CAREER:Unraveling the metabolic networks underlying plant stress adaptation

本奖项全部或部分由《2021年美国救援计划法案》（公法117- 2）资助。植物必须不断应对不利的环境变化，这些变化往往会对它们的生长产生负面影响。例如，不断增强防御的植物往往会损害生长，反之亦然。这种生长与防御的权衡很大程度上是由于有限的资源，这些资源用于产生昂贵的防御代谢物。近年来，随着气候变化的持续，这一问题变得更加紧迫，这加速了病原体感染和害虫侵袭。然而，我们对植物如何同时协调防御和生长的理解仍然很少。这项拟议的研究将揭示由一类称为醛肟的应激化合物控制的生长调节机制。醛肟与植物防御（它们是防御化合物的前体，受压力诱导）和生长（它们影响植物生长激素生长素以及苯丙素（如木质素）的产生）有关。本项目将阐明醛肟如何产生生长素，以及醛肟如何阻碍植物中苯丙素的产生。该项目的完成将为植物在逆境条件下协调激素、防御化合物和木质素的代谢网络提供基础认识。该项目的成果将为提高作物中花青素等苯丙素的含量提供机会，并将有助于培养具有竞争力和成功的农业劳动力。该项目还包括一项名为“植物探测”的K-12教育活动，该活动将制作一系列视频，旨在提高年轻学生对植物化学物质的认识。醛肟是应激诱导化合物，是防御化合物的前体。此外，它们通过调节植物生长激素生长素和苯丙素的产生来影响植物生长。醛肟的积累部分通过F-box基因的转录激活抑制了苯丙氨酸解氨酶（PAL）的降解，从而抑制了苯丙素的生物合成。由于PAL在苯丙素途径的入口点起作用，醛肟的积累关闭了整个苯丙素途径。不同的植物从各自的醛肟中产生两种主要的天然生长素，吲哚-3-乙酸（IAA）和苯基乙酸（PAA），这表明醛肟代谢在许多不同的植物中具有重要意义。虽然醛肟介导的代谢网络在植物应激触发的生长调节中起着至关重要的作用，但醛肟介导的苯丙素抑制和醛肟衍生的生长素产生的分子机制尚不清楚。本项目将利用拟南芥和番茄两个模型系统来阐明这一隐藏的代谢网络。利用组学和遗传学方法，本项目将确定醛肟衍生生长素产生的代谢途径，确定醛肟介导的苯丙素抑制机制，并阐明醛肟代谢在植物逆境适应中的作用。教育目标是培养下一代农业劳动力，提高公众对植物和植物基化合物的认识。通过暑期本科生实习为青年学生制作和传播教育录象带，以及举办K-12教师会议，将为提高公众对植物化学物质的认识提供教育工具。此外，研究生和博士后将在参与本项目的同时接受全面的研究训练。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117- 2). Plants must constantly deal with adverse environmental changes, which often negatively impacts their growth. For instance, plants with continuously enhanced defense frequently have compromised growth and vice versa. This growth-defense tradeoff is largely due to limited resources, which are used to produce costly defense metabolites. This issue has become more pressing in recent years with ongoing climate change, which accelerates pathogen infection and pest infestation. However, our understanding of how plants simultaneously coordinate defense and growth remains scarce. This proposed research will reveal mechanisms underlying growth regulation governed by a class of stress compounds called aldoximes. Aldoximes are linked to both plant defense - they are precursors of defense compounds and are induced by stresses - and growth - they affect the production of the plant growth hormone auxins as well as phenylpropanoids such as lignin. This project will elucidate how auxins are made from aldoximes and how aldoximes impede phenylpropanoid production in plants. Completion of this project will provide fundamental understanding of plant metabolic networks coordinating hormones, defense compounds, and lignin under stress conditions. The outcome of this project will provide opportunities to enhance levels of phenylpropanoids such as anthocyanins in crops, and will help foster a competitive and successful agriculture workforce. This project also includes a K-12 educational activity called Phyto-Detective, which will develop a series of videos aimed to raise awareness of phytochemicals for a young student audience. Aldoximes are stress-inducive compounds and are precursors of defense compounds. In addition, they affect plant growth through modulating the production of plant growth hormone auxins and phenylpropanoids. The accumulation of aldoximes represses phenylpropanoid biosynthesis partially through the transcriptional activation of the F-box genes that function in the degradation of phenylalanine ammonia lyase (PAL). Since PAL functions at the entry point of the phenylpropanoid pathway, aldoxime accumulation shuts down the entire phenylpropanoid pathway. Various species produce two major natural auxins, indole-3-acetic acid (IAA) and phenyl acetic acid (PAA), from their respective aldoximes, indicating the significance of aldoxime metabolism in a multitude of different plants. Although the aldoxime-mediated metabolic network plays a crucial role in stress-triggered growth regulation in plants, molecular mechanisms underlying aldoxime-mediated phenylpropanoid repression and aldoxime-derived auxin production remain elusive. This project will elucidate this hidden metabolic network using two model systems, Arabidopsis and tomato. Using omics and genetics approaches, this project will identify the metabolic route of aldoxime-derived auxin production, determine mechanisms of aldoxime-mediated phenylpropanoid repression, and elucidate the roles of aldoxime metabolism in plant stress adaptation. The educational goal is to foster the next generation of the agriculture workforce and increase public awareness of plants and plant-based compounds. The production and dissemination of educational videos for young students through summer undergraduate interns and a K-12 teacher conference, respectively, will provide educational tools to raise awareness of phytochemicals to the public. In addition, graduate students and postdoctoral associates will receive comprehensive research training while participating in this project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.