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Plant Breeding at BOKU > All In One > Flashcards

All In One Flashcards

1
Q

Induced mutation approaches are non-transgenic and not regulated

A

True

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2
Q

Define general combining ability

A

The mean deviation of a hybrid from the overall mean of all hybrids tested in the experiment

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3
Q

Define specific combining ability

A

The deviation of the performance of a hybrid from what would be expected based on the GCA of its parents

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4
Q

Name and describe 2 methods for the production of hybrid seeds

A

1) Mechanical method: manual emasculation and crossing such as maize detassling.
2) Chemical method: Using a chemical hybridizing agent, called a gametocide, to chemically emasculate the egg-cell parent.

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5
Q

What breeding problems are associated with non-adapted genetic resources (wild relatives)?

A

Often needs pre-breeding, needing years to regain the yield of modern varieties, linkage drag, competition drag

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6
Q

What is CMS?

A

Cytoplasmic male sterility

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7
Q

You breed hybrid rye using CMS for hybrid seed production, must the male parent contribute restorer alleles?

A

Yes

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8
Q

You breed hybrid sugar beets using CMS for hybrid seed production, must the male parent contribute restorer alleles?

A

No

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9
Q

Name 2 methods for maintaining genetic resources

A

Ex-situ, such as a seed bank. In-situ, such as natural habitats

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10
Q

What is a synthetic cultivar?

A

Synthetic cultivars are based on an open pollination or targeted crossing of a limited number of parental units.

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11
Q

What is the breeding scheme for a synthetic cultivar?

A

Base population, pre-selection of parents, test crosses, GCA testing, inter-crossing of selected parental units, Syn-1, Syn-2

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12
Q

What are the advantages and disadvantages of hybrid cultivar?

A

Hybrid vigor of the F1 generation. Farmers are dependent on seed producers for seed, they can no longer, practically or legally, save their seed

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13
Q

What is genetic vulnerability?

A

Due to monocultures there exists a high risk of epidemics

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14
Q

What is genetic erosion?

A

Permanent loss of genetic material, often due to large scale monocultures in agriculture.

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15
Q

Describe and discuss selection for multiple traits.

A

Breeders often use an intuitive index based upon personal preference. First round of selection strict criteria are applied and undesirable line removes. Second round of selection, find the candidates with the best combination of traits.

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16
Q

The magnitude of an experimentally estimated heritability coefficient depends on which 3 factors?

A

1) The plant population under investigation, genetic variation.
2) The investigated trait.
3) The extent and conditions of testing

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17
Q

Describe the process for breeding open pollinated cultivars using mass selection.

A

The simplest breeding method. Select “nice” plants and grow them in the next generation, select, grow, select, grow.

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18
Q

Describe a typical procedure for breeding clonal cultivars.

A

1) One round of generative propagation. 2) Continue with vegetative propagation. 3) Generate new genotypes. 4) Selection of seedlings. 5) Selection of clones over several stages. 6) The clones remain genetically constant.

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19
Q

With what equation can we test expected gain by selection?

A 
R = I h σg
i = selection intensity
h = square root from heritability
σg = square root of genotypic variance
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20
Q

What is heterosis?

A

Vigor and productivity of the F1 generation which is often higher than the parental mean

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21
Q

What is indirect selection?

A

Improve one trait, but the goal is to improve another trait, this is because breeders rarely work with single traits, this can be challenging if the traits are conflicting

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22
Q

If a breeder can test his breeding line at infinite number of environments the heritability coefficient for the trait would be:

A

1, because at this intensity of testing all observed variance is due to genetics

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23
Q

Describe the procedure for breeding line cultivars.

A

A) Generate new variability by crossing parents
B) Then inbreeding
C) Selection of candidate cultivar

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24
Q

What are double haploids?

A

Double haploids (DH) are a genotype formed when haploid cells undergo a chromosome doubling.

