Genetic Analysis of Grain Shape for Paddy and Brown Rice Using Introgression Lines

Abstract

ABSTRACTGrain shape–related traits are important components determining rice (Oryza sativa L.) grain yield, and they are controlled by quantitative trait loci (QTL). To study the genetic basis of grain shape–related traits, we performed an experiment using a population of rice introgression lines (ILs) in two different environments. The results revealed that the 10 traits investigated were affected by 84 QTL that individually explained 5.04 to 66.26% of the phenotypic variation. Most of these QTL explained a modest proportion of the phenotypic variance, confirming that grain shape was inherited polygenically. Meanwhile, 75 of all the 84 QTL showed a pleiotropic effect or linkage association as a cause of these observed phenotypic correlations between the grain shape traits. Among the regions showing pleiotropic effect or linkage association, 71.4% were associated with both paddy and brown grain shape traits, which suggested that paddy and brown grain shape might be controlled by the same genes. Furthermore, 13 major stable QTL were detected in both environments, which offers an opportunity for marker‐aided improvement of rice grain shape quality and QTL cloning. The introgression lines harboring the 13 major stable QTL also represent a useful genetic resource for rice yield improvement via a design‐breeding approach in the future.