol­
lination of the head is when nearly all the florets start showing stigm as,
o r when the capitulum appears to be "fuzzy". Pollinations before this stage
m ay lead to erroneous conclusions because the seed set may be consider­
ably reduced and the plants assumed incompatible. Compatible pollina­
tions at this stage yield 20-55 ripe seeds/head 11 to 20 days after pollina­
tion, depending upon the species.
-
46 -
Fig. 10. Coreopsis*Individual flowers in a
head. Left, only a few flowers of
outer whorl have opened. Right,
almost all the flowers are open.
•47-
Plants were first verified for self- incompatibility; three open capitula
were chosen in each self-incompatible plant for pollinations. Pollinations
were carried out by rubbing a pollen-filled head from the male plant across
the capitulum. This was best accomplished about 10 A.M. Three hundred
crosses w ere made in each species during the first week of July, 1969.
Scores on self-incompatibility and cross-com patibility were recorded by
counting the number of seeds produced per capitulum.
At the end of 1969 all parental plants in 3 species which showed recipro­
cal differences in their crossibility behavior were transplanted to the green­
house. Selected crosses were made and F1 plants were raised and backcrossed to both the parents. AU F1 plants were scored for th eir c ro ss­
incompatibility and cross-com patibility behavior with the p a re n ts. A
test of goodness of fit was applied to the data grouped in these two classes
(cross-com patible vs. cross-incom patible) to compare them with a theor­
etical ratio based on the hypothesis of a sporophytic type of incompatibility.
Plants of C . calliopsidea did not survive transplanting (they were truly
annual in habit); therefore, this species was not included in the back-cross
studies. Crosses involving self-incompatible plants of C tinctoria
"Petite Purple’ as a female parent and a self-compatible mutant as a
male parent, were made in the winter of 1969. The self-compatible mutant
-4 8 -
was not used as a female parent because of the complexity of emasculating
the hi-sexual disc florets .in the capitulum. Fifteen F1 plants were raised
in the greenhouse in 25 cm . pots . Three heads in each plant were bagged
for studying the expression of the "S" gene in F1 plants . The remaining
flowers were allowed to bloom in isolation for mixed pollination, hi the fall
of 1969, mix-pollinated seeds were collected. T hirty-six F^ plants were
raised and studied for segregation of the "S” gene. These plants were kept
in isolation and not allowed to intercross. Each plant was studied for self­
incompatible or self-compatible status. This type of study was possible only
in C . tinctoria. No self-compatible plants were available in the other 3
species of Coreopsis under study, so that appropriate generations could not
be developed. Any cross which gave 20 or.m ore seeds was regarded as
cross-com patible. In plants which were recorded as cross-incom patible,
seed set was never more than 3/head. All m aterials for seed counts were
hand-thrashed .
O
The data collected were analyzed statistically , using X
techniques.
Results:
Three mating groups were identified among crosses within
C . tin cto ria. These groups are referred to as groups I, II and II r e s ­
pectively. Groups of plants in C. tinctoria are summarized in Table 4.
Grouping was done on the following basis:
Plants belonging to one group were always self-incompatible.
-
49 -
These were also cross - incompatible, barring some reciprocal
differences.
Plants belonging to 2 different groups w ere, barring some anomalous
conditions, cross-com patible in both directions.
Plants of Group I were 100% cross-com patible with the plants of Group II
(both ways). In crosses involving Groups I and HI, plant number 4 of Group I,
when used as a female parent, was found to be cross-incom patible with the
plants 8 and 9 of Group HI, but for this exception, Group I was cross-compatible
with Group III both w ays. Groups II and III w ere cross-com patible both ways
(Table 5).
Group I consisted of four plants (I, 2, 4 and 6). Barring reciprocal dif­
ferences listed in the table, these plants formed a separate self and c ro ssincompatible group. Detailed in tra-class c ro ssibility behavior along with
reciprocal differences in these four plants are given in Table 6.
Group II consisted of .two plants (3 and 7). No reciprocal differences
w ere found among these plants. Crossability behavior of this Group or class
is presented in Table 7.
Group HI consisted of three plants (5, 9 and 8). Barring one reciprocal
difference (and a cross -compatible combination between plants 5 and 8) .
plants of this group formed a separate self and cross-incom patible group
(Table 8).
-50-
TaBle 5
Inter-group Crossability Behavior of the Plants
Comprising the Three Compatibility GroupsStudied in Coreopsis tinctoria
Group. I
(Plants
1,2,4,61
Group I
Plants
1,2,4,6
Group T I .
(Plants
3,7)
Group III
(Plants
5,8,9)
(0) Reciprocal
differences
(see text)
+
+
+
(0)
Group II
Plants 3,7
Group III
Plants 5,8,9
+ with exceptions of recipro­
cals (see text)
Cross-compatible.
= +
Cross-incompatible
^
Self-incompatible
0.
0
+
(0) with exceptions of reci­
procals (see
text
-51Table 6
Crossability Behavior of the Four Flants of Coreopsis
tinctorla Falling Into Incompatibility Group X
Cross
Seed set observed:
'None..
Full
Cross is therefore:
. Cross
compatible
Cross:in=,
compatible
Self
compatible
Self in=
compati­
ble
1 x 2
2 x 1
1x4
4x1
2x4
4 x 2
x
2 x 6
x
6 x 2
Ix l
x
2 x 2
X
4x4
6 x 6
x
1 x 6
x
6 x 1
%
4x6
%
6x4
Reciprocal differences have been boxed
-
52 -
T iE L b l e ; ?
Crossablllty Behavior of the Two Plants of Coreopsis
tlnetbria Palling Into Compatibility Group II.
----
Cross
•
f
Seed set observed:
None
Full
Cross is. therefore:
Cross,
compatible
'j
Cross in­
compatible
Self
compatible
Self in­
compati­
ble
■3x7
x
x
7 x 3
x
x
3x3
x
x
7x7
x
x
-
53-
Table 8
Crqssahility Behavior of the Three Plants of Coreojp^is
'tinctoria Falling into pompability Group T H
Cross Seed set observed:
None'
5. x„ 9
9x5
Full
x
Cross is therefore:’
Cross in­
Crosscompatible ,compatible
Self
compatible
Self incompati?
ble
;
•
X
X
X
5x8
X
X
8x5
X
X
8x9
X
x
8x8
X
X
5x5
X
X
8x8
X
X
9x9
X
X
■
Reciprocal differences have been boxed
Plants No.,-5 and No , 8, though, hot cprss—incompatible,, had to be in­
cluded in this group, being common with plant number 9.
-
54-
Three mating groups were identified among crosses with C. califom ica.
These groups are referred to as Groups I, II, and III respectively. Group­
ing was based on the same c riteria as for C. tin cto ria.
Plants of group I were 100% cross-com patible with the plants of Group II
and III in all directions. T hus, there were no anomalies between the three
groups, an ideal situation not met in other species (Table 9).
Four plants, 1 , 2 , 9 and 10, formed Group I. These plants formed a
separate self and cross-incom patible group. Reciprocal differences were
observed: When plant number 9 was used with plants I, 2 or 10 it proved to
be cross-com patible. Details of in tra-group :cr.o,ssability behavior are given
in Table 10.
Group H consisted of three plants, 3, 4, and 6 . No reciprocal differ­
ences were found among these plants. Crossability behavior of this group
is presented in Table 11.
Three plants, 5, 7 and 8 formed Group HI. No reciprocal differences
were found among these plants. Cross ability behavior of this group is present­
ed in Table 12.
Three mating groups were identified among the C. bigelovii c ro s se s.
These groups a re referred to as groups I, II and III respectively. Grouping
was based on the c rite ria used for C. tinctoria.
-
55-
Table 9
Intergroup Crossability Behavior of the Plants Comprising
Three lntra^self, Cross-incompatible but Cross­
compatible Groups Studied in Coreopsis
californica as Measured by Seed Set Success
Group I
Plants 1,2,9,10
Group II
Plants 3,4,6
Group III
Plants 5,7,8
0
Except recipro­
cal differences
+
+
Group II
Plants 3,4,6
4*
0
+
Group III
Plants 5,7,8
+
+
0
Group I
Plants 1,2,9,10
CrossT'Compgtlble
=
+
Cross^incoiapatihle '—
Q
Self ^incompatible.