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25
Q

Name 2 methods for producing double haploids

A

Production method 1: regeneration from haploid cells = gametes.
Production method 2: wide crosses resulting in fertilization, but foreign chromosomes are quickly eliminated, leading to a haploid embryo

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26
Q

Propagation systems in the plant kingdom, name them. Name some crops.

A

A) Cross pollination, allogamy, corn, sunflower
B) Partial cross or partial self-pollination, faba bean, cotton
C) Self-pollination, autogamy, wheat barley
D) Vegetative propagation, potato, taro

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27
Q

If for a specific trait GxE play a big role, but the breeder wants to make good progress, what do you recommend?

A

Test the breeding lines in several environments.

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28
Q

Define genotype frequency.

A

The frequency of genotypes in a population.

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29
Q

Define allele frequency.

A

A measure of the relative frequency of an allele on a genetic locus within a population.

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30
Q

Define fitness within population genetics.

A

Relative contribution of a genotype to a population.

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31
Q

Define selection within population genetics.

A

Different individuals contribute differently to the next generation, natural selection.

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32
Q

What is yield stability?

A

The variance of a genotype across multiple environments, the lower the variance the more stable.

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33
Q

Name and describe at least two ‘useful’ measures for stability a breeder
could apply

A

1) Static stability concept.

2) Dynamic stability concept

34
Q

Define static stability concept and dynamic stability concept.

A

Static stability concept: Variance of genotype that was tested over environments.
Dynamic stability concept: variance of a genotype but including average yield level of the testing environments.

35
Q

What is the selection differential? What is gain by selection? What is the relation between the two
parameters?

A

1) Selection differential is the phenotypic difference between selected group and population mean.
2) Gain by selection is the difference in the mean value of the selection criterion between the original
generation and the next generation, which is formed from only the selected individuals, when they are
compared in the same environment.

36
Q

What is meant with the term breeding value? How is the breeding value defined?

A

The value of an individual as a (genetic) parent.
The part of an individual’s genotypic value that is due to independent and therefore transmittable
gene effects. The value is not fixed because it is only an estimation based upon the genetics of an individual and those closely related to it.

37
Q

What is meant with complementary gene action?

Explain one example for complementary gene action in the sense of classical genetics.

A

Complementary gene action: When one trait is governed by two genes which must complement each other. For example, the red flower color in anthocyanin needs a precursor via several enzymatic steps. If one of these steps is blocked the flower remains white

38
Q

What measure is used for defining the distance between loci along a chromosome?

A

The unit of measurement is called Centimorgan, abbreviated to cM, after Thomas Morgan.
Experiment: Two loci are 1 cM apart when the recombination rate between these is 1% per meiosis event, thus 1 crossover per 100 meiosis events.

39
Q

Explain the impacts of plant breeding during the last 30 years in central Europe.

A

The impacts of plant breeding during the last 30 years in central Europe: 30% wheat yield increase due to improved cultivars. The projected yield increase must be 1.7% per annua to keep up with projected population growth.

40
Q

What is the typical reason a segregation event does not follow the expected ratio according to the rule of independent segregation?

A

Unexpected segregation ratios, such as 9:3:3:1, can be explained by interactions of different alleles, such as dominant and recessive, and interactions between several genes.

41
Q

When and by whom were Mendels Laws “rediscovered”?

A

Mendelian Laws were “rediscovered” “independently” in 1900 by de Vries, Correns and Erich von TS. Johannsen showed, in 1903, that the seed of beans varied continuously, being influenced by genetic and non-genetic factors.

42
Q

Explain intra-chromosomal recombination and inter-chromosomal recombination

A

Intra-chromosomal recombination: within the same chromosome, alleles are exchanged due to crossing over.
Inter-chromosomal recombination: During meiosis, it is chance which parental chromosome moves to which pole, and it is chance which gamete fertilize and form a zygote.

43
Q

What is the Green revolution?

