Collaborative Research: Metabolomic Profiling and Functions of Oxidized Membrane Lipids in Plant Stress Responses

Ruth Welti和Gary L.Gadbury，堪萨斯州立大学Jyoti Shah，北得克萨斯大学学民大学(Sam)Wang，密苏里大学圣路易斯分校和丹福斯植物科学中心越来越多的证据表明，环境胁迫，如冰冻、高盐度和病原体感染，会导致植物膜脂的氧化修饰，产生“牛脂”。与氧化脂，如茉莉酸及其衍生物，其在植物生长和防御逆境中的重要性已被充分证明，而对氧化脂在植物中的功能知之甚少。氧化应激脂类可能起到调节应激反应的作用，它们可能代表损伤，可以作为细胞其他地方的氧化损伤的保护性缓冲，或者它们可能是长期的修饰，可能起到应激“记忆”的作用。因此，氧化磷脂有可能成为植物对环境反应的重要介体。这项研究的目的是了解氧化脂在植物对生物和非生物胁迫反应中的作用，并确定脂氧合酶和酰基水解酶这两个酶家族的成员的功能，这两个家族可能在氧化脂质的代谢中发挥重要作用。该项目将检验这样的假设，即OX-脂质的模式是个体胁迫的指纹，以及脂肪氧合酶和酰基水解酶产生和/或去除特定的OX-脂质有助于植物适应胁迫。在冰冻和高盐胁迫(非生物胁迫)以及真菌病原菌灰霉病菌和细菌病原菌丁香假单胞菌的侵染(生物胁迫)下，野生型植物和脂氧合酶和酰基水解酶缺失突变植物的胁迫响应表型和氧化脂质的产生将被记录下来。这些数据将阐明脂肪氧合酶和酰水解酶在应激反应中的作用，以及在特定牛脂模式的产生中的作用。对胁迫表型和氧化脂质谱的分析将导致鉴定出可能参与植物胁迫反应的氧化脂质。候选脂类介体的功能将通过脂类分析和植物过度表达产生候选脂类的酶的表型分析，并通过向突变体和野生型植物补充假定的介体来测试。这些结果有可能填补在理解脂代谢酶、细胞脂及其代谢物如何相互作用影响植物表现方面的关键空白。更广泛的影响：开展拟议的工作将为四个机构的多名学生和博士后实习生提供培训，并将代谢图谱、功能基因组学和应激生物学的当前知识带到课堂上。它将通过北得克萨斯大学的麦克奈尔计划、堪萨斯州立大学的夏季本科生研究机会计划、密苏里大学的得斯·李合作奖学金和丹福斯植物科学中心NSF REU-SITE计划扩大代表不足群体参与研究的范围，在过去几年中，代表不足的少数群体参与了30%以上的研究。它将通过北德克萨斯大学的德克萨斯数学与科学学院和圣路易斯的学生和教师作为研究科学家(STAR)计划，让高中生参与这项研究。将植物脂类，特别是胁迫诱导的脂类的光谱数据组织到一个网络可访问的数据库中，将为进一步研究脂类，特别是新的脂类的结构和功能提供基础，并将促进脂类组学数据与其他代谢组学和功能基因组学数据的整合。在这项工作中开发的分析能力将成为通过堪萨斯脂肪组学研究中心提供给世界各地研究人员的使能技术。这项工作还将深入了解具有增强植物抗逆性和提高农业生产力和质量的潜在代谢步骤的特性。

Metabolomic profiling and functions of oxidized membrane lipids in plant stress responses Ruth Welti and Gary L. Gadbury, Kansas State University Jyoti Shah, University of North Texas Xuemin (Sam) Wang, University of Missouri, St. Louis and Danforth Plant Science Center Increasing evidence indicates that environmental stresses, such as freezing, high salinity, and pathogen infection, lead to oxidative modification of plant membrane lipids to produce "ox-lipids". In contrast to oxylipins, such as jasmonic acid and its derivatives, whose significance in plant growth and defense against stress has been well documented, little is known about the functions of ox-lipids in plants. Ox-lipids may function as mediators signaling stress responses, they may represent damage that could serve as a protective buffer against oxidative damage elsewhere in the cell, or they may be long-term modifications that might function as stress "memory". Thus, ox-lipids have the potential to be essential mediators of plant response to the environment. The goals of the research project are to understand the role of ox-lipids in plant responses to biotic and abiotic stresses and to determine the function of members of two enzyme families, lipoxygenases and acyl hydrolases, which are likely to play important roles in the metabolism of oxidized lipids. The project will test the hypotheses that patterns of ox-lipids are fingerprints of individual stresses and that production and/or removal of specific ox-lipids by lipoxygenases and acyl hydrolases contributes to plant adaptation to stress. Under freezing and high salinity stress (abiotic stress) and infection by a fungal pathogen, Botrytis cinerea, and a bacterial pathogen, Pseudomonas syringae (biotic stresses), the stress-response phenotype and production of ox-lipids by wild-type plants and lipoxygenase- and acyl hydrolase-deficient mutant plants will be documented. The data will shed light on the roles of lipoxygenases and acyl hydrolases in stress responses and in production of specific ox-lipid patterns. Analysis of the stress-phenotype and ox-lipid profiles will lead to identification of ox-lipids that are candidates for mediating plant stress responses. The function of candidate lipid mediators will be tested by lipid analysis and phenotypic analysis of plants overexpressing enzymes that produce the candidate lipids and by supplementing mutant and wild-type plants with the putative mediators. The results have the potential to fill critical gaps in understanding of how lipid metabolic enzymes, cellular lipids, and their metabolites interact to influence plant performance. Broader Impacts: Carrying out the proposed work will provide training for multiple students and postdoctoral trainees at four institutions and bring current knowledge of metabolic profiling, functional genomics, and stress biology to the classroom. It will broaden the participation of underrepresented groups in research through the McNair Program at the University of North Texas, the Summer Undergraduate Research Opportunity Program at Kansas State University, the Des Lee Collaborative Scholarships at the University of Missouri, and the Danforth Plant Science Center NSF REU-Site program, which has achieved over 30% participation by underrepresented minority groups in the past several years. It will involve high school students in the research through the Texas Academy of Mathematics and Science at University of North Texas and through the Students and Teachers as Research Scientists (STARS) program in St. Louis. Organization of mass spectral data on plant lipids, and particularly on stress-induced lipids, into a web-accessible database will provide a foundation for further investigation of the structure and function of lipids, and particularly novel lipids, and will facilitate integration of lipidomics data with other metabolomics and functional genomics data. Analytical capabilities developed in this work will become enabling technologies available to researchers worldwide via the Kansas Lipidomics Research Center. This work also will provide insight into the identity of metabolic steps with potential to enhance stress tolerance in plants and improve agricultural productivity and quality.