玉米穗上叶片数主效位点 qLA7-1的克隆和功能验证

The leaves above the primary ear (LAPE) play essential roles in maize architecture and yield, thus appropriate number of LAPE is an important goal of maize architecture modification. In our previous study, we constructed a segregation population derived from a cross between Y915 (more LAPE) and Zheng 58 (Less LAPE) and identified a major quantitative trait locus (QTL) qLA7-1 on chromosome 7 under three different environments, which accounted for 10.32%-20.32% of phenotypic variation. Using fine‐mapping strategy based on both genotypes and phenotypes of progeny derived from recombinants, we successfully narrowed the locus into a 266-kb interval. In this project, we will first compare the phenotypic variation between near-isogenic lines, including three LAPE related traits like heading date, leaf emergence rate and the position of uppermost primary ear, as well as the cell morphology observation and endogenous phytohormone measurement in meristematic tissues. Combined fine mapping with sequence analysis, expression analysis and subcellular localization, the candidate genes will be obtained. Then, the biological function of candidate genes will be further verified by mutants, transgenic lines and association analysis populations, which will also be applied for elite haploid exploration. In addition, transcriptome analysis between the wild-type and the mutant will shed light on the regulation network of our target gene. Taken together, our results will provide theoretical guidance and gene resources for the genetic improvement of maize architecture.

穗上叶片对玉米植株形态和产量具有重要影响，适宜的穗上叶片数是玉米株型改良的重要目标。在前期的研究中，我们利用自交系Y915（穗上多叶）和郑58（穗上少叶）构建分离群体，在扬州、淮安和海南三个不同环境条件下定位到控制玉米穗上叶片数的主效位点qLA7-1，并将其定位区间缩小到266-Kb的区间内。本项目拟在此基础上，比较近等基因系材料在生育期、出叶速率和雌穗着生部位等性状上的差异，并结合分生组织的细胞学观察和激素含量测定，分析表型变异的成因；利用重组后代群体验证的方法进一步精细定位，整合序列分析、时空表达分析及亚细胞定位的结果确定候选基因；利用突变体、转基因株系和关联分析群体验证候选基因的功能，并筛选优良单倍型；利用野生型与突变体材料进行转录组分析，探索目的基因的表达调控网络。本项目将挖掘控制穗上叶片数的关键基因，明确基因的生物学功能与作用机制，为开展玉米株型的遗传改良提供理论支持和基因资源。

穗上叶片对玉米植株形态和产量具有重要影响，适宜的穗上叶片数是玉米株型改良的重要目标。在本研究中，我们对调控玉米穗上叶片数主效位点qLA7-1进行精细定位，并将其定位区间缩小到191.6kb的物理区间内；整合序列分析、表达分析及转基因功能验证等手段确定候选基因ZmARR, 该基因编码A型细胞分裂素响应调节因子；亚细胞定位结果显示ZmARR编码的蛋白主要定位于细胞核；顶端分生组织形态学观察显示候选基因影响叶原基的分化速率；转录组测序和内源激素含量分析表明ZmARR可能通过激素途径调控玉米穗上叶片数目。本项目研究结果为开展玉米株型的遗传改良提供理论支持和基因资源。