大豆叶面茸毛密度和长度的QTL定位

大豆叶茸毛形态对抗虫性、耐旱性等均有重要作用。本研究利用2个重组自交系群体NJRIKY (KY)和NJRIXG (XG)进行叶面茸毛密度和长度的遗传与QTL定位分析。结果表明，2个性状在2个群体中均有大幅度变异，存在不同程度的超亲分离，两者有极显著负相关(r= –0.49和–0.62)，叶面茸毛密度的遗传率(75.7%~76.8%)高于叶面茸毛长度的遗传率(45.2%~62.9%)；检测到2个叶面茸毛密度主效QTL (XG群体的PD1-1和KY群体的PD12-1，表型贡献率分别达20.7%和21.7%)；两群体叶面茸毛密度遗传构成中加性QTL贡献率占20.7%~36.2%，互作QTL只占0%~1.4%，而未定位到的微效QTL所占份额很大，为38.1%~56.1%，是以往只用定位程序而未注意遗传构成解析所没有发现的特点；未在KY中检测到叶面茸毛长度加性QTL，互作QTL贡献率也仅4.2%，而微效QTL贡献率达58.7%；但在XG中叶面茸毛长度加性QTL Pl1-1和Pl12-1贡献率分别达18.3%和22.5%，占主要成分，互作QTL和微效QTL贡献均较小，说明该性状两群体的遗传构成有很大差异。大豆叶面茸毛密度和长度的遗传涉及多个效应不同的基因/QTL。

QTL Mapping of Pubescence Density and Length on Leaf Surface of Soybean

Soybean pubescences are known to play important roles in resistance to pests and tolerance to drought stress. QTL mapping of leaf pubescence density and length was conducted in recombinant inbred line populations of NJRIKY (KY) and NJRIXG (XG). The results obtained were as follows: (1) There existed great variation and certain transgressive segregation in leaf pubescence density and length among lines; highly significant negative correlations (r= −0.49 and −0.62, respectively) between the two traits were observed; the heritability values for pubescence density ranged from 75.7% to 76.8%, higher than that for pubescence length ranged from 45.2% to 62.9% in the two populations. (2) Two major QTL for pubescence density detected were PD1-1 accounted for 20.7% of phenotypic variation in XG, and PD12-1 contributed 21.7% of phenotypic variation in KY. The genetic constitution of pubescence density was composed of additive QTL (20.7−36.2% of phenotypic variation), epistatic QTL pairs (0−1.4%) and collective unmapped minor QTL (38.1−56.1%) in the two populations. Here the unmapped minor QTL was the most important part for the trait, which was not recognized if only using mapping procedures without the consideration of the total genetic variation among the lines. (3) The phenotypic variation of pubescence length in KY was accounted for by epistatic QTL pairs (4.2%) and collective unmapped minor QTL (58.7%) without additive QTL (0%), while that in XG mainly by additive QTL, including Pl1-1 and Pl12-1 on chromosomes 1 and 12 accounting for 18.3% and 22.5% of phenotypic variation, respectively, with very small contribution by epistatic QTL pair and collective unmapped minor QTL. Therefore, the genetic constitutions of pubescence length in the two populations were different from each other. The genetic mechanisms of leaf pubescence density and length in soybean are complicated and involve many genes/QTL with different effects.