0
=
56-
Table 10
Crossability Behavior of the Four Plants of Coreopsis
californica Falling Into Incompatibility Group I
Cross
Seed set observed:
None
Full
Cross is therefore:
Cross
compatible
Cross in­
compatible
Self
compatible
Ixl
x
x
2x2
x
x
9x9
x
x
10 x 10
x
x
1x2
x
X
2x1
x
X
1x9
X
X
9x1
I x 10
10 x I
2x9
x
x
X
x
X
x
9x2
2 x 10
10 x 2
X
X
X
x
X
x
•X
9 x 10
10' x 9
X
X
X
x
Reciprocal differences have been boxed
X
Self in­
compati­
ble
-57-
Table 11
Crqssability Behavior of the Three Plants of Coreopsis
californica Falling Into Incompatibility Group II
Cross
Seed set observed:
None
Full
Cross is therefore:
Cross
compatible
Cross in­
compatible
3x3
x
4x4
x
6x6
x
3 x .4
x
x
4x3
x
X
3x6
x
X
6x3
x
X
4x6
x
X
6x4
x
x
Self
compatible
Self in­
compati­
ble
x
I
x
x
-
58-
Table 12
Crossability Behavior of the Three Plants of Coreopsis
californica Falling Into Incompatibility Group III
Cross
Seed set.observed:
None
Full
Cross is therefore:
Cross
compatible
Cross in­
compatible
Self
compatible
Self in­
compati­
ble
5x5
x
x
7x7
x
x
8x8
x
x
5x7
x
x
7x5
x
x
5x8
x
x
8x5
x
x
7x8
x
x
8x7
x
x
All plants in this group are 100% self- and cross-^incompatible
-
59-
Plants of Group I were 100% cross-com patible with the plants of Group II
in any direction. Plants of Group I were also 100% cross-com patible with the
plants of Group III in both directions. In crosses involving Groups II and
III, plant number 5 of Group E, when used as a female parent, was c ro ssincompatible with plant numbers 6 , 7, 8 and 10 of Group HI, used as pollen
parents; but for these exceptions, the other plant of Group II was c ro ss­
compatible with plants of Group III both ways (Table 13).
Two plants (I and 4) formed Group I (Table 14). These plants formed
a separate self and cross-incom patible group. No reciprocal differences
in mating were observed. Intra-group crossability behavior is given in Table
14.
Two plants (3 and 5) formed cross and self-incompatible group II.
No reciprocal differences were found. Crossability behavior of this class
is presented in Table 15.
Three plants (6 , .7 and 8) formed cross and self-incompatible Group HI.
No reciprocal differences were found. Crossability behavior of this group
is presented in Table 16.
Two mating groups were identified among the C. calliopsidea crosses.
These groups are referred to as Group I and Group H respectively. Group­
ing was done as previously described.
-
60-
Table _13
Intergroup Crossability Behavior of the Plants Comprising
the Three Incompatibility Groups Studied in Coreopsis
bigelovii as Measured by Seed Set Success
Group I
Plants 1,2,9,10
Group I
Plants
I, 2, 9, 10
0
Except recipro­
cal differences
Group II
Plants 3,4,6
Group III
Plants 5,7,8
+• '
+
Group II
Plants 3,4,6
+
0
+
Group III
Plants 5,7,8
+ '
+
0
Cross—compatible
=
+
Cross—incompatible
=
0
Self—incompatible
0
-
61-
■ Table 14
Crossability Behavior of the Two Plants of Coreopsis
higelovii Falling Into Incompatibility Group I
Cross
Seed set observed:
None
Full
'
Cross is therefore:
■ Cross
Cross in­
compatible r_ compatible
Self
compatible
Self in­
compati­
ble
Ixl
x
x
4x4
x
x
1x4
x
x
4x1
x
x
All plants 100% self^ and cross^incompatible
-62-
Table 15
Crossability Behavior of the Two Plants of Coreopsis
bigelovii Falling Into Incompatibility Group II
Cross
Seed set observed:
None
Full
Cross is therefore:
Cross
compatible
Cross in­
compatible-
Self
compatible
Self in­
compati­
ble •
3x3
x
x
5x5
x
x
3x5
x
x
5x3
x
x
All plants .within this group 100% crossr and self^incompatible.
-
63-
Table 16
Crossabiiity Behavior of the Three -Plants of Coreopsis
bigglovii •,Falling Into Incompatibility Group. Ill
Cross
Seed set observed:
None
Full
Cross is therefore:
Corss
compatible
Cross in­
compatible
Self compatible
Self in­
compati­
ble
6 x. 6
X
X
7x7
X
X
8x8
X
X
6x7
X
X
7x6
X
X
6x8.
X
X •
8 x 6
X
-X
7x8
X
X
8x7
X
X
All plants in this-group are 100%'s e l f a n d cross-incompatible;
-
64 “
Plants of Group I were 100% cross-com patible with the plants of Group II
in both directions. No reciprocal differences were observed (Table 17).
Six plants, I, 3, 4, 7, 9 and 10, formed Group I. These plants formed
a separate self-and cross - incompatible group. No reciprocal differences
w ere found among plants in this group. Crossability behavior of this group
is presented in Table 18.
Four plants, 2, 5, 6 and 8 , formed Group II. These plants formed a
separate self-and cross-incom patible group. No reciprocal differences were
found among plants in this group. . C rossability behavior of this group is
presented in Table 19.
Seed set data for F j's and reciprocal backcrosses are summarized in
Tables 20 and 21 for C . tin cto ria, Table 22 for C_. californica and Table 23
for C. bigelovii. hi C. tinctoria reciprocal differences between F j's of the
sam e parent were detected. Similarly, backcross results.depended on the
rec u rren t parent. A sim ilar pattern was detected for C. californica and for
C . bigelovii.
Data from the C. tin c to ria F? of a c ro ss, self-incompatible (female)
x self-compatible (male) are summarized in Table 24. Of 36 Fg plants
scored, 7 were self-compatible and 29 were self-incompatible.
Table 17
Tntergro'up Crossability Behavior of the Plants Comprising
Two, Intra-shlf and Cross-incompatible but. Ititer-cross-r
compatible"Groups Studied in Coreopsis calliopsidea
as.Measured by Seed Set Success
Group I
Plants
I, 3, 4, 7, 9, 10
Group I
Plants
I, 3, 4, 7, 9, 10
Group.II
Plants
2, 5, 6, 8
0
+
+
0
■7
Group II
Plants
2, 5, 6, 8
Cross-compatible
=
+
Cross—incompatible
=
0
Self-incompatible
0
-6 6 -
Table 18
i
Crossability Behavior of the Six Plants in Coreopsis
calliopsidea Falling Into Incompatibility Group I
Cross
Seed set observed:
None
Full
Cross is therefore:
Cross
compatible
Cross .in­
compatible
Self
compatible
Self, in­
compati­
ble
X
3x3
4x4
7x7
9x9
X
X
X
X
10 x 10
X
I x 3
x
3x1
X
.1x4
4 x I
1x7
7x1
.1 x 9
9 -x I
I
X
10
10 x I
3 x 4
4x3
3x7
7x3
3x9
9x3
3
10
4
7
4
9
4
10
7
9
7
10
9
X
x 10
x 3
x 7
x4
x5
x4
x 10
x 4
x 9
x7
x 10
x 7
x 10
+j
CU
CO
H j-
CU
OJ
CO
§
■
67 -
Table 19 ,
Crossability Behavior of Four Plants of C_. calliopsidea
Falling Into-Incompatibility Group II
Cross
Seed set observed:
None
Full
Cross i 3 •therefore:
Cross
compatible
Cross in­
compatible
Self
compatible
Self in­
compati­
ble
2x2
X
5x5
X
X
6x6
X
X
8 x( 8
X
X
2x5
X
X
5 x 2
X
X
2x6
X
X
6x2.
X
X
2x8
X
■X
8 x 2
X
X•
5x6
X.
X
6x5
X
X
5x8
X
X.'
8x5
X
X
6x8
X
X•
8x6
x
X
•
-
X
Table 20
Results of the Backcross Using, Plants Showing Reciprocal Differences in a
Diallel Cross in Ch tinctoria Reciprocal Cross I . Plants 5 and 9
.
Crosses
Genotypes
Crossability behavior
Actual ratios
S4S4 x S3S4
Plant 9.x
Plant 5
S5S4 X
Plant 5 x
h
S4 S4 X S3S4
S4S4
Plant 9 x
S3S4 -X
F1
S4S4
S3S4
S4S4
.
.
.
Prpb >
level
Hypothetical ratios
Cross comp. i Cross incomp.
Plant 5 x
Plant 9
.
Cross comp. I Cross incomp..
' 60
0
N/a'
N/a
' N/a
N/a
"0
60
N/a
N/a
N/a
N/a
27
33
0.6
(30) I
:
1(30)
.50- 250.
2
58
o.o
( 0) 0
:
I(SO)
X
(see Text)
Table 21
Results of the Back Crosses Using Plants Showing Reciprocal Differences in a
Diallel Cross in C. tinctoria Plants Chosen here are Nos. I' and 4
Crosses
Crossability behavior
Genotypes
Actual ratios
Cross comp.
PI
x PU
I
4
PU x
PI
pi
x F .
(80) I
SlS, x
S1S3
Si:? =V 2
Sl^Z= sIsI
X
X
X
sIsS
S1S2
S2S3
X2
Cross .incomp.
Prob.
level
Hypothetical ratios
Cross comp.
Cross incomp.
