Agriculture Reference
In-Depth Information
Fig. 2.3.
Hypothetical ef
ciency of gene detection (
y
-axis) in plant species represented by
probability curves for various techniques of gene discovery and utilization, including AM
(association mapping), BSA (bulked segregant analysis), or gene tagging, CG (candidate
gene approach), GWAS (genome-wide association scan approach), MAGIC (multiparent,
NAM (nested association mapping), relative to the heritability expressed in percentage (%)
for the phenotypic trait or characteristic being evaluated (
x
-axis). GS (genomic selection) is
placed in a theoretical location without a probability curve given that its ef
ciency is still to
be determined for crop plants.
discovery with each technique mentioned in this chapter as shown in
Fig. 2.3.
Association genetics research is not common in the developing world
or for minor crops, but should become so. The greatest limitations are
technical and in training rather than in germplasm diversity. The
genotyping gap that exists between high- and middle-income countries
has been an issue for carrying out association genetics, especially for
GWA or GS, where a larger number of markers or resequencing is
needed. There are, however, several alternatives for genotyping such
as the use of the CG approach that reduce cost and time involved. Access
to genotyping by sequencing appears to be solvable by outsourcing and
certainly can be cheaper than using in-house labs with GBS costs down
to 5 dollars a sample based on new multiplexing methods (Elshire et al.
2011).
In conclusion, the use of association genetics analysis provides a huge
opportunity to evaluate and explore diversity of plant species in bio-
diversity-rich tropical and subtropical countries and to bring them into
