玉米光周期敏感相关性状发育动态QTL定位

玉米是短日照作物，大多数热带种质对光周期非常敏感。光周期敏感性限制了温、热地区间的种质交流。研究玉米光周期敏感性的分子机理，有利于玉米种质的扩增、改良、创新，提高玉米品种对不同光周期变化的适应性。本研究以对光周期钝感的温带自交系黄早四和对光周期敏感的热带自交系CML288为亲本配置的组合衍生的一套207个重组自交系为材料，在长日照环境条件下对不同发育时期的叶片数、株(苗)高变化进行QTL分析。结果表明，双亲间的最终可见叶片数和株高差异很大；发育初期CML288的叶片数和苗高都低于黄早四，而发育后期CML288的叶片数和株高都明显高于黄早四；测定各时期F₇重组自交系间也存在显著差异。利用包含237个SSR标记、图谱总长度1 753.6 cM、平均图距7.40 cM的遗传连锁图谱，采用复合区间作图法，分别检测到控制叶片数和株(苗)高发育的QTL 11个和20个。但是，没有一个条件QTL 能在测定的几个时期都有效应。在长日照条件下，控制叶片数与株(苗)高的非条件与条件QTL主要集中在第1、9和10染色体上，特别是在第10染色体的标记umc1873附近均检测到了影响这两个性状的QTL，且在不同的发育时期单个条件和非条件QTL所解释的表型变异分别为4.34%~25.74%和10.02%~22.57%，表明这一区域可能包含光周期敏感性关键基因。

QTL Analysis of the Photoperiod Sensitivity-Related Traits at Different Developmental Stages in Maize (Zea mays L.)

Maize is originally a short-day species and most tropical materials remain highly sensitive to photoperiod. Photoperiod sensitivity limits the potential for successful exchange of germplasm across temperate-tropical regions. Therefore, it would be very useful for breeders to better investigate the genetic basis of photoperiod sensitivity due to not only being benificial to expansion, improvement and innovation of germplasm but also enhancing adaptation of maize varieties to seasonal changes in the length of a day (photoperiod). For identifying the genetic controls underlying this adaptation at different development stages in maize, a set of 207 recombinant inbred lines derived from a temperate and a tropical inbred line cross was evaluated for leaf number and seedling or plant height at different developmental stages in a long-day environment. The results showed there was apparent difference in the average of leaf number and plant height for two parents. Leaf number and seedling height of the parent CML288 were less than those of Huangzao 4 at the beginning of plant development tested, but were more than those of Huangzao 4 at the later developmental stages. There was significant difference in the traits at the tested developmental stages for F₇ recombinant inbred lines. The unconditional and conditional QTLs for these traits were detected using genetic linkage maps constructed by 237 SSR markers with a total length of 1753.6 cM and an average space between two markers of 7.4 cM, and composite interval mapping (CIM). Eleven and twenty QTLs were detected for leaf number and plant height, respectively. But there was no effect of conditional QTL at all the tested developmental stages. The conditional and unconditional QTLs for leaf number and plant or seedling height were mapped on chromosomes 1, 9 and 10. Especially, the QTLs located on chromosome 10 (near to umc1873) were for two traits at the later developmental stages, accounting for 4.34–25.74% and 10.02–22.75% of total phenotypic variation by single conditional and unconditional QTL, respectively. These results showed that these regions might encompass some crucial candidate genes controlling photoperiod sensitivity.