AN ABSTRACT OF THE THESIS OF
Doris A. Prehn for the degree of Master of Science in Crop and Soil Science
presented on December 20, 1993. Title: Analysis of Genetic Resistance to Barley
Stripe Rust (Puccinia strilformis f sp. horded.
Redacted for Privacy
Abstract approved:
Patrick M. Hayes
Stripe rust (Puccinia striiformis f. sp. hordei) is a serious disease of barley that can
cause up to 70% yield loss in susceptible varieties. The fungus is moving northward,
threatening major barley production areas in the US, where most cultivars are susceptible.
Fungicides are available for control of stripe rust, but economic and environmental
considerations favor genetic resistance. Two stripe rust resistance quantitative trait loci
(QTLs) located in chromosomes 4 and 7 have previously been reported. One hundred and
ten doubled haploid progeny from a stripe rust susceptible x resistant cross were derived
using the Hordeum bulbosum technique and phenotyped for agronomic and malting
quality traits in order to assess the importance of linkage drag associated with the mapped
stripe rust resistance QTLs. Data on 33 markers were combined with phenotypic data for
QTL analysis. A molecular marker-assisted backcross program was implemented to
initiate the transfer of the stripe rust resistance loci into susceptible US germplasm. No
negative QTLs for agronomic or malting quality traits were detected within or adjacent to
the intervals that were targeted for marker-assisted selection. A minor leaf rust resistance
QTL, however, was found adjacent to the stripe rust locus on chromosome 7. Linkage
drag in this region could operate in favor of the breeder. Epistatic interaction between the
two stripe rust resistance QTLs confirms the necessity of introgressing both chromosome
intervals.
Analysis of Genetic Resistance to Barley
Stripe Rust (Puccinia striiformis f. sp. hordei)
by
Doris A. Prehn
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Completed December 20, 1993
Commencement June 1994
APPROVED:
Redacted for Privacy
Associate Professor of Crop and Soil Scieri e in charge of major
Redacted for Privacy
Head of the Department of Crop and Soil Science
Redacted for Privacy
Dean of Graduate Sc
Date thesis is presented
Typed by
Doris A. Prehn
December 20, 1993
Acknowledgment
I would like to thank Dr. Patrick Hayes, my major professor, for his continuous support and
encouragement. He provided a challenging, honest, and friendly working environment. I thank
him for having confidence in me.
I would also like to thank Dr. Fuqiang Chen for sharing his valuable lab experience with me
and for providing data that was used in the preparation of this thesis.
I want to thank Dr. Andre Laroze, my husband, for helping with database management and
statistical analyses. I thank him for his patience.
Special thanks to Aihong Pan and Mary-Jo Lundsten for their friendship, for not letting me
give up. Thanks also to Donna Mulrooney for making those long lab hours enjoyable. Thanks to
all my friends within and outside the barley group that contributed, day-in day-out, to make this
experience meaningful and unforgettable.
Last but not least, I would like to thank Dr. Patrick Hayes for providing financial support.
TABLE OF CONTENTS
INTRODUCTION
1
MATERIALS AND METHODS
6
RESULTS AND DISCUSSION
9
CONCLUSIONS
15
FIGURES
17
TABLES
22
REFERENCES
28
LIST OF FIGURES
Figure
Page
1 a. Frequency distribution of stripe rust and leaf rust disease severity
in two spring barley genotypes and their doubled haploid progeny.
18
lb. Frequency distribution of agronomic traits in two spring barley
genotypes and their doubled haploid progeny.
19
lc. Frequency distribution of malting quality traits in two spring
barley genotypes and their doubled haploid progeny.
20
2. Epistatic interaction between stripe rust resistance loci on
chromosomes 4 and 7.
21
LIST OF TABLES
Table
1.
Means and ranges for stripe rust and leaf rust disease severity in
parents and the doubled haploid population in different environments.
2. Means and ranges for agronomic and malting quality traits in two
spring barley genotypes and their doubled haploid progeny.
Page
23
24
3. Location, LOD score, and r2 values for disease, agronomic, and
malting quality QTLs in the doubled haploid progeny of Bowman x
LBIran/Una8271//Gloria/Come.
25
4. QTL genotype differences for disease, agronomic, and malting
quality traits.
26
5. Number of larger value QTL alleles contributed by each parent
and multilocus r2 values for disease, agronomic, and making
quality traits.
27
6. Number of backcross lines with target marker genotypes in the
BC1 and BC2 generations of BSR41/Colter, where Colter is the
recurrent parent.
