玉米穗行数基因zmqKRN8.03功能及调控机理研究

Kernel row number (KRN) is one of the most important yield traits in maize. In our previous study, candidate gene zmqKRN8.03 have been mapped and cloned via map-based clone in our lab. In this research, mutant genetic analysis, association analysis, genetic transformation and expression analysis of zmqKRN8.03 will be done to help us deeply understand its biological function, gene interaction model and allelic variation locus, and clarify the relationship between zmqKRN8.03 and the cloned genes of maize inflorescence development.The methods of molecular biology, such as in situ hybridizaiton, immunohistochemical analysis, ChiP-seq, Y2H and RNA-seq etc, will be used to elucidate the regulatory network and molecular mechanism of zmqKRN8.03 in maize kernel development.The other aims are to clarify the origin and selection mode of zmqKRN8.03 in the process of domestication and genetic improvement by population genetics and molecular evolution analysis. The results of this study not only help us to clarify the genetic and molecular basis of KRN formation, but also provide genetic resources and theoretical guidance for the genetic improvement of maize yield traits.

玉米穗行数（KRN）是决定玉米产量最为重要的性状之一；课题组前期利用图位克隆的方法精细定位并克隆了KRN关键候选基因zmqKRN8.03；本项目拟在此基础上，利用突变体的遗传分析、关联分析、遗传转化、表达分析等手段，深入研究zmqKRN8.03的生物学功能、基因作用方式及其等位变异位点，探明已克隆的玉米花序发育基因与zmqKRN8.03的关系。利用原位杂交、免疫组化、ChiP-seq、酵母双杂、时空表达模式分析和RNA-seq分析等分子生物学手段，阐明zmqKRN8.03参与玉米籽粒发育的调控网络及分子机制。通过群体遗传学和分子进化分析，探明zmqKRN8.03位点在玉米驯化和遗传改良过程中优良等位基因的起源和选择模式。本研究结果不仅有助于阐明KRN形成的遗传和分子基础，也能为玉米产量性状遗传改良提供基因资源和理论指导。

本研究利用玉米自交系V54和Lian87构建的近等基因系鉴定到一个新的控制玉米穗行数的主效位点KRN8，该基因编码一个含有START结构域的蛋白。候选基因重测序和候选基因关联分析结果表明KRN8编码区第493位的SNP与穗行数显著相关，且V54单倍型是可以增加穗行数的优良单倍型。利用Ubi启动子对KRN8的V54单倍型进行超表达，发现其遗传转化后代的穗行数显著高于阴性对照。表达分析结果表明KRN8在成熟叶片中高表达且KRN8蛋白定位于细胞膜和细胞核。通过fat-western、代谢组和转录组分析, 验证了KRN8能够特异性结合PA并促进PA在幼穗中的积累，进而调控生长素通路相关基因的表达，最终影响幼穗中的生长素含量。总之，该研究表明KRN8通过结合PA间接影响生长素通路从而调控玉米穗行数建成。