A

The green revolution refers to a series of research, development and technology transfer initiatives, occurring between the 1940’s and the late 1970’s that increased agricultural production around the world. Criticism: It also had negative effects, for example, food security (socio-economic problems) environment (biodiversity), and health (agro-chemicals).

44
Q

Define narrow sense heritability and broad sense heritability.

A

Narrow sense heritability: Considers just the additive genetic variance, is typically used when we consider population improvement.
Broad sense heritability: Considers the total genetic variance, is typically used when we consider more or less fixed genotypes

45
Q

Under which mating system is the removal of excessive recessive alleles from a population very difficult?

A

Allogamy, because cross-fertilization results in a heterozygous population, therefore recessive alleles are able to hide in the population.

46
Q

What is a panmitic population? What mating system leads to this? Define.

A

A panmitic population is one where individuals are potential mating partners. This assumes, no mating restrictions, whether genetic or behavioral.

47
Q

What is migration in the sense of population genetics? And drift?

A

Migration is the transfer of alleles or genes from one population to another
Drift is variation in the different frequency of the various genotypes in a small population.

48
Q

Define Population genetics. Name 5 fundamental factors

A

Population genetics is a subfield of genetics that deals with genetic differences within and between populations. The fundamental factors are:
Mode of reproduction, migration, mutation, drift, and selection (MMMDS)

49
Q

Under which mating system is the removal of excessive recessive alleles easy?

A

Autogamy, because eventually all members become homozygous.

50
Q

What is inbreeding? What is the inbreeding coefficient?

A

Inbreeding results from mating two related parents.
Coefficient of inbreeding F, the probability, between 0 and 1, that genes at a randomly chosen location are identical by descent.

51
Q

What is epistasis in the context of quantitative genetics?

A

Epistasis is the phenomenon where the effect of one gene (locus) is dependent on the presence of one or more ‘modifier genes’.

52
Q

What is epistatic gene action, give an example?

A

The interaction of alleles between two or more loci influencing a specific trait. For example, dominant epistasis: A is epistatic over B and b, where A codes for the black color of beans, and B/b codes for white/brown color of beans, in these cases A is dominant of B and b.

53
Q

Define Genotype by Environment Interaction.

A

A genotypes interaction with the environment, for example, one genetic line may perform well in one environment and not in another.

54
Q

What is the typical genetic constitution of a population of wild autogamous plant species.

A

Highly homozygous individuals, but heterogenous population, such as an old landrace of wheat.

55
Q

What are two approaches to obtain “useful” estimates for heritability coefficients in a breeding population?

A

A) Genotypes tested in the same environments

B) Selection experiments

56
Q

Name and describe two methods with which you can induce mutations.

A

Radiation: Treating Drosophila with gamma radiation, these treatments can induce point mutations or deletions.
Chemical: These work by inducing point mutations, called transitions (A to G, G to A, T to C, C to T) or transversions (A to T or C, G to T or C, etc).

57
Q

In quantitative genetics, what are the parameters a and d?

A

If a>d>0, then dominance is partial.
If a=d, then dominance is classical.
If a

58
Q

A plant character is governed by two genes in an additive manner, which segregation ratio is likely in the F2?

A

The dominant alleles A and B are acting in an additive manner. For example, seed color in wheat, the parents are dark red and white, the F2 generation segregates into five color classes, white, slightly red, medium red, red, and dark red.

59
Q

When did plant breeding begin?

A

Plant breeding began around 10,000 years ago with the domestication of crop plants called the Neolithic revolution in the Fertile Crescent. Plant breeding as a scientific discipline is only 120-150 years old. The Assyrians crossed Palms 4,000 years ago. A bas-relief showing pollination of dates from 883 BC to 859 BC.

60
Q

What are some important crops and their origins?

A

Fertile Crescent known as Cradle of Agriculture, wheat and grains come from the Near East, Corn comes from Central America, Sunflower from North America, sweet potato, potato and yam from South America, yam and coffee from Africa, soybean from China, and banana, citrus, taro and rice from Southeast Asia.

