Background‐Independent Quantitative Trait Loci for Drought Tolerance Identified Using Advanced Backcross Introgression Lines in Rice

Abstract

ABSTRACTDrought is one of the major abiotic stresses limiting rice (Oryza sativa L.) production. Quantitative trait loci (QTL) for drought tolerance (DT) at the reproductive stage were identified with two sets of advanced backcross introgression lines (ILs) using a common donor Tarom Molaei introgressed separately into two recipients used as female parents, Teqing and IR64. A total of 24 and 22 QTL were identified in the IR64 and Teqing backgrounds, respectively, during the reproductive stage under drought and irrigated conditions for thousand‐grain weight, panicle number per plant, filled grains per panicle, seed fertility, and grain yield per plant. Most of these QTL showed obvious differential expression in response to drought stress. In addition, another 12 QTL were detected by the ratio of trait values under drought stress relative to the normal irrigation condition in the two backgrounds. The Tarom Molaei alleles at 8 of 12 loci with increased trait values could improve tolerance under drought stress. Only three (18.8%) DT QTL (QTgw7, QSf7, and QFgp11) were in common in the two backgrounds, clearly suggesting overwhelming genetic background effects on QTL detection for DT. Eight of the DT QTL identified were found to share the same genomic regions with previously reported DT‐related genes. Introgressing and pyramiding of favorable alleles from Tarom Molaei into Teqing and IR64 backgrounds may facilitate development of superior ILs with greater DT levels.