GmE1与MtE1L开花调控功能差异的探究及其直接调控靶标筛选

大豆是一种典型的短日照植物，GmE1为开花抑制因子；而蒺藜苜蓿是长日豆科植物，MtE1L为开花促进因子。基于GmE1与MtE1L分别参与短日大豆和长日蒺藜苜蓿对于光周期开花调控功能的特异性，本项目拟借助生物信息学和遗传转化等方法明确其功能特异位点；同时以大豆Williams82和蒺藜苜蓿R108为受体，借助基因编辑+交互转化技术获得的转基因植株为实验材料，通过高通量转录组测序和染色质免疫共沉淀-高通量测序技术，筛选获得GmE1与MtE1L下游调控的直接靶基因及其重要结合元件，拓展GmE1与MtE1L下游分子调控通路。且基于不同材料中的靶基因表达差异分析，明确GmE1与MtE1L的功能差异以及不同光周期条件下下游靶基因调控关系。本研究将为长、短日豆科植物开花调控研究提供重要理论依据，也将为低纬度栽培大豆的分子育种提供重要候选分子元件，具有重要的理论和生产应用价值。

GmE1 is a flowering inhibitor in a typical short-day plant soybean (Glycine max), whereas its ortholog MtE1L acts as a flowering activator in a long-day legume Medicago truncatula. Although it has been shown that GmE1 and MtE1L play critical roles in the photoperiodic control of flowering in G. max and M truncatula, respectively, the molecular mechanisms of how the orthologs play distinct roles in the closely related species are still elusive. This project aims to reveal the functional specificity of GmE1 and MtE1L in flowering time control using genomics and genetics. CRISPR/Cas genome editing technology will be adopted to generate gme1 and mte1l loss-of-function mutants in a soybean variety Williams82 and a M. truncatula ecotype R108, respectively. Reciprocal transformation experiments will be conducted in the resulting mutants to express GmE1 in mte1l and MtE1L in gmel. The developmental phenotypes of the mutants and the transgenic plants will be characterized under different photoperiods, and transcriptome profiles will be investigated using high-throughput RNA sequencing (RNA-seq). Further, chromatin co-immunoprecipitation followed by high-throughput sequencing (ChIP-seq) will be employed to identify the direct target genes of GmE1 and MtE1L in the G. max and M. truncatula genomes. A combined analysis of the molecular and developmental phenotypes of gme1 and mte1l mutants and the transgenic plants resulted from the reciprocal transformation experiments and the direct targets of GmE1 and MtE1L will lead to a profound insight into the molecular mechanisms by which GmE1 and MtE1L diverge in their function in regulating flowering time under different photoperiodic conditions. Therefore, this study will provide an essential theoretical basis for understanding how long-day and short-day legumes align their flowering with their favorite daylengths. Furthermore, our research will also identify key targets for molecular breeding for low-latitude cultivated soybean, which has significant theoretical and practical value in modern agriculture.