L. Silvela et al., GENETIC AND ENVIRONMENTAL CONTRIBUTIONS TO BREAD-WHEAT FLOUR QUALITY USING THE SDS SEDIMENTATION TEST AS AN INDEX, Theoretical and Applied Genetics, 86(7), 1993, pp. 889-894
The contribution of a locus to the genotypic variance depends not only
on the effects of its genes but also on their frequency and on the ge
netic background in which it segregates. In two synthetic populations,
involving common cultivars of our collection, estimates were made of
the contributions of alleles at the homoeologous high-molecular-weight
glutenin (HMW) loci, Glu-A1, Glu-B1, and Glu-D1, to the variation in
flour quality using SDS sedimentation as an index. These estimates wer
e of the magnitude of the contributions relative to each other, relati
ve to the residual genetic variance, and relative to the environmental
variance. The first population was a synthetic formed from ten bread-
wheat cultivars known for their good quality, and selected under force
d random mating for high SDS sedimentation. The second was the selfed
progeny of a cross of Ribereno, a very poor quality bread-wheat of gen
otype(Null, 7-8,2-12), with line 7681, a very good quality bread-wheat
with the genotype (2, 7-9, 5-10). Slightly over one-half of the phen
otypic variance is under genetic control and over one-half of this was
accounted for by HMW contributions. The initial response to selection
was very rapid, as is expected when genes with large effects are invo
lved. In addition, the frequencies of good HMW alleles increased so qu
ickly that their contribution to the genetic variance was exhausted by
the fourth generation of selection. If our estimates are correct, ove
r one-half of the maximum possible advance in quality in heterogeneous
populations similar to ours can easily be achieved in 2 years, or les
s, of marker-assisted selection.