Lecture 6 - Gathering Variability

Question 1

where do different alleles come from

Answer 1

• mutations
• variation in chromosomes
• gene duplication

Question 2

subfunctionalization

Answer 2

genes are inherited separately but perform a function together

Question 3

neofunctionalization

Answer 3

new function generated

Question 4

degeneration/gene loss

Answer 4

duplication is lost (often detrimental)

Question 5

insufficient genetic variability leads to:

Answer 5

• genetic vulnerability
• limited potential for genetic improvement

Question 6

bottlenecks

Answer 6

losing frequency of alleles

Question 7

current issues reducing variability

Answer 7

• focus on uniformity to meet market requirements
• narrowing of the genetic base of many crop species due to the commercialization of plant breeding effort

Question 8

process of genetic erosion

Answer 8

landraces –> pure-line cultivars/hybrids –> genetic diversity becomes limited –> occasional catastrophic losses

Question 9

where to find variability for traits of interest

Answer 9

• elite material from your own program
• elite material from other breeders
• germplasm collections
• unselected populations
• wild relatives

Question 10

hybridization and recombination

Answer 10

breeder crosses 2 parents in hopes of identifying superior recombinants

Question 11

_________ is critical to hybridization and recombination

Answer 11

parent selection

Question 12

field evaluation to use wild or un-adapted germplasm in a breeding program

Answer 12

• general adaptation
• agronomic characteristics
• quality characteristics
• disease nursery

Question 13

why must wild or un-adapted germplasm be field evaluated before being incorporated into a breeding program

Answer 13

make sure it can actually grow here

Question 14

what do you need to watch out for when using wild or un-adapted germplasm

Answer 14

• dilution of elite populations
• introduction of deleterious traits
• sterility

Question 15

what to do if you cant find the right variation in your species

Answer 15

• interspecies gene transfer
• synthetic polyploids
• mutagenesis
• genetic engineering

Question 16

interspecies gene transfer

Answer 16

• moving genes from a related species into your crop species

Question 17

related species belong to _________

Answer 17

gene pools

Question 18

types of gene pools

Answer 18

primary gene pools
secondary gene pool
tertiary/quaternary gene pool

Question 19

primary gene pool

Answer 19

the genetic variation in the breeding population of a species and closely related species that commonly interbreed with, or can be routinely crossed with, the species

Question 20

secondary gene pool

Answer 20

the genetic variation in the breeding populations of related species that can be crossed with the species but usually only in one direction or requiring embryo rescue

Question 21

tertiary/quaternary gene pool

Answer 21

the genetic variation in the breeding populations of related species that can be crossed with the species but intervention of more than just embryo rescue is necessary

Question 22

what do you do if you cant find the right variation in your species

Answer 22

interspecies gene transfer
synthetic polyploids

Question 23

synthetic polyploids

Answer 23

triticale
resynthesized wheat
resynthesized canola

Question 24

colinearity

Answer 24

means that the chromosome structure is very similar and align well

Question 25

what is collinearity important

Answer 25

if it is not colinear, meiosis will be messy and often lethal

Question 26

what do resynthesized genomes always contain

Answer 26

new gene combinations (new variability)

Question 27

what do resynthesized genomes sometimes contain

Answer 27

- alternative splicing of genes - methylation changes (epigenetic changes) - homoeologous non-reciprocal translocations (all lead to increased variation)