Three Quantitative Trait Loci Conferring Resistance to Kernel Fissuring in Rice Identified by Selective Genotyping in Two Tropical Japonica Populations

Abstract

ABSTRACTKernel fissures in rice (Oryza sativa L.) caused by pre‐ or postharvest stresses are the leading cause of breakage among milled rice, causing economic losses for producers, millers, and processors. The present study identified three quantitative trait loci (QTLs) associated with fissure resistance (FisR) through selective genotyping of two mapping populations, one derived from ‘Cypress’ × ‘LaGrue’ and the other derived from ‘Cybonnet’ × ‘Saber’. Two QTLs were identified on chromosome 1 and one on chromosome 8 in both populations. Further QTL verification as well as improved estimates of QTL locations and effects were obtained using a set of 275 Cybonnet × Saber recombinant inbred lines (RILs) tagged with markers along chromosomes 1 and 8 and phenotyped using seven replications of seed harvested in four environments. Both QTLs on chromosome 1 were statistically significant in all four environments; the chromosome 8 QTL was significant in three. All alleles for FisR originated from Cypress, which was the FisR parent of Cybonnet. The QTL with largest effect, qFIS1‐2, which explained 13% of the RIL variance for FisR, was found linked to the semidwarf sd1 locus on chromosome 1. This explains earlier reports of putative association between FisR and short plant height. This is the first report of rice FisR QTLs whose effects were verified in multiple mapping populations and seed‐production environments.