Dimensions: Collaborative Proposal: Molecular, ecological and evolutionary dynamics of carbon fixation and diversification in Agavoideae (Asparagaceae) and Oncidiinae (Orchidaceae)

维度：合作提案：龙舌兰科（Asparagaceae）和Oncidiinae（兰科）碳固定和多样化的分子、生态和进化动力学

• 批准号: 1442199
• 负责人: James Leebens-Mack
• 金额: $ 152.13万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-01-01 至 2020-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1442199&HistoricalAwards=false
• 关键词: Dimensions; Collaborative; Proposal; Molecular; ecological

Photosynthesis is a basic process supporting the vast majority of life on Earth. However, for plants living under water-limited conditions, photosynthetic productivity can be reduced by hotter and drier climatic conditions. To counteract these conditions, some plants utilize forms of photosynthesis that increase the efficiency with which they use water. One such innovation seen in plants that grow in deserts or other water-limited habitats is referred to as CAM (Crassulacean Acid Metabolism). The CAM innovation is found in a large number of diverse plant lineages and typically associated with stem (e.g. cacti) or leaf (e.g. agaves) succulence. The proposed research project will use several approaches to address fundamental questions about how plants use CAM and how genes involved in performing CAM are regulated in response to varying environmental conditions. To achieve this, the project will focus on the independent evolution of CAM in the orchid and agave plant families, both of which have species known for their ability to thrive in water-limited environments. This research will provide a foundation for understanding the genetic basis of CAM pathways and potentially transfer to economically important plants for improved water use efficiency under drought conditions leading to improved productivity. Additionally, this project would result in the training of undergraduate and graduate students, including individuals from under-represented groups. There are also plans to integrate the results of the project into classroom learning and broader outreach activities.This project utilizes an integrated research program on two instances of CAM photosynthesis to illuminate the mechanisms that link ecological, genetic and molecular dimensions of the evolutionary processes that contribute to the origin and maintenance of biodiversity. Photosynthesis is a fundamental process supporting biodiversity in the vast majority of ecological communities on our planet, while at the same time a physiological challenge for primary producers living under water-limited conditions. The evolutionary history of photosynthetic organisms has included repeated origins of carbon concentrating mechanisms that increase water-use efficiency and productivity in extreme environmental conditions. Crassulacean acid metabolism is one such innovation that has facilitated diversification of vascular plant lineages in an array of habitats. The proposed project will integrate ecological, physiological, phylogenetic, genetic and genomic approaches to address fundamental questions about how plants use CAM and how genes involved in performing CAM are regulated in response to different environmental conditions. The study systems for this project are the species-rich Agavoideae (Asparagaceae) and Oncidiinae (Orchidaceae) lineages, both of which include CAM, C3 (typical form of photosynthesis) and facultative or weak CAM species. These systems will aid in inferring the phylogenetic and environmental context for multiple gains and losses of CAM photosynthesis in both lineages. Comparative analyses of RNA will illuminate the interacting molecular and environmental drivers of shifts between C3 and CAM photosynthesis and the impact of these shifts on the origin and maintenance of species diversity. Furthermore, shifts in gene function associated with the gain and loss of CAM will be tested through genetic analyses of a yucca hybrid, resulting from a natural cross between a CAM and C3 parental species, and experimental manipulations of gene expression in the emerging orchid model species, Erycina pusilla (Oncidiinae).

光合作用是维持地球上绝大多数生命的基本过程。然而，对于生活在水分有限条件下的植物，光合生产力可能会因更热和更干燥的气候条件而降低。为了抵消这些条件，一些植物利用光合作用的形式，提高它们利用水的效率。在沙漠或其他水资源有限的栖息地生长的植物中看到的一种创新被称为CAM（景天科酸代谢）。CAM创新在大量不同的植物谱系中发现，并且通常与茎（例如仙人掌）或叶（例如龙舌兰）肉质有关。拟议的研究项目将使用几种方法来解决有关植物如何使用CAM以及参与执行CAM的基因如何响应不同的环境条件进行调节的基本问题。为了实现这一目标，该项目将专注于CAM在兰花和龙舌兰植物家族中的独立进化，这两种植物都以其在水资源有限的环境中茁壮成长的能力而闻名。这项研究将为理解CAM途径的遗传基础提供基础，并可能转移到经济上重要的植物，以提高干旱条件下的水分利用效率，从而提高生产力。此外，该项目还将培训本科生和研究生，包括来自代表性不足群体的个人。此外，还计划将该项目的成果纳入课堂学习和更广泛的外联活动，该项目利用一个关于CAM光合作用两个实例的综合研究方案，阐明有助于生物多样性起源和维持的进化过程的生态、遗传和分子层面之间的联系机制。光合作用是地球上绝大多数生态群落支持生物多样性的基本过程，同时也是生活在水资源有限条件下的初级生产者面临的生理挑战。光合生物的进化史包括碳浓缩机制的重复起源，这种机制在极端环境条件下提高了水的利用效率和生产力。景天科酸代谢就是这样一种创新，它促进了一系列栖息地中维管植物谱系的多样化。拟议的项目将整合生态学，生理学，系统发育，遗传学和基因组学方法，以解决有关植物如何使用CAM以及参与执行CAM的基因如何响应不同环境条件的基本问题。本项目的研究系统是物种丰富的龙舌兰亚科（芦笋科）和文心兰亚科（兰科）谱系，这两个谱系都包括CAM，C3（光合作用的典型形式）和兼性或弱CAM物种。这些系统将有助于推断系统发育和环境背景下的多个收益和损失的CAM光合作用在两个谱系。RNA的比较分析将阐明C3和CAM光合作用之间的相互作用的分子和环境驱动力的变化，以及这些变化对物种多样性的起源和维持的影响。此外，与CAM的获得和丧失相关的基因功能的转变将通过对丝兰杂种的遗传分析（由CAM和C3亲本物种之间的自然杂交产生）以及对新兴兰花模式物种Erycina pusilla（文心兰亚科）基因表达的实验操作来测试。