绿豆结荚习性控制基因的鉴定与功能位点分析

Mung bean (Vigna radiata) stem growth habit is a key plant architecture trait that directly affects the crop’s yield potential and adaptability to different environment. It thus is very important to dissect stem growth habit towards effective modification and improvement of the crop’s stem growth habit and enhancement of the crop’s adaptability and yield potential. Previously, we have identified one gene in Mung bean, tentatively designated as VrDt1, the orthologous/homologous of the soybean gene Dt1, which control soybean stem growth habit. Subsequently, we obtained and compared the full-length sequences of VrDt1 in 5 representative indeterminate varieties and 6 representative determinate varieties of Mung bean, and identified single nucleotide polymorphism (SNP) sites within VrDt1 that were able to distinguish the indeterminate varieties from the determinate varieties. VrDt1 as a candidate gene underlying stem growth habit was also indicated by gene expression analysis. This project aims to identify and validate the candidate gene controlling stem growth habit and causative mutation responsible for the transition from indeterminate to determinate stem growth habit by a combination of multiple approaches that include candidate gene association analysis using a collection of Mung bean germplasm, bucked segregant analysis (BSA) using a F2 mapping population that will be constructed through this project, complementation test by heterologous transformation using a determinant (tfl1) Arabidopsis mutant, gene interaction analysis, and point-mutation and sequence replacement of the candidate gene. We anticipate that this project will not only lay the foundation for further dissection of molecular networks underlying Mung bean stem growth habit, but also provide molecular tools for optimization of the plant’s stem growth habit and other related traits of agronomic importance for Mung bean improvement.

绿豆结荚习性是一个极其重要的株型性状，直接影响绿豆的产量潜力和对环境的适应性。研究绿豆结荚习性分子调控机制对有效实施株型遗传改良，增强绿豆对生态环境的适应性及产量潜力具有重要意义。本项目组前期利用种间同源基因比较及聚类分析，获得了与大豆结荚习性控制基因Dt1高度同源的绿豆基因VrDt1。继而通过对该基因在5个无限型和6个有限型结荚习性绿豆品种中的全序列测定及表达分析，初步鉴定出与结荚习性相关的功能SNP候选位点。在此基础上本项目拟采用基于候选基因关联分析，基于作图群体的混合分组分析，候选基因定点突变，异源转基因互补检验，蛋白互作等方法，快速鉴定控制绿豆结荚习性的基因和功能突变位点，及该基因控制结荚习性的分子机制，开发基于该基因的功能分子标记。本研究将为进一步破解绿豆结荚习性的分子调控网络，以及通过分子手段对绿豆结荚习性及相关性状进行遗传改良和优化奠定基础。

豆类作物结荚习性是一个极其重要的株型性状，直接影响豆类作物的产量潜力。无限型野生绿豆向有限型栽培绿豆的转变是一个重要的驯化过程。在本研究中，我们利用基于候选基因关联分析，基于作图群体的连锁分析，候选基因定点突变，异源转基因互补检验等方法，鉴定控制绿豆结荚习性的基因及其功能突变位点。研究发现绿豆结荚习性是由单基因VrDet1控制的，该基因是大豆Dt1同源基因，在茎尖组织编码一个信号蛋白。无限型绿豆中VrDet1表达量高于有限型中Vrdet1的表达量。绿豆无限型向有限型的转变，主要是由于驯化过程中对VrDet1启动子区域两个连锁的功能位点筛选得到的。这两个功能位点的突变，导致VrDet1表达量降低，进而引起无限型向有限型的转变，因而这两个位点对VrDet1功能至关重要。另外，我们发现了Vrdet1分为两种亚型，进而说明绿豆有限型结荚习性可能存在两种驯化类型。本研究不仅为研究绿豆驯化过程提供了理论依据，还为进一步破解绿豆结荚习性的分子调控网络，以及通过分子手段对绿豆结荚习性及相关性状进行遗传改良和优化奠定基础。