Grain yield QTLs with consistent-effect under reproductive-stage drought stress in rice

In this study, consistent-effect QTLs associated with grain yield under drought stress were identified using two mapping populations derived from crossing Kali Aus, a drought-tolerant rice landrace from India with mega varieties IR64 and MTU1010 as recipient parents. Two populations were phenotyped for yield and yield-component traits under reproductive-stage drought-stress and non-stress conditions in the 2011 and 2012 dry seasons (DS) at IRRI. Bulk-segregant analysis, followed by whole genotyping with selected markers, was used to identify significant markers putatively linked with high grain yield under drought. Six polymorphic markers RM246, RM450, RM250, RM232, RM518, and RM19 were found significant in bulk segregant analysis (BSA) of the Kali Aus/IR64 mapping population. Eight polymorphic markers RM495, RM572, RM246, RM211, RM250, RM231, RM3, and RM340 were found significant in the Kali Aus/MTU1010 mapping population. Analysis revealed major-effect grain yield QTLs qDTY2.3 and qDTY2.2 under drought stress consistently over two seasons in the Kali Aus/IR64 and Kali Aus/MTU1010 populations, respectively. qDTY2.3 explained 9% of phenotypic variance, with an additive effect of 451 kg ha−1 whereas qDTY2.2 explained 6% of phenotypic variance, with an additive effect of 121 kg ha−1. The QTLs showed consistent effect over two years of combined stress conditions. The two consistent-effect QTLs qDTY2.2 and qDTY2.3 can be used to improve the grain yield of mega varieties IR64 and MTU1010, respectively, across varying severity of drought stress through marker-aided backcrossing and thus provide farmers with improved varieties that effectively combines high yield potential with good yield under drought.