Sb. Yu et al., IMPORTANCE OF EPISTASIS AS THE GENETIC-BASIS OF HETEROSIS IN AN ELITERICE HYBRID, Proceedings of the National Academy of Sciences of the United Statesof America, 94(17), 1997, pp. 9226-9231
The genetic basis of heterosis was investigated in an elite rice hybri
d by using a molecular linkage map with 150 segregating loci covering
the entire rice genome, Data for yield and three traits that were comp
onents of yield were collected over 2 Sears from replicated field tria
ls of 250 F-2:3 families, Genotypic variations explained from about 50
% to more than 80% of the total variation, Interactions between genoty
pes and gears were small compared with the main effects, A total of 32
quantitative trait loci (QTLs) were detected for the four traits; 12
mere observed ill both years and the remaining 20 were detected in onl
y one year, Overdominance was observed for most: of the QTLs for yield
and also for a few QTLs for the component traits, Correlations betwee
n marker heterozygosity and trait expression were low, indicating that
the overall heterozygosity made little contribution to heterosis, Dig
enic interactions, including additive by additive, additive by dominan
ce, and dominance by dominance, were frequent and widespread in this p
opulation, The interactions involved large numbers of marker loci, mos
t of which individually were not detectable on single-locus basis; man
y interactions among loci were detected in both years, The results pro
vide strong evidence that epistasis plays a major role as the genetic
basis of heterosis.