27
Analysis of Genetic Resistance to Barley
Stripe Rust (Puccinia striiformis f. sp. hordei)
INTRODUCTION
Barley (Hordeum vulgare L.) is a key component of agroecosystems in the western
US. The crop is threatened by barley stripe rust (causal agent Puccinia striiformis f. sp.
hordei West), as most cultivars in this region are highly susceptible. P. striiformis f. sp.
hordei, race 24, reached the Americas in 1975. Race 24 and its variants subsequently
spread throughout the region and by 1982 nearly all commercial barley growing areas
were infected. Yield losses attributable to the pathogen ranged from 30 to 70%. Barley
stripe rust reached Mexico in 1987, and rapidly spread northward. Stripe rust reached
Texas in 1991 and was reported in Colorado in 1992, and, Idaho and California in 1993.
Fungicides are available for control of stripe rust, but economic and environmental
considerations favor genetic resistance. Sources of resistance are available. The
underlying genetic mechanisms, however, are largely unknown. Five resistance genes
have been reported (yr, yr2, yr3, Yr4, and Yr5; Stubbs 1985). Yr4 is located on
chromosome 5 (von Wettstein Knowles, 1992), but it does not confer resistance to race
24. Chen et al. (1994) reported quantitative trait loci (QTLs) located on chromosome 4
and 7 that conferred resistance to field inocculum of unspecified race composition, but
2
presumed to be race 24, in Mexico. This was reported to be a quantitative type of
resistance, as progeny of a resistant x susceptible cross showed a continuous range of
trait expression, and some disease was observed on the resistant parent. This may
represent a horizontal, as opposed to a vertical, resistance mechanism and could be
expected to be durable (Vanderplank,
1978).
Johnson and Law
(1975)
defined durable
resistance as a resistance source that remained effective after widespread deployment
over a considerable period of time. A general concept of durable (or race-nonspecific)
resistance source for a cereal rust is as follows: (i) it may be controlled by more than a
single gene; (ii) it is more likely to operate at the adult-plant stage, and (iii) it confers a
non-hypersensitive response to infection.
Knowledge of the relationship between the number of loci conferring resistance and
disease severity could be useful in constructing gene pyramids. Kolmer et al.
(1991)
suggested a relationship between number and longevity of resistance genes in both stem
and leaf rust of wheat (Triticum aestivum). They concluded that wheat cultivars with
combinations of two or more effective adult plant, or adult and seedling, resistance genes
have retained higher levels of resistance than closely related wheat cultivars with single
resistance genes. However, Mundt (1990) demonstrated, in an example of the
combination of Sr6 with other resistance genes, that there are factors other than gene
number that are more closely associated with the durability of resistance. The
relationship between specific genes and durability remains unclear. Examining which
genes are present in resistant genotypes and studying how they interact can contribute
greatly to the development of disease control strategies.
3
Quantitative resistance is more difficult to manipulate in a breeding program than
monogenic resistance. This fact, coupled with the complications imposed by the need to
develop resistant germplasm for the western US prior to the arrival of the pathogen, led
Chen et al. (1994) to use molecular markers to locate resistance loci in the doubled
haploid (DH) progeny of a resistant x susceptible cross. The stripe rust resistant parent
was also known to be resistant to leaf rust (causal agent Puccinia hordei G. Otth). The
quantitative trait locus (QTL) analysis of the full population of DH lines identified one
resistance locus with a large effect, located on chromosome 7, and one with a smaller
effect on chromosome 4. The larger value QTL had a peak interval of 12 cM, which
accounted for 56% of the variation in disease severity. The QTL peak of the smaller
effect locus on chromosome 4 spanned a 32 cM interval and explained 10% of the
variation. Molecular marker-assisted introgression of these resistance loci into genotypes
adapted to the western US is a priority, but given the size of the introgressed intervals,
linkage drag is of a critical concern.
Genes introduced into cultivars by backcross breeding programs are flanked by
segments of DNA derived from the donor parent. This phenomena is known as 'linkage
drag' and is frequently thought to affect traits other than those originally targeted.
Brinkman and Frey (1977) introduced this concept while reporting yield component
differences in oat near-isogenic lines containing specific crown-rust resistance loci.
Apparently, yield factors closely associated with crown-rust reaction loci in the donor
parents were added to the recurrent parent background during backcrossing. Young and
Tanks ley (1989) analyzed the process of introgression by examining several cultivars of
4
tomato (Lycopersicon esculentum) derived from various breeding programs in which a
disease resistance locus (Tin-2) was introgressed from L. peruvianum. RFLP analysis of
chromosome segments introgressed with Tm-2 demonstrated that backcross breeding is
only moderately effective in reducing linkage drag around gene targets. The estimated
size of the introgressed fragments observed in these experiments ranged from 4 to 51 cM.
The length of the chromosome segment transferred depends on several factors such as the
site of the locus on the chromosome and the number of backcrosses. This length may be
greater than it is often assumed (Stam and Zeven, 1981). For instance, it was found that
in a 100 cM long chromosome the length of the transferred segment was 32 cM in BC6.
Molecular marker assisted selection can expedite backcrossing and minimize linkage
drag in bringing resistance factors from exotic germplasm into adapted backgrounds.
