Sb. Yu et al., EPISTASIS PLAYS AN IMPORTANT ROLE AS GENETIC-BASIS OF HETEROSIS IN RICE, SCIENCE IN CHINA SERIES C-LIFE SCIENCES, 41(3), 1998, pp. 293-302
The genetic basis of heterosis in rice was studied in a cross between
Zhenshan 97 and Minghui 63, the parents of the best hybrid widely used
in rice production in China. Field data for yield and yield component
s traits were collected over two years from 240 F-2:3 families of this
cross planted in replicated field trials. These families were assayed
with 151 marker loci that were polymorphic between the parents and a
linkage map was constructed with Map-maker analysis. A total of 32 qua
ntitative trait loci (QTLs) were identified for yield and the three co
mponent traits; 12 QTLs were detected in both years and the remaining
20 QTLs were observed in only one year. A search for the entire genome
by using two-way analyses of variance with all possible two-locus com
binations detected a very large number of significant digenic interact
ions involving both the QTLs resolved by single-locus analysis and loc
i that did not show significant effects by single-locus analysis. Many
of the interactions were simultaneously detected in both years. Parti
tioning of the epistatic interactions recovered all three types of int
eractions, i. e. additive by additive, additive by dominance and domin
ance by dominance, for all the traits. Some of the epistatic interacti
ons even showed pleiotropic effects by simultaneously affecting two or
more traits. The results clearly indicate that epistasis plays a sign
ificant role in the inheritance of yield traits as well as in the gene
tic basis of heterosis.