Identification of QTLs controlling rice drought tolerance at seedling stage in hydroponic culture |
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Authors: | Yoichiro Kato Sawa Hirotsu Keisuke Nemoto Junko Yamagishi |
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Affiliation: | (1) Graduate School of Agricultural and Life Sciences, The University of Tokyo, Nishitokyo, Tokyo 188-0002, Japan;(2) Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan |
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Abstract: | ‘Drought avoidance’ and ‘drought tolerance’ are two mechanisms by which plants adapt under water stress. These mechanisms are difficult to evaluate separately in field experiments. Using hydroponic culture, we studied the genetic control of drought tolerance in rice (Oryza sativa L.) without the effect of drought avoidance. A backcross inbred population of ‘Akihikari’ (lowland cultivar) × ‘IRAT109’ (upland cultivar) with 106 lines was cultured with (stressed condition) and without (non-stressed condition) polyethylene glycol (PEG) at seedling stage. The relative growth rate (RGR), specific water use (SWU), and water use efficiency (WUE) showed significant genotype × environment interactions with or without PEG, indicating that each line responded differently to water stress. A quantitative trait locus (QTL) analysis revealed that these interactions were QTL specific. A total of three QTLs on chromosomes 2, 4, and 7 were detected for RGR. The QTL on chromosome 7 had a constant effect across environments, while the QTL on chromosome 4 had an effect only under non-stressed condition and that on chromosome 2 only under stressed condition. The stress-specific QTL on chromosome 2 was not co-located with any QTLs for root system depth previously reported from the same mapping population. However, this QTL was co-located with a stress-specific QTL for SWU, suggesting that the control of transpiration was relevant to dry matter production under drought. We concluded that PEG-treated hydroponic culture is very effective for use in genetic analyses of drought tolerance at seedling stage. |
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Keywords: | Drought tolerance Hydroponic culture Oryza sativa L. Polyethylene glycol QTL Rice |
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