ABA调控MYB30介导的文冠果蜡质积累的分子机理

Cuticular wax is the first barrier for plants in response to environmental challenge and plays an important role in drought stress. The phytohormone ABA is closely related to the response to drought stress in plants, but the study on its relationship with cuticular wax is very limited. Xanthoceras sorbifolium is one of the most important woody oil tree in the “Three North” area, whose development is mainly affected by drought stress. In this project, XsMYB30, a transcription factor related to wax synthesis discovered in early study, was used as the research point to analyze the ABA content and the expression level of ABA response genes in transgenic Xanthoceras sorbifolia. The wax content and composition in XsMYB30 transgenic plants were further detected by applying ABA or ABA synthesis inhibitor to investigate the effects of ABA pathway on XsMYB30-modulated wax accumulation. Meanwhile, the interaction factors of XsMYB30 in ABA signal and wax synthesis were explored by immunoprecipitation and yeast screening library to analyze its regulatory network. The mechanism of ABA in XsMYB30-regulated wax formation in Xanthoceras sorbifolia was elucidated, which can provide a theoretical basis for breeding and improving new varieties of Xanthoceras sorbifolia with drought resistance.

表皮蜡质是植物应对外界环境变化的第一道屏障，在植物抵御干旱胁迫过程中起着非常重要的作用。而ABA是一种与植物干旱响应密切相关的内源激素，但关于其与表皮蜡质关系的研究非常有限。文冠果作为“三北”地区重要的木本油料树种之一，其大规模发展主要受到干旱胁迫的影响。因此，本项目以前期发掘的与蜡质合成相关的转录因子XsMYB30为切入点，分析其转基因文冠果中ABA含量和ABA响应基因的表达水平，进一步通过外施ABA或ABA合成抑制剂检测XsMYB30转基因植物中蜡质含量和组分的变化，探讨ABA途径对XsMYB30调控的文冠果蜡质积累的作用。同时利用免疫共沉淀和酵母筛库等手段挖掘XsMYB30在ABA响应和蜡质合成中的互作因子，解析其调控网络，进而阐明ABA在XsMYB30调控的文冠果蜡质形成方面的分子机理，为文冠果抗旱性性状的新品种选育与改良提供理论依据。

表皮蜡质是植物应对外界环境变化的第一道屏障，在植物抵御干旱胁迫过程中起着非常重要的作用。而ABA是一种与植物干旱响应密切相关的内源激素，但关于其与表皮蜡质关系的研究非常有限。文冠果作为“三北”地区重要的木本油料树种之一，其大规模发展主要受到干旱胁迫的影响。通过对不同文冠果种质资源在干旱条件下干旱相关指标的分析，筛选出四类抗旱性差异显著的文冠果种质资源；通过不同类型文冠果种质资源的转录组分析，发现了与水分利用率（WUE）和生长性状密切相关的共表达网络、通路和枢纽基因，它们可能是文冠果耐旱节水的关键调节因子。进一步研究发现，转录因子XsMYB30在高蜡质的文冠果种质资源中表达上调。在干旱条件下，XsMYB30的过量表达显著提高植物的ABA含量、叶片蜡质含量和抗旱性，在ABA合成抑制剂处理后，XsMYB30转基因材料的抗旱性和叶片蜡质含量被不同程度的抑制，表明ABA参与XsMYB30调控的文冠果蜡质积累过程；通过DAP-seq、EMSA和RT-PCR实验，发现并验证了XsMYB30蛋白与ABA合成基因XsNCED3启动子的特异性结合并激活其表达。研究表明ABA通过ABA合成基因XsNCED3启动子与XsMYB30的特异性结合，参与XsMYB30调控的叶片蜡质积累和植物抗旱性，为高抗旱文冠果新品种的选育与改良提供理论依据。