80
0
N/a
N/a
N/a
N/a
0
. 80
N/a
N/a
N/a
N/a
38
42
0,2
1(40)
:
1(40)
0.75- 0.50
Table 22
Results of the backcross Using Plants Showing Reciprocal Differences
In a Diallel Cross in C . califprnica Plants 9 and I
Crosses
Genotypes
Crossability behavior
Actual ratios
Cross comp.
9x1
1x9
Female
parent
9 x F1
S2S3 x SlS2
S1S2 x S2S3
S2S3 x S1S2
,X2
Cross incomp.
Prob.
level
Hypothetical ratios
Cross comp.
Cross incomp.
80
0
N/a
N/a
N/a
0
80
N/a
N/a
N/a
43
37
0*45
0
80
(AO) I
:
1(40)
.750 - 0.500
( 0) 0
:
1(80)
No deviation
in.observed
and expected
ratios
SiS3
S2S2
S2S3
Male .
parent
S1S2 X S1S2
I x F1
SiS3
52 52
5253
Table 23
Results of the Backcross Using Plants Showing Reciprocal Differences
In a Diallel cross in U- bigelovii Plants 5 and 6
Crosses
Crossability behavior
Genotypes
X2
Actual ratios
Cross comp.
6x5
5x6
S4 S5 x S2^ S4
S254 X S4 ) S5
Cross incomp.
Prob. •
level
Hypothetical ratios
Cross comp t
Cross inComp.
100
0
N/a
N/a
N/a
N/a
.0
100
N/a
N/a
N/a
N/a
i
I
Male
parent
5 x
82^4 x S2 ) S 4
0
100
53
47
0
0 Co).
1 (100 )
No different
ces in obser­
ved and exj
pected
ratios'
I (50)
0.750 - 0.500
S2>S5
s4 > s4
s4
Female
parent
6 x F^
plants
> s5
S4 S5 x S2 > S4
32 > 8 5
S4
S4
84 > 8 5
0.36
I (50)
:
-
73-
Table ^24 •
Segregation in F l Generation of. a ■Cross Between Self-incom­
patible and self-compatible mutant.of C. tinctofia
No. of plants
s.r?
29
Total
Prob.
level
S.C.
7
3 : I
36 .
0.50
/
.500-.250
-7 5 -
Discussion: Results of the diallel c ro ss, reciprocal differences, as
well as the anomalies in Groupfs';I found in inter-class compatibility and
and intra- class - incompatibility can be explained by a scheme proposed by
L . K. Crowe(1954) for Cosmos bipinnatus. This scheme is a modified form
of the scheme proposed e arlie r by Gerstel (1950) and by Hughes and Babcock
(1950), which was known as the Compositae scheme, but now is referred to
as the sporophytic form of self-incom patibility. According to this scheme
the following assumptions are made:
1. A single locus controlling self-incompatibility
2. Multiple alleles for the locus
3. Dominance relationship in the pollen grains (allelomorphic genes)
4. Dominant o r independent relationship in the maternal tissue ( i . e . ,
stigm a, style) between allelomorphic genes.
Following this scheme genotypes can be assigned to the 10 plants in­
volved in the diallel crosses of C . tinctoria. These genotypes (along with the
dominance relationship of "S" alleles) explain the three mating groups that
form in tra-cro ss and self-incompatible groups with reciprocal differences.
Explanation of anomalous behavior of some plants that cause inter-class
incompatibility can also be given. The genotypes assigned to these plants,
along with the dominance relationship of "S" alleles (on male as well as on
-
76 -
female side) is given in Table 25.
Results of the diallel crosses in C . californica could not be explained
on the basis of Nicotiana scheme proposed by E ast et al (1925) and designated
as the gametophytic system of self-incom patibility.
In order to explain the reciprocal differences involving plant number 5
of Group II with plant numbers 6 , 7, 8 and 10 of Group HI (one directional
in ter-class cross - incompatibility), the scheme proposed for Coreopsis
tinctoria is appropriate.
Following this scheme genotypes can be assigned to the 10 plants chosen
for diallel c ro s s e s . These genotypes (along with the dominance relationship
of "S" alleles) explain the presence of three mating groups that form intra­
c la ss, cross and self-incompatible groups. These genotypes also explain
the reciprocal differences involving plant numbers 6 , 7 , 8 and 10 of Group HI
with plant number 5 of Group II. The genotypes assigned to these plants,
along with the dominance relationship in "S" alleles (on male as weU as
female side) have been presented in Table 26.
As in the case of G- tinctoria, results, of the diallel cross in C. bigelovii
could not be explained on the basis of the Nicotiana scheme proposed by East
et al (1925) and designated as the gametophytic system of self-incom patibility.
.
In order to explain the reciprocal differences (involving plant number 9
77-
-
Table 25
Genotypes Assigned tp -the Ten Plants of .CL
tinctoria Chosen for Dialled. Cross'
Plant No.
Genotype
Dominance relationship
C?
I
SS
I 2
Pollen
■s, -
\
I
/
S
S1
SlSi'
3
S9S
Z X
S2
>
Sx
4
S1 S0
I 3
S0
3
\
Z
S
I
6
7
8
9
10
S1
1
■
.L
\
/
4
>
S3
>
2
S0
No dominance
S1
I
\
/
S0
3
N/a
S'
Sx.
N/a
S3S3 -
\
/
N/a-
N/a,
S1 S 1
1-4
S3S4.
1
N/a
S4S4
'%
Stigma & style
2
2
5
^
S
I
^
z
S
4
No dominance
■ N/a
S4
N o 'dominance.
Crossed wi th all other plants, 'ience it has a
separate genotype S^S^ or SgS^
-
78 -
Table ■26
Genotypes Assigned to Ten Plants.Chosen for
Dialled. Cross in _C. calif6,m i c a
Plant No,
Genotypes
side dominance
relationship in
S alleles
side (stigma
& style) domin­
ance in S alleles
C f
f
t
I
2
No dominance
S1S2
S 1
>
S 2
S 1
>
S 2
No dominance
SiS2
:
3
S3S4
S 3
>
S 4
S3S4
S 3
>
S 4 -
S 3
>
s 4
3 3
>
S 4
.7
4
5
No dominance
S4 S5
>
S 5
7
S2S3
S 4
S 4
>
S 5
No dominance
S 4 S 5
9
>
No dominance
S4S5-
8
S 3
3 4
•
>
S 5
S 2
>
S 3
S 1
>
3 2
10
s I s 2
S 2
>
S 3
No dominance.
>
dominance
J P
;S3S4
V
6
J P
.
S 4
-
79 -
when used as a female parent with plant numbers I, 2 and 10) in plants of
Group I, a scheme proposed in Coreopsis tinetoria seems to be appropriate.
Following this scheme we can assign genotypes to the ten plants chosen for
diallel c ro s s . These genotypes (when keeping in view the dominance relation­
ship of "S" alleles) explain the presence of three mating groups that form
in tra -class, cross and self-incompatible groups. ■These genotypes also ex­
plain some of the anomalies discussed above. The genotypes assigned to
these plants, along with dominance relationship in "S" alleles (on male as
well as on female side) are presented in Table 27.
No backcrosses were possible because of cultural difficulties. This
species is strictly annual and F j*s could not be maintained for attempting
■crosses with the parents .
Interpretation of the diallelic cross in Coreopsis calliopsidea was the
most difficult task. Absence, of reciprocal differences, along with the inability
to maintain parents for backcrosses was the main stumbling block.
Results of the diallelic cross could be, interpreted both for the gametophytic or the sporophytic system of self-incompatibility; Both views
a re being presented h e re . It is unlikely that this species has a gametophytic
system of self- incompatibility. Cytological studies pertaining to the site
of inhibition discussed la te r show that the sporophytic system of self-incom- .
-
80 -
Table 27
;
Genotype Assigned, to Ten Plants Chosen for
Diallel Gross in Cv bigelo^ii'
Plant No.
I
3
Genotype •
S1 > S2
5I > S2
S2S3
S2>V
S2
S1S2
.
'
S1 > S2
S2S4
S2 > S4
6
V5
S4 > S5
7
V5
S4 > S5
S4S5
S4 > S5
S4 S5
s4 > s5
8
10
$ side dominance
Cstigma &.style)
relationship i n .
S alleles
S 1S2
4
5
Cf side dominance
relation in S
alleles
> S3
Si > S,
^
No dominance
No dominance
No dominance
No dominance
No dominance
2 and 9 - These plants were universally cross-compatible so could not
be assigned a genotype in absence of.any reciprocal differences or
otherwise. The only thing that can be said is that they had•genotypes
different .f from each other and the rest of the plants.,
81=
—
patibility is operative in this species as w ell. (There is a strong correlation
between the incompatibility system , pollen morphology and germination as
well as the site of inhibition.)
