ERF2-like转录因子调控植保素capsidiol的抗病分子机制研究

Alternaria alternata is a necrotrophic fungal pathogen causing severe losses of many economic important plants, including cotton and tobacco, while hosts will usually produce anti-fungal phytoalexins to counter-attack. Our early experiments have demonstrated that wild tobacco plants (Nicotiana attenuata) produce large amount of sesquiterpene, capsidiol, to defend against this fungus，but this chemical defense will be strongly decreased in plants silenced with an ERF2-like transcription factor. However, the mechanism behind is still not clear. We hypothesize that host plants will activate certain signalling pathways to regulate capsidiol production by directly binding of ERF2-like protein to the promoter region of capsidiol biosynthetic genes. We are trying to identify the key signalling pathways, and the detail mechanisms of how ERF2-like protein functions in the controlling of capsidiol biosynthesis through, gel shifting, yeast-one and two-hybrid, chromatin immuno-precipitation, RNAi and overexpression techniques, and transgenic plants impaired in JA, or ethylene, or SA signalling pathway. This work will provide molecular insights into the resistant mechanisms of wild tobacco against A. alternata, and some new clues for Alternaria disease control.

链格孢菌是一种农业上对烟草、棉花等诸多作物危害严重的腐生性病原真菌，而合成植保素是植物用来抵御该类病原菌的重要手段。我们的前期工作表明：与栽培烟草相比，高抗的野生近缘种Nicotiana attenuata可以通过合成大量的倍半萜类植保素capsidiol来抵御该菌的入侵，然而当一个ERF2-like转录因子被沉默后，植物中的这种化学防御就显著的降低了，但机理目前未知。为此，我们提出假说：植物在感受到病原菌的入侵后，会激活特定的上游信号，使ERF2-like蛋白直接结合到capsidiol合成关键酶基因的启动子区，通过转录激活来控制这种抗病反应。为此，我们将利用各种信号通路缺失的转基因植物和凝胶阻滞、酵母单双杂交、染色质免疫共沉淀，转基因介导的沉默及超表达等手段，来寻找并确定ERF2-like蛋白的上游信号，及该蛋白调控capsidiol具体的分子机理，为下一步该病害的防控提供重要的靶点。

链格孢菌是一种农业上对烟草、棉花等诸多作物危害严重的腐生性病原真菌，而合成植保素是植物用来抵御该类病原菌的重要手段。我们的前期工作表明：与栽培烟草相比，高抗的野生近缘种Nicotiana attenuata可以通过合成大量的倍半萜类植保素capsidiol来抵御该菌的入侵，然而当一个ERF2-like转录因子被沉默后，植物中的这种化学防御就显著的降低了，但机理目前未知。为此，我们综合利用凝胶阻滞、酵母单双杂交、染色质免疫共沉淀、转录激活、转基因等手段证明了ERF2-like转录因子直接结合到capsidiol合成关键酶基因EAS12的启动子区，通过转录激活来调控植保素的合成；还证明了基于capsidiol的这种化学防御，与香豆素类植保素scopoletin不一样，它并不依赖于植物体内的茉莉酸和乙烯信号通路；同时还发现还发现了bZIP60，Patatin-like，PDR和KTI2等参与植物抗病或抗虫的防御反应。本研究聚焦植物抗腐生性病原菌的学科前沿，独辟蹊径的从植保素的调控机制方面深入解析ERF2-like调控植保素椒二醇的分子机制，极大的加深了我们对植物抗病的防御反应的理解，不仅将为揭示野生烟草抵御链格孢菌的分子机理奠定扎实的基础，而且在病害防治和农业生产上也起着重要的指导作用。