Young and Tanks ley (1989) have shown that, with appropriate markers, two generations
of RFLP-assisted backcrossing could reduce the segment flanking a target gene to only
2 cM. Using traditional backcross breeding, over 100 generations would be required to
obtain such a small segment of flanking DNA.
The introduction of exotic germplasm can also bring risks with respect to other
diseases that are normally minor. Leaf rust became an important problem on new stripe
rust resistant cultivars in Germany (Dubin and Stubbs, 1986). Yet, linkage drag can
operate in favor of the breeder when genes conferring resistance to different diseases are
joined together. Linkage of stripe rust and stem rust, and of stripe rust and leaf rust
resistance genes have been reported in wheat (Zeven et al., 1983; McIntosh, 1992).
5
The objectives of this study were, therefore, (i) to determine if there are QTLs for
agronomic and malting quality traits within, or adjacent to, the intervals defining the
resistance loci, (ii) if leaf rust resistance could be mapped within the available genotype
data, (iii) to determine if there is a relationship between the two stripe rust resistance loci
identified by Chen et al. (1994), and (iv) to initiate the transfer of these resistance loci
into susceptible US germplasm by means of a molecular marker-assisted backcross
program.
6
MATERIALS AND METHODS
The development of the genetic reference population and mapping strategy were
reviewed by Chen et al. (1994). Briefly, 110 DH lines were derived from the Fl of the
cross LBIraniUNA8271//Gloria Come///Bowman. The stripe rust susceptible parent, a
Bowman backcross derivative that putatively carries the yd2 gene for resistance to barley
yellow dwarf virus, was kindly provided by Dr. Jerry Franckowiak of North Dakota State
University. Bowman is a 2-row feed barley. The resistant parent is a stripe rust resistant
6-row feed barley developed by Dr. Hugo Vivar of the International Center for
Agricultural Research in Dry Areas (ICARDA). The first three parents in the pedigree
are all uncharacterized sources of resistance to stripe rust. This line is also reported to be
resistant to prevalent virulence types of leaf rust in Mexico. The DH population was
developed by the Hordeum bulbosum technique, as described by Chen and Hayes (1989).
The DH population was assessed for response to stripe rust in field tests at Toluca,
Mexico, in 1991 and 1992. In the first year each DH line was planted in a 3-m long, one
row plot. The following year, 5-m, two row plots were established at three planting dates.
Data were taken at flowering and grain filling. Disease severity was rated by the
modified Cobb scale (Melchers and Parker, 1922), which is based on the percentage of
leaf area affected by stripe rust on a whole plot basis.
The population was planted at Corvallis, OR in the summer of 1992 for preliminary
seed increase and malting quality assessment. Each genotype was represented by a 4-m,
7
one row plot. Malt analyses were performed on 90 g samples at the Cereal Crop Research
Unit (Madison, WI), as described by Tragoonrung et al. (1990). As a leaf rust epidemic
developed during the course of this investigation, each DH line was scored for leaf rust
reaction (rating based on Melchers and Parker, 1922).
In the summer of 1993, the DH population was grown at Klamath Falls and
Corvallis, OR. At each location, two-replicate randomized complete block designs were
used. Plot sizes were 7.4 in' at Corvallis and 6.3 m2 at Klamath Falls. Agronomic
practices, including seeding rate, fertilizer formulation and rate, weed control, and
irrigation scheduling were in accordance with recommended practices for each location.
Plots were combine-harvested. The following data was recorded at each location: grain
yield, lodging percentage, plant height, and heading date.
A total of 33 markers have been mapped in this population (Chen et al., 1994). Most
markers are on chromosomes 4 and 7, defining the two stripe rust resistance QTLs.
Single intervals were defined by pairs of markers on chromosomes 2, 5, and 6. Data on
the 33 markers were combined with phenotypic data for QTL analysis. Morphological
markers, such as spike type and rachilla hair, were scored visually or under a
stereo-microscope. The marker nomenclature is that used by Hayes et al. (1993) and
Kleinhofs et al. (1993). Linkage maps were generated with MAPMAKER 3.0 (Lander et
al., 1987).
QTL analyses were performed using two interval mapping procedures. First, data
were analyzed with QTL-STAT (B.H. Liu and S.J. Knapp, unpublished) to test
hypotheses regarding QTL x environment interaction. This procedure was described by
8
Hayes et al. (1993). Data were then analyzed with MAPMAKER/QTL (Paterson et al.,
1988).
The presence of additive x additive epistasis between the stripe rust loci was tested
by classifying individual genotypes for the marker intervals on chromosomes 4 and 7.
Only non-recombinant genotypes were used. The two locus interaction was tested based
on a Type III Sums of Squares GLM analysis (SAS Institute, 1988) of the severity data
for these genotypes.
