茉莉酸与脱落酸互作调控胡杨水分胁迫响应的分子机制研究

As a model tree to study abiotic stress response，revealing the stress resistance mechanism of Populus euphratica is important for poplar genetic resources innovation utilizing important gene resources from P. euphratica. This project is based on the scientific theory that both jasmonic acid and abscisic acid signal transduction are involved in water stress response in plants. On basis of illustrating the jasmonic acid signal first, the cross-talk study between jasmonic acid and abscisic acid signals will be further performed. Using yeast-two hybrid, bimolecular fluorescence complementation and surface plasmon resonance methods and chromatin immunoprecipitation, the key components of jasmonic acid signal will be identified. This project focuses on the function of JAZs, which were considered as hub of jasmonic acid signal, by performing genetic transformation in poplar. We will perform comparative study between transgenic plants and wide type after jasmonic acid and abscisic acid treatment as well as the downstream gene expression analysis of JAZs, and the interaction relationship between the key components of two phytohormones. The project will reveal water stress response mechanism involving jasmonic acid and abscisic acid. Our results will facilitate better understanding of the roles of phytohormones regulation in water stress response, provide theoretical breakthrough for abiotic stress response mechanism in P. euphratica as well as technological basis for poplar breeding.

胡杨为模式抗逆树种，揭示胡杨抗逆机制对利用胡杨优良基因资源进行杨树种质创新具有重要意义。本项目旨在围绕茉莉酸和脱落酸信号均参与植物水分胁迫响应这一理论依据，解析胡杨茉莉酸信号通路，并探索茉莉酸和脱落酸在水分胁迫响应中的互作机制。通过酵母杂交、双分子荧光标记、表面等离子共振以及染色质免疫共沉淀等技术鉴定茉莉酸信号途径的重要组分。重点针对位于茉莉酸途径交叉节点的JAZ家族基因实施杨树遗传转化研究，鉴定胡杨主要JAZs的基因功能，解析茉莉酸途径参与气孔运动和水分胁迫响应的作用机制。通过对阳性转基因植株JAs、ABA处理下的对比研究、JAZ调控的末端基因分析，以及茉莉酸信号和脱落酸信号组分之间的互作关系和互作模式分析，建立胡杨茉莉酸和脱落酸途径参与水分胁迫的互作调控模型，丰富胡杨水分逆境胁迫下的激素调节理论，实现胡杨非生物逆境胁迫响应机制上的理论突破，为评价树木抗逆性，创制高抗树种提供技术基础。

茉莉酸和脱落酸作为植物激素在植物对各种非生物胁迫中起着重要作用，但两者之间的交叉互作关系还不明晰。本项目以木本模式抗逆树种胡杨为研究材料，探索茉莉酸（JAs）和脱落酸（ABA）在水分胁迫响应中的互作机制。JAZ蛋白是JA信号转导中的关键因子，通过酵母杂交、双分子荧光标记我们发现胡杨多个JAZ成员与脱落酸中的关键因子存在相互作用，且这些JAZ成员可以同时受到干旱、高盐、JAs和ABA的诱导，其中PeJAZ1和PeJAZ2受干旱和ABA诱导最为强烈。PeJAZ1和PeJAZ2均可以与茉莉酸受体COI1和下游转录因子MYC2互作。亚细胞定位显示，PeJAZ1和PeJAZ2定位在细胞核中，我们将PeJAZ1和PeJAZ2同时转化烟草和杨树并进行了逆境控制实验，发现PeJAZ1和PeJAZ2可以降低了植物对干旱、盐碱的敏感性，其中过表达PeJAZ2能够显著提高转基因杨树的抗旱性。RNA-seq分析表明，在正常浇水、干旱胁迫及ABA处理下，PeJAZ2过表达植株与对照相比，ABA和JA信号通路中的多个基因如PYL、MYC2、ABF表达水平存在显著差异。对转基因杨树和野生型的离体叶片进行ABA喷施处理后转基因杨树中气孔闭合速度较野生型更快, 说明过表达PeJAZ2增强了植株对ABA的敏感性。茉莉酸通路中的JAZ成员参与了ABA介导的气孔调控在植物中报道较少，关于JAZ正调控抗旱性的研究鲜有报道，这些结果和结论对于进一步研究茉莉酸和脱落酸交叉信号在非生物胁迫逆境中的作用具有重要意义，也表明了PeJAZ2作为ABA和JA信号途径中的重要交叉因子调控了胡杨抗旱性。