水稻EIS1调控逆境诱导衰老的分子机理研究

Premature senescence is one of the important factors that restricting the increase of rice yield, and abiotic stress is one of the main environmental conditions that cause premature senescence in rice. We screened the rice premature senescence mutant library by dark treatment, and obtained a mutant eis1(environmental-stress induced senescence 1). Its leaf senescence is very obviously induced by darkness, high temperature and drought. Further study found that the expression level of EIS1 was significantly negatively correlated with the leaf senescence phenotype and the promoter region contains a large number of high-temperature and drought stress responsive elements, suggesting that it plays important role in the regulation of environmental-stress induced senescence. Current project will be based on the previous study, further studying the biological function of EIS1; identifying the upstream regulation elements and the possible downstream interaction proteins of EIS1; analyzing the possible role of EIS1 involved in senescence signaling pathway and regulatory network and exploring the possibilities of its application in molecular design of breeding. It is hoped to elucidate the molecular regulation mechanism of EIS1 in rice senescence, thereby understanding the relationship between senescence and abiotic-stress, and complementing the molecular regulation network of rice senescence.

早衰是制约水稻产量提高的重要因素之一，而非生物逆境胁迫是引起水稻早衰的主要外界条件之一。我们用暗处理的方法筛选到一个逆境胁迫诱导的早衰突变体（environmental-stress induced senescence 1）eis1，其叶片衰老非常明显地受黑暗、高温和干旱的诱导。研究发现，EIS1的表达水平与衰老表型呈负相关，其启动子中含有大量的干旱、高温等逆境响应元件，暗示其在逆境诱导的衰老信号调控中发挥功能。本项目将在前期研究基础上，对EIS1的生物学功能进行详尽的研究；鉴定调控EIS1的上游元件及其下游可能的互作靶蛋白；分析EIS1可能参与的衰老信号传导途径和调控网络，分析EIS1在延缓水稻衰老中的作用并探讨其应用于分子设计育种的可能性。希望能够阐明EIS1在水稻衰老中的调控机理和分子机制，从而在更深层次上了解非生物逆境诱导的水稻叶片早衰的分子机制，进一步完善水稻衰老的调控网络。

叶片作为植物最主要的光合作用和源器官，为植物生长提供了大量的能量和有机物质。以占我国谷物种植面积1/3的水稻为例，籽粒灌浆所需营养物质的约60%～80%来自叶片光合作用。因此，叶片的寿命直接影响着水稻的最终产量和品质，目前，早衰是制约水稻产量提高的重要因素之一。作为影响植物生长的重要外源因素，逆境胁迫如干旱、极端高/低温、强光、黑暗、重金属及营养元素、盐碱胁迫、病虫害、机械损伤等对叶片的衰老起始和发展均具有重要影响。通过对逆境胁迫诱导的早衰突变体（environmental-stress induced senescence 1）eis1的研究，我们发现其叶片衰老非常明显地受黑暗、高温和干旱的诱导；EIS1的表达水平与衰老表型呈显著负相关，其启动子中含有大量的干旱、高温等逆境响应元件；融合GFP定位实验发现EIS1定位于叶绿体；进一步分析发现，该蛋白有6个跨膜结构域，很可能定位在叶绿体内膜、外膜或类囊体膜上；EIS1的表达在茎叶部表达受干旱、高温等非生物胁迫诱导，而在根部主要受高温与ABA诱导表达；通过酵母双杂鉴定EIS1下游可能的互作靶蛋白，我们发现与ABA、carotenoids合成相关的两个关键酶均与EIS1互作；分析发现EIS1可能通过影响类异戊二烯类物质的稳定参与衰老信号传导途径和调控网络。本项目研究了EIS1在延缓水稻叶片衰老中的调控机理并分析其应用于分子设计育种的可能性，有助于人们从更深层次上了解非生物逆境诱导的水稻叶片早衰的分子机制，进一步完善水稻衰老的调控网络。