Genetic Basis of Drought Resistance at Reproductive Stage in Rice: Separation of Drought ...
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Genetic Basis of Drought Resistance at Reproductive Stage in Rice: Separation of Drought Tolerance from Drought Avoidance Bing Yue(1), Weiya Xue(1), Lizhong Xiong(1), Xinqiao Yu(2), Lijun Luo(2), Kehui Cui(1), Deming Jin(1), Yongzhong Xing(1) and Qifa Zhang(1*) 1 National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University 2 Shanghai Agrobiological Gene Center * To whom correspondence should be addressed. E-mail: Submitted on May 1, 2005 Revised on October 11, 2005 Accepted on 19 October 2005 Genetics, Vol. 172, 1213-1228, February 2006, Copyright 2006 doi:10.1534/genetics.105.045062 Abstract Drought tolerance (DT) and drought avoidance (DA) are two major mechanisms in drought resistance of higher plants. In this study, the genetic bases of DT and DA at reproductive stage in rice were analyzed using a recombinant inbred line population from a cross between an indica lowland and tropical japonica upland cultivar. The plants were grown individually in PVC pipes and two cycles of drought stress were applied to individual plants with unstressed plants as the control. A total of 21 traits measuring fitness, yield and the root system were investigated. Little correlation was detected of relative yield traits with potential yield, plant size and root traits, suggesting that DT and DA were well separated in the experiment. A genetic linkage map consisting of 245 SSR markers was constructed for mapping QTL for these traits. A total of 27 QTL were resolved for seven traits of relative performance of fitness and yield, 36 QTL for 5 root traits under control, and 38 for 7 root traits under drought stress conditions, suggesting the complexity of the genetic bases of both DT and DA. Only a small portion of QTL for fitness and yield related traits overlapped with QTL for root traits, indicating that DT and DA had distinct genetic bases. Key Words: Drought avoidance, Drought tolerance, Oryza sativa, QTL mapping