Building and Operating Chemical Factories: Comparative Studies of Biochemical Pathways for Specialized Metabolites in the Solanum

PI: Robert Last（密歇根州立大学）CoPIs: Cornelius Barry和A. Daniel Jones（密歇根州立大学）和Eran Pichersky（密歇根州立大学）这项研究的长期目标是了解植物特化代谢物（也称为次生代谢物或天然产物）巨大多样性背后的原理。这些化学物质是植物抵御生物和环境压力的武器库的一部分，包括产生风味和香气的化合物以及重要的医学药物。植物空气表面的储存/分泌腺毛状体（sgt）在产生这些化合物方面特别活跃，因此对研究它们的生物合成非常有利。栽培番茄（Solanum lycopersicum）及其相关物种在叶片、茎和生殖结构上具有解剖学上不同的sgt类型，每种sgt类型产生一组独特的专门代谢物，包括萜烯、甲基化或糖基化黄酮类化合物和酰基糖，在物种内部和物种之间观察到惊人的多样性。越来越清楚的是，茄类sgt利用新的生化机制来生产这些产品，最近的研究结果表明，比较基因组学和功能基因组学、代谢组学和生化方法的结合是一种特别有前途的方法来阐明这些途径及其多样化的总体模式。在上一个资助期取得的进展的基础上，本项目将详细分析萜烯和酰基糖的生物合成，这两类化合物在不同类型的sgt中具有针对生物应激因子的生物效应。该方法旨在阐明特定的反应和酶，但也途径进化和调控模式。目前人们对酰基糖的生物合成知之甚少，而在这个项目下创建的遗传学和基因组学资源将为如何合成这些不同的化合物提供有价值的见解。对萜烯生物合成的了解更多，但先前的结果表明，关于底物利用和特定种类萜烯合成酶的作用的一些原则是不完善的，相反，这些蛋白质显示出巨大的潜力来进化新的功能，这一过程将在本项目中进行研究。该项目的广泛影响可分为两大类：项目影响的生物学领域的进步和教育推广。这些研究结果将揭示植物在sgt和其他细胞类型中产生这些重要化合物的生化和遗传机制，并为育种和转基因方法提供信息，以修改它们在作物植物中的合成，以增强对病虫害的抗性。新机制的发现也为利用这些生物化学途径生产生物活性化学品和化学原料的新技术提供了机会。为了最大限度地利用本项目产生的数据，数据将提交给长期社区数据库，包括NCBI （http://www.ncbi.nlm.nih.gov/）、Trichome （http://www.trichome.msu.edu/）、Trichome （http://www.planttrichome.org/trichomedb/）和Sol Genomics Network （http://solgenomics.net/）。由于该项目包括分析化学、生物化学、遗传学和基因组学方面的实验室专家，它为跨学科培训提供了一个天然的平台。除了全年对本科生、研究生和博士后研究人员进行交叉培训外，该项目还将以互补的方式将研究和教育结合起来：首先，作为密歇根州立大学植物基因组学项目的一部分，每年为三名本科生提供夏季研究经验，重点是招募女性和代表性不足的少数群体成员；第二，为主要来自本科院校的教师提供培训机会。

PI: Robert Last (Michigan State University)CoPIs: Cornelius Barry and A. Daniel Jones (Michigan State University) and Eran Pichersky (University of Michigan)The long-term goal of this research is to understand the principles that underlie the tremendous diversity of plant specialized metabolites (also known as secondary metabolites or natural products). These chemicals are part of the plant's arsenal for defense against biological and environmental stress and include compounds that contribute to flavors and aromas as well as medically important drugs. Storage/secreting glandular trichomes (SGTs) on the aerial surfaces of the plant are especially active in producing such compounds and thus are excellent for studying their biosynthesis. Cultivated tomato (Solanum lycopersicum) and related species have anatomically diverse types of SGTs on leaves, stems, and reproductive structures and each type produces a distinct set of specialized metabolites including terpenes, methylated or glycosylated flavonoids, and acylsugars, with surprising diversity observed within and between species. It is becoming increasingly clear that Solanum SGTs utilize novel biochemical mechanisms for producing some of these products, and recent results indicate that the combination of comparative and functional genomics, metabolomics, and biochemical methods is a particularly promising approach to elucidate these pathways and the overall pattern of their diversification. Building on the progress made in the previous funding period, this project will provide a detailed analysis of the biosynthesis of terpenes and acylsugars, two classes of compounds with documented biological effects against biotic stress agents, in distinct types of SGTs. The approach is designed to elucidate specific reactions and enzymes but also patterns of pathway evolution and regulation. Acylsugar biosynthesis is currently poorly understood, and the genetics and genomics resources created under this project will provide valuable insight into how these diverse compounds are synthesized. More is known about terpene biosynthesis, but previous results indicated that some of the tenets about substrate utilization and roles of specific classes of terpene synthases are imperfect and instead these proteins display a tremendous potential to evolve new functions, a process that will be examined in this project. The broader impacts of this project fall into two general categories: advancement of the fields of biology impacted by the project and educational outreach. The results of these studies will reveal the biochemical and genetic mechanisms by which plants produce these important compounds in SGTs and other cell types, and inform breeding and transgenic approaches to modify their synthesis in crop plants to enhance resistance to insects and disease. Discovery of novel mechanisms also offers opportunities to exploit these biochemical pathways in new technologies for the production of bioactive chemicals and chemical feedstocks. In order to maximize the utility and accessibility of the data generated through this project, data will be submitted to long-term community databases that include the NCBI (http://www.ncbi.nlm.nih.gov/), Trichome (http://www.trichome.msu.edu/), TrichOME (http://www.planttrichome.org/trichomedb/) and the Sol Genomics Network (http://solgenomics.net/). Because the project includes laboratories expert in analytical chemistry, biochemistry, genetics and genomics, it provides a natural platform for interdisciplinary training. In addition to cross-training of undergraduate and graduate students and postdoctoral researchers throughout the year, this project will integrate research and education in complementary ways: first, through summer research experiences for three undergraduate students each year as part of the Plant Genomics @ Michigan State University program which places an emphasis on the recruitment of women and underrepresented minority group members; and second, through training opportunities for faculty from primarily undergraduate schools.