QTL Mapping and QTL × Environment Interactions of Milling Quality and Percentage of Chalky Grain in Upland Rice Introgression Lines under Upland and Lowland Environments

Abstract

Milling quality and percentage of chalky grain of rice(Oryza sativa L.) are important traits to producers and consumers.The objectives of this study were to characterize the response of brown rice(BR),milled rice(MR),head milled rice(HMR),and percentage of chalky grain(PCG) to upland water stress and to identify QTLs for the traits.A set of 271 introgression lines(ILs)(BC5F3),carrying segments from upland cultivar IRAT109 in the background of lowland rice cultivar Yuefu,were used,and data were collected under upland and lowland environments.Great changes were detected between upland and lowland conditions in head milled rice and percentage of chalky grain,but relative stability in brown rice and milled rice.Head milled rice increased and percentage of chalky grain significantly decreased under upland condition.A total of ten additive QTLs and two pairs of digenic epistatic interactions QTLs for BR,MR,HMR,and PCG were detected on chromosomes 3,4,7,8,and 9.The contribution of single QTL ranged from 1.81% to 17.49%,three QTLs(qMR9,qHMR7,qHMR9) and one pairs of digenic epistatic interactions(qHMR3-qHMR9) accounted for above 10% of the phenotypic variation.Six QTLs were no significant QTL×Environment interaction effects,seven QTLs were the same with those from previous reports,and two genomic intervals,RM1112-RM1272 on chromosome 4 and RM1189-RM410 on chromosome 9,were cluster regions of the QTLs.These co-localized QTLs and common QTLs will facilitate marker-assisted selection for grain quality traits in rice breeding.