Identification of major and stable QTLs conferring drought tolerance in rice RIL populations

Rice production in a rain-fed environment during the reproductive period is significantly hindered by drought, which is one of the critical issues limiting yield. Therefore, finding grain yield-related quantitative trait loci (QTL) during the reproductive stage can potentially provide researchers with additional benefits when taken in the context of marker-assisted breeding. CT-9993 and Samba Mashuri were considered to develop recombinant inbred lines (RILs) for tagging QTLs associated with drought tolerance. During the dry and wet experimental conditions, there was a significant difference in the yield and yield-attributing variables. Sixty polymorphic microsatellite markers were utilized to genotype the RILs by employing Inclusive Composite Interval Mapping (ICIM). Especially eight QTLs were identified for four traits viz., plant height, root length, root dry weight and grain yield under stressed and control conditions. QTLs for Root Length (_QRL-6-1 and _QRL-8-1) were identified on chromosomes 6 and 8 with PVEs of 20.35% and 10.29%, respectively under stressed situation. A QTL, _QPH-4-1, was also identified on Chromosome 4 with a PVE of 19.73% for plant height under drought stress. _QGY-6-1 was identified on Chromosome 6 with a LOD value of 7.95 and a PVE of 22.14% to grain yield under stress. Throughout the growing seasons, two QTLs, _QPH-4-1 and _QPH-8-1, were identified for the Plant Height trait, with PVEs of 25.13% and 3.21%, respectively. Three QTLs (_QRL-3-1, _QRL-6-1, and _QRL-11-1) were identified as having the highest PVE and LOD score for root length. Two stable quantitative trait loci for grain yield, (_QGY-6-1 and _QGY-7-1) were identified. It was flanked by the markers RM19425 and RM19521. These quantitative trait loci might prove to be very beneficial in the marker-assisted breeding of rice that is resilient to climate change, especially drought.