棉花的产量及产量构成因子性状是以复杂的方式遗传，遗传力较低并易受环境条件影响。经典数量遗传学指出，上位性是复杂性状的遗传基础。本研究以湘杂棉2号F8和F9世代重组自交系为材料，调查了3个环境下的产量及产量构成因子性状，并构建了遗传连锁图。旨在定位产量及产量构成因子性状的上位性QTL并分析QTL与环境的互作效应。所有产量及产量构成因子性状均检测到上位性QTL，共检测到16对加性互作QTL（AA），涉及的位点中仅4个有单位点效应，这反映了上位性的复杂性及其对产量和产量构成因子性状的重要贡献。共检测到17对QTL加性和环境互作（AE），以及14对上位性QTL与环境的互作，表明环境因素对产量和产量构成因子性状起重要影响作用。研究结果还表明上位性效应作为湘杂棉2号的遗传基础起着重要作用。对各性状在不同环境的优良基因型进行了预测。综合优良家系（GSL）和特定环境下的优良家系（SL）的性状表现高于两亲本，表明湘杂棉2号重组自交系各性状都有提高的潜力。由于QTL加性和环境互作以及上位性QTL与环境互作的影响，预测的优良家系基因型会随着环境的改变而不同，表明应针对特定环境开展棉花育种。
Yield and yield component traits of cotton are inherited quantitatively with low heretibility and tend to vary with environmental variation. Classical quantitative genetics has indicated that epistasis is the foundation of such complex traits. In this study, a genetic linkage map was constructed using the recombinant inbred line (RIL) populations developed from an elite upland cotton hybrid Xiangzamian 2 (XZM2). Yield and yield component traits were investigated in F8 and F9 generations of RILs in three environments in China. The purpose of the study was to map epistatic QTL and analyze QTL by environment interactions in yield and yield components of cotton. Epistatic QTL were detected for all yield and yield component traits. Altogether 16 pairs of QTL interactions (AA) were identified. However, only 4 of the loci involved had single-locus effects, indicating the complexity of epistasis and their important contributions to yield and yield component traits. Altogether 17 pairs of QTL by environments interactions (AE) and 14 pairs of epistasis by environment (AAE) interactions were detected, indicating that environment influenced yield and yield componment traits greatly. The results suggest that epistatic effects might be importantly involved in the genetic basis of heterosis in the cotton hybrid of XZM2. Superior genotypes under different environments were predicted for all traits, indicating that there existed potential of increasing yield and yield components from XZM2-derived RILs. Due to influence of AE and AAE, the predicted SLs in different environments might be different. In cotton breeding, it is a practical strategy to perform breeding program according to special environment.
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