Ten plants used for diallelic cross could have come from parents with
genotypes (I) S]S2 and (2) S2 S3 , with dominance in ”S" alleles operating in
pollen as well as in stigma and style. Four genotypes of plants with 2 inter­
cross-com patible and in tra-cro ss -incompatible groups will be present from
such a c ro s s .
81)82x82)83
S1>S2
S2^2
81)83
82)53
Group Ei
Group II
Plants of genotype 81)82 and S]) S3 in Group I will form a single intra­
incompatible group with each other, provided there is a dominance in " 8"
alleles on both p a ren ts.
Plants of genotype 8^82 and 8^83 in Group II will form a single intra­
compatibility group with each other, provided there is a dominance in " 8"
alleles in both the p a ren ts.
Based on our assumptions (I and IQ plants of Group I will cross readily
with those of group II in both directions. Alternatively, even if the gametophytic system of self-incompatibility is operating there will be 2 genotypes
and 2 groups.
-
82 -
S]S2 x S2Ss
SjSs
Group I
S2 S3
Group H
The crossability behavior will also be like the one we got from the diallelic
c ro ss.
However, the true picture could have been clear from backcrosses since
dominance relationship would have changed the ratios of such a c ro s s . A
hypothetical model which could not be put to test because of the reasons
stated e a rlie r is being presented.
Sporophytic system :
Let original parents,?! and PH,have the following
genotype with dominance operating in "S" alleles both bn male and female sides.
P I - Si>S2 and P H S2)S3
A cross involving P I x P H wiH give plants of 4 genotypes:
S1S2 , S1S3 , S2S2 , S2S3 . Four genotypes will form two groups, each
group will have self and cross - incompatible plants, with two genotypes,
SiS2 and S1S3 - Group I; S2 S2 and S2Ss - Group DL On crossing P1 with Fi
plants, 50% of the plants wiH be cross-com patible. The re s t (%0%) will be
cro ss -incompatible.
Thus:l:l.rp.tio of cross-com patible to cross - incompatible
will be obtained with Pi.
pI
x
Fi
-8 3 -
S])S2 x S])S2 cross-incom patible
Si)S3 cross-incom patible
82)82 cross-com patible
82)83 cross-com patible
On crossing PU with Fj plants 50% of the Fj plants will be cross-compatible;
the re s t will be cross-incom patible with PH. Thus, once again 1:1 ratio of
cross-com patible to cross-incom patible will be obtained.
PE
x Fj .
81)82 cross -compatible
81) 83 cross - compatible
82) 82 cross - incompatible
82)83 cross-incom patible
Gametophytic system : Let original parent plants have the sam e genotype,
but let the poUen reaction of " 8 " allele be influenced by the male gametophyte
itself; also let there be no dominance relationship in "8 " alleles in stigma,
and style.
PI - SjS2J HI S2Ss
A cross involving PI x P II will give plants of 2 genotypes only:
SjSs and S2 S s. These plants wiU form two cross-com patible groups;
however plants of same genotype will form a self and cross-incompatible
-
84 “
group. Thus, purely on the basis of mating system , it will look like the
firs t case; however backer os s data will be different from the one expected
if the sporophytic system is functioning in the plants forming these two major
groups.
On crossing PI with Fj plants, .100% of the plants will be cross-compatible;
therefore, instead of I: I ratio of cross -compatible F j's to cross - incompatible
F i’s, there will be I : 0 ratio of cross-com patible F j’s to cross-incompatible
F i’s.
PIxF1
S1S2 S1S3 cross -compatible
S2 S3 cross-com patible
On crossing PU with F 1 plants the ratio of cross-com patible Ff plants
to cross-incom patible Fi plants will rem ain I : I as in sporophytic system .
P II x F 1
S2S3 x S1Sg cross-com patible
S2 S3 cross - incompatible
This hypothetical model has tried to explain how backcross data (PI x Fi)
would have confirmed the genetic system of self-incompatibility operating in
this species.
However, based on cytological studies, it is proposed that a system
sim ilar to the other three species is operative in Coreopsis calliopsidea.
-8 5 -
The backcross data for C. tinctoria can be explained in term s of the
genotypes assigned as a result of the diallel study. The backcross data sup­
port the diallel resu lts. Expected backcross ratios are either 1:1 or 0:1
o r 1:0 for self-compatible ys . self-incompatible, on the assumptions p re­
viously discussed. These ratios were tested using
methods and in all
cases the fit of observed to expected was satisfactory (P ).10).
For the other two species for which backcross data are available, C .
californica and C . bigelovii, sim ilar conclusions are reached based on the
same logic.
The F 2 data for C_. tinctoria further support the assumptions previous­
ly discussed. A classical Mendelian ratio .75 (self-incompatible):.25 (self­
compatible). is expected. This ratio was tested using
techniques and the
fit was satisfactory (P ). 10).
The results indicate that Coreopsis tinctoria, Coreopsis californica
and Coreopsis bigelovii have a sporophytic system of self-incompatibility.
In Coreopsis calliopsidea data do not clearly support the hypothesis of a
sporophytic system of self-incom patibility.
In term s of classical genetics each of the three species has multiple
alleles at a single locus. Dominance relationship is obligatory in pollen
g rain s, while variable on the female sid e. With the presently known tools
-8 6 “
of genetical investigations, it was not possible to differentiate the dominance .
relationship within female gametophyte (ovules). Variable dominance relation­
ship could be expressed in stigma, style, ovary and ovules or could be
operative only in diploid tissue.
In term s of number of alleles C. tinctoria had a minimum of seven alleles,
C . californica had five alleles and C_. bigelovii had five a llele s: It was not
possible to assign number of alleles in C. calliopsidea. The number of
alleles is less than 10 as is expected in the sporophytic system of self-in­
compatibility (Gerstel,1950j Lewis,19545 Pandey,1960$ Ramanamurtfey 1963;
Sampson,1967). Fortunately, incompatibility alleles had high penetrance
and expressivity. This was helpful in the analysis of data based on number
of seeds set per head, a criterion used in differentiating self-incompatible
and cross - incompatible crosses from compatible cro sses.
Expression of the self-compatible allele (SC allele) in C . tinctoria
was not clear cut. Fg progeny of the cross self-incompatible female X
self-compatible m ale, kept at 70°F with a 12 hour light period in a growth
chamber had self-compatible plants which did set seeds, but the seed set
was reduced (7 to 15 seeds per head). Normal seed set, as recorded earlier
in self-compatible plants, ranged from 20 to 30 per head. Out of 7 self­
compatible plants only 2 did show normal expected seed set." One possible
explanation for the low seed set is the presence of modifying genes which
a lter the behavior of SC genes.
-
87-
Factors Associated with "S" Gene Action
In many cases, sporophytic and gametophytic systems of incompat­
ibility can be separated on either a cytologicalbasis or by the site of in­
hibition of pollen growth. Generally, in the case of the sporophytic system ,
m eiotic configurations are norm al, and cytolqiBjiesis'occurs relatively late in
m icrosporogenesis. Also, the stigma is the site of pollen inhibition, and pollen
tubes fail to function norm ally. Cytological studies and stigma decapitation
studies were carried out to verify genetic results supporting the hypothesis
of a sporophytic system of iimcompatibility in the four species of Coreopsis
studied.
■M aterials and Methods: Young heads (buds) were fixed in 3:1 absolute
alcohol and glacial acetic acid. Ten random plants per species were used
in the study of the course of m icrosporogenesis. At least 10 pollen mother,
cells per plant were scored. The aceto-orcein sm ear method (La1G pur,-1941)
was used for staining. A representative pollen mother cell was-photographed
in each sp ecies.
Pollinated heads of 60 plants of each of the four species, two heads per
plant were fixed in absolute alcohol overnight at. room tem perature o r in a
refrig era to r. Pistils were dissected, and following the method described
by Boiler (1948 pp. 14-16) for pollen tube studies in sweet ch erries, m aterial
was stained on microscope slides with Resorcin Blue (Lacmoid Blue) in 30%
-8 8 -
alcohol. The tissue was covered with a standard cover slip and squashed byhand (thumb pressure on the cover slip).
After one minute excess stain
was drawn off. Slides were examined under a compound microscope at 250X.
The callose plug of the pollen tube stains a brilliant deep blue.
Bud pollinations were carried out on 60 plants of each species, two heads
per plant. Young heads were mechanically opened and pollinated with its
own mature pollen from a plant known to be incompatible. Seed set was
scored on each head so pollinated as an estim ate of the effectiveness of bud
pollination in overcoming self-incompatibility. In addition, stigmas and the
distal portion of styles of the same number of plants were excised and mature
pollen was applied to the remaining portion of the style . Pollen from incompat­
ible plants was used in this study. Seed set in compatible pollinations was
compared with seed set from incompatible pollinations to estim ate the effect
of decapitation in overcoming incompatibility.
Results; All cytological studies indicated normal meiotic behavior
during microsporogenesis in all species studied. In all four species, most
notably in C . calliopsidea, secondary associations between different bivalents
was regularly observed (Figures 11a, 11b, 12a, 12b andl-3). Cytokinesis
occurred after telophase I.
