玉米穗行数主效QTL位点qKRN5.04的精细定位与候选基因挖掘

Kernel row number of maize is one of key factors determining grain yield, and an important target trait for germplasm enhancement and genetic improvement. Thus, fine mapping and key genes mining of major QTLs underlying kernel row number have important theoretical and practical significance for revealing the genetic basis of kernel row number and carrying out molecular breeding. In this project, a near-isogenic line (NIL), that incorporates the target QTL-qKRN5.04 for kernel row number, was developed by several cycles of backcrossing and selfing. Massive fine-mapping populations will be constructed by using the NIL. Genotypes of the target QTL and phenotypes of kernel row number of these populations will be evaluated and used in the fine mapping of the qKRN5.04. Based on the results of the fine mapping of the qKRN5.04, bioinformatics analysis and transcriptional analysis will be used to identify the candidate gene(s) responsible for the qKRN5.04. Then, sequence analysis, gene expression analysis and transgene analysis will be carried out to reveal the biological function of candidate gene(s) of the qKRN5.04. In addition, candidate gene-based association analysis will be conducted to mine the functional loci and the elite haplotypes. This project may provide key gene(s) and functional markers for maize breeding.

穗行数是玉米产量的重要决定因子之一，也是玉米种质创新和品种改良的重要目标性状。穗行数主效QTL的精细定位与关键基因挖掘，对揭示玉米穗行数形成的遗传基础、开展分子设计育种具有重要的理论价值和实践意义。本项目以穗行数主效QTL-qKRN5.04为研究对象，利用多代回交和自交获得的近等基因系为基础试验材料，构建大规模的精细定位群体，进行目标区段基因型和穗行数表型鉴定，实现穗行数主效QTL-qKRN5.04的精细定位。在此基础之上，结合生物信息学分析和转录组分析，确定qKRN5.04的候选基因。然后，利用序列分析、时空表达分析和转基因实验分析，明确候选基因的生物学功能，并利用候选基因关联分析挖掘功能位点与优异单倍型。本项目可为玉米育种提供重要的功能标记以及基因资源。

穗行数是玉米产量的重要决定因子之一，也是玉米种质创新和品种改良的重要目标性状。穗行数主效QTL的精细定位与关键基因挖掘，对揭示玉米穗行数形成的遗传基础、开展分子设计育种具有重要的理论价值和实践意义。前期通过玉米骨干亲本农531（N531）和地方品种四路糯（SLN）构建的分离群体，结合多年多点表型鉴定，成功挖掘到一个与穗行数显著相关的主效位点qKRN5.04。在此基础之上，本研究通过构建高代回交群体，利用连锁分析将qKRN5.04缩小到玉米基因组5号染色体65 kb范围内，同时结合区域关联分析和表达量分析，确定了Zm00001d016075为控制主效位点qKRN5.04的重要候选基因。Zm00001d016075启动子区序列分析结果显示，Indel308与玉米穗行数显著相关。通过CRISPR-Cas9基因编辑，我们发现Zm00001d016075在玉米中负调控穗行数的形成，并且对玉米的其他重要农艺性状具有重要影响。这些结果为有助于理解玉米穗行数的遗传基础，同时为玉米高产分子育种提供重要支撑。