Agriculture Reference
In-Depth Information
an invaluable resource for genetic mapping considering the multiallelic
nature of the population and the numerous cycles of genome recom-
bination performed (Breseghello and Sorrells 2006; King et al. 2012).
Prerequisites for using synthetic populations for association study or
genomic selection are (1) the absence of strong selection pressure that
would induce a genetic bias with overrepresentation of favorable alleles
and lower frequency or absence of alternative alleles for a particular
trait under selection, and (2) a broad genetic base to best represent crop
allelic diversity.
With more widespread use of molecular markers in plant breeding,
population improvement can be adapted to a marker-assisted recurrent
selection (MARS) scheme. The method becomes extremely ef
cient as
the synthetic population used for the identi
cant marker/
phenotype associations is also a candidate for population improvement
through MARS. Early selection on S
0
plants through MARS allows con-
trolling the crosses and thus presents an advantage by hastening the
assembly of favorable combinations.
The CIRAD
cation of signi
-
fixed lines
derived from an RS population with a broad genetic base to perform
population improvement through recurrent genomic selection. In the
genomic selection (GS) scheme, individuals of a training population
are phenotyped and genotyped with genome-wide markers to develop
a GS model. Multienvironment trials within the LAC network could
play a key role in improving the prediction of genomic breeding values
by accounting for genotype-by-environment interactions in the model.
Individuals of a breeding population candidate for selection are then
genotyped and genomic estimated breeding values (GEBV) are de
CIAT rice project is using a population of
ned
from the GS model. GS accounts for a most complete set of QTLs,
including those with large and small effects, thus capturing most of the
genetic variance of a trait. Phenotyping plays an important role in GS,
as it did previously for marker-assisted selection (MAS), and selection
is improved through accounting for kinship or pedigree information.
C. Expanding LAC Rice Population Improvement Experiences
The factor that has played a key role in the LAC rice population im-
provement success story is the strong network of breeders who worked
together for many years to develop, improve, and share genetic material
and methods (Guimarães 2005). Population improvement has resulted in
interinstitutional collaboration with strong efforts in training, germplasm
exchange, and innovation for the development of rice cultivars having
an impact on the regionand additional geographic areas (Guimarães 2009).
