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 IR64 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, qDTY1.1, for grain yield under drought was identified on chromosome 1 between the marker intervals RM431 and RM12091 in both populations. The Dhagaddeshi allele at qDTY1.1 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 × Swarna and Dhagaddeshi × IR64 populations, respectively. A consistent effect of qDTY1.1 has also been reported earlier. The presence of qDTY1.1 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.

► The QTL qDTY1.1 shows consistent effect for grain yield under drought across different genetic backgrounds.
► The positive QTL allele for qDTY1.1 is contributed by different donors-N22, Dhagaddeshi and Apo.
► qDTY1.1 could be efficiently used to improve high yielding varieties through marker assisted breeding.