玉米氮素吸收相关性状的遗传解析

An important approach to increase grain yield and decrease nitrogen supply is to improve the nitrogen use efficiency, which is usually determined by three interacting processes, nitrogen (N) uptake, N translocation and N assimilation. As the first step of N acquisition, the underlying genetic information of N uptake is not very clear in maize. In this study, we will employ multiple methods to localize the genetic and genomic regions responding for maize N uptake. The recombinant inbred lines and the bulks from two tails of F2 segregating population, derived from the parents with contrasting capabilities of N uptake, will be used to construct the linkage and pinpoint the potential genomic regions aided with the calculation of allele frequency alteration between bulks. The QTL of N uptake will be aligned to the candidate genomic regions for further validation. Some differentially expressed homologous genes for N uptake between two parents will be evaluated, and possible cis- and trans- regions responding mRNA abundance variation will be identified. Finally, the causal regions for N uptake will be introgressed to a Chinese elite line, Zheng 58, by continuous backcrossing and flanking molecular markers with the purpose of improving its N uptake capability and nitrogen use efficiency.

玉米氮素利用效率主要由吸收、转运和同化三个重要环节相互作用所决定，氮素吸收作为植物体内氮素同化的第一步，其遗传控制位点和对应的分子调控机理有待研究。本项目以玉米重组自交系（RIL）和F2:3分离群体为研究对象，运用集群分离分析（BSA-Seq）、连锁群构建、QTL定位以及eQTL分析手段解析玉米控制氮素吸收的遗传位点和对应的调控机制。通过RIL群体构建较高密度连锁遗传图谱并分析控制氮素吸收率相关QTL位点，同时采用BSA-seq法验证候选区域，获得影响玉米氮素吸收的遗传位点信息；通过关联氮素吸收转运蛋白相关基因mRNA的表达水平和相应基因型数据，明确调控转运蛋白基因表达丰度的顺式和反式区域；发展加密候选位点分子标记，利用连续回交、前景选择和背景选择手段提高玉米优良自交系郑58的氮素吸收能力。本项目拟在明确控制氮素吸收性状的位点和调控机制的基础上为分子育种改良中国玉米氮素吸收能力提供科学依据

玉米氮素利用效率主要由吸收、转运和同化三个重要环节相互作用所决定，氮素吸收作为植物体内氮素同化的第一步，其遗传控制位点和对应的分子调控机理有待研究，这是与籽粒的蛋白和淀粉合成密切相关。为了挖掘控制氮吸收性状的关键基因，我们利用玉米氮吸收差异的RIL群体材料，结合两个环境的表现型数据，遗传定位控制氮素吸收相关性状的基因组区域，结果检测到染色体5上的1个QTL（qNC5：umc2026-umc1155：399.65~411.81cM），共覆盖了12.6cM，LOD值为2.5~3.1，解释了6.44-7.22%的表型变异，利用GO富集分析鉴定出9个候选基因与氮吸收有关，其中ZmNPF9是重要的氮转运基因，根据eQTL和共表达网络分析挖掘出可能调控ZmNPF9的MYB转录因子（GRMZM2G118693）。