Lipid derived signaling involving chloroplasts

根据该项目产生的基本知识将启发新的战略，以生产更具弹性的作物，以更好地应对快速变化的气候。在数百万年的进化过程中，植物已经建立了在波动的环境中生活在陆地上的能力，遇到了严酷的环境条件，如寒冷、干旱、营养短缺、病原体攻击、昆虫暴发或其他非生物或生物胁迫。为了应对这些挑战，固着植物足智多谋地调整它们的内部生物过程，例如通过将它们的新陈代谢从生长转变为防御。该项目探索了两种植物激素--脱落酸(ABA)和茉莉酸(JA)--分别在调节对非生物和生物胁迫的反应中的相互作用。后者来源于植物光合作用所在的叶绿体中的膜。这个项目有可能发现新的信号分子和机制及其修饰物，从而增加我们对生物和非生物应激反应整合的理解，而不是我们目前对单个信号分子作用的了解。该项目的概念和技术为研究生物和非生物应激反应的整合提供了一个令人兴奋的实验平台，所有培训水平的科学家都可以很容易地接触到这些应激反应。该项目非常适合本科生在课堂上的参与，以及通过实验室参与让他们直接接触到正在进行的现实生活研究，同时向他们传授基本的科学原理。已经开发了一门实验室课程，即以课程为基础的本科生研究经验(CURE)，以使学生参与分离与项目相关的植物突变及其初步特征。个别本科生在参与研究的博士后研究人员的直接指导下，在研究实验室环境中参与特定突变体的更深层次表征，博士后研究人员反过来获得指导经验，为他们的下一阶段职业生涯做准备。叶绿体是动态细胞器，其特征是具有广泛的光合膜和独特的脂类，经常通过脂类重塑来响应生物和非生物胁迫。脂代谢对外界信号的响应通常涉及酰基的释放。它们还可以进一步转化为信号媒介，如茉莉酸、二乙烯基醚、醛或其他分子，它们可以被植物感知并触发植物反应。在许多情况下，当植物面临营养缺乏、寒冷或高温等胁迫时，具有脂肪水解酶活性的脂肪酶催化脂质重塑过程中的第一反应，导致酰基循环的启动。该项目是基于最近从拟南芥中鉴定出的叶绿体脂肪酶PLIP1-3。各自编码序列的过度表达通过启动氧脂代谢产物的生物合成和过量生产，将代谢从生长重定向到防御。PLIP1-3功能缺失的三重突变体表现出对ABA的敏感性。此外，其中两个基因PLIP2和PLIP3的表达对非生物胁迫和ABA都有响应，这表明在拟南芥中可能存在基于PLIP2和PLIP3的连接JA和ABA信号转导途径的机制。虽然JA的产生最常见的是生物胁迫，如食草性昆虫的伤害，而ABA的产生主要是由非生物胁迫，如冷、热或脱水引起的，但越来越多的证据表明，这些信号通路之间的相互作用可以刺激JA的生物合成，JA可以影响植物对ABA的敏感性。该项目的长期目标是更深入地了解叶绿体膜脂信号是如何在拟南芥中产生、运输、持久、感知并与不同的信号途径整合以协调生物或非生物胁迫反应的。为了实现这一目标，该项目遵循三个目标：1.使用PLIP3-OX(PLIP3过表达)背景下的遗传抑制屏幕，查询从基于脂质的信号的起源到其他信号通路的感知、转导和修改的整个信息链。2.通过对分离的抑制子突变群体进行批量测序分析，确定了抑制子的基因座。3.研究了抑制突变体和受影响蛋白在JA生物合成、信号转导和其他信号转导途径修饰中的作用。目标1和部分目标2由本科生在课堂环境中进行。目标3涉及在参与博士后研究人员的指导下的本科生个人。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The basic knowledge generated under this project will inspire novel strategies to produce more resilient crop plants that can better cope with a rapidly changing climate. During millions of years of evolution, plants have established the ability to live on land in a fluctuating environment, encountering harsh environmental conditions such as cold, drought, nutrient shortage, pathogen attack, insect outbreaks, or other abiotic or biotic stresses. To combat these challenges, sessile plants resourcefully adjust their internal biological processes, for example by shifting their metabolism from growth to defense. The project explores the interplay of two plant hormones, abscisic acid (ABA) and jasmonic acid (JA), in mediating responses to abiotic and biotic stresses, respectively. The latter originates from membranes in the chloroplast, the place of plant photosynthesis. This project has the potential to discover novel signaling molecules and mechanisms and their modifiers, thereby increasing our understanding of the integration of biotic and abiotic stress responses beyond our current knowledge about the roles of individual signaling molecules. The concepts and techniques of this project offer an exciting experimental platform for studying the integration of biotic and abiotic stress responses that are readily accessible to scientists at all training levels. The project is ideally suited for undergraduate student involvement in a classroom setting as well as through in-lab participation exposing them directly to ongoing real-life research, while teaching them basic scientific principles. A laboratory course, namely a Course-based Undergraduate Research Experience (CURE), has been developed to engage students in the isolation of project-relevant plant mutants and their initial characterization. Individual undergraduate students are involved in the deeper characterization of specific mutants in a research lab environment under the direct mentorship of the participating postdoctoral researchers, who in turn gain mentoring experience preparing them for their next stages in their careers.Chloroplasts are dynamic organelles characterized by an extensive photosynthetic membrane with unique lipids and often respond to biotic and abiotic stresses by lipid remodeling. Lipid turnover in response to external cues often involves the release of acyl groups. These can be further converted into signaling mediators such as JA, divinyl ethers, aldehydes, or other molecules, which can be perceived by plants and trigger plant responses. In many instances, lipases with their lipid hydrolytic activity catalyze the first reaction during lipid remodeling, leading to the initiation of acyl group recycling, when plants are facing insults such as nutrient deprivation, cold, or heat. The project is based on recently characterized plastid lipases, PLIP1-3, from Arabidopsis. Overexpression of the respective coding sequences redirects the metabolism from growth to defense by initiating the biosynthesis and overproduction of oxylipin metabolites such as JA. Loss of PLIP1-3 function triple mutants show sensitivity to ABA. Moreover, the expression of two of the genes, PLIP2 and PLIP3, is responsive to abiotic stressors and ABA, suggesting a possible PLIP2,3-based mechanism in connecting JA and ABA signal transduction pathways in Arabidopsis. Although JA production is most commonly induced by biotic stressors such as wounding due to herbivorous insects, and ABA production is mainly increased by abiotic challenges such as cold, heat, or dehydration, there is increasing evidence of interaction of these signaling pathways as abiotic stressors can stimulate JA biosynthesis and JA can affect the sensitivity of the plant to ABA. The long-term goal of the project is to gain a deeper understanding of how chloroplast membrane lipid-derived signals are produced, transported, perpetuated, perceived, and integrated with different signaling pathways in Arabidopsis to coordinate biotic or abiotic stress responses. To accomplish this goal, the project follows three objectives: 1. Using a genetic suppressor screen in the PLIP3-OX (PLIP3 overexpression) background, the entire information chain from the origin of the lipid-based signal to its perception, transduction, and modification by other signaling pathways is being queried. 2. Suppressor loci are identified by bulk sequencing analysis of segregating suppressor mutant populations. 3. Individual suppressor mutants and affected proteins are characterized for their roles in JA biosynthesis, signaling, and modification by other signaling pathways. Objective 1 and partially objective 2 are conducted by undergraduate students in a classroom setting. Objective 3 involves individual undergraduate students under the mentorship of the participating postdoctoral researchers.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.