Deciphering the Complex Metabolic Network in Snapdragon Flowers: An Integrative Approach

近年来，次生代谢领域的研究进展揭示了次生代谢物不仅对植物，而且对人类的重要性。次生代谢物参与植物在周围生态系统中的生存及其对食物质量、观赏植物吸引力和人类健康的影响，揭示了导致其形成的遗传改良的重要性。次生代谢物的基因工程具有巨大的潜力。然而，它的成功很大程度上取决于我们对整个细胞代谢网络的理解。该项目的长期目标是提供对体内代谢的全面了解，并表征在花的生命周期中光合和非光合花组织中通过代谢网络的碳流。一种独特的综合方法，包括瞬态稳定同位素标记和花发育过程中的代谢通量分析，结合相应的转录组分析，将被用来获得花体内通量与中心碳、氮和次生代谢基因表达谱之间动态关系的新图景。这项研究将产生一个时间通量图，其中每个生化步骤将包含相应通量和基因表达的发展概况。将通量分析的发展方面纳入时间通量图，将为我们对初级和次级代谢的认识增加一个新的维度。整合全球通量分析和酶活性与基因表达将揭示通路或分支内潜在的调控步骤。本研究开发的综合图谱将有助于概念化网络调控的时间和空间方面，并指导植物次生代谢工程的各种工作。此外，该项目将填补对花代谢认识的重要空白，并为植物代谢途径的代谢工程提供强大的建模工具。更广泛的影响：该项目为下一代植物科学家提供了强有力的多学科培训。参与本研究的本科生和研究生以及博士后科学家（包括女性和少数民族）将获得细胞代谢的“大图景”，并了解整个植物生理学，体内同位素标记，分析生物化学，分子生物学，遗传学和综合建模。总体教学目标是让学生对植物代谢有更全面的了解。除了培训学生外，普渡大学还将开发新的课程模块，包括次级代谢、代谢工程和综合建模，并将其通过WebCT网络整合到普渡大学的现有课程中。作为该项目的一部分开发的植物代谢建模软件以及教学模块将作为免费软件发布在普渡大学园艺网站服务器上。

Recent progress in the field of secondary metabolism has uncovered the importance of secondary metabolites, not only for plant life, but also for humans. The involvement of secondary metabolites in plant survival in the surrounding ecosystem and their impact on food quality, attractiveness of ornamentals, and human health reveal the importance of genetic improvements leading to their formation. Genetic engineering of secondary metabolites has enormous potential. However, its success largely depends on our understanding of the entire cellular metabolic network. The long-term goal of this project is to provide a comprehensive understanding of in vivo metabolism and to characterize the carbon flow through the metabolic network in photosynthetic and non-photosynthetic floral tissues over the lifespan of the flower. A unique integrative approach, including transient stable isotope labeling and metabolic flux analysis over flower development, combined with corresponding transcriptome analysis, will be used to obtain a novel picture of the dynamic relationships between in vivo flux and gene expression profiles in central carbon, nitrogen, and secondary metabolism of flowers. This research will lead to the generation of a temporal flux map in which each biochemical step will contain a developmental profile for the corresponding flux and gene expression. The developmental aspect of flux analysis incorporated into the temporal flux map will add a new dimension to our vision of primary and secondary metabolism. The integration of global flux analysis and enzyme activity with gene expression will uncover the potential regulatory steps within pathways or branchways. An integrative map developed in this research will help to conceptualize the temporal and spatial aspects of the network regulation and guide diverse efforts in metabolic engineering of plant secondary metabolism. Moreover, this project will fill important gaps in the understanding of floral metabolism and provide powerful modeling tools for general use in the metabolic engineering of plant metabolic pathways. Broader impacts: This project has a strong multidisciplinary training component for the next generation of plant scientists. Undergraduate and graduate students, as well as post-doctoral scientists (including women and minorities) participating in this research will get 'the big picture' of cellular metabolism and gain an appreciation of whole plant physiology, in vivo isotopic labeling, analytical biochemistry, molecular biology, genetics and integrative modeling. The overall instructional goal is to provide students with a more comprehensive understanding of plant metabolism. In addition to training students, new course modules on secondary metabolism, metabolic engineering, and integrative modeling will be developed and incorporated via the web using WebCT into existing courses at Purdue University. Plant metabolic modeling software developed as part of this project as well as the teaching modules will be released as freeware on the Purdue Horticulture web server.