番茄根结线虫抗性反应中redox 介导的温敏性及其调控机制

Mi-1gene-mediated resistance to nematode is accompanied by changes of Ca2+, ROS, MPK cascade and HR response in tomato. The resistance is suppressed by high root temperature; however, the mechanism is still unclear. In recent years, the applicant has discovered that cellular redox state is critical for the induction of stress tolerance and acclimation for the temperature of the habitat of the plant species. Therefore, the applicant proposes the hypothesis that the oxidized cellular redox state is attributable for the impaired SA signaling and inhibition of nematode resistance under high temperature. By using qRT-PCR, gene profiling, and VIGS, the project is aimed at elucidating the role of redox signaling in temperature-dependent nematode resistance. The project will also study changes of the content and subcellular localization of components of defence protein complex and the relationship with thermo-stability of nematode resistance. Finally, the project plans to regulate the nematode resistance of tomato by applying BR and SA, and meanwhile, understand the physiological and molecular mechanisms underlying these effects. The project is expected to provide theoretic and practical bases for the efficient use of resources of resistance genes and the chemical regulation of nematode resistance.

番茄Mi-1基因介导的根结线虫抗性伴随着Ca2+、ROS、MPK级联反应以及HR反应等，而根系温度升高对根结线虫的抗性具有抑制作用，但具体的机制仍不清楚。申请者近年来研究发现，细胞氧化还原（redox）信号与植物的抗性具有重要的联系，并且温度对redox的调控可能与植物的温度适应性有关，因而提出根系高温环境下细胞redox状态趋于氧化，阻断了SA等抗病信号通路，继而抑制根结线虫抗性。本项目拟以不同温敏性抗根结线虫番茄品种为材料，利用qRT-PCR、基因表达谱和VIGS等技术，阐明redox信号在不同温度下对根结线虫抗性的作用。研究抗病复合体蛋白组分如HSP90水平、亚细胞定位和抗病热稳定性之间的相互关系，同时，希望利用BR和SA等调控手段提高温敏性抗性番茄的根结线虫抗性，并研究其生理与分子机制。研究有望为抗病基因资源的高效利用和根结线虫的抗性调控提供理论与实践基础。

本项目以不同温敏抗性的番茄品种为研究材料，通过诱变育种手段，创建了具有高温耐性的番茄抗根结线虫新种质A123。再此基础上，通过转基因和基因沉默技术，发现在Mi-1介导的根结线虫抗性中转录因子HsfA1a能够通过调控Wfi1表达，产生活性氧（ROS）产生，激发植物超敏反应来抑制线虫生长。通过外源处理和基因沉默技术，发现植物信号分子NO在JA能通过诱导PI蛋白表达，提高番茄对根结线虫的基础抗性。利用番茄不同油菜素内酯（BR）水平材料，发现BR能够通过RBOH激活MAPKs信号级联，诱导番茄对根结线虫的基础抗性。利用不同光质处理番茄光敏色素突变体材料，发现红光能够通过光敏色素A（PhyA）调控H2O2产生，诱导茉莉酸（JA）合成，提高植物对根结线虫的抗性。通过转基因手段和生物物理检测，发现线虫浸染能够刺激番茄根系细胞膜内外离子变化，产生电信号，并能传递到地上部诱导JA合成，产生系统防御反应。研究还发现，新型植物激素独脚金内酯番茄根结线虫基础抗性中也起着重要作用。