长日照条件下J基因调控大豆开花的功能研究

Flowering time is one of the important factors that influence the yield of soybean. Our team has previously cloned the J locus and proposed the PHYA-J-E1-FT model of the photoperiod-regulated flowering pathway under short-day conditions. Using the NIL pairs for J locus, we found that the NIL-j allele flowered significantly later than the NIL-J allele under long-day conditions, and the suppression of expression of FT2a and FT5a by J was independent of regulating the transcriptional expression of E1, which was different from short-day conditions. This indicates that J regulates time of flowering through distinct pathways under short- and long-day conditions, yet the mechanism that J regulates flowering time under long-day conditions still remains unclear. Here we will further investigate the regulatory network involved in J regulating flowering under long-day conditions by using NIL plants, overexpression plants and knock-out mutants of J as research materials. We will investigate the expression pattern of J under long-day conditions, identify and characterize downstream genes and interacting proteins of J through RNA-seq and Yeast two hybrid system respectively, reveal the regulatory relationship between J and E1, E2, E3, E4 under long-day conditions, finally map a regulatory network of J under long-day conditions. The elucidation of regulatory mechanism of J will provide important theoretical foundation for understanding the adaptation and molecular breeding of soybean.

开花期是影响大豆产量的重要因子之一。申请人所在团队前期成功克隆了J位点，并提出大豆短日照下的PHYA-J-E1-FT开花调控网络。申请人前期以J基因近等基因系为材料，发现在长日照下NIL-j也有延迟开花表型；但与短日照不同，长日照下J对FT2a和FT5a表达量的调控并不依赖于J对E1的转录调控，说明J在长短日照下通过不同的分子机制调控开花。然而，J在长日照下调控开花的分子机制尚不清楚。因此，本研究拟以J近等基因系、超表达与CRISPR突变体为材料，对J在长日照下调节开花的调控网络进行深入研究：分析J在长日照下的表达模式；通过转录组分析，筛选与J功能相关的关键下游基因，并对其功能进行研究；筛选J的互作蛋白，进一步挖掘J的功能机制；解析长日照下J与E1、E2、E3、E4的调控关系，绘制长日照下J 基因相关分子调控网络。J 基因调控机制的进一步阐明将为理解大豆适应性和分子育种提供重要的理论基础。

大豆作为世界上重要的经济粮食作物，在全球范围内的种植区域跨度非常大，大豆的广泛适应性是由一些调控开花的重要基因和数量性状位点的自然变异造成的。因此，阐明大豆开花关键基因功能及其调控机制对提高大豆产量、培育大豆优良品种具有重要意义。申请人所在团队前期成功克隆J位点，并提出大豆短日照下的PHYA-J-E1-FT开花调控网络。本项目在前期工作的基础上，进一步探索J基因在调控大豆开花中的角色和功能，以期为大豆优良品种的培育提供理论依据和重要的候选基因。本项目对J基因的表达模式进行了分析；通过CRISPR/Cas9和转基因技术获得J与其同源基因的突变体植株，以及J的超表达植株，并对其开花期进行统计；验证了J与大豆LUX蛋白之间的相互作用；解析了J及其同源基因与E1及其同源基因的遗传关系。以期更全面地解析J及其同源基因调控开花的分子机制和生物学功能。