In all cases pollen fertiflity was over 80%. A byproduct of this study
was determination of chromosome numbers for three previously unreported
-
89 -
W 5
*• t » a
■r
Fig. 11a. Meiotic studies C. t Inctoria 4
A P.M .C . Metaphase I with
12 bivalents.
Fig. 11b. Meiotic studies C. tine tor ia *
A P.M .C. Diakinesis with 12
bivalents grouped, in group of
I fours, I th rees, and 2 twos.
Fig. 12a. Meiotic studies C. califom ica,
A P.M .C . Diakinesis with 12
bivalents. One group of four
bivalents.
I
' i
A
■« e I
-
:<
Fig. 12b. Meiotic studies C. Mgeloviia
A P.M .C . F irs t anaphase
N s 12.
-
91-
r
*
Fig. 13. Meiotic studies C. calliopsidea.
A P.M .C . Metaphase I with 12
bivalents . 5 groups of tw os.
species (Figures 11a, 11b, 12a, 12b and 13). C. californica' (n =. 12), C. Mgelovii (n = 12) and C. call i ops idea (n = 12), (Sharma, Metcalf, Chapman and
Smith,in p re s s ).
Pollen germination was examined 4, 6 , 8 , 12, 24, 48 and 72 hours after
pollination. The methods of examination have already been discussed. In
3 out of the 4 species (C. californica was different) studied, germination of
a.few pollen grains started after 8 hours, but the maximum number of the.
pollen grains around the ‘stigma were germinated only after 48 h o u rs. Studies
of pollen tube growth were thus done only after 48 hours (Table 28).
Cros s - compatible pollinations could be easily differentiated from
the incompatible ones by the number of germinated and penetrated pollen grains
■around the stigmatic area. There were considerable changes in the size of
the stigma and style in compatible pollinations, where the size was much
la rg e r in comparison to the incompatible one (Figure 14a). Total number of
pollen grains germinated (both those that penetrated and the ones that could
not) and ungerminated, around the stigma were markedly large in compatible
pollinations. In compatible pollinations, C. calliopsidea was the only
species which had maximum number of pollen grains around the stigma.
These grains, however, failed to germinate as expected. In other species
not many pollen grains were found around the stigmatic area.
Bud pollinations, were ineffective in three species, C. californica,
-
93 -
Fig. 14a. Pollen studies C. tinctoria compatible
pollination. Pollen grains germinating
after 48 hours.
Fig. 14b. Pollen studies C . tinctoria Incompatible
pollination. Pollen grains (a few in number)
not germinating after 48 h rs.
Table 28
R e s u lt s o f Study o f S i t e o f I n h i b i t i o n o f P o lle n Germination in Four
S e lf - in c o m p a t ib le /c o m p a t ib le S p ecie s o f C oreopsis L.
S p e c ie s and
form
Cross
Time in hours T otal p o lle n Mean number Mean no.
fo r p o l l e n to g r a in s around germinated p e n e tr a ­
ted
p e n e tr a te
p o lle n
stigma
stigma
fie ld
g r a in s
g ra in s
Mean no.
Mean no.
g ra in s
g ra in s
n ot pene­ n ot cvgert r a te d
' minated
C. t i n c t o r i a
(self-in co m p .)
selfed
48
11
3 .8 7
2.76
1.83
7.80
C. t i n c t o r i a
(se lf-c o m p .)
se lfe d
48
198
195.67
192.00
3.67
2.56
C. t i n c t o r i a
(se lf-in c o m p .)
S i 1XSi2
48
288
285.00
280.00
5 .0 0
3.00
C. t i n c t o r i a
( S e lf - in c o m p .)
S i 1XSC
48
285
281.37
279.00
3 .0 0
4 .0 0
S i 1XSi2
72
241
236.00
228.54
7.57
5.00
•Y
C. c a l i f o r n i c a
( S e lf - in c o m p .)
Table 28 (continued)
S p ecie s and
form
Cross
Time in hours T otal p o lle n Mean number Mean no.
fo r p o lle n to g r a in s around germinated penetra#
p e n e tr a te
p o lle n ’
stigm a
ted
fie ld
stigma
g ra in s"
g r a in s
selfed
72
10
C. b i g e l o v i i
( s e lf - in c o m p .)
Si^xSig
48
199 '
C. b i g e l o v i i
( s e lf - in c o m p . )
selfed
48
C. c a l l i p p s i d e a Si^xSig
( s e lf - in c o m p .),
se lfe d
Mean n o. .
grain s
not ger­
minated
5 .0 0
3.37
2.76
5.00
197.00
190.87
6.67
2.00
20
3 .5 0
3 .5 0
0.00
18.33
48
213
200.00
196.57
4 .0 0
13.00
48
36
2.87
2.00
32.21
-95-
C. c a l i f o r n i c a
( S e lf-in c o m p . )
Mean no.
g ra in s
n o t pene­
t r a te d
C. c a l l i o p s i d e a
Note:
4 .8 7 '
S tu d ies done on 20 p l a n t s , 2 heads per p l a n t , w ith 3 g yn oecia per head examined
-
96-
C. bigeloyii and C. calliopstdea. In C. tinctoria 10 to 15 seeds were set in
three of the 60 plants examined.
In the decapitation studies the results are sim ilar. Only three plants
of C. tinctoria set seed following pollination of the decapitated style. These
w ere the same plants which set seed from bud pollinations.
Discussion: Cytological studies in four species of Coreopsis revealed
that cytokinesis takes place as late as after Anaphase.II during m icrosporogenesis; hence even a late "S" gene action will give rise to pollen,under sporophytic influence with all the attributes of a sporophytic system (like dom­
inance among "S" alleles), irrespective of the number of nuclei in the pollen
grains at anthesis. The experimental results show the stigma as the site
of inhibition. This^points towards two things: F irst, "S" gene products in
the pistil are also distributed in stigma; and second, the pollen grains have
the "S" gene products in them as soon as they land on the. stigmatic surface.
Bud pollination and stigma decapitation studies performed in all four
species of Coreopsis point out that "S" gene products are distributed all
•
over the pistil,, and tim e of "S" gene action is very early in the development
of the female sex organ. How early cannot be answered from these studies.
Bud pollinations did succeed in,3 plants of C. tinctoria due to some unknown
physiological reasons their "S" gene products accumulated only in the stigma,
o r there were some modifying genes which altered the general trend of "S"
-
97 -
gene action in this regard. Townsend (1970) has selected some incompatible
lines with modifying genes in alsike clover. These genes altered the "S"
gene action, making them tem perature sensitive. Three plants of g . tinctoria
thus offered a good opportunity to study "S" gene action in C. tin cto ria.
-
98 -
Hybrid vigor studies In Coreopsis tinctorta N utt., using self-incompati­
bility as a tool for producing Fj hybrids.
H eterosis,, or hybrid vigor, is a well-known phenomenon in many plant
species „ A study was initiated to determine if significant heterosis for
important horticultural tra its was expressed in C . tinctoria .
M aterials and methods: Three Fj lines were developed by crossing
three open-pollinated cultivars with a. self-compatible male p a re n t, The
Fj lines w ere compared with their respective parents and with each other
with respect to five morphological t r a i ts .
Parental m aterials were:
1. 'Petite Purple* (open-pollinated cultivar)
2. 'T iger Star' (open-pollinated cultivar)
3. Un-named dwarf (open-pollinated Mont. A gr. Exp. Sta. selection)
4. Self-compatible mutant (inbred for 2 generations only)
Fp hybrids developed were:
!. 'Petite Purple' x self-compatible mutant
2. 'T iger Star' x self-compatible mutant
3. MAES selection x self-compatible mutant
Use of the self-compatible mutant as common male parent facilitated. Fj .
seed production. >
hi 1968, 12 plants of each parent and of the resultant Fj hybrids were
-
99 -
arranged at random in each of three blocks in the field at Bozeman, Montana.
The following tra its were m easured on all plants: (I) plant height in c m .,
m easured from the soil surface to the tip of the tallest portion of the mature
plant; (2) plant spread or width in c m ., m easured at the widest portion of .
the plant; (3) number of buds per plant; (4) number of flowers per plant;
(5) diam eter of flower heads in c m . , m easured across the spread of the fully
open flower head. Data were analyzed by standard analysis of variance (ANOVA)
techniques.
Results: Mean values and standard deviations for all crosses and
parents for all tra its m easured are summarized in Table 29.
The m ajor difference between the Fj hybrids and their parents was
found to be greatly increased flower production by the Fj hybrids, as indicated
by the bud and flower counts. Plant dimensions were modified, in the F^
hybrids, more in term s of spread than in height. This is indicated by the
height/spread ra tio s, which were all less than 1.0 for the Fj hybrids, but
clearly less than 1.0 for but one of the four parental lin es. Only small
differences in flower size w ere found among the Fj hybrids and th eir parents.
