Quantitative Trait Loci Associated with Seed Dormancy in Rice

Abstract

Seed dormancy is a key agronomic trait related to the quality of seed and rice production because it imparts resistance to preharvest sprouting. A population was constructed from a three‐way cross, IR50/Tatsumimochi//Miyukimochi, in which IR50 was an indica donor of strong seed dormancy and Tatsumimochi and Miyukimochi were nondormant japonica cultivars. Seed dormancy was tested for 166 F1 plants of the three‐way cross and their progeny population (F2). A total of 108 simple sequence repeats (SSR) markers were mapped on 12 rice chromosomes, and quantitative trait locus (QTL) analysis was performed for seed dormancy in the two segregating generations. Three putative QTLs affecting seed dormancy were detected on chromosomes 1, 3, and 7 in the F1 generation. Phenotypic variations explained by each QTL ranged from 4 to 21%, indicating that seed dormancy is affected by a number of minor genetic effects. The putative QTLs on chromosomes 1 and 3 were also detected in the F2 generation at the same map sites. Considering the present and past results there are a number of genetic factors that affect rice seed dormancy; however, the two SSR markers on chromosomes 1 and 3 could be used to develop near‐isogenic lines (NILs) for map‐based cloning of seed dormancy genes in the regions to thus improve the dormancy of japonica rice.