棉花花药赤霉素稳态调节及其在高温耐性上的分子作用机制研究

棉花花药发育时期尤其是减数分裂期对高温胁迫最为敏感，其耐性强弱与育性、结铃性及产量形成直接相关。前期研究中我们发现不同棉花品种材料对赤霉素合成抑制剂缩节胺的敏感性与其高温耐性有着密切关系，外施GA3和缩节胺对高温胁迫下花药育性、GA含量及其代谢酶基因表达均有显著影响。因而，推测棉花内源激素GA特别是花药GA含量水平可能在花药高温耐性上起着重要作用。本项目拟利用耐高温与敏感棉花品系为材料，详细比较高温胁迫条件下发育花药中GA、可溶性糖等含量变化及其对外施GA3和缩节胺的响应，分析GA含量水平与花药高温耐性的关系；从全基因组转录水平对花药GA与其他激素等代谢酶、信号转导和发育相关的基因进行表达调控研究，解析GA稳态调节的影响因素及其生物学功能，并阐明花药高温胁迫响应中GA的分子作用过程。该项目将有助于揭示GA在棉花花药高温耐性差异上的作用机理，为调控和改良棉花高温耐性提供理论基础和基因资源。

The cotton anther development, particularly at meiosis stage, is the most sensitive to high temperature stress (HTS), and the tolerance directly relates with anther fertility, boll-setting and yield formation. In our previous study, we found the sensitivity to mepiquat chloride (MC), an inhibitor blocking gibberellins (GA) biosynthesis, in different cotton cultivars was closely related with tolerance to HTS, and the primarily investigation also showed that application of exogenous GA3 and MC had significant effect on anther fertility, GA content and the expression of key enzyme encoded genes in GA biosynthesis. These findings suggest that the endogenous GA level, especially in cotton anther, may play a pivotal role in anther tolerance to HTS. In the project, we propose to compare the content of endogenous GA, soluble sugar and so on in detail during anther development under high temperature conditions with the application of exogenous GA3 and MC treatments using high temperature tolerant and susceptible cotton lines as materials, analyze the relationship of GA level with HTS tolerance in anther, investigate the expression and regulation of GA and other endogenous phytohormones metabolic enzymes, signal components and anther development related genes at the whole genome-wide level, detect the factors affecting GA homeostasis and their biological functions, and clarify the molecular mechanism of GA in cotton anther responding to HTS. The project will help to reveal the role of GA in different tolerance to HTS during cotton anther development, and provide theoretical basis and genes for regulating and improving tolerance to HTS in cotton breeding program.