大豆LUX基因在光周期调控开花中的功能研究

The long-juvenile (LJ) trait in soybean [Glycine Max (L.) Merr.] has been defined as delayed flowering time under short-day conditions. This characteristic is especially important as it increases the range of adaptation of soybean in low latitudes and improves the yield for low latitudes. In our previous study, we found that, the major gene for long-juvenile trait, J depends genetically on the legume-specific flowering repressor, E1, and J protein physically associates with the E1 promoter of LBS site (conserved DNA binding sites for LUX) to down-regulate its transcription, but the mechanism about LUX has not been elucidated. In this research, we planned to get transgenic plant, which will help us to identified the influence of LUX on photoperiod and yield. In addition, we demonstrated the complex LUX-J and LUX binds to E1 promoter by yeast system, Pull-down and ChIP-PCR. At last the genetically regulative relationship of J with known maturity genes will be determined using these maturity gene isolines and transgenic lines. This study not only made us to understand more deeply of the molecular mechanism for LUX and the photoperiod, but also provided theory basis and genetic resources for molecular breeding, which eventually improved the soybean yield.

长童期性状是指大豆品种在短日照条件下延迟营养生长期，该性状的应用打破了大豆不能在低纬度地区种植的限制，改变了大豆生产和贸易格局。申请人前期结果表明，J（控制长童期性状的关键基因）结合到大豆开花期核心调控因子E1启动子的LUX结合元件负调控E1基因转录表达，进而影响生育期和产量，暗示J与LUX形成蛋白复合物且LUX与E1基因启动子直接结合。但是，大豆中LUX基因功能及分子机制的研究尚属空白。申请者拟通过基因敲除和过表达遗传转化获得转基因株系，鉴定LUX基因对光周期的影响；利用酵母杂交系统、蛋白体外结合试验和染色体免疫共沉淀等技术解析LUX蛋白与J蛋白的相互作用并验证LUX对E1基因的调控作用；利用近等基因系或转基因株系验证LUX基因与已克隆生育期基因之间的调控关系。LUX基因功能的研究和作用机理的解析，不仅能够促进对光周期调控大豆开花机制的深入认知，而且可以为分子育种提供理论依据和育种材料。

大豆是光周期敏感的短日照作物。如何在低纬度区域延迟大豆开花期，对于低纬度区域大豆产量的提高具有重要意义。前期研究结果表明，J由ELF3编码，调控短日照条件下的生育期。在拟南芥中，ELF3发挥功能主要通过与LUX形成EC复合物来调控下游基因，但大豆中LUX基因的功能未被研究。为此，我们针对大豆中的两个LUX ARRYTHMO (LUX)基因，利用基因敲除和过表达技术，结合分子生物学技术，明确大豆的两个LUX同源蛋白与J相互作用形成EC复合物，且LUX通过结合开花关键抑制子E1及其两个同源基因E1La，E1Lb启动子上的LUX结合位点而抑制三者的转录。在短日照条件下，与野生型相比，lux1单突变体和lux2单突变体花期与野生型没有差异，但是lux1lux2双突变体却表现出极度晚花表型，表明LUX两个基因在调控大豆光周期途径中功能是高度冗余的。.综上，LUX参与的EC复合物以及E1家族的基因可作为选育具有特定开花和适应性的大豆品种的潜在靶点，这一目标可以通过导入这些基因的自然变异或通过基因编辑创制新的突变体来实现。