Lecture 21 - Hybrids of Various Sorts Flashcards
upsides of F1 hybrids
increased vigour and enhanced performance
downsides of F1 hybrids
must isolate, need 2 programs (male and female), more expensive
synthetic variety
mixture of genotypes maintained by open pollination/random mating for a limited # of generations (genetically heterogeneous)
how are parents selected in synthetic varieties
based on GCA
how many parents are used in synthetic varieties
no more than 16 parents
steps for generating synthetic varieties
- identify components/parents
- polycross and test (get rid of bad offspring/parent)
- random mating to start seed production in isolation
- seed is harvest and grown again to randomly mate and repeated until there is enough seed (heterozygote individuals)
why are synthetic variety population SYN0 grown in isolation
because they are outcrossers, so you dont want outsider pollen
can seed be reused from synthetic varieties
yes, but you lose heterosis
when are synthetic varieties used as an alternative to hybrids
- for crops that dont have effective pollination control system
- for crops that experience severe inbreeding depression
-hybrid seed is not economically feasible
clonal propagation
plants are derived through mitosis not meiosis and allow retention of heterosis
when are clones used instead of hybrids
-poor seed set or only produce under certain conditions
-heterozygote parents (every offspring is different)
- high levels of inbreeding depression
- species difficult to cross
-species with high ploidy
what does the lack of sexual production in clonal propagation lead to
-reliance on older varieties
- lack of genetic diversity
- challenges with germplasm preservation (storage)
is every clone identical
not always, as mutations with small effects can effect it and somaclonal variation can change it (epigenetics)
why should you buy new stocks when using clonal propagation
- they are disease free
- latest variety (better)
- intellectual property rights
apomixis
plant embryos develop without fertilization and seed is entirely of maternal orgin
potential value of apomixis
- able to maintain/fix heterosis across generations, decreasing seed production costs in hybrids and making the process easier
steps to registering a variety
- cooperative/private registration testing of line
- recommendation of line for registration to CFIA
- submit documentation to officially register line
- breeder seed and pedigreed seed/clone production
- documentation for plant breeder rights
who handles the registration testing
17 recommending committees that are recognized by CFIA
what does the seeds act do
-prohibits the sale of seed of unregistered varieties of most field crops in canada
- recognized recommending committees
-recognizes Canadian seed growers association as official Canadian seed pedigree agency
what is the official canadian seed pedigree agency
canadian seed growers association
how to deal with non-schedule 3 crops (i.e. chickpea, corn, forages)
CSGA form 300, where basic info must be provided but no testing data is needed
