Evaluation of Backcross Inbred Lines (BILs) introgressed with drought tolerant QTLs using Polyethylene Glycol (PEG) induced water stress in rice
Drought is a never-ending climatic vagary that imposes worldwide high impact on crop yield reduction. Plants show a wide range of physiological responses including reduction of seed germination, leaf size and overall plant structure but with increased root proliferation. Incorporation of such traits for drought tolerance improvement in rice is found to be difficult and to evolve a new cultivar, it is essential to employ a rapid screening strategy for those traits. In this study, water stress was induced by using polyethylene glycol (PEG) and its impact on germination percentage and rate, root and shoot length, fresh and dry weight and water content among Backcross Inbred Lines (BILs; BC2 F6 ) that were generated from backcrossing of a recurrent parent CBMAS1405 harbouring two drought-tolerant QTLs qDTY1.1 and qDTY2.1 with two different donor parents FR13A (Sub1) and 562-4 (Pi9, Gm4, Xa21, xa13). Four levels of osmotic stress (0 MPa, -0.5 MPa, -0.75 MPa, and -1 MPa) were generated using PEG-6000 and the seeds were grown. Data on the investigated traits indicated that water stress has a strong impact on the performance of the drought susceptible lines. However, the lines viz., 27-1-7-8-65-4-1 and 27-1-7-8-14-4-1, introgressed with target drought tolerance QTLs have shown better performance on par or higher than that of the drought-tolerant donor variety Apo (that harbours qDTY1.1 and qDTY2.1). Thus, this study has helped to rapidly select the drought-tolerant breeding materials introgressed with drought-tolerant QTLs under simple laboratory conditions, and avoid extensive, costlier
and laborious screening under field conditions. Though the results have to be confirmed with field studies, it may require lesser inputs and efforts, as the PEG screening strategy drastically reduced the sample size.
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