The Fj hybrid 'T iger Star' x self-compatible mutant was significantly
sh o rter than the two other Fj hybrids. The Fj hybrid 'Petite Purple' x
self-compatible mutant was also of desirable height. These two hybrids were
Table 29
Comparison o f P la n t H e ig h t, P la n t Spread, Number o f Buds Per P l a n t ,. Number, o f
Flowers Per P la n t , and Flower Diameter fo r Four P a r e n ta l Lines o f Coreopsis
f i n e t o r i a w ith t h e i r r e s u l t a n t F^ h y b r id s , Bozeman, Montana, 1968
Buds per
p la n t
no.
P lant
h e ig h t
cm.
P lant
spread
cm.
H/S
ra tio
ilP e t i t e Purple"
1 9 .4 + 1 .0
2 2 .0 ± 1 .3
0 .8 8
5 8 .0 ± 5 .4
60,4+ 4.8
3 . 8 1 0 .4
,2.
"Tiger Star"
2 6 .5 ± 1 .7
2 1 .8 ± 2 .2
1.22
6 0 .5 ± 7 .8
6 1 .4 ± 7 .0
4 .0 ± 0 .4
"3.
Unnamed MAES
dwarf s e l e c t i o n
2 1 . 2±2.0
2 1 .3 + 1 .1
0.99
6 2 . 8±2.5
6 3 .3 1 2 .3
3 .9 1 0 .1
4.
S e lf - c o m p a t ib le
mutant
3 2 .6 + 1 .3
2 9 . 8±5.8
1.09
4 3 .5 ± 1 .4
3 8 .6 1 5 .9
3 .2 1 0 .1
Line
no.
Line
■ id e n tity
Flowers/
p lan t
no.
Flower
diameter
cm.
I.
-OOT-
P aren tal. l i n e s :
Table 29 (con tin u ed )
Line
no.
Line
id en tity -
P lant
h e ig h t
Plant
spread
cm.
cm.
H/ S
ratio
Buds per
plant
no.
Flowers/
p lan t
no.
Flower
diameter
cm.
F-l hybrid l i n e s :
I.
" P e t i t e Purpler
x se lf-c o m p .
2 7 . 8±2.2
3 2 .7 ± 2 .3
0.85
2 5 7 .6 + 6 .1
258.9+2.7
4 .1 + 0 ,3
2.
"Tiger S tarrt
x s e lf - c o m p .
2 5 .6 ± 2 .8
5I . 6±2.2
0 .5 0
2 71.0± 16.8
2 7 3 .9±18.9
4 .6 + 0 .I
3.
Unnamed, dwarf
x s elf-co m p .
2 9 .7 ± 0 .4
3 9 .8 ± 0 .8
0 .7 5
2 5 2 .2 ± 8 .4
257.9 ± 9 .5
4 .4 + 0 .4
-
102 -
sim ilar in height to 'T iger S tar', but differed significantly in height from the
other parental lines-. They were judged to be of desirable height.
All three Fj hybrids produced plants with greater spread than their
p a re n ts. The Fj hybrid 'T iger Star' x self-compatible mutant had maximum
spread and was significantly different from the other Fjs in this regard.
AU the Fj hybrids were significantly superior to the-parents in numbers
of buds and flowers produced. Among the F1 hybrids, 'Tiger Star' x self­
compatible mutant was superior to 'Petite Purple* x self-compatible mutant
and to ' un-named dwarf x self-compatible mutant* in flower and bud production.
The Fi hybrids did not differ among themselves or from 'T iger Star'
v.
in size of bloom, but produced la rg e r flowers than 'Petite Purple*, the un­
named MAES dwarf selection, and the self-compatible mutant.
The Fi hybrids all had the sta r ray floret p attern . The self-compatible
mutant parent, common to all, had sta r ray florets . It is apparent that, in
these hybrids, sta r ray floret pattern was dominant over flat ray floret pattern.
The Fi hybrids could be segregated in the field from the parental lines with­
out the aid of precise m easurem ents. Apparently, the F 1 hybrids are much
b etter, hort!culturally speaking, than their parents, and, if put into production,
could readily displace current commercial lin e s.
Production of Fi hybrid seed on a comm ercial scale: A simple mechanism
for production of Fi hybrid seeds of annual species of Coreopsis cvvfv .
A
-
103 -
could be of significant value to flower b ree d ers. In essence, such a mech­
anism calls for two homozygous self-incompatible but cross-com patible lines.
Such lines would be grown side-by-side in alternate row s, cross-pollination
being achieved via insect activity.. The seed harvested from the self-incompat­
ib le parent would be Fj hybrid in nature; that from the individual row's could
be bulked o r segregrated depending on the nature of the progeny from various
parental lines and/or the intended commercial end-use of the seed.
There are two problems that must be solved before such a program
could be successful. F irst, production of homozygous self-incompatible but
cross -compatible lines that are good combiners is quite a task;, secondly,
maintenance of.these lines is possible only if "S" gene action occurs some­
tim e after floral morphogenesis (only then are bud pollination and other
techniques effective).
The technique to be followed is a simple one; the only requirements
a re that the pollen parent must be self-compatible and that the incompatible
plant should be capable of being multiplied vegetatively. We have discover­
ed these requirem ents to be satisfied in Coreopsis tinctoria, in which diverse
genetic m aterial, lines with good combining ability, and at least one self­
compatible mutant are available as a result of our research and from other
sources. Herbaceous cuttings of C. tinctoria strike root with 90% success,
-
104-
which is significant since the female self-incompatible parent must be m ulti­
plied vegetatively from an initial single plant. In order to have adequate
stocks of this type, the increase program can be started in autumn in the
greenhouse. The stock plant will rem ain vegetative at night tem peratures
of 55-60°F and will yield a large number of cuttings which, when suitably
manipulated, will afford a further increase of stock. Reserve stock for use
in succeeding years should be maintained.
The plants raised from cuttings should then be planted out with the
seedlings of self-compatible plants (raised from seeds' and maintained in
isolation) in alternate ro w s. Seed harvested from the self-incompatible
plants will be
hybrid for comm ercial s a le .
Discussion: Fp hybrids were superior, as ornamental plants, to the
best p aren t. What constitutes , a better variety in an ornamental plant and
how FI. hybrids may be better can be described in term s of a medium tall
plant with many flowers which p ersist over a long period.
Heterosis is apparent for important horticultural tr a its . A simple
mechanism to produce Fl seeds could be of significant value to flower breeders.
Fig. 15. Hybrid Vigor in C. tin cto ria.
z/
Fj hybrid: Petite Purple'(female) x SelfCompatible mutant" (m ale).
-106-
F ig . 16. Hybrid V igor in C. tin c to r ia .
C u ltiv ar: 'P etite P u r p le '.
Fig. 17. Hybrid Vigor in C. tln cto rta.
CultivanUnnamed dwarf?
-
108 -
Fig. 18. Hybrid Vigor in C. tinctoria.
^
Fj hybrid? Unnamed dwarf'1[female) x self-compatible
mutant (m ale).
-
109 -
F ig . 19. H ybrid V igor in C . tin c to r ia ,
C u ltiv a n s e lf - com patible m u ta n t.
SUMMARY AND CONCLUSIONS
Studies concerning variation in four annual species of the genus
Coreopsis revealed that there is considerable variation within and among
species in important horticultural tra its, such as plant height, plant width,
branching habit and size of the capitulum . Such variations may be of consider­
able importance to plant b ree d ers.
Diallel backcross and Fg studies revealed that three of the four species
(C. tinctoria, C. califorriica and C. bigelovii)have a m ultiallelic, monogenic
system of self- incompatibility. Pollen reaction was influenced by the sporophyte, which is expressed as obligatory dominance of "S" alleles in the
pollen grains. Dominance relationship between "S" alleles in the pistil was
v ariab le.
Cytological, bud pollination and stigma and style decapitation studies
have revealed norm al meiosis with secondary associations between different
bivalents present in all the four species. This phenomenon points out a
probable role of polyploidy associated with this genus. The stigma as the
site of pollen inhibition, is, exhibited in all four species. Distribution of "S"
gene products all through the pistil does not allow breakdown of self-incompati­
bility b a rrie r by stigma and style decapitation. Chromosome numbers for
th ree perviously unreported species have been determined.
Genetical and cytological studies show a strong correlation between the
-
111-
stigma as the site of pollen inhibition,associated with the sporophytic system
of self-incompatibility. Based on these observations it is suggested that.C .
calliopsidea has also a sporophytic system of self-incom patibility.
Self-incompatibility could be used with advantage in producing
hybrid
seeds. In C . tinctoria heterosis expresses itself in form of m ore (greater
number) buds and flowers in
hybrids than in p a ren ts. Fj hybrid seed
production on a commercial scale is feasible.
LITERATURE CITED
A llard, R. W.
