玉米籽粒性状关键基因分子机理研究

Maize kernel is one of the most important components that affect maize agronomic yield. However, the genetic regulation for factors involving maize kernel development (such as the rate of grain filling) is still poorly understood. We propose to dissect the genetic regulation of maize kernel development using both genome-wide association analysis approach and a reverse genetics approach based on CRISPR/Cas9 mediated targeted genome editing. We have now established GWAS panel of 700 diverse inbred lines collected from China and USA, and have completed the genotyping of all these 700 lines, with which initial GWAS for grain filling rate was conducted. Resulted from an analysis of transcriptome data of developing maize kernel, embryo and endosperm at 52 time-tissue points, we have identified 1258 genes expressing specifically in the embryo or in endosperm respectively. Among them, 91 are transcription factors. In the same time, we have recently established the CRISPR/Cas9 mediated gene targeting system with very high targeting efficiency in stable transgenic maize lines. We are going to address 2 to 3 major regulatory player of maize kernel traits, and understanding its regulatory mechanism using GWAS, CRISPR/Cas9 based mutagenesis system and other molecular biology tools. We will also develop functional molecular markers based on favorable haplotypes of the regulatory genes, which will then be used in the genetic improvement. This project will provide important knowledge for the molecular breeding of the yield of maize.

玉米籽粒性状是影响产量的重要性状之一。玉米籽粒性状（如籽粒灌浆速率）的遗传调控却依然非常不清楚。我们计划利用全基因组关联分析方法和基于CRISPR/Cas9基因定向突变的反向遗传学方法，研究玉米重要籽粒性状的遗传调控，阐明控制籽粒性状关键基因的功能。我们利用700份自交系所组成的群体，已经对玉米籽粒灌浆速率等性状进行了初步的关联分析。同时，通过分析籽粒52个不同发育时间点的转录组数据，发现了胚、胚乳特异表达的基因1258个，其中转录因子有91个。我们也建立基于CRISPR/Cas9的基因定向突变系统，得到在稳定的转基因株系中高效的基因定点突变率。综合利用关联分析，基因定点突变及其它分子生物学技术，我们将重点研究2-3个控制玉米籽粒性状的关键基因，并阐明其分子调控机理，同时利用对应的优良等位基因开发分子标记，开展籽粒性状的遗传改良。本项目的实施将为玉米产量性状分子设计育种提供重要理论指导。

本项目围绕玉米籽粒性状（如籽粒灌粒重），利用全基因组关联分析和基于CRISPR/Cas9基因定向突变的反向遗传学方法，研究玉米籽粒性状关键基因的分子调控机理。利用国内外538份玉米骨干自交系，对授粉后10天的籽粒进行转录组测序，结合基因型数据、表达量数据和表型（百粒重）数据建立三者之间的相关模型。通过关联分析，共得到了754个与百粒重显著相关的基因；通过反向遗传学的方法获得控制籽粒性状过程关键候选基因11 个，通过转基因互补试验，获得3个控制籽粒性状的关键基因，明确了控制籽粒重要性状3关键基因的分子调控机理；发表SCI 论文7篇，培养4名硕士研究生，3名博士研究生。