A backcross breeding program was implemented to begin the development of stripe
rust resistant germplasm. A 6-row DH-line (BSR-41) that consistently showed low stripe
rust reaction during the two years of disease assessment in Mexico was chosen as the
resistance donor. The recurrent parent was the 6-row feed barley 'Colter'.
First backcross generation plants were grown in the greenhouse (in 18 cm pots, at 16
to 18 ° C, under a 16 hour light period). DNA was extracted from individual plants, at 4
weeks of age, and subjected to RFLP analysis, following the procedure described by
Chen et al. (1994).
BG123 and CD057 (spanning a 28 cM interval) were the target RFLP markers used
to select for stripe rust resistance on chromosome 7. Selection for resistance on
chromosome 4 was assisted by the markers ABG397 and Bmyl (spanning a 32 cM
interval). Only plants whose DNA showed the banding pattern characteristic to both pairs
of markers were backcrossed to 'Colter' again. The procedure was repeated on individuals
of the second backcross generation, advancing only those with target marker intervals to
a third cycle.
9
RESULTS AND DISCUSSION
Intense stripe rust epidemics in 1991 and 1992 in Mexico facilitated disease
assessment of the DH population used in this study (Table 1). The average disease
seventies were 59% in 1991 and 42% in 1992. Although there was considerable
between-year variation, the performance of individual lines was rather consistent in both
years, as indicated by a correlation coefficient (r) of 0.87. Planting dates did not
significantly affect disease severity (r = 0.90 ). The susceptible parent was rated from 70
to 90%, whereas the resistant parent consistently had a much lower infection, with a leaf
area covered by stripe rust lesions averaging 12 to 15%. The frequency distribution for
mean disease severity among the DH lines was continuous, ranging from 3 to 90%
(Figure 1 a). The frequency distribution of disease severity favors a quantitative model for
resistance.
The reaction of the DH population to a light epidemic of leaf rust enabled
differentiation of susceptible and resistant genotypes. The skewed frequency distribution
of disease severity suggests monogenic inheritance (Figure 1a).
Plant development was excellent in all of the field experiments. As expected, given
the diverse parentage of this population, there was considerable variation in phenotypic
trait expression. Population frequency distribution for agronomic traits, with the
exception of lodging, were essentially normal (Figure lb).
10
Grain yield of DH-lines ranged between 2214 and 4424 kg/ha (Table 2). Plant height
ranged from 70 to 114 cm. The average Julian heading date was 189 days, with a
difference of 13 days between the earliest and latest genotypes. The lodging data were
skewed, suggesting control by a major gene. In the analyses of variance of agronomic
traits, significant genotype by environment interaction was detected only for grain yield
(p < 0.01).
With the exception of kernel weight, malting quality traits showed normal
distributions (Figure 1c). Malt extract values ranged from 70.2 to 81.3%, grain protein
from 8.8 to 18.5% (data not shown), diastatic power from 63 to 180 (Degrees), and alpha
amylase ranged between 18.0 and 62.1 (20 degree units). These values indicate that
several DH lines had reasonably good malting quality, even though both parents are
classified as feed types. The kernel weight frequency distribution showed two peaks, at
32 mg and 50 mg, suggesting monogenic inheritance. This was expected, since the
population of DH lines was derived from a 2-row x 6-row cross. In this population 53%
of progeny are 6-row and 47% are 2-row.
Although significant genotype x environment interaction was detected in the analysis
of variance of grain yield (p = 0.0096), no QTL x environment interaction was detected
for any trait. QTL analyses were therefore conducted using MAPMAKER (Lander et al.,
1987). The analyses were performed on a 33-point linkage map developed by Chen et al.
(1994). In general, the linkage profile of these markers was parallel to existing barley
maps (Heun et al., 1991; Graner et al., 1991; Kleinhofs et al., 1993). The objective of
this investigation was not to map agronomic trait QTLs per se, but rather to determine if
11
linkage drag would be a problem when using molecular marker-assisted selection for the
resistance loci. The large size of the marker intervals that carry the resistance factors
could present problems in terms of linkage drag if important quantitative trait factors are
located within the same or adjacent regions. A number of QTL effects for agronomic,
and malting quality traits were detected and these are summarized in Tables 3 and 4.
Three yield QTL were detected with peaks at ABG387b- ABG458 on chromosome 6,
BCD265b- v on chromosome 2, and Hor2b- CD099 on chromosome 5. On chromosomes
6 and 2, the resistant parent contributed favorable alleles, while the susceptible parent
contributed the favorable allele on chromosome 5. A coincident QTL effect for plant
height, with Bowman contributing the higher value allele, was detected on chromosome
6. These same markers were used by Hayes et al. (1993), who reported a yield QTL in
this region in the cross of Steptoe x Morex, providing an example of orthologous QTLs.
