氮胁迫与非胁迫条件下玉米不同时期株高的动态QTL定位

以玉米杂交种农大108的203个F_2:3家系为材料，在施氮（N+）和不施氮（N－）2种条件下对拔节期到灌浆期的株高变化进行了动态QTL分析。结果表明，N胁迫条件对亲本许178影响较小，而对亲本黄C的影响较大，F_2:3群体在不同时期的株高均值在2种施肥水平下没有显著差异，但变异范围存在一定的差异。利用包含199个SSR标记的遗传连锁图谱与复合区间作图法，在N－条件下，拔节期、小喇叭口期、大喇叭口期、灌浆期分别定位1、1、2和2个非条件QTL，可分别解释各时期株高表型变异的8.42%、13.86%、24.33%和22.66%；在N＋条件下，相应时期分别定位1、1、2和4个非条件QTL，可分别解释各时期株高表型变异的8.10%、12.92%、21.30%和44.41%。在N－条件下，拔节期至喇叭口期、开花期至灌浆期分别定位了1和5个条件QTL，可分别解释该时期株高动态变异的9.14%和50.98%；在N＋条件下，相应时期分别定位1和4个条件QTL，可分别解释该时期株高动态变异的13.33%和44.47%。这些非条件QTL和条件QTL多数表现以显性和部分显性为主。

QTL Analysis of Plant Height under N-Stress and N-Input at Different Stages in Maize

Nitrogen is a large necessary element in maize development, and the nitrogen use efficiency is an important factor in deciding the cost of maize production, and also the plant height is served as an important index of the biomass. The purpose of this study was to locate the QTL for plant height in maize（Zea mays L.）in different developing stages under N-input (N+) and N-stress (N－) conditions. The unconditional and conditional QTLs for plant height were detected using F_2:3 population derived from an elite maize cultivar Nongda 108 (Huang C × Xu 178). The results showed that N-stress had more influence to plant height in the parent Huang C than in Xu 178, and there was no significant difference in the average of plant height for the F_2:3 families between the two nitrogen treatments, but the ranges of variation were different. The QTLs for plant height at different stages were detected with the composite interval mapping method and a molecular linkage map including 199 SSR markers. Under N- treatment, 1, 1, 2, and 2 QTLs were detected for plant height at elongation stage, small bell stage, large bell stage and grain filling stage, respectively. The total contribution of the detected QTLs could explain 8.42%, 13.86%, 24.33%, and 22.66% of phenotypic variation. Under N+ treatment, there were 1, 1, 2, and 4 QTLs for plant height in the four different stages above, accounting for 8.10%, 12.92%, 21.30%, and 44.41% of total phenotypic variation respectively. One and five QTLs for plant height were detected from elongation to bell stage and from large bell to grain filling stage under N- treatment, while 1, 4 QTLs were detected under N+ treatment, the total contributions of the detected QTLs were 9.14% and 50.98% as well as 13.33% and 44.47%, respectively. The inbred line Xu178 was less sensitive to low N stress than Huang C for plant height and was an inbred with high nitrogen use efficiency under low N condition. The 12 conditional and unconditional QTLs for plant height mainly located on chromosomes 1, 4, 5, and 9, four of them are different from those reported by predecessors in gene locations. About all of the conditional and unconditional QTLs detected appeared to be of dominant and partially dominant effects on plant height with explained the phenotype variation nearly ranging from 8% to 16%. Some QTLs such as qPH4b, qPH1c, and qPH7 only expressed in specific stages, that is the spatial temporal expression characteristics during the formation of plant height, which may be related with high N use efficiency.