玉米粒型和粒重基因ZmKWL7的功能研究

Maize (Zea mays ssp. mays) is one of the most important crops. The improvement of maize yield is always a central goal of maize breeding. Kernel size and weight are important components of maize yield. Cloning the genes for kernel size and weight and dissecting the function of these genes will provide insights of the genetic basis of yield and facilitate maize yield improvement. Previously, we had fine-mapped a major QTL (qKWL7) for kernel weight and length and finally cloned the underlying gene (ZmKWL7) for this QTL. ZmKWL7 encodes a GNAT transcription factor and its relationship with kernel traits were not reported before. This study will use over-expression and CRISPR-Cas9 gene editing to validate the function of ZmKWL7 and RNA-seq in near-isogenic lines and transgenic positive and control lines to identify differential expressed genes. We will also identify the proteins and DNA elements which could interact with ZmKWL7 through yeast two hybrid and ChIP-Seq to dissect the pathway in which ZmKWL7 involved. Candidate gene association analysis and selection analysis will be performed to identify favourable allele and to develop markers for the improvement of kernel size and weight.

玉米是最重要的作物之一，提高玉米产量一直都是玉米遗传改良的重要目标之一。粒型和粒重是玉米产量的重要组成因素，因此对控制粒型和粒重的基因进行克隆和功能解析，有助于我们理解产量的遗传基础和对玉米产量的遗传改良。在前期工作中，我们对一个控制玉米粒长和百粒重的主效QTL（qKWL7）进行了精细定位并成功克隆了此QTL的功能基因—ZmKWL7，此基因编码一个GNAT类转录因子，此类转录因子对籽粒性状的影响此前未见报道。本研究拟用超表达和CRISPR-Cas9基因编辑对ZmKWL7的功能验证；结合近等基因系和转基因材料的RNA-Seq、酵母双杂交、ChIP-Seq等技术鉴定与ZmKWL7互作的蛋白质和DNA，解析ZmKWL7调控玉米粒型和粒重的网络；结合候选基因关联分析和驯化改良过程中的选择分析来鉴定ZmKWL7的优良等位变异，并开发功能分子标记用于玉米粒型和粒重的遗传改良。

籽粒作为玉米产量来源的主要器官，其粒型和粒重调控基因及分子机制一直是研究热点。目前已定位到大量籽粒相关性状的QTL，但克隆的基因较少，相关调控机制仍不清晰。在本项目中，课题组完成了调控玉米籽粒大小和重量的基因ZmKWL7及其同源基因的克隆与功能验证，同时解析了此基因调控粒长和粒重的机理，并发现该基因在物种间功能存在一定保守性。这一研究将进一步加深我们对于玉米籽粒的粒型和粒重调控机制的认识，也为作物籽粒和产量的遗传改良提供基因资源。利用该项目的资助，课题组还在《Plant Communications》、《Journal of Plant Physiology》、《Plant and Cell Physiology》发表了两篇第一作者论文和一篇通讯作者论文。