Lecture 6 - Gathering Variability Flashcards
where do different alleles come from
- mutations
- variation in chromosomes
- gene duplication
subfunctionalization
genes are inherited separately but perform a function together
neofunctionalization
new function generated
degeneration/gene loss
duplication is lost (often detrimental)
insufficient genetic variability leads to:
- genetic vulnerability
- limited potential for genetic improvement
bottlenecks
losing frequency of alleles
current issues reducing variability
- focus on uniformity to meet market requirements
- narrowing of the genetic base of many crop species due to the commercialization of plant breeding effort
process of genetic erosion
landraces –> pure-line cultivars/hybrids –> genetic diversity becomes limited –> occasional catastrophic losses
where to find variability for traits of interest
- elite material from your own program
- elite material from other breeders
- germplasm collections
- unselected populations
- wild relatives
hybridization and recombination
breeder crosses 2 parents in hopes of identifying superior recombinants
_________ is critical to hybridization and recombination
parent selection
field evaluation to use wild or un-adapted germplasm in a breeding program
- general adaptation
- agronomic characteristics
- quality characteristics
- disease nursery
why must wild or un-adapted germplasm be field evaluated before being incorporated into a breeding program
make sure it can actually grow here
what do you need to watch out for when using wild or un-adapted germplasm
- dilution of elite populations
- introduction of deleterious traits
- sterility
what to do if you cant find the right variation in your species
- interspecies gene transfer
- synthetic polyploids
- mutagenesis
- genetic engineering
interspecies gene transfer
- moving genes from a related species into your crop species
related species belong to _________
gene pools
types of gene pools
primary gene pools
secondary gene pool
tertiary/quaternary gene pool
primary gene pool
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
secondary gene pool
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
tertiary/quaternary gene pool
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
what do you do if you cant find the right variation in your species
interspecies gene transfer
synthetic polyploids
synthetic polyploids
triticale
resynthesized wheat
resynthesized canola
colinearity
means that the chromosome structure is very similar and align well
what is collinearity important
if it is not colinear, meiosis will be messy and often lethal
what do resynthesized genomes always contain
new gene combinations (new variability)
what do resynthesized genomes sometimes contain
- alternative splicing of genes
- methylation changes (epigenetic changes)
- homoeologous non-reciprocal translocations
(all lead to increased variation)
