大豆生物钟基因LCL3调控开花途径的研究

Soybean is a short-day plant (SDP) and highly sensitive to photoperiod. The photoperiod-regulated flowering not only affects soybean adaptability, but also determines its yield. Clock genes LHY and CCA1 play important roles in regulating plant flowering, four LHY/CCA1 homologous genes LCLs were identified in soybean. Knockout mutants were created by CRISPR/Cas9 and used to investigate flowering time. Fifteen type combinations of LCLs soybean mutants have be obtained by backcrossing between quadrable mutant with Harosoy wild plant. Moreover, compared with the wild type (Harosoy), the lcl3 mutant significantly delaying flowering in long day and short day. These results indicated that LCL3 plays an important role in soybean photoperiod-regulated flowering pathway. However, its underlying molecular mechanism is not clear. In this study, LCL3 directly binding target genes will be identified by DAP-seq and RNA-seq, and the interaction networks related to flowering will be further analyzed. Furthermore, the SNP polymorphism of LCL3 gene will be analysis in 700 natural varieties resequencing data and the excellent allele variation of LCL3 gene will be screen. Domestication and evolution process of LCL3 gene will also be analysis. The findings of this study will not only add more knowledges on photoperiod regulated flowering but also facilitate the molecular breeding towards soybean adaptation and improving grain yield.

大豆是对光周期反应敏感的短日照作物，大豆开花时间决定着大豆的产量。生物钟基因LHY和CCA1在调控植物开花方面扮演者重要的角色，大豆中含有四个LHY/CCA1的同源基因LCLs。申请者前期利用CRISPR/CAS9和杂交的方法获得了15种突变体组合，并对四个单突变体的表型分析，发现lcl3突变体在延迟大豆开花上具有最大的效应。然而LCL3调控大豆光周期开花具体的分子机理尚未清晰。因此，本研究拟重点研究LCL3调控大豆开花的途径。本研究通过对lcl3突变体进行RNA-seq分析，并结合DAP-seq实验筛选LCL3调控的下游关键基因，进而深入解析开花途径相关的互作网络。通过分析LCL3基因在700份重测序自然品种的SNP多态性，筛选LCL3基因的优异等位变异，解析其驯化与进化历程。通过本研究不但能够促进对植物开花调控的理论认知，而且对提高大豆产量分子育种效率具有十分重要的意义。

大豆是短日照作物，对光周期反应敏感，大豆光周期开花决定着大豆的产量。大豆中含有四个拟南芥生物钟基因LHY/CCA1的同源基因LCL1，LCL2，LCL3，LCL4。利用CRISPR/CAS9技术和稳定转基因方式获得lcl1/lcl2/lcl3/lcl4大豆四突变体植株；并利用杂交方式，获得15种突变体组合，通过长短日照下田间表型观察，发现lcl3突变体显著延迟大豆开花；找到了LCL3的下游基因E1，并通过ChIP-qPCR方法，证明LCL3能够直接结合E1的启动子区，并抑制E1的表达；通过将LCL3与E1，J进行杂交，获得各种组合突变体材料，表型观察后发现，LCL3行使功能完全依赖于E1，同时和J具有加性效应，LCL3和J是大豆适应低纬度地区的遗传基础；本研究提出了两个短日照大豆高产模型，即LCL3家族基因的纯合三突变体和lcl3/j/E1，对提高大豆产量分子育种效率具有十分重要的意义。

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