Regulation of defense signaling in tomato

描述（由申请人提供）：多不饱和脂肪酸（PUFAs）的氧化代谢产生一组氧合化合物，称为氧脂素，其调节多细胞生物的基本生理过程。我们的长期研究目标是了解控制氧化脂类合成和代谢的一般原理，并剖析这些生物活性物质调节防御相关过程的分子机制。在目前的应用中，我们将在之前成功建立番茄（Lycopersicon esculentum）作为对食草节肢动物系统诱导抗性的分子遗传分析模型系统的基础上。本研究旨在验证脂肪酸来源的植物激素茉莉酸（jasmonic acid， JA）是宿主防御反应的细胞间信号，并且JA的生物合成受肽信号系统的调控。该项目的具体目标是：(i)使用基于图谱的方法克隆和表征在系统感知中起作用的Sprl基因；（ii）完成JL1基因的图谱克隆，该基因是JA的环戊酮前体12-氧-植物二烯酸代谢或运输所必需的；（iii）利用基因嵌合体分析JA生物合成和JA感知在细胞间损伤信号传导中的作用；（iv）结合生化和功能分析，分析韧皮部分泌物中JA、系统素和其他诱导防御基因表达的信号的存在。

DESCRIPTION (provided by applicant): Oxidative metabolism of polyunsaturated fatty acids (PUFAs) gives rise to a group of oxygenated compounds, called oxylipins, which regulate essential physiological processes in multicellular organisms. Our long-term research objective is to understand the general principles governing the synthesis and metabolism of oxylipins, and to dissect the molecular mechanisms by which these bioactive substances regulate defense-related processes. In the present application, we will build on our previous success in establishing Lycopersicon esculentum (tomato) as a model system for molecular genetic analysis of systemic induced resistance to herbivorous arthropods. The proposed research seeks to test the hypothesis that the fatty acid-derived plant hormone jasmonic acid (JA) is an intercellular signal for host defense responses, and that the biosynthesis of JA is regulated by the peptide signal systemin. The specific aims of the project are: (i) to use a map-based approach to clone and characterize the Sprl gene that plays a role in systemin perception; (ii) to complete map-based cloning of the JL1 gene that is required for the metabolism or transport of 12-oxo-phytodienoic acid, a cyclopentenone precursor of JA; (iii) to use genetic chimeras to analyze the role of JA biosynthesis and JA perception in intercellular wound signaling; and (iv) to combine biochemical and functional assays to analyze phloem exudate for the presence of JA, systemin, and other signals that induce defense gene expression. The systemin/JA signaling pathway provides a unique opportunity to study the mechanism by which peptide and oxylipin signals coordinate systemic immunity. The biochemical pathways for oxidative metabolism of PUFAs in plants are remarkably similar to those involved in the production of arachidonic acid-derived compounds that play an essential role in numerous aspects of human health and disease. Thus, the proposed research is expected to illuminate general principles of oxylipin metabolism in diverse biological systems. Results obtained from these studies will also provide insight into specific mechanisms by which fatty acid-derived signals regulate host defense responses and, more generally, the role of PUFAs in healthy and diseased organisms.