Role of Amino Acid Transporters in Seed Development

同化物在植物中的分布（分配）被假设是由位于进口器官（库）的运输过程调节的，如发育中的种子。特别是氨基氮的运输是影响植物生产力、作物产量和繁殖成功的一个主要因素。然而，关键的氮转运过程仍有待确定和表征。本项目利用多学科方法表征汇组织中的氨基酸转运过程，特别是确定生殖结构中表达的氨基酸转运蛋白的功能。总的目标是了解，在细胞和分子水平上，氨基酸转运体在控制氮转运到种子和种子内部的作用。以拟南芥果实（硅酸）和种子为库模型，我们打算(1)确定硅酸/种子发育过程中表达的氨基酸转运蛋白家族成员的细胞和亚细胞定位；(2)通过表征氨基酸转运蛋白的生理和分子调控来了解氨基酸转运库的控制机制。(3)通过对氨基酸转运体表达和活性的分子遗传调控，评价氨基酸转运体在控制有机氮进入种子发育中的功能意义。从本研究中获得的信息将为理解各种氨基酸转运体在氮向种子组织和种子组织之间的转移和分配中的功能奠定基础。此外，这将为未来更详细地研究转运体对其他植物种子养分积累的贡献提供平台。该计划还将为生物技术创新的发展提供一个框架，以提高作物产量和修改种子的氨基酸补体营养品质。

Assimilate distribution (partitioning) in plants is hypothesized to be regulated by transport processes located in importing organs (sinks) such as developing seeds. The transport of amino nitrogen, in particular, is a major factor influencing plant productivity, crop yield and reproductive success. However, key nitrogen transport processes remain to be identified and characterized. This project utilizes a multidisciplinary approach to characterize amino acid transport processes in sink tissues and specifically to determine the function of amino acid transporters expressed in reproductive structures. The overall goal is to understand, at a cellular and molecular level, the role of amino acid transporters in controlling nitrogen transport to and within seeds. Using Arabidopsis fruits (siliques) and seeds as a sink model, we intend (1) to identify the cellular and subcellular localization of members of the amino acid transporter family that are expressed during silique/seed development, (2) to understand mechanisms controlling amino acid transport in sinks by characterizing the physiological and molecular regulation of amino acid transporters, and (3) to assess the functional significance of amino acid transporters in controlling import of organic nitrogen into developing seeds using molecular genetic manipulation of transporter expression and activity. The information obtained from the proposed work will form the basis for understanding the function of various amino acid transporters in nitrogen transfer and partitioning to and among seed tissues. In addition, it will provide a platform for more detailed future studies to evaluate transporter contribution to nutrient accumulation by seeds in other plant species. The program will also offer a framework for the development of biotechnological innovations to increase crop yield and for modifying nutritional qualities of seeds with respect to their amino acid complement.