Plant Science 446/546
Class Test February 18, 1998
9:30 to 10:20
Ag.Sci Room 339
Name :
Answer all 8 questions
A bonus question is available for an extra 5 points
A total of 100 points are available
Points available from each part of each question
are shown in bold square parenthesis
Try to be as brief and concise as possible
Please write in a legible form
Show any working/calculations
Make sure that any additional paper used
1
is attached to the questionnaire
2
1a.
The transition of mankind from a hunter/gatherer to a farmer involved: (1)
domestication of livestock, and (2) domestication of crops. Which (livestock or
crops) did humans domesticate first? Explain your answer [10 points].
1b.
A combination of natural selection and selection directed by plant breeders (early
and modern), has influenced the crops we now grow. List five characters that
mankind has selected for which would not have been selected by a natural evolution
process [5 points].
1.
2.
3.
4.
5.
2a.
In order to produce a hybrid cultivar using cytoplasmic male sterility you require
three types of genotypes. Describe the difference between the three types required
[4 points].
2b.
You are to embark on a backcrossing study designed towards convergence breeding.
You have at your disposal two genotypes coded C and M. Genotype C is a
cytoplasmic male sterile line, but one that does not have very good hybrid
combining ability; genotype M has great hybrid combining ability and is male fertile
(without a male fertile restorer gene). Design a scheme (listing each operation
necessary) that will result in a genotype which is 95% the genotype of the M line but
is cytoplasmic male sterile [6 points].
3a.
Briefly outline the main features of a crop species that would allow you to design a
breeding program to develop a Hybrid, synthetic, multiline, pure-line and clonal
cultivar. List one species which would be appropriate to develop cultivars of each
type [20 points]:
a.
A hybrid cultivar
Features:
Suitable crop species:
b.
a synthetic cultivar
Features:
Suitable crop species:
3
c.
a multiline cultivar
Features:
Suitable crop species:
d.
A pure-line cultivar
Features:
Suitable crop species:
e.
A clonal cultivar
Features:
Suitable crop species:
4a.
4c.
Explain the main features of the two mechanisms for plant resistance in plant
breeding [6 points].
a.
Resistance to inhibition of infection:
b.
Resistance to inhibition of subsequent growth after infection:
Four single, dominant, genes (Coded, A, B, C, and D) have been identified each
which offers complete immunity to a specific race of powdery mildew. Virulence
genes have also been identified in the pest (a, b, c, and d). Given the information
below, indicate whether each genotype would be resistant or susceptible to the
disease [4 points].
Genotype 1.
Genotype 2.
Genotype 2.
Genotype 3.
5a.
Genotype of
the plant
AaBBccdd
aabbccDD
AabbCCDd
AABBCCDD
Genotype of
the pest
aaBbCCdd
AAbbCCdd
aaBBccdd
aabbccdd
Plant
response
You have recently been appointed as consultant to a large plant breeding company
with a whopping great salary, great benefits and wonderful pension fund (aren't you
glad that you did this course now?). The company wants to develop a breeding
program to develop superior peach cultivars. Outline five points you will consider
before setting your breeding objectives [5 points].
1.
2.
4
3.
4.
5.
5b.
Briefly indicate factors you would consider if asked to design a taste test to
determine which of your top three peach breeding lines had best organoleptic
characters [5 points].
6.
Describe the difference between a pedigree breeding scheme, a bulk breeding
scheme, and a pedigree/bulk breeding scheme, and outline the advantages and
disadvantages that each breeding scheme would offer for developing superior spring
wheat cultivars [12 points].
7a.
List five different plant parts that can be responsible for asexual reproduction [5
points].
1.
2.
3.
4.
5.
7b.
List three disadvantages associated with breeding clonal crops [3 points].
1.
2.
3.
7b.
Mass selection and recurrent phenotypic selection are often used in developing outpollinating cultivars. Describe the main difference between the selection methods
and indicate any problems that each selection method could have in a breeding
program [5 points].
8.
You are walking along a deserted beach in Southern California (are there any of
these left) and you inadvertently kick a brass oil lamp. On picking up the lamp you
gently rub the side and - poof! - out appears a 20 foot tall genie. "Oh master!" says
the genie," I can grant you two wishes" (well times are hard and the old three wished
thing does not apply any more). You think for a few minutes then say "I would like
you to conjure me up the most wonderful plant that exists within the Universe, so
that I can grow it on my farm in Idaho and make millions of dollars in profit". Poof!
this plant appears before you. A plant species that has never appeared on earth
before.
5
As a plant breeder, list five questions you would ask the genie about the biology of
this plant that would help you design a cultivar development program to increase the
value of it's crops [5 points].
1.
2.
3.
4.
5.
Having sorted that out, you begin to think of your other wish. "I would like you to
tell me the formula for a chemical apomict" (a chemical, when applied to a crop will
result in 100% apomictic seed from the crop). "Well" says the genie. "I can do this,
but, you must specify which crop species the chemical will work on (it can only
work on one chosen species)". What crop species would you chose to have
apomictic seeds, and why? [5 points].
Bonus Question
What is the most likely center of origin of the following crop species [5 bonus points].
Species
Brassica napus, Canola
Sorghum bicolor, Sorghum
Musa, Banana
Glycyrhiza glabra, Liquorice
Helianthus, Sunflower
Center of origin
-
6