Additive and Epistasis Effects of Quantitative Trait Loci for Plant Height and Its Components in Single Segment Substitution Lines of Rice

To detect quantitative trait loci (QTLs) for plant height and its components in rice (Oryza sativa L.) as well as their gene action, 16 secondary single segment substitution lines (SSSLs) and 15 double segment pyramiding lines (DSPLs) with Huajingxian 74 background were used as mapping populations. A total of 11 QTLs were identified on chromosomes 4, 6, and 10, containing 3 for plant height, 1 for the first internode from the top, 2 for length of the second internode from the top, 2 for length of the third internode from the top, and 3 for length of the fourth internode from the top. Furthermore, 23 pairs of digenic interactions were detected for plant height and the other 5 traits. Among them, 7 interactions occurred between 2 loci without obvious effects on the traits, and 16 interactions each involving 1 locus with and another without main effect at the single-locus level. The results suggest that both additive effect of QTL and epistasis effect between QTLs play important roles in the heritance of plant height and its components. Secondary SSSLs and DSPLs derived from crosses of primary SSSLs are favorable in improving efficiencies of QTL identification and epistasis effect analysis.