Genomic Selection (GS) predicts the breeding values of an offspring in a population by associating their traits (i.e. resistance to pests) with their high-density genetic marker scores.
GS is a method proposed to address deficiencies of
marker-assisted selection
Marker assisted selection or marker aided selection (MAS) is an indirect selection process where a trait of interest is selected based on a marker ( morphological, biochemical or DNA/ RNA variation) linked to a trait of interest (e.g. producti ...
(MAS) in breeding programs. However, GS is a form of MAS that differs from it by estimating, at the same time, all genetic markers, haplotypes or marker effects along the entire genome to calculate the values of genomic estimated breeding values (GEBV).
The potentiality of GS is to explain the genetic diversity of a
breeding program
A breeding program is the planned breeding of a group of animals or plants, usually involving at least several individuals and extending over several generations. There are a couple of breeding methods, such as artificial (which is man made) and ...
through a
high coverage of genome-wide markers and to assess the effects of those markers to predict breeding values.
MAS limitations
In contrast to MAS and its focus on a few significant markers, GS examines together all markers in a population. Since the initial proposal of GS
for application in breeding populations, it has been emerging as a solution to the deficiencies of MAS.
The MAS has presented two main limitations in breeding applications. First, the bi-parental mapping populations are used for most
QTL analyses, limiting their accuracy.
[
] This represents a problem because a single bi-parental population cannot represent allelic diversity and genetic background effects in a breeding population.
Furthermore,
polygenic traits
A quantitative trait locus (QTL) is a locus (section of DNA) that correlates with variation of a quantitative trait in the phenotype of a population of organisms. QTLs are mapped by identifying which molecular markers (such as SNPs or AFLPs) co ...
(or complex traits) controlled by several small-effects markers have been an incredible hassle for MAS. The statistical methods applied for identifying target markers and implementing MAS for improvement of polygenic traits have been unsuccessful.
References
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Breeding