Detection of Quantitative Trait Loci for Chalky Traits in japonica Rice

Using an F2 population including 200 individuals derived from a cross between two japonica rice DL115 with large grain and XL005 with small grain,the quantitative trait loci(QTLs) for chalky traits of rice were identified by composite interval mapping using SSR markers.Three chalky traits,i.e.percentage of grains with chalkiness(PGWC),area of chalky endosperm(ACE) and degree of endosperm chalkiness(DEC),exhibited a continuous distribution in F3 lines,indicating that these chalky traits were quantitative traits controlled by multiple genes.Five,two and one QTLs conferring chalky traits were detected on chromosomes 3,5 and 6,respectively,including three QTLs for PGWC,two QTLs controlling ACE and three QTL conferring DEC.qPGWC3,qACE3b and qDEC3b were located in RM6832-RM411,RM15456-RM6832 and RM6266-RM15456,and explained 43.89%,18.83% and 19.57% of the observed phenotypic variance for PGWC,ACE,and DEC,respectively.They were major QTLs and new QTLs.Among the detected eight QTLs,qPGWC6 allele was derived from XL005 without chalky grain,the other seven QTL alleles were derived from DL115 with big chalky grain.The gene actions were partially dominant at PGWC and ACE,and additive at DEC.