籽粒大小是玉米产量的重要构成因子。突变体基因Sem1可能是一个新的调控玉米籽粒发育的关键基因。但其调控籽粒发育的分子机理仍不清楚。项目组前期通过组学手段与转座子标签法相结合的策略，已鉴定到sem1突变体候选基因-组蛋白乙酰化转移酶复合体基因，在此基础上，本项目拟通过CRIPR/Cas9与超表达转基因实验及等位测验等，验证Sem1候选基因生物学功能；通过酵母双杂技术筛选SEM1互作蛋白，并用双分子荧光互补进行互作验证，进而利用RNA-Seq与ChIP-Seq技术开展籽粒发育不同时期突变体与野生型的转录组比较分析、共表达调控网络分析及全基因组组蛋白乙酰化的比较分析，鉴定Sem1调控网络，解析Sem1影响玉米籽粒发育的分子机制；通过重测序、关联分析与进化分析，鉴定Sem1基因在玉米驯化与育种中的选择位点，挖掘优良等位基因。探索调控玉米籽粒发育的分子机制，为玉米产量分子育种提供理论指导与基因资源。

Kernel size is one of the major factors constituting grain yield. Maize kernel mutants are of special importance to study the development process of maize kernel. Cloning and functional analysis of maize kernel mutant genes have deepened our understanding of the molecular mechanisms conferring maize kernel development, which may aid maize high-yield breeding. sem1 kernel defective mutant was identified by the screening of Robertson’s Mutator stocks. Recessive mutants in Sem1 result in small and viable seeds, which can be germinated and grow to mature plant with dramatic altered plant architecture. Previous study indicates that Sem1 can negatively regulate the expression of gnarley1, rough sheath1 and other homeobox genes, through which it modulates the developmental process of seeds (Scanlon et al., 2002). However, Sem1 has not been cloned and the molecular mechanisms underlying kernel development is still elusive. We have isolated and cloned sem1 candidate combining omic techniques (SHOREmap and BSR-Seq) and Mutator transposon tagging. Here, we propose to：1） conduct CRISPR/Cas9 silencing and over-expression of sem1 candidate through transformation, and complementary test of other alleles of sem1 candidate from maize UniformMu or EMS mutant libraries, to functionally validate the causal gene of sem1 mutant. 2） perform Yeast Two-Hybrid, followed by bimolecular fluorescence complementation (BiFC) to screen the interacting proteins of SEM1, further conduct RNA-Seq, coexpression network analysis and H3K14ac ChIP-Seq on the shoot apical meristem and kernels of sem1 mutants and its related wild types for the identification of regulatory network of SEM1. 3) conduct candidate re-sequencing on an association panel of ~500 diverse inbred lines and maize relative-teosinte, followed by association mapping and evolutionary analysis, to identify favorable alleles for high-yield breeding and the selection sites during maize domestication and selection. Our proposal will not only enhance our understanding of the molecular mechanism of maize kernel development, decipher the regulatory network of SEM1 during maize kernel development, but also potentially provide a new functional marker for maize high-yield breeding.