高温高湿下Homeobox类转录因子GmSBH1调控春大豆种子田间劣变抗性的分子机制

The seed vigor decrease due to the pre-harvest seed deterioration frequently occurs in many tropical and sub-tropical soybean production areas around world，which seriously impact the seed quality as well as the soybean industry. The molecular regulation mechanism of the pre-harvest seed deterioration resistance is poorly understand. It has been shown that GmSBH1 related to the pre-harvest seed deterioration, but the regulation roles of GmSBH1, a homeobox transcription factor, was not fully studied. The objective of this project is to reveal the molecular regulation mechanism of GmSBH1 on the pre-harvest seed deterioration resistance of spring soybean from three aspects, first is to analyze the upstream protein that regulated GmSBH1 transcription under the high temperature and humidity, second is to identify the key proteins that regulated the pre-harvest seed deterioration resistance under high temperature and humidity by interaction with GmSBH1, third is to identify the function of GmSBH1 and the interactions protein gene that regulated the pre-harvest seed deterioration resistance under high temperature and humidity, and fourth is to study the downstream genes that regulated by GmSBH1 and related to the pre- harvest seed deterioration resistance under high temperature and humidity. This results of this project expected to facilitate the construction of the molecular regulation mechanism network for the pre-harvest seed deterioration resistance under high temperature and humidity, to implement molecular design breeding of new spring soybean germplasm with the pre-harvest seed deterioration resistance.

田间劣变导致的种子活力降低已成为许多热带和亚热带大豆产区的共性问题，严重影响了春大豆种子质量乃至大豆产业的发展。目前对春大豆种子田间劣变抗性的调控机制尤其是分子调控机制尚缺乏系统研究。项目组前期研究表明大豆Homeobox类转录因子基因GmSBH1参与春大豆种子田间劣变过程，但作为转录因子，高温高湿下GmSBH1在调控春大豆种子田间劣变抗性过程中是如何发挥作用的尚不清楚。本项目拟从高温高湿下调控GmSBH1转录的上游蛋白及作用方式、高温高湿下与GmSBH1互作的关键蛋白及互作方式、GmSBH1及其关键互作蛋白基因共调控种子田间劣变抗性的功能验证、高温高湿下受GmSBH1调控且与种子田间劣变抗性相关的下游基因4方面为切入点，揭示高温高湿下GmSBH1调控春大豆种子田间劣变抗性的分子机制。为构建春大豆种子田间劣变抗性的分子调控网络和开展春大豆种子田间劣变抗性品种分子设计育种奠定理论基础。

为了探明Homeobox类转录因子基因GmSBH1是如何调控春大豆种子田间劣变抗性的，在前期研究基础上，以种子田间劣变抗性品种湘豆3号和不抗品种宁镇1号为材料，在生理成熟期（R6-R7期）进行高温高湿胁迫，开展了高温高湿的下调控GmSBH1表达的上游蛋白及作用方式的确定、高温高湿胁迫下与 GmSBH1 互作的关键蛋白及互作形式研究、GmSBH1 及其关键互作蛋白基因共调控种子田间劣变抗性的功能验证、高温高湿下受 GmSBH1 调控且与种子田间劣变抗性相关的下游基因研究四个方面的研究。通过研究基本明晰高温高湿下 GmSBH1 调控春大豆种子田间劣变抗性的分子机制，即高温高湿下GmCOL4通过与GmZTL1互作并于GmSBH1启动子中应响应高温高湿的核心顺式作用元件HSE结合，从而调控GmSBH1的表达； GmSBH1与GmBLH4互作形成异源二聚体参与种子田间劣变过程；GmSBH1与GmXTH6启动子区顺式作用元件（TGACATGTGAC）存在结合关系并且对GmXTH6的表达具有上调的作用，GmXTH6与GmDHN和GmPUB互作并与种子田间劣变抗性相关。研究结果对构建春大豆种子田间劣变抗性的分子调控网络和开展春大豆种子田间劣变抗性品种分子设计育种具有重的理论指导意义。