1960. Principles of plant breeding.
New York: John Wiley & Sons. 485.pp„
A rasu, N. T .
1968. Self-incompatibility in angiosperm s. - A review.
Genetica 39: 1-25 .
A scher, P. D.
1966. A gene action model to explain gametophytic self-incompatibility.
Euphytica 15: 179-183.
A scher, P . D .
1971. The influence of RNA-synthesis inhibitors on in vivo pollen tube
growth arid the self-incompatibility reaction in Lilium IongifLorum
Thunberg.
T heor. AppL Genet, 41':' 75-78.
A scher, P. D, and 8 , J. Peloquin.
1970. Tem perature and the self-incom patibility reaction in Lilium longiRorum Thunb.
J. A m er. Soc. H ort. Sci. 95(5): 586-588 .
Atwood, S. S. and J. L. Brewbaker.
1950 . Multiple oppositional alleles in autoploid white clover.
Genetics 35: 653. (Abstract)
Bailey, L. H.
1949. Manual of cultivated plants most commonly grown in the continental
United States and Canada (revised edition).
New York: The Macmillan Com pany.. pp. 1002-1004.
Bateman, A. J;
1952. Self-incompatibility systems in angiosperm s. I. Theory.
Heredity 6 : 285-310.
Bateman, A. J.
1954. The diversity of incompatibility system's in flowering plants.
In;.W Congr. Lit. Bot. 138-145.
-
113-
Bateman, A. J.
'1955. Selfr-incompatibility systems in angiosperm s. HI. C ruciferae.
Heredity 9: 53-68 .
Beatus, R .
1934. Die Selbsterilitat von Cardamine p rate n sis.
Jah r. W iss. Bot. 80:457-504.
Boiler, C„ A.
1948. The effect of tem perature on the rate of pollen tube growth in
sweet cherry carp els. '
M .S. thesis, University of California (Davis).
Brewbaker, J. L.
1954. Incompatibility in autotetraploid Trifolium .repens:
I. Competition and self-compatibility.
Genetics 39: 307-316.
Brewbaker, J. L.
1957. Pollen cytology and- incompatibility systems in plants..
J. Heredity 48: 271-277.
■
•
'
Brewbaker, J. L.
1964. A gricultural genetics.
Englewood Cliffs: Prentice-Hall, Inc.
Britikov, E. A.., N. A. Musatova, S. V. Vladim irtseva and M . A. Protsenko.
1964. Proline in the reproductive system of plants.
In: Pollen physiology and fertilization (ed.: Linskens).
Amsterdam: North Holland PubL Co. pp. 77-85.
Chittenden, F . J. and P. M. Synge (eds.).
1956. The Royal Horticultural Society Dictionary of ,Gardening, ed. 2.
Oxford: Clarendon P re ss. pp. 543-544.
Chu, Y . - E . , H. Morishima and H.-I. Oka.
1969. Partial self-incompatibility found in Oryza perennis ssp. b arthii.
Jap. J. Genet..44(2): 225-229.
-
114-
Cope, F . W.
1958. Incompatibility in Theobroma cacao.
Nature;. 279.
Cope, F . W.
1962. The mechanism of pollen incompatibility in Theobroma cacao.
J. Heredity 17; 157-182.
Crane,
• M. B. .and
/ A. G. Brown.
1937. Incompatibility and sterility in the sweet cherry, Prunus avium L.
J. Pomol. H ort. Sci. 15: 86-116.
C rane, M. B- and W. J. C. Lawrence.
1952. The genetics of garden plants (ed. 4).
London: The Macmillan Company. 301pp.
Crawford, D. J.
1969. A new species of Coreopsis (Compositae) from Mexico.
Brittonia 21: 353-354.
Crawford, D. J.
1970a.Systematic studies on Mexican Coreopsis (Compositae). Coreopsis
mutica: Havonoid chem istry, chromosome numbers, morphology, .
and hybridization.
Brittonia 22 (2): 93-111.
Crawford, D. J.
1970b.Systematic studies on Mexican Coreopsis (Sect. Anathysana), with
special reference to the relationship between C . cyclocarpa and
C. pinnatisecta.
Bull. T orrey Bot. Club. 97: 161-167.
Crawford, D. J.
1971. Systematics of the Coreopsis petrophiloides-lucida- teotepecensis
complex=
A m er. J. Bot. 58 (4): 361-367.
Crowe, L. K.
1954. Incompatibility in Cosmos bipinnatus.
Heredity 8 : 1-11.
-115-
Crowe, L. K.
1964. The evolution of outbreeding in plants. I. The angiosperm s.
Heredity 19: 435-457.
Darlington, C. D. and A. Wylie.
1956. Chromosome atlas of flowering plants (ed. 2) .
London: George Allen & Unwin, Ltd. 519 pp.
Darwin, C. R.
. 1876. The effect of cross and self-fertilization in the vegetable kingdom.
New York: D. Appleton & Co. 352 pp.
Darwin, C. R.
1880. The different form s of flowers on plants of the same species.
New York: D. Appleton & Co. 482 pp.
De Nettancourt, D.
1969. Radiation, effects on the one locus-gametophytic system of self­
incompatibility in higher plants. (A review)
T h eo r. AppL Genet. 39 (5): 187-196.
E ast, E. M.
1926. The physiology of self-sterility in plants.
J. Gen. Physiol. 8 : 403-416.
E ast, E . .M.
1929. Self-sterility.
Bibliogr. Genet. 5: 331-370.
E a s t,-E . M. and A. J. Mangelsdorf.
1925. A new interpretation of'the hereditary behavior of self-sterile
plants.
P roc. Natl. Acad. U.S.A. 11: 166-171.
Em sw eller, S. L. and N. W., Stuart.
1948. Use of growth regulating substance's to overcome incompatibilities
in Lilium .
Proc. Amer.' Soc. H ort. Sci. 51: 581t589.
Everett, T . H. (ed.)
1960. New illustrated encyclopedia of gardening, vol. III.
New York: Greystone P re ss. pp. 473-474.
-116-
Fisher., R. A. and K. M ather.
1943. The inheritance of style length in Lythrum sa lic a ria .
Ann. Eugen.T2: 1-23.
Gel in, E. 0 . V.
1937. Embryologische und cytologtsche studien in Heliantheae - Coreopsidinae
Acta Horti' Berg. 11^6): 99-128'.' (> ?•••;.-.dir! ;
Ger ste l, D. V .
1950. Self-incompatibility studies in Guayule. II. Inheritance.
Genetics 35: 482-506.
Glenk,,H„ 0 .
1964. Untersuchungen uber die sexuelle Affinitat bei Oenotheren.
hi: Pollen physiology and fertilization (ed. Linskens) .
Amsterdam: North Holland Publ. Co. pp. 170-184.
Godley, E . G.
1955. Monoecy and incompatibility.
Nature 176:1176-1177.
Hecht, A.
1958 . Partial restoration of fertility in a sterile Oenothera mutant
following infection by a parasitic moth larva.
P roc. X hit. Congr. Genet. 2:118.
H erm sen, J. G. T.
1969. Frequencies of reciprocally compatible single, three-w ay and
double crosses as determined by the number of S homozygotes,
the number of lines per S-homozygote and the types of inheritance
of incompatibility in cruciferous c ro p s.
Euphytica 18 (2): 170-177.
Higuchi, H.
1968. Induction of pseudo-fertility by means of repeated pollination in
self-incompatible Petunia hybrida.
Jour. Jap. Soc. H ort. Sci. 37 (4): 349-356.
Hoffman, 0 .
1894. Compositae..
hi: Engler, K. and A. Prantl, Die Naturlichen Pflanzenfamilien,
IV(5): 87-391.
-
117-
Hughes, M. M. and E . B. Babcock.
1950. Self-incompatibility in Crepis foetida L. ssp. rhoedifolia (Bieb.)
Schinz et K eller.
Genetics 35: 570-588.
■ ■
Im rie, B. C.
1969. Studies of variability and self-incompatibility in Carthamus
fiavescens Spreng. and its genetic relationship to C. tinctorius L.
Bh.D ..dissertation, Uniyersity of California (Davis)..
Im rie, B. C. and P. F , Knowles.
1971. Genetic studies of self-incompatibility in Carthamus fiavescens Spreng.
Crop ScL (Madison) 11: 6-9.
Kakizaki, Y.
1930. Studies on the genetics and physiology of self and cross-incom pati­
bility in the common cabbage (Brassica oleracea L. v a r. capitata L.)
Jap..J. Bot. 5:133-208. La Cour, L. F .
1941. Acetic orcein.
'
. Stain Technol. 16:169-174.
Lewis, D.
1943. Physiology of incompatibility in plan ts. III. Auto-polyploids.
J. Genet. 45: 171-185.
Lewis, D. .
1944. Incompatibility in plants, its genetieal and physiological synthesis.
Nature 153: 575-582.
Lewis, D.
