在干旱和正常水分条件下玉米穗部性状QTL分析

穗部性状与产量密切相关，因此对其进行遗传剖析可为玉米高产育种提供理论基础，尤其是对干旱胁迫下的稳产有重要意义。本研究以玉米骨干亲本黄早四分别与自交系掖478和齐319进行杂交，构建了两套F_2:3群体(分别记为Y/H和Q/H)。在正常水分灌溉和干旱胁迫下对穗长、穗粗、轴粗、穗行数、行粒数、穗粒重和穗重等7个穗部性状进行了表型鉴定，采用基于混合线性模型的单环境分析和相同处理水平的联合分析方法进行了QTL分析。结果表明，在干旱胁迫下，2个群体的亲本及F_2:3家系的各性状值均低于正常水分条件，且穗粒重与穗长、穗重、穗粗呈正相关。在干旱胁迫下和正常水分条件下，通过两种检测方法共定位到75个玉米穗部性状QTL，其中Y/H群体共定位了20个QTL，分布在第1、第2、6、第5、第7、第10染色体上；Q/H群体共定位了55个QTL，分布在第2、第3、第4、第5、第6、第7、第9、第10染色体上；但是在干旱条件下两群体分别只检测到4个和19个QTL，明显低于正常水分条件下检测到的QTL数目。通过联合分析只检测到3个QTL与环境发生显著互作和6对QTL存在上位性互作效应，说明玉米穗部性状的遗传基础较为复杂。同时还发现，Y/H群体在正常灌溉与干旱条件下检测到2个一致性的QTL，分别是qKRE1-5-1和qKRE1-7-1，对表型变异解释的变化范围是6.15%~19.48%；Q/H群体检测到3个一致性QTL，分别是qKRE2-5-1、qGW2-10-1和qKRE2-3-1，对表型变异解释的变化范围是7.14%~16.65%，说明这些QTL受环境影响较小，能够稳定遗传，可以作为分子标记辅助选择的候选区间应用于玉米穗部性状抗旱性改良。

QTL Mapping of Ear Traits of Maize under Different Water Regimes

Ear traits are closely associated with maize yield. Therefore, genetic dissection of ear traits can provide clues to maize high-yield breeding and is especially important in breeding for drought tolerance. In this study, seven ear related traits including ear length (EL), ear diameter (ED), row number (KRN), kernel number per row (KRE), grain yield per ear (GW), cob diameter (AD) and weight per ear (EW), were investigated using two sets of F_2:3 populations, which were derived from crosses of Ye478×Huangzaosi (Y/H) and Qi319×Huangzaosi (Q/H), respectively. The two populations were evaluated under different water conditions in Xinjiang in 2007 and 2008. The results showed that those ear traits under drought were phenotypically lower than those under normal water regime and ear length, ear diameter, weight per ear had positive correlation with GW. A total of 75 QTL were identified under different water regimes using mixed linear model with two methods of single-experiment analysis and water regime joint analysis, including 20 QTL detected under normal water regime and 55 QTL detected under drought stress. The QTL detected in Y/H were located on chromosome 1, 2, 5, 6, 7, and 10, and the QTL detected in Q/H were distributed on chromosome 2, 3, 4, 5, 6, 7, 9, and 10. However, only four and nineteen QTL was identified in the two populations under drought stress respectively, significantly lower than that detected under normal water regime. Meanwhile, in the joint analysis, only three QTL had significant interaction with environments and six QTL had epistatic interaction, showing that the genetic feature of ear traits was complex. In Y/H, two congruent QTL, qKRE1-5-1 and qKRE1-7-1, were detected under different water levels, with the phenotypic contribution from 6.15% to 19.48%, while in Q/H, three congruent QTL, qKRE2-5-1, qGW2-10-1, and qKRE2-3-1, were detected under different water levels, with the phenotypic contribution from 7.14% to 16.65%. These results implied that these QTL were little influenced by environment and could stably expressed, which can be used in marker-assisted selection.