Lipid derived signaling involving chloroplasts

在这个项目下产生的基本知识将激发新的策略，以生产更有弹性的作物，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，遇到了恶劣的环境条件，如寒冷、干旱、营养短缺、病原体攻击、昆虫爆发或其他非生物或生物压力。为了应对这些挑战，无根植物机智地调整了它们的内部生物过程，例如将它们的新陈代谢从生长转变为防御。该项目探讨了两种植物激素，脱落酸（ABA）和茉莉酸（JA）在介导非生物和生物胁迫反应中的相互作用。后者来自叶绿体膜，植物光合作用的地方。该项目有可能发现新的信号分子和机制及其修饰因子，从而增加我们对生物和非生物应激反应整合的理解，超越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，这对所有培训水平的科学家都很容易获得。这个项目非常适合本科生在课堂上的参与，也可以通过实验室的参与，让他们直接接触到正在进行的现实生活中的研究，同时教授他们基本的科学原理。一门实验课程，即基于课程的本科研究经验（CURE），已经开发出来，让学生参与与项目相关的植物突变体的分离和它们的初步表征。在博士后研究人员的直接指导下，本科生个人在研究实验室环境中对特定突变体进行更深入的表征，博士后研究人员反过来获得指导经验，为他们的下一阶段的职业生涯做好准备。叶绿体是动态的细胞器，具有广泛的光合膜和独特的脂质，经常通过脂质重塑来应对生物和非生物胁迫。脂质周转响应外部信号通常涉及酰基的释放。这些可以进一步转化为信号介质，如JA、二乙烯醚、醛或其他分子，这些可以被植物感知并引发植物反应。在许多情况下，当植物面临营养剥夺、寒冷或炎热等损害时，具有脂质水解活性的脂肪酶催化脂质重塑过程中的第一个反应，导致酰基再循环的启动。该项目基于最近从拟南芥中鉴定出的质体脂肪酶PLIP1-3。相应编码序列的过表达通过启动生物合成和过量生产氧脂素代谢物（如JA），将代谢从生长转向防御。PLIP1-3功能缺失的三突变体对ABA敏感。此外，PLIP2和PLIP3两个基因的表达对非生物应激源和ABA有响应，这表明在拟南芥中可能存在一个基于plip2,3的连接JA和ABA信号转导途径的机制。尽管JA的产生通常是由生物应激源（如草食性昆虫的伤害）诱导的，而ABA的产生主要是由冷、热或脱水等非生物挑战引起的，但越来越多的证据表明，这些信号通路之间存在相互作用，因为非生物应激源可以刺激JA的生物合成，而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拟南芥中叶绿体膜脂源性信号是如何产生、运输、延续、感知和整合不同信号通路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。利用PLIP3- ox （PLIP3过表达）背景下的基因抑制筛选，从脂质信号的起源到其他信号通路的感知、转导和修饰的整个信息链正在被查询。2. 抑制基因座是通过分离抑制基因突变群体的大量测序分析确定的。3. 单个抑制突变体和受影响蛋白的特征在于它们在JA生物合成、信号传导和其他信号通路修饰中的作用。目标1和部分目标2是由本科生在课堂环境中进行的。目标3涉及参与博士后研究人员指导下的本科生个体。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。

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.