61
Q

If one trait can be governed by two genes that can replace each other. What is the typical reason for such a situation? What is the expected segregation ratio at F2?

A

When one trait is governed by two genes which can replace each other, typically a duplicated gene action, in this case A can replace B and vice versa. F2 segregation is 15:1 when the parents are AABB and aabb.

62
Q

What are typical quantitative traits, and qualitative traits? B) Reason for quantitative trait variation.

A

A) Quantitative: grain yield, grain size, protein content, oil content.
Qualitative: dwarf-type, monocarpy.
B) Several to many genes contribute to trait variation, the expression of a trait is modulated by the environment.

63
Q

Define fixed environmental factors. Can these factors be accounted by a breeder?

A

Factors which are fixed in an experiment, for example, location of the trial, sowing density.
A breeder should select fixed factors which mimic the practices of farmers so that the product can be properly marketed to farmers.

64
Q

The effects of genes on quantitative traits can be in which 3 components?

A

The more genes contribute to a character the more quantitative it is.
The more a characteristic is modified by the environment the more quantitative it is.
The 3 components: main effect, interaction of alleles at one locus, interaction of alleles at 2 or more loci.

65
Q

Define random environmental factors.

A

Random, such as weather, drought, temperature, pests.

66
Q

What is the static and dynamic stability concept?

A

Static stability concept: Variance of a genotype tested over environments.
Dynamic stability concept: Variance of a genotype but including average yield level of the testing environments.

67
Q

What is Hardy Weinberg Equilibrium?

A

Is met under the following conditions: Random mating (in a panmictic populations), no change in allele frequencies, infinite population size.
Can only happen in a closed population where no alleles appear or disappear.

68
Q

Define Gene and Allele.

A

Gene: A unit of heredity which is transferred from a parent to offspring.
Allele: Each of two or more alternative forms of a gene that arise by mutation and are found at the same location on the chromosome.

69
Q

Tell me about Gregor Mendel.

A

Gregor Mendel, and Augustinian monk working in Brno, worked with peas. Published his results with pea-crosses in 1866 in Versuche an Pflanzen Hybriden.

70
Q

Estimated heritability coefficients can be between -100 and +100? Estimated heritability coefficients are a fixed constant in nature, H = 0,5? Estimated heritability coefficients can be between 0 and 1?

A

FALSE, FALSE, TRUE

71
Q

Define genotype and phenotype.

A

Genotype: The genetic constitution of an individual.
Phenotype: The observable characteristics of an individual.

72
Q

Define phenotypic value, and genotypic value.

A

Genotypic value: The mean value of a genotype under all conditions.
Phenotypic value: P = G + E + GE

73
Q

Why are breeders so interested in knowing about the heritability of traits in a breeding program?

A

Heritability is the proportion of total variation between individuals in a given population due to genetic variation, traits are ranked from 0 to 1. This rating allows a breeder to know if a characteristic is due to genetic variation or phenotypic variation.

74
Q

Summarize the findings of Mendel.

A

Mendel’s Laws: Law of Segregation, Law of Independent Assortment, Law of Dominance. Mendel counted traits in the F1 and F2 generations to develop his laws.

75
Q

Who first demonstrated that mutations could be induced in crop plants?

A

Lewis John Stadler

76
Q

Datasets show that mutagenesis with EMS causes primarily what type of mutations?

A

Point Insertions

77
Q

All mutagens have pretty much the same effect on the DNA sequence of plant genomes.

A

FALSE

78
Q

What are primary, secondary, and tertiary gene-pools?

A

Primary: The species itself
Secondary: Closely related species
Tertiary: Distantly related species

79
Q

What is a genetic bottleneck?

A

Are imposed on crop plants during domestication and breeding, reduces the number of allelic variation. These lost alleles can only be regained by going back to wild relatives.

80
Q

How many mutant crop varieties have been officially releases world-wide?

A

Between 3 and 300

Plant Breeding at BOKU (1 decks)

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