Molecular Mechanism of Plant Response to Wounding: Impact of JA Catabolism

植物可以感知昆虫摄食造成的组织损伤，并迅速激活几种关键的防御反应。茉莉酸盐（JA）是植物激素，它协调这些防御反应，并指示植物在逆境条件下的生长抑制。JA也是许多具有重要生态功能的特化代谢物的强力诱导剂。这些代谢物也是许多供人类使用的高价值天然产品（如营养保健品）的可再生来源。该项目将阐明如何精确调节JA水平以适应植物的各种胁迫适应机制。这项研究的长期目标是帮助减少或消除对化学农药的需求，并通过新的虫害控制方法增加全球粮食产量。这项研究促进了对植物防御机制的更好理解，这对农民和园艺学家都有好处。该项目旨在通过为大学生、毕业生和研究生提供多学科培训来改善STEM教育。将通过参与科学家为此目的设立的机构外展项目，从传统上代表性不足的科学群体中寻找学生。将以中学科学教师为对象，开发名为“未来教师的科学素养”（Sci-LiFT）的科学素养课程。参与的学生将参与与本项目相关的主题的真实实验室研究，并开发一个高中教学模块。Sci-LiFT项目将给项目参与者留下不可磨灭的印记，并对他们未来在中学的教学产生积极的影响。虽然核心JA生物合成途径已经被描绘出来，但JA生物合成是如何启动、维持或终止的尚不清楚。本项目的主要科学目标是更好地了解JA信号的终止，并研究其在植物对伤害的反应中的作用。分离出JA分解代谢缺陷的突变体，导致JA过度积累。在这些突变体中高度升高的JA浓度预计会组成性地激活JA介导的防御反应。与此预期相反，突变体表现出相反的症状，对JA脱敏，从而揭示了JA分解代谢与植物之间的重要联系。S对压力条件的长期反应。本项目将利用多种内源JA突变体，在一个完善的拟南芥遗传系统中研究JA衍生物的相对水平与植物对伤害的反应之间的动态关系。该项目的具体目标是：i)确定JA转换和氧化JA衍生物在植物损伤反应中的作用，ii)描绘JA分解代谢突变体中伤口反应的重要信号通路，以及iii)表征通过突变筛选鉴定的JA分解代谢新基因的功能。拟议的项目有可能确定以前未被认识的JA信号和JA依赖的伤口反应的调节机制。该项目还有望通过研究似乎违背生长-防御-权衡规则的突变体，提供有关植物如何优先考虑生长与防御的新信息。

Plants can perceive tissue damage inflicted by insect feeding, and they rapidly activate several key defense responses. Jasmonate (JA) is the plant hormone that orchestrates these defense responses and dictates an inhibition of growth for plants under stress conditions. JA is also a powerful inducer of many specialized metabolites that have important ecological functions. These metabolites are also a renewable source of many high-value natural products for human use such as nutraceuticals. This project will elucidate how JA levels are precisely regulated to accommodate the various stress adaptive mechanisms of plants. The long term goal of this research is to help reduce or eliminate the need for chemical pesticides and to increase global food production through new approaches to pest control. This research promotes a better understanding of plant defense mechanisms, which can benefit both farmers and horticulturists. This project seeks to improve STEM education by providing multidisciplinary training to college students, graduates and postgraduates. Students from traditionally underrepresented groups in science will be sought through participation in the scientist's institutional outreach programs set up for that purpose. A science literacy program called Sci-LiFT (Science Literacy for Future Teachers) will be developed for students who are in training to become secondary school science teachers. Participating students will engage in real laboratory research on topics relevant to this project and develop a high school teaching module. The Sci-LiFT program is expected to leave an indelible mark on program participants and will positively impact their future teaching in secondary schools. Although the core JA biosynthetic pathway has been delineated, how JA biosynthesis is initiated, maintained, or terminated is unclear. The major scientific goal of this project is to gain a better understanding of the termination of JA signal and to investigate its role in plant responses to wounding. Mutants were isolated that are defective in JA catabolism, and as a result, overaccumulate JA. Highly elevated JA concentration in these mutants was expected to constitutively activate JA-mediated defense responses. Contrary to this expectation, the mutants displayed opposite symptoms, becoming desensitized to JA, thus revealing an important link between JA catabolism and the plant?s long-term responses to stress conditions. This project will use a variety of mutants that are altered in endogenous JA profiles to investigate the dynamic relationship between the relative levels of JA derivatives and plant response to wounding in a well-established Arabidopsis genetic system. The specific aims of this project are: i) to determine the roles of JA turnover and oxidized-JA derivatives in plant response to wounding, ii) to delineate the signaling pathways important for wound response in JA catabolic mutants, and iii) to characterize the function of a new gene identified through a mutant screen for JA catabolism. The proposed project has the potential to identify previously unrecognized regulatory mechanisms of JA signaling and JA-dependent wound responses. This project is also expected to provide new information about how plants prioritize growth versus defense by studying the mutants that appear to defy the growth-defense-tradeoff rule.