Identification and mapping of a QTL (qDTY1.1) with a consistent effect on grain yield under drought

The identification and introgression of QTLs for grain yield under drought is a preferred breeding strategy to improve the drought tolerance of popular elite rice varieties. Swarna and 11264 are two high-yielding rice varieties widely grown in rainfed areas of South and Southeast Asia but they are highly sensitive to drought. Dhagaddeshi, a traditional drought-tolerant donor, was crossed with Swarna and IR64 to develop two recombinant inbred line populations. The two populations were phenotyped for grain yield under reproductive-stage drought stress and non-stress during DS2010 and DS2011. Bulk segregant analysis was followed to identify the loci linked to grain yield under drought. A major-effect QTL, qDTY(1.1), for grain yield under drought was identified on chromosome 1 between the marker intervals RM431 and RM12091 in both populations. The Dhagaddeshi allele at qDTY(1.1) contributed to increased yield under drought and explained 32.0% and 9.3% of the phenotypic variance and 24.9% and 8.6% additive effect of the trial mean yield in Dhagaddeshi x Swarna and Dhagaddeshi x IR64 populations, respectively. A consistent effect of qDTY(1.1) has also been reported earlier. The presence of qDTY(1.1) in several traditional drought-tolerant donors and its consistent effect across the genetic backgrounds makes it a suitable QTL for use in marker-assisted breeding to improve the grain yield of drought-susceptible rice varieties. (C) 2012 Elsevier B.V. All rights reserved.