Genetic and Genomic Approaches to Understanding Long-Distance Transport and Carbon Partitioning in Plants

Clifford Weil和Rebecca Doerge(普渡大学)，Jiri Adamec(内布拉斯加州大学林肯分校)和Mark Lubkowitz(圣迈克尔学院)：Judith Van Houten(佛蒙特州大学伯灵顿分校)全植物碳水化合物分配是指通过叶片光合作用同化的碳通过叶脉转移，并输入到花、果实、种子和根等非光合作用组织中以维持其生长和发育的过程。在大多数作物中，蔗糖是主要的碳水化合物，通过韧皮部组织在叶脉内进行远距离运输。虽然生理学研究已经确定了蔗糖合成的位置及其通过韧皮部的运输途径，但对控制植物内碳水化合物分布的基因知之甚少。该项目的目标是全面了解控制玉米全株碳水化合物分配的基因调控网络，玉米是一种对美国农业和经济具有重要意义的作物。该项目将利用遗传和基因组实验来确定调控叶片碳输出和输入种子的基因，使用下一代测序来表征沿蔗糖运输途径通过韧皮部表达的基因，并利用玉米中巨大的遗传多样性来发现碳水化合物分配的新的遗传修饰基因。总而言之，这些知识将产生关于碳水化合物长途运输所依据的基因功能的可验证假说，提供新的见解，可能转化为粮食生产、环境胁迫耐受性、用于生产生物燃料的生物量积累以及利用植物进行碳固存的策略。该项目将通过从一所小型文理学院招收本科生，并与主要研究型大学的本科生、研究生和博士后同事合作，帮助培养和指导下一代科学家。与佛蒙特州EPSCoR计划协调，该项目将为高中生和教师开发一个夏季研讨会，重点关注该项目的研究目标，并将帮助参与者开发一个关于植物基因组学和碳水化合物分配的高中教学模块。包括质量控制表达数据的社区资源将被存入公共数据库，如GenBank(www.ncbi.nlm.nih.gov/GenBank/)、玉米基因组数据库(www.maizegdb.org/)和Gramene(www.gram ene.org/)。基因库存将通过玉米遗传合作库存中心(www.maizecoop.cropsor.uiuc.edu/)提供。将开发一个项目网站，向其他科学家和公众广泛传播该项目的研究发现和教育成果。

PI: David Braun, University of Missouri - ColumbiaCoPIs: Karen Koch and Byung-Ho Kang (University of Florida - Gainesville), Clifford Weil and Rebecca Doerge (Purdue University), Jiri Adamec (University of Nebraska - Lincoln), and Mark Lubkowitz (Saint Michael's College)Key Collaborator: Judith Van Houten (University of Vermont - Burlington)Whole-plant carbohydrate partitioning is the process whereby carbon, assimilated through photosynthesis in leaves, is translocated through the veins, and imported into non-photosynthetic tissues like flowers, fruits, seeds and roots to sustain their growth and development. In most crop plants, sucrose is the principal carbohydrate translocated long-distance through the phloem tissue within veins. Although physiological studies have determined the site of sucrose synthesis and its translocation path through the phloem, very little is known about the genes that control the distribution of carbohydrates within plants. The objectives of this project are to provide a comprehensive understanding of the gene regulatory network controlling whole-plant carbohydrate partitioning in maize, a crop of vital significance to the agriculture and economy of the U.S. The project will use genetic and genomic experiments to identify the genes regulating carbon export from leaves and import into seeds, employ next generation sequencing to characterize genes expressed along the sucrose transport route through the phloem, and exploit the vast genetic diversity within maize to discover novel genetic modifiers of carbohydrate partitioning. Collectively, this knowledge will generate testable hypotheses about the functions of genes that underlie long-distance transport of carbohydrates, providing new insight that may translate into gains in food production, environmental stress tolerance, biomass accumulation for production of biofuels, and strategies to use plants for carbon sequestration. This project will help train and mentor the next generation of scientists by recruiting undergraduate students from a small liberal arts college and partnering them with undergraduate, graduate, and postdoctoral colleagues from major research universities. In coordination with the Vermont EPSCoR program, the project will develop a summer workshop for high school students and teachers that will focus on the research goals of the project and will help the participants develop a high school teaching module on plant genomics and carbohydrate partitioning. Community resources that include quality-controlled expression data will be deposited into public databases such as GenBank (www.ncbi.nlm.nih.gov/GenBank/), the Maize Genome Database (www.maizegdb.org/), and Gramene (www.gramene.org/). Genetic stocks will be made available through the Maize Genetics Cooperation Stock Center (www.maizecoop.cropsci.uiuc.edu/). A project website will be developed to communicate the research discoveries and educational outcomes of this project broadly to other scientists and to the public.