Norry F M, Dahlgaard J, Loeschcke V
Department of Ecology and Genetics, University of Aarhus, Ny Munkegade, Bldg 540, DK-8000 Aarhus C, Denmark.
Mol Ecol. 2004 Nov;13(11):3585-94. doi: 10.1111/j.1365-294X.2004.02323.x.
Knockdown resistance to high temperature is an ecologically important trait in small insects. A composite interval mapping was performed on the two major autosomes of Drosophila melanogaster to search for quantitative trait loci (QTL) affecting knockdown resistance to high temperature (KRHT). Two dramatically divergent lines from geographically different thermal environments were artificially selected on KRHT. These lines were crossed to produce two backcross (BC) populations. Each BC was analysed for 200 males with 18 marker loci on chromosomes 2 and 3. Three X-linked markers were used to test for X-linked QTL in an exploratory way. The largest estimate of autosome additive effects was found in the pericentromeric region of chromosome 2, accounting for 19.26% (BC to the low line) and 29.15% (BC to the high line) of the phenotypic variance in BC populations, but it could represent multiple closely linked QTL. Complete dominance was apparent for three QTL on chromosome 3, where heat-shock genes are concentrated. Exploratory analysis of chromosome X indicated a substantial contribution of this chromosome to KRHT. The results show that a large-effect QTL with dominant gene action maps on the right arm of chromosome 3. Further, the results confirm that QTL for heat resistance are not limited to chromosome 3.
对高温的击倒抗性是小型昆虫的一个具有重要生态意义的性状。对黑腹果蝇的两条主要常染色体进行了复合区间作图，以寻找影响对高温击倒抗性（KRHT）的数量性状基因座（QTL）。在KRHT上人工选择了来自地理上不同热环境的两个差异极大的品系。将这些品系杂交产生了两个回交（BC）群体。对每个BC群体中的200只雄性个体进行分析，在第2和第3号染色体上有18个标记基因座。使用三个X连锁标记以探索性方式检测X连锁QTL。在第2号染色体的着丝粒周围区域发现了常染色体加性效应的最大估计值，占BC群体表型变异的19.26%（回交至低温品系）和29.15%（回交至高温度品系），但它可能代表多个紧密连锁的QTL。在第3号染色体上的三个QTL表现出完全显性，热休克基因集中在该染色体上。对X染色体的探索性分析表明该染色体对KRHT有很大贡献。结果表明，一个具有显性基因作用的大效应QTL定位在第3号染色体的右臂上。此外，结果证实耐热性的QTL不限于第3号染色体。
