Abstract
Reproductive stage drought stress (RSDS) is detrimental for rice, which affects its productivity as well as grain quality. In the present study, we introgressed two major quantitative trait loci (QTLs), namely, qDTY2.1 and qDTY3.1, governing RSDS tolerance in a popular high yielding non-aromatic rice cultivar, Pusa 44, through marker-assisted backcross breeding (MABB). Pusa 44 is highly sensitive to RSDS, which restricts its cultivation across drought-prone environments. Foreground selection was carried out using markers, RM520 for qDTY3.1 and RM 521 for qDTY2.1. Background selection was achieved with 97 polymorphic SSR markers in tandem with phenotypic selection to achieve faster recurrent parent genome (RPG) recovery. Three successive backcrosses followed by three selfings aided RPG recoveries of 98.6% to 99.4% among 31 near isogenic lines (NILs). Fourteen NILs were found to be significantly superior in yield and grain quality under RSDS with higher drought tolerance efficiency (DTE) than Pusa 44. Among these, the evaluation of two promising NILs in the multilocational trial during Kharif 2019 showed that they were significantly superior to Pusa 44 under reproductive stage drought stress, while performing on par with Pusa 44 under normal irrigated conditions. These di-QTL pyramided drought-tolerant NILs are in the final stages of testing the All India Coordinated Rice Improvement Project varietal trials for cultivar release. Alternately, the elite drought-tolerant Pusa 44 NILs will serve as an invaluable source of drought tolerance in rice improvement.
Highlights
Rice (Oryza sativa L.) is an important food crop of Asian countries, including India.Globally, rice is widely consumed as a staple food by more than half of the human population, contributing over 20 percent of the total calorie intake
Pusa 44 used as the recurrent parent and a drought-tolerant near isogenic lines (NILs) of Swarna, namely, IR81896-B-B-142 was used as a donor for the two QTLs, qDTY2.1 and qDTY3.1, for tolerance to Reproductive stage drought stress (RSDS)
The marker-assisted transfer of two major QTLs, qDTY2.1 and qDTY3.1, for grain yield under reproductive stage drought stress, into the variety Pusa 44 was accomplished, which will help in managing yield losses under drought stress, which is a major stress affecting rice production, especially under the changing climate and water limitations imposed by this change
Summary
Rice (Oryza sativa L.) is an important food crop of Asian countries, including India.Globally, rice is widely consumed as a staple food by more than half of the human population, contributing over 20 percent of the total calorie intake. To meet the growing food demand, rice production has to be boosted by 0.6–0.9% annually [1]. Among the rice-growing countries of the world, India holds the first position in acreage (44 mha), but is second in rice production. Fourteen NILs were found to be significantly superior in yield and grain quality under RSDS with higher drought tolerance efficiency (DTE) than Pusa 44. The evaluation of two promising NILs in the multilocational trial during Kharif 2019 showed that they were significantly superior to Pusa 44 under reproductive stage drought stress, while performing on par with Pusa. These di-QTL pyramided drought-tolerant NILs are in the final stages of testing the All India Coordinated Rice Improvement Project varietal trials for cultivar release. The elite drought-tolerant Pusa 44 NILs will serve as an invaluable source of drought tolerance in rice improvement
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