In Steptoe x Morex the parents also contributed contrasting alleles for plant height and
yield. The yield effect on chromosome 2 was not surprising, as this interval is defined by
the v locus, which controls fertility of lateral florets, thus determining 2- versus 6-row
morphology. This pattern of QTL expression related to a single gene Mendelian locus (v)
underscores the complexity of traits such.as yield and may explain to some extent the
lack of response for yield selection in 2 row x 6 row crosses. LBIran/UNA8271//Gloria-
/Come contributed the favorable allele for grain yield at this interval, despite the fact that
the Bowman-BC contributed the favorable allele for kernel weight. LBIran/UNA8271//Gloria/Come contributed the higher lodging susceptibility allele, despite the fact that
Bowman had the larger value allele for plant height. No other QTL effects were detected
12
in the chromosome 5 interval, where Bowman contributed the favorable allele, and yield
effects were not detected in this interval by Hayes et al. (1993).
A heading date QTL was detected on chromosome 4, in the interval defined by
ABG397- Bmyl. Hayes et al. (1993) also reported a heading date effect in this region.
The chromosome 4 region is also of interest from the malting quality perspective.
Significant QTL effects for diastatic power (a measure of joint a and 13-amylase
activity) and alpha-amylase were detected in this interval and also by Hayes et al. (1993).
Bmyl is a known function clone for a 13-amylase locus (Kreis et al., 1987), providing an
additional example of orthologous QTL expression and coincident QTL effects and
known function genes.
Malt extract QTLs were identified at the same two intervals on chromosomes 6 and
2, where yield QTL effects were detected. Positive alleles were contributed by the
resistant parent in both cases.
The number of QTLs contributed by each parent, and their cumulative effects are
summarized in Table 5. Multilocus r2 values were estimated with MAPMAKER using
logarithm of odds (LOD) peaks. The susceptible parent (a 2-row feed barley) contributed
higher susceptibility alleles for both stripe and leaf rust. This parent also contributed a
positive yield allele, two alleles for increased height, and one for higher kernel weight.
The resistant parent (a 6-row feed barley) contributed two positive yield alleles, one
allele for increased lodging, and favorable alleles for malt quality (including two for malt
extract).
13
A leaf rust locus was mapped within the region of the major stripe rust resistance
locus on chromosome 7. This QTL accounted for 18% of the variation in leaf rust
severity. The peak (LOD = 4.4) was located toward the end of the linkage group, in a
11.2 cM interval defined by ABG387C and PRI68A. No agronomic or malting quality
QTLs were mapped to this region. The leaf rust resistance QTL was located immediately
downstream of the stripe rust locus. Jin et al. (1993), in a study of linkage between leaf
rust resistance genes and morphological markers in barley, located an incompletely
dominant gene, designated as Rph12, in the M arm of chromosome 7. The Rph12 locus
was found to be linked to the r (semismooth awn) and s (short rachilla hair) loci with
recombination values of 26.1 ± 2.3% and 39.5 ± 2.9%, respectively. The location of
Rph12 coincides with the QTL effect detected in this study.
When leaf rust data were analyzed as a discrete variable, i.e., as a marker genotype
for linkage map construction, the "locus" was linked to KSUA1A (LOD 7.0, distance 32
cM). This marker confers a complex banding pattern and is presumed to be located on
chromosome 1. Thus, the existence of another leaf rust resistance gene, probably located
on chromosome 1, is suspected.
Stripe rust data were examined for epistatic interactions. Based on a Type III Sums
of Squares GLM analysis, significant additive x additive epistasis (p < 0.05) was detected
between the two stripe rust loci. The epistatic interaction is illustrated in Figure 2. The
results of a series of t-tests substantiate the ANOVA results and indicate that when the
susceptibility allele was present on chromosome 7, the average disease severity of
genotypes with and without the resistance allele on chromosome 4 were not significantly
14
different. However, in the presence of the resistance allele on chromosome 7, genotypes
with the chromosome 4 resistance allele were significantly (p < 0.01) more resistant than
genotypes with the chromosome 4 susceptibility allele. The average disease severities of
these two populations of genotypes were 25% versus 44%, respectively.
The molecular marker-assisted selection performed on the first backcross generation
of BSR-41 (a DH line) x Colter resulted in 9 plants out of 77 with resistant parent alleles
at the flanking markers on both chromosomes 7 and 4 (Table 6). In the second backcross
generation 15/100 plants had resistant parent alleles at all flanking markers. The values
obtained are in line with expectations, considering the large sizes of these intervals (28
and 32 cM on chromosomes 7 and 4, respectively). The third cycle of molecular
marker-assisted selection is in progress.
15
CONCLUSIONS
No negative QTLs for agronomic or malting quality traits were detected within or
adjacent to the intervals that were targeted in marker-assisted selection for stripe rust
resistance. Thus, linkage drag should not be an issue as these chromosome regions are
backcrossed into adapted varieties. The epistatic interaction of the two stripe rust
resistance loci confirms the necessity of introgressing both QTLs, despite the small
individual effect of the chromosome 4 QTL.