1947. Competition and dominance of incompatibility alleles in diploid
pollen.
Heredity I: 85-108.
Lewis, D.
1949. Incompatibility in flowering plants.
Biol. Rev. 24: 472-496.
-
118-
Lewis, D.
1954. Comparative incompatibility in angi os perms and fungi.
Advances Genet. 6 : 235-285.
Lewis, D.
.
1956. Incompatibility and plant breeding.
BrooMiaven Symp. Biol. 9: 89-100.
Lewis, D.
1958. Gene control of specificity and activity: Loss by mutation and
restoration by complementation.
Nature 182: 1620-1621.
Lewis, D.
1965. A protein dim er hypothesis on incompatibility.
P roc. XI hit. Congr. Genet. 3: 657-663.
Linskens, H. F.- •
1965. Biochemistry of incompatibility.
Prod. XI hit. Congr. Genet. 3: 629-636.
Lundquist, A.
1965. The genetics of incompatibility.
Proc. XI hat. Congr. Genet. 3: 637-647.
Luciano, A.-, M. L. Kinman and J". Di Smith.
1965. Heritability of self-incompatibility in the sunflower, Helianthus
: •arinuus L i
Crop Set. (Madison) 5: 529-532.
M artin, F . W.
1965. Incompatibility in the sweet potato: A review.
Econ. Bot. 19: 406-415.
Mayo, 0 .
1966. On the problem of self-incompatibility alleles.
Biometrics 22:111-120.
Melchert,. T . E . '
1968. Systematic studies in the Co reops idinae. Gytotaxonomy of Mexican
and Guatemalan Cosmos.
x
A m er. J. Bot. 55(3): 345-353.
-119-
Munz, P„ A. and D. D. Keck.
1959. A California flora.
Los Angeles: University of California P ress. 1681pp.
Naik, S. S. and B. S. Panda.
1968. Time of bud pollination in increasing fertility in self-incompatible
■ niger (Guizotia abyssinica).
Indian J. Sci. & Ind., Sect. A. (A gr.- Animal Sci.) 2(3/4): 177-180.
N asrallah, M. E. and D. H. Wallace.
1967a .Immunogenetics of self-incompatibility in Brassica oleracea L.
Heredity 22: 519-527.
N asrallah, M. E. and D. H. Wallace.
1967b.Immunochemical detection of antigen in self-incompatibility
genotypes of cabbage.
Nature 213: 700.
N asrallah, M. E ., J. T . Barber and D. H. Wallace.
1970. Self-incompatibility proteins in plants: detection, genetics and
possible mode of action.
Heredity 25(1): 23-27.
Odland, M. L. and C. J. Noll..
1950. The utilization of cross-incom patibility and self-incompatibility
in the production of Fj hybrid cabbage.
Proc. A m er. Soc. H ort. Sci. 55: 391-402.
Pandey, K. K.
1957. Genetics of incompatibility in Physalis ixocarpa Brot. A new system .
A m er. J. Bot. 44: 879-887,
Pandey, K. K.
. . .
1960. Evolution of gametophytic and sporophytic systems of self-incompati­
bility in angiosperm s.
Evolution 14: 98-115.
Pahdey, K. K.
1962. Genetics of incompatibility behavior in the Mexican Solanum
species, S. pinnatisectum .
Z. V ererbungsl. 93: 378-388.
I
-
120=
Pandey, K. K.
1967. Origin of genetic variability: Combinations of peroxidase
isozymes determine multiple allelism of the S gene.
Nature 213: 669
Pandey, K. K.
1970. Time and site of the S gene action, breeding system s and
relationships in incompatibility.
Euphytica 19: 364-372.
Powell, A. M. and B. L. T u rn e r.
1963. Chromosome numbers in the Compositae. VII. Additional species
from the southwestern U. S. and .Mexico.
Madrono 17:17-128-140.
P rell, H.
1921. Das Problem der Unbefrucht Barkeit. N aturw iss. Wochenschr. N .F . 20: 440-446.
Ramanamurthy, G. V.
1963. Relationships of cultivated safflower (Carthamus tinctorius L .)
to the wild species, C. oxyacantha M.B.
Ph.D. dissertation. University of California (Davis).
Reimann, P. R.
1965. The application of incompatibility in plant breeding.
P roc. X Int. Congr. Genet. 3: 649-656.
Safonov, V. I. and A. E. Veidenberg.
1969. Non-identity of proteins and enzyme system s is a factor of
physiological ,incompatibility of apple trees during crossing
and grafting. (In Russian, with English summary).
F iziol. R ast. 16 (5): 810-818.
Sampson, D. R.
1967. Frequency and distribution of self-incompatibility alleles in
Raphanus and Raphanistrum.
Genetics 56: 241-251.
Sears, E. R.
1937. Cytological phenomena connected with self-sterility in the flowering
plants.
Genetics 22:130-181.
-
121-
Shelton, L 0 A.
1968. An isolated species of Coreopsis on a granite monadnock.
Bull. T orrey Bot. Club 95:166-171.
Sherff> E . E.
■ 1936. Revision of the genus C oreopsis.
Field Mus.. Nat. Histo, Bot. S er. 11 (6): 279-475.
Sherff, E. E .
1955. The North American species of Coreopsis.
N. A m er. Flora II. 2: 4-40.
Smith, E. B., Jr.
1971. Personal communication, 19 July 1971.
Synge, P. M. (ed.)
1956. Supplement to the Royal Horticultural Society Dictionary of
' Gardening (ed.2 ) .
Oxford: Clarendon P ress, pp. 18, 186.
Synge, P. M. (ed.)
1969. Supplement II to the Royal Horticultural Society Dictionary
of Gardening, ed. 2.
Oxford: Clarendon P re ss. pp. 23, 244.
Tam misola, J. and A. Ryynanen.
1970. Incompatibility in Rubus arcticus L .
Hereditas 66 : 269-278.
Thompson, K. F.
1957. Self-incompatibility in marrow^stem kale, Brassica oleracea var.
acephala L . I. Demonstration of a sporophytic system .
J. Genet. 55: 45-60.
Thompson, K. F.
1964. T rip le-cro ss hybrid kale.
Euphytica 13: 173-177.
Townsend, C. E.
1966. Self-incompatibility response to tem perature and the inheritance
of response in tetraploid Alsike clover, Trifolium hybridum L;
Crop Sci. (Madison) 6 : 409-414.
-
122-
Townsend, C.-E.
1968. Self-incompatibility studies with diploid Alsike clover, Trifoliutn
hybridum L. i n . Response to tem perature.
Crop Set. (Madison) 8: 269-272.
Townsend, C. E.
1970. Inheritance of a self-compatibility response to tem perature and.
the segregation of S alleles in diploid Alsike clover, Trifolium
hybridum L.
Crop ScL (Madison)-10 (5): 558-563.
Tupy, J.
1964. Metabolism of proline in styles and pollen tubes of Nicotiana alata.
In: Pollen physiology and fertilization (ed .: Linskens).
Amsterdam: North Holland Publ. Co. pp. 86-94.
T urner, B. L;
1960. Meiotic chromosome numbers in Texas species of the genus Coreopsis
(Compositae - Heliantheae).
Southw. Naturalist 5:12-15.
T urner, B. L . , M. Powell and R. M. King.
1962 Chromosome numbers in the Compositae. Vi. Additional Mexican
and Guatemalan species.
Rhodora 69: 252-271
T u rn er, B. L. and D. F ly r.
1966. Chromosome numbers in the Compositae. X. North American
species.
A m er. J. Bot. 53(1): 24-33.
T urner, B. L ., A..M . Powell and J. C uatrecasas.
1967. Chromosome numbers in Compositae. XI. Peruvian species.
Ann. M issouri Bot. Card. 54(2): 172-177.
T urner, B. L. and R. M. King.
1964. Chromosome numbers in the Compositae. VIII. Mexican and Central
American species. .
Southw. Naturalist 9(1): 27-39.
-
123: -
Turner , B. L. and W. H. Lew is.
1965. Chromosome numbers in the Compositae. IX. African species.
J. South African Bot. 31(3): 207-217.
Van Der M eer, 0 . P. and M. Nieuwhof.
1968. Production of hybrid seed.using male sterility or self-incompatibility.
Euphytica 17: 284-288.
Wallace, D. H. and M. E. N asrallah.
1968. Pollination and serological procedures for isolating incompatibility
genotypes in the c ru c ife rs.
Cornell Univ. Agr.. Exp., Sta.' Mem. 406. 23 pp.
W illiams, W.
1964. Genetical principles and plant breeding.
Oxford: Blackwell Scientific Public. pp. 211-234.
.Wright,, Sewall
: 1964.. The distribution of- self-incompatibility alleles in populations.
Evolution 18: 609-619.
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Sharma, Jagan If
The genetics, nature
a n d occurrence of selfand cross incompatibility
in four annual species
of Coreonsis L________
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AMg AND AO PRK Sa