Lecture 13 - Selecting Flashcards
when to use indirect selection
when the related trait has higher heritability, is less expensive, easier, and expressed earlier in the life cycle
is digital phenotyping direct or indirect selection
it can be both, depending on how you think of it
indirect selection limitations
- linked trait is not desirable
- correlated trait associated with complex phenotype
why do molecular markers overcome many of the limitations associated with indirect selection
genotype is not influenced by the environment and tend to phenotypically neutral (aside from gene you are looking at
molecular/genetic markers
landmarks/known locations on the genome that are in proximity to genes but not necessarily known genes
type of molecular marker
single nucleotide polymorphisms (SNPs)
what is a snip
a heritable natural (or unnatural) variant of the DNA sequence of a species (typically highly abundant and distributed throughout the genome
what that markers are linked to traits
genetic studies such as genetic mapping experiments, QTL analysis, gene sequencing, syntenic relationships with model species
problems with using molecular markers for quantitative traits
- region of the genome is typically associated with the trait
- need markers spanning the geneome
- likely that the trait is controlled by many genes
syntenic relationships
how chromosomes/genes correlate between species
when to use markers for traits…
- strongly affected by environment
-difficult or expensive to assay
-recessive
-in species with long life cycles
-not expressed until after flowering
-when already screening markers for other traits (less expensive)
example of when to use markers
evaluating for resistance, avoiding escaped unresistant plants, and pyramiding R genes
when can markers be tested
almost anytime the plant is growing (seed, seedling, etc.)
T/f: some markers only work in certian crosses
t, the more distant the marker is from a gene of interest, the more likely it will be a problem
how effective are markers
it depends on how closely it is linked
the closer to the trait, the more effective the marker will be
markers less than _____ away from a trait of interest are considered by breeders to be effective
10cM
what does a marker 10cM away from the trait mean for selection accuracy
it mean there will be around 10% error in accuracy