Effective phenotypic selection for stripe rust resistance could be complicated by the
quantitative nature of trait expression. Although no negative QTL effects were detected
within or adjacent to the intervals bracketing the resistance loci, Hayes et al. (1993)
reported the presence of agronomic and malting quality traits elsewhere on these
chromosomes. As demonstrated by Young and Tanks ley (1989), backcrossing
exclusively based on phenotype can lead to the introgression of large chromosome
segments. Orthologous QTL effects were seen for yield and height on chromosome 6 and
heading date on chromosome 4. Linkage drag could be an issue if large regions were
inadvertently introgressed.
A positive yield QTL was detected on chromosome 2. The presence of this yield
effect was not surprising, as the interval in this region was defined by the v locus, which
controls fertility of lateral florets, thus determining 2- versus 6-row morphology.
16
A minor leaf rust resistance QTL was located downstream of the stripe rust locus on
chromosome 7. Linkage drag in this region could operate in favor of the breeder. The
existence of another leaf rust resistance gene, probably on chromosome 1, is suspected.
These considerations, together with the pressing need to develop stripe rust resistant
varieties, warrant the expense and logistics of the molecular marker-assisted selection
backcrossing effort. Finally, these analyses underscore the effectiveness of traditional
plant breeding, as employed in the ICARDA program based at CIMMYT (Mexico), in
developing multiple resistance trait genotypes.
17
FIGURES
LEAF RUST
STRIPE RUST
60
60
50
50
40
40
30
30
20
20
10
10
0
0
7
17
27
37
47
57
Disease severity (%)
67
77
87
0.0
2.5
4.5
7.5
10.5
13.5
16.5
19.5
22.5
25.5
28.5
Disease severity (%)
Figure 1 a: Frequency distribution of stripe rust and leaf rust disease severity in two spring barley genotypes and their doubled
haploid progeny
GRAIN YIELD
LODGING
40
80
Resistant
Susceptible
70
30
60
50
C 20
40
z30
10
20
10
0
2250
2550
2850
3150
3450
Yield (kg/ha)
3750
4050
0
4350
0
5
15
25
35
HEIGHT
65
55
75
85
HEADING
35
30
45
Lodging (%)
40
Resistant
30
25
4., 20
Susceptible
20
1 15
z
z
10
10
5
0
72.5
77.5
82.5
87.5
92.5
97.5
102.5
107.5
112.5
Height (cm)
Figure lb: Frequency distribution of agronomic traits in two
0
181
183
185
187
189
191
193
195
197
Heading (days)
barley genotypes and their doubled haploid progeny
KERNEL WEIGHT
ALPHA-AMYLASE
35
30
Resistant
25
0
20
15
Susceptible
10
5
26
30
34
46
Kernel weight (mg)
38
42
50
54
58
0
18
22
=
26
30
DIASTATIC POWER
35
30
30
0
Resistant
Susceptible
11
34
38
42
46
50
Alpha-amylase (20 Deg units)
54
58
62
79.5
80.5
81.5
MALT EXTRACT
35
25
111111
Susceptible]
25
20
IResistanT1
20
0....
15
115
10
10
5
5
0
65
75
85
95
105
115
125
135
Diastatic power (Deg)
145
155
165
175
185
0
70.5
71.5
72.5
73.5
74.5
75.5 76.5 77.5
Malt extract (%)
78.5
Figure 1 c: Frequency distribution of malting quality traits in two spring barley genotypes and their doubled haploid progeny
Figure 2: Epistatic interaction between stripe rust resistance loci
on chromosomes 4 and 7
80
+ Susceptible on chromosome 4
0 Resistant on chromosome 4
70
60
50
40
30
20
1
1
Resistant
Susceptible
Chromosome 7
22
TABLES
23
Table 1: Means and ranges for stripe rust and leaf rust disease severity in parents
and the doubled haploid population in different environments
Disease
Parents /1
Susceptible
Resistant
DH Population
Mean
Range
Stripe rust
1991
1992
90
70
15
12
59
42
5
Average
80
13
50
3 - 87
20
0
6
0 - 30
2
90
90
Leaf rust
1992
/1: Susceptible = Bowman derivative; Resistant = LBIran/Una8271//Gloria/Come
24
Table 2: Means and ranges for agronomic and malting quality traits in two spring barley
