水稻抗旱性属于复杂性状，近年的遗传研究日益关注胁迫下的产量相关位点。选用来自同一抗旱性较好的供体亲本（BG300），具有两种遗传背景（IR64和特青）和两种选择条件（低地和旱地）的4个水稻高代回交（BC2）抗旱性定向选择导入系群体。通过SSR分子标记，检测群体中供体等位基因的导入频率，分析了选择条件和遗传背景对供体等位基因导入频率的影响。在此基础上，利用基于遗传搭车原理的卡方检验对等位基因导入频率的偏离进行检测，同时结合表型-基因型方差分析（ANOVA）的方法，对上述群体进行了和抗旱性相关位点的QTL分析。共检测到显著位点24个，其中卡方检验发现20个，方差分析检测到8个。有4个被这两种方法都检测到，很可能是与胁迫下的产量直接相关的位点。同时也对非胁迫下的产量位点进行了检测，发现上述抗旱性位点与非胁迫下产量的关系不大。还就选择条件和遗传背景的效应等对目标性状QTL定位的影响进行了讨论。研究结果将为进一步的水稻抗旱性分子育种研究提供有用的信息和材料。
Drought tolerance (DT) in rice is a complicated trait. Recent genetic research has focused on yield under stress instead of physiological traits. Due to the limits from the huge labors required for both phenotyping and genotyping in traditional mapping work, progress in DT-QTL mapping is relatively slow. An attempt to identify DT-QTL based on genetic hitch-hiking theory in breeding population was described in this paper. With the combination of advanced backcrossing and artificial directional selection for yield under drought stresses of both rain-fed lowland (stress at the reproductive stage) and upland (stress through the whole life time), four sets of 43 introgression lines (ILs) with two relatively uniform genetic backgrounds (IR64 and Teqing) and the same donor of relatively good drought tolerances (BG300) were developed. Introgression of donor alleles in the DT ILs were characterized with 214 well distributed SSR markers representing 98 bins throughout the whole genome. A total of twenty-four significant loci (DT-QTL) were found, of which 20 belonged to allelic-frequency-deviation loci detected by chi-square test at the significant level of P<0.005 and 8 were detected by analysis of variances (ANOVA) with data from progeny test in replicated experiments at the significant level of P<0.01, respectively. Of the 20 loci detected by chi-square test, four (about 20%) were verified by ANOVA and supposed to be directly associated with yield under drought stress. The analysis for yield under irrigation for the same populations was also carried out; few overlap with the DT-QTL was found. The above DT-QTL as well as the DT ILs supposed to offer useful information and materials for the further rice DT molecular breeding. The genetic overlaps between the different selections and the effects of genetic backgrounds were discussed.
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