Deciphering the guard cell metabolome in plant pathogen defense

细菌性病原菌对农作物的危害日益严重，每年都给农作物的产量和经济价值造成巨大损失。病原体通过伤口和叶片表面的小孔进入植物体内。这些气孔称为气孔，由高度特化的保卫细胞形成。保卫细胞介导的气孔开放允许二氧化碳吸收。吸收后，二氧化碳被光合作用捕获，产生碳水化合物等有机物质;因此气孔开放对农业产量和生物能源生产至关重要。然而，开放的气孔也允许水蒸气损失，并为病原体创造入口，这是植物的责任。众所周知，当保卫细胞感知到病原体时，它们会在一小时内关闭气孔，作为免疫反应。然而，随后，气孔再次打开，病原体进入。本项目旨在阐明脂质和脂肪酸在病原菌感染过程中调节气孔关闭和开放的功能。该研究将使科学家能够深入了解保卫细胞脂质代谢产物对病原体触发气孔关闭和打开的重要作用。研究结果具有广泛的社会影响，例如，为合理的作物育种提供信息，以提高病原体防御和作物产量。研究结果将通过社区知识库和免费出版物（例如Metabolight，Plant Journal）向公众提供。该项目还将为不同级别的学生，包括妇女和代表性不足的学生提供跨学科培训。培养下一代科学家和公民对社会和世界有着深远的积极影响。Chen实验室观察到，在由鞭毛蛋白N端22个氨基酸肽（flg 22）组成的细菌诱导剂处理后，保卫细胞中的脂质代谢物发生了显著变化。Assmann实验室先前已经证明了脂质代谢物鞘氨醇-1-磷酸（S1 P）作为脱落酸信号传导组分的作用。然而，S1 P和其他脂质和脂肪酸在气孔免疫中对假单胞菌的作用。tomatao（Pst DC 3000）是未知的。这里的假设是，脂质代谢物的功能作为重要的监管机构的保卫细胞病原体信号。目标是：1）确定在Pst DC 3000触发气孔运动期间保卫细胞中脂质和脂肪酸的动态变化; 2）确定由脂质组学分析暗示的脂质生物合成和代谢的相关突变体中由Pst DC 3000触发的气孔运动，并表征脂质代谢物作为信号分子在触发气孔运动中的作用。使用的方法包括脂质组学、细胞生物学、遗传学和生物化学。本研究的重点是脂质和脂肪酸在抗Pst DC 3000的气孔免疫中的作用。结果预计将揭示新的脂质代谢物功能，促进理解的分子机制，气孔免疫力的基础，并说明涉及脂质组学的综合方法的力量，以揭示新的生物mechanismThis奖反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Crops are constantly challenged by bacterial pathogens, which cause huge losses in yield and economical value every year. The pathogens enter the plant body through wounds and through tiny pores on leaf surfaces. These pores are called stomata, and are formed by highly specialized cells called guard cells. Stomatal opening mediated by the guard cells allows carbon dioxide uptake. After uptake, carbon dioxide is captured by photosynthesis, generating organic materials such as carbohydrates; therefore stomatal opening is critical for agricultural yield and bioenergy production. However, the open stomatal pores also allow water vapor loss, and create entries for pathogens, which are liabilities for plants. It is known that when guard cells sense pathogens, they close stomata within an hour as an immune response. However, subsequently, the stomata open again and pathogens go in. This project aims to elucidate how lipids and fatty acids function in regulating the stomatal closure and opening during pathogen infection. This research will enable scientists to gain an in-depth understanding of guard cell lipid metabolites important for pathogen triggered stomatal closing and opening. The outcome of the research has broad societal impact, e.g., for informing rational crop breeding to enhance pathogen defense and crop yield. The results will be made available to the public via community repositories and no-cost publications (e.g. Metabolight, the Plant Journal). The project will also enable cross-disciplinary training of students at different levels, including women and under-represented students. Training the next generation of scientists and citizens has far-reaching positive impacts for society and the world.The Chen lab has observed significant lipid metabolite changes in guard cells in response to treatment with a bacterial elicitor comprised of the flagellin N-terminal 22 amino acid peptide (flg22). The Assmann lab has previously demonstrated the effect of the lipid metabolite sphingosine-1-phosphate (S1P) as a component of abscisic acid signaling. However, the roles of S1P and other lipids and fatty acids in stomatal immunity against Pseudomonas syringe pv. tomatao (Pst DC3000) are not known. Here the hypothesis is that lipid metabolites function as important regulators of guard cell pathogen signaling. The goals are to: 1) determine dynamic changes of lipids and fatty acids in guard cells during Pst DC3000 triggered stomatal movement; 2) determine stomatal movement triggered by Pst DC3000 in relevant mutants of lipid biosynthesis and metabolism implicated from the lipidomics analyses, and characterize the effects of lipid metabolites as signaling molecules in triggering stomatal movement. Approaches to be used include lipidomics, cell biology, genetics and biochemistry. This focused project specially targets the functions of lipids and fatty acids in stomatal immunity against Pst DC3000. The results are expected to reveal novel lipid metabolite functions, boost understanding of molecular mechanisms that underlie stomatal immunity, and illustrate the power of integrated approaches involving lipidomics to reveal novel biological mechanismsThis 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.