genotypes and their doubled haploid progeny
Trait
Bowman
derivative
Parents
LBIran/Una8271
//Gloria/Come
Mean
DH Progeny
Range
Yield (kg/ha)
3708
4089
3403
2214
4424
Lodging (%)
0.0
10.0
17.0
0.0
88.0
Height (cm)
95.0
86.0
89.0
70.0
114.0
Heading date (days)
188.0
193.0
189.0
183.0
196.0
Kernel weight (mg)
48.1
37.0
40.2
25.4
57.9
Alpha-amylase (20 Deg units)
32.8
38.0
41.3
18.0
62.1
Diastatic power (Deg)
82.0
122.0
108.7
60.0
180.0
Malt extract (%)
77.2
76.4
76.7
70.2
81.3
25
Table 3: Location, LOD score, and r2 values for disease, agronomic, and malting quality QTLs
in the doubled haploid progeny of Bowman x LBIran/Una8271//Gloria/Come
Trait
Chromosome
2
Yield
Lodging
Height
Kernel weight
Malt extract
LOD score
r2
3.0
0.12
0.28
0.39
0.78
0.16
7.3
11.7
34.6
3.7
Stripe rust
Heading
Alpha-amylase
Diastatic power
2.2
4.3
2.7
9.3
0.10
0.24
0.11
0.33
5
Yield
2.3
0.10
6
Yield
Height
Malt extract
5.5
6.0
0.21
0.23
0.12
4
7
Stripe rust
Leaf rust
2.8
15.1
4.4
0.56
0.18
Table 4: QTL genotype differences for disease, agronomic, and malting quality traits /1
Chromosome
Marker interval
Length
(cM)
Stripe rust
(%)
Leaf rust
( %)
Yield
(kg/ha)
Lodging
Height
(%)
(cm)
350R
24R
11S
Heading date
(days)
Kernel weight Alpha-amylase Diastatic power
(20 Deg units)
(Deg)
(mg)
Malt extract
(%)
Chromosome 2
BCD265b
Spike type-v
17.0
ABG472
ABG54
19.0
15.9
1.6R
16.3S
Chromosome 4
BCD265a
ABG472
ABG54
WGI I 4
ABG498
MWG652
ABG397
WGI I 4
ABG498
MWG652
ABG397
0.0
0.9
0.0
8.3
Brhy I
28.1
CD099
15.7
ABG378
ABG387B
ABG458
27.0
WG364b
KSUA I b
11.1
KSUA I b
Rachi
BCD402
0.0
0.9
0.0
8.2
20.3
2.6
3.7
11.2
8.4
6S
12S
12S
12S
12S
13S
14S
2.4R
3.1R
4.4R
26.9R
Chromosome 5
Hor2B
315S
Chromosome 6
ABG466
ABG378
ABG387B
10.0
465R
14.8
6S
9S
Chromosome 7
Rachi
BCD402
ABC I 68
CDO 57
Ale
BGI 23
ABG387C
PRI68A
ABC] 68
CD05 7
Ale
BGI 23
ABG387C
PRI68A
ABC I 64b
5S
32S
7S
6S
7S
7S
7S
/1: Values in bold indicate LOD peaks, adjacent values indicate the confidence interval, and the letter suffix indicates the parent contributing the larger value allele: S, 'susceptible' (Bowman
derivative), R, 'resistant' (LBIran/Una8271//Gloria/Come).
0.8R
1.4R
27
Table 5: Number of larger value QTL alleles contributed by each parent and multilocus
r2 values for disease, agronomic, and malting quality traits
Susceptible
parent /1
Trait
Stripe rust
Leaf rust
2
Yield
Lodging
Height
Heading date
1
Resistant
parent /2
0.65
0.18
1
0.37
0.28
0.52
0.24
2
1
2
1
Kernel weight
Alpha-amylase
Diastatic power
Malt extract
Multi locus r2
0.78
0.11
0.33
0.22
1
1
1
2
/1: Bowman derivative
/2: LBIran/Una8271//Gloria/Come
Table 6: Number of backcross lines with target marker genotypes in the BC1 and
BC2 generations of BSR41/Colter, where Colter is the recurrent parent
Chromosome
Marker interval
(n = 77)
BC2
(n = 100)
BC1
4
CD057-BG123
36
37
7
ABG397-Bmyl
27
31
9
15
4&7
28
REFERENCES
Brinkman, M.A., and K.J. Frey. 1977. Yield-component analysis of oat isolines that
produce different grain yields. Crop Science 17:165-168.
Chen, F., and P.M. Hayes. 1989. A comparison of Hordeum bulbosum -mediated haploid
production efficiency in barley using in vitro floret and tiller culture. Theor. Appl.
Genet. 77:701-704.
Chen, F.Q., D. Prehn, P.M. Hayes, D. Mulrooney, A. Corey, and H. Vivar. 1994.
Mapping genes for resistance to barley stripe rust (Puccinia striiformis f. sp. hordei).
Theor. Appl. Genet. (in press).
Dubin, H.J., and R.W. Stubbs. 1986. Epidemic spread of barley stripe rust in South
America. Plant Disease 70:141-144.
Graner, A., A. Jahoor, J. Schondelmaier, H. Siedler, K. Pillen, G. Fischbeck, G. Wensel,
and R.G. Hellmann. 1991. Construction of an RFLP map of barley. Theor. Appl.
Genet. 83:250-256.
