高粱粒重基因SG1的克隆与功能分析

高粱是世界第5大粮食作物，同时具有食用，饲用，工业用和能源用等多项用途。我国目前高粱生产主要以粒用和酒用高粱为主，提高高粱单位面积产量是育种的重要目标之一。我们利用EMS诱变的方法获得了1个粒重突变体sg1，与野生型相比，该突变体的籽粒长度变短，千粒重降低，但其株高和生育期等其他性状和野生型相比均没有明显的变化。我们利用图位克隆和Mut-map测序相结合的方法，成功克隆了控制该高粱粒重突变的基因SG1，并通过水稻同源基因的CRISPR-Cas9遗传转化实验和玉米的同源基因的两个EMS等位突变体对该基因进行了初步的功能验证。本项目拟在上述研究工作基础上，以高粱粒重突变体sg1为主要材料，对SG1基因在高粱组织中的时空表达，基因功能和基因调控网络进行探索和分析，同时利用其在玉米和水稻中的同源基因对该基因在3个物种中进行平行进化研究，为高粱基因组学研究、高粱性状改良及遗传育种提供理论和应用基础。

Sorghum（Sorghum bicolor (L.) Moench）is one of the world’s five most important cereals for food, and it also can be used as forage, sugar and biofuel worldwide. In the current time, main cultivated sorghum in China were for grain (feed) and wine-making use, increasing of yield per hectare still is one of the main goals of sorghum breeding. We have isolated a grain weight ethyl methanesulfonate (EMS)-mutagenized line, sg1, compared with the wild type, the sg1 mutation line showed shorten grain length and lower grain weight, while no clear differences on the other traits like plant height and heading date. Combinates with Mut-map and map-based cloning methods, we cloned the candidate gene SG1 for this sg1mutation, and confirmed the candidate gene based on CRISPR-Cas9 edited homologues genes of SG1 in rice and two EMS mutation line of homologues genes of SG1 in maize. In this study, future functional analysis of the SG1 gene will be conduct. Using sg1 and its wild type, we will conduct subcellular localization and in situ hybridization of the candidate gene of SG1; In addition, gene expression pattern using different growth stages and tissues will be studied. Gene regulation network of SG1 gene will be checked by transcriptome analysis by using the sample of younger panicle, unmatured seed and matured seed of mutation line and wild type. And to study the parallel evolution of the SG1 gene between sorghum, maize and rice, we will check the gene expression level in the RNAi transgenic sorghum, and gene expression level of homologues genes related to SG1 in maize and rice using its EMS mutation line in the B73 background, CRISPR-Cas9 edited maize and rice plants. The results of this study will be useful to clarify the molecular mechanism of SG1 gene, understanding of gene regulation network and the parallel evolution between the three major crops-sorghum, maize and rice.