转录因子ZmBES1/BZR1-5调控玉米籽粒大小的分子机理

BES1/BZR1是油菜素内酯信号途径唯一报道的转录因子，调控植物生长发育和逆境应答，但调控籽粒大小的研究鲜有报道。前期，我们发现玉米ZmBES1/BZR1-5有特殊结构域，其编码基因突变导致玉米籽粒变小，在拟南芥和水稻中过量表达促使种子变大。本项目拟开展以下三方面研究：第一，分析玉米过量表达、CRISPR/Cas9敲除、UniformMu及EMS突变体株系的籽粒性状及生理生化代谢差异，多途径验证ZmBES1/BZR1-5调控籽粒大小的功能。第二，利用文库筛选ZmBES1/BZR1-5互作蛋白，进一步开展BiFC与Co-IP验证及磷酸化实验，鉴定其上游作用因子。第三，结合RNA-seq和ChIP-seq，鉴定ZmBES1/BZR1-5的靶基因，并进行功能和代谢途径分析，揭示其下游调控网络。最终，明确ZmBES1/BZR1-5调控籽粒大小的分子机理，为玉米高产分子育种提供理论依据和基因资源。

The BES1/BZR1 proteins are reported as unique transcription factors in Brassinosteroide signaling pathway and play pivotal roles in plant growth, development and stress response. However, the study of BES1/BZR1s regulating kernel size has been rarely reported. In previous study, we found that maize ZmBES1/BZR1-5 possessed specific domain, maize ZmBES1/BZR1-5 mutant produced smaller kernels than wild type, and over-expression of ZmBES1/BZR1-5 could significantly increase seed size in transgenic Arabidopsis and rice. In this project, the below studies will be performed. First, to further validate the function of ZmBES1/BZR1-5 regulating kernel size from different way, kernel traits and difference of physiological and biochemical metabolome of over-expression lines, knockout lines by CRISPR/Cas9, UniformMu and EMS mutants of ZmBES1/BZR1-5 gene in maize will be analyzed, respectively. Second, to uncover upstream pathway of ZmBES1/BZR1-5, the interacting proteins of ZmBES1/BZR1-5 will be identified through Y2H library screening, then BiFC, Co-IP and phosphorylation assay will be performed. Third, to explore downstream regulatory network, the target genes regulated by ZmBES1/BZR1-5 will be screened through combination of transcriptome sequencing (RNA-seq) and Chromatin Immunoprecipitation sequencing (ChIP-seq), and were used for function and metabolic pathway analysis. Finally, the results will contribute for illuminating molecular mechanism of ZmBES1/BZR1-5 regulating maize kernel size, and provide theoretical reference and gene resource for molecular breeding of maize high-yield production.