Hayes, P.M., B.H. Liu, S.J. Knapp, F. Chen, B. Jones, T. Blake, J. Franckowiak, D.
Rasmusson, M. Sorrels, S.E. Ullrich, D. Wesenberg, and A. Kleinhofs. 1993.
Quantitative trait locus effects and environmental interaction in a sample of North
American barley germplasm. Theor. Appl. Genet. (in press).
Heun, M.,A.E. Kennedy, J.R. Anderson, N.L. Lapitan, M.E. Sorrells, and S.D. Tanksley.
1991. Construction of a restriction fragment length polymorphism map for barley
(Hordeum vulgare). Genome 34:437-447.
Jin, Y., G.D. Statler, J.D. Franckowiak, and B.J. Steffenson. 1993. Linkage between leaf
rust resistance genes and morphological markers in barley. Phytopathology
83:230-233.
29
Johnson, R., and C.N. Law. 1975. Genetic control of durable resistance to yellow rust
(Puccinia striiformis) in the wheat cultivar Hybride de Bersee. Ann. App. Biol.
81:385-391.
Kleinhofs, A., A. Kilian, M.A. Saghai Maroof, R.M. Biyashev, P.M. Hayes, F.Q. Chen,
N. Lapitan. A. Fenwick, T.K. Blake, V. Kanazin, E. Ananiev, L.Dahleen, D.
Kudrna, J. Bollinger, S.J. Knapp, B. Liu, M. Sorrel ls, M. Heun, J.D. Frankowiak, D.
Hoffman, R. Skadsen, B.J. Steffenson. 1993. A molecular, isozyme and
morphological map of the barley (Hordeum vulgare) genome. Theor. Appl. Genet.
(in press).
Kolmer, J.A., P.L. Dyck, and A.P. Roelfs. 1991. An appraisal of stem and leaf rust
resistance in North American hard red spring wheats and the probability of multiple
mutations to virulence in populations of cereal rust fungi. Phytopathology
81(3):237-239.
Kreis, M., M. Williamson, B. Buxton, J. Pywell, J. Hejgaard, and I. Svendsen. 1987.
Primary structure and differential expression of 0-amylase in normal and mutant
barleys. Eur. J. Biochem. 169:517-525.
Lander, E.S., P. Green, J. Abrahamson, A. Barlow, M.J. Daly, S.E. Lincoln, and L.
Newburg. 1987. MAPMAKER: An interactive computer package for constructing
primary genetic linkage maps of experimental and natural populations. Genomics
1:174-181.
McIntosh, R.A. 1992. Close genetic linkage of genes conferring adult-plant resistance to
leaf rust and stripe rust in wheat. Plant Pathology 41:523-527.
Melchers, L.E., and J.H. Parker. 1922. Rust resistance in winter wheat varieties. US Dep.
Agr. Bull. 1046.
Mundt, C.C. 1990. Probability of mutation to multiple virulence and durability of
resistance gene pyramids. Phytopathology 80(3):221-223.
Paterson, A., E. Lander, S. Lincoln, J. Hewitt, S. Peterson, and S. Tanksley. 1988.
Resolution of quantitative traits into mendelian factors using a complete RFLP
linkage map. Nature 335:721-726.
30
SAS Institute. 1988. SAS/STAT user's guide 603. SAS Insti., Cary, NC.
Stam, P., and A.C. Zeven. 1981. The theoretical proportion of the donor genome in
near-isogenic lines of self-fertilizers bred by backcrossing. Euphytica 30:227-228.
Stubbs, R.W. 1985. Stripe Rust. p. 89-91. In The Cereal Rusts. Vol. 2. Academic Press,
New York.
Tanks ley, S.D., N.D. Young, A.H. Paterson, and M.W. Bonierbale. 1989. RFLP
mapping in plant breeding: New tools for an old science. Bio/Technology 7:257-264.
Tragoonrung, S., P.M. Hayes, and B.L. Jones. 1990. Comparison of hill and row plots
for agronomic and quality traits in spring malting barley (Horde= vulgare L.). Can.
J. Plant Sci. 70:61-69.
Vanderplank, J.E. 1978. Genetic and molecular basis of plant pathogenesis.
Springer-Verlag Berlin, Heidelberg, New York.
von Wettstein-Knowles, P. 1992. Cloned and mapped genes: current status. p. 73-98. In
Shewry, P.R. (ed) Barley: Genetics, biochemistry, molecular biology and
biotechnology. CAB International, Wallingord, UK.
Young, N.D., and S.D. Tanks ley. 1989. RFLP analysis of the size of chromosomal
segments retained arround the Tm-2 locus of tomato during backcross breeding.
Theor. Appl. Genet. 77:353-359.
Zeven, A.C., D.R. Knott, and R. Johnson. 1983. Investigation of linkage drag in near
isogenic lines of wheat by testing for seedling reaction to races of stem rust, leaf rust
and yellow rust. Euphytica 32:319-327.