Ureide metabolism and abiotic stress in plants

生物固氮是全球氮循环的组成部分。豆科植物与土壤细菌形成共生体，形成称为根瘤的特殊根结构。植物向细菌提供来自光合作用的碳，细菌将大气中的氮（蛋白质、DNA和其他生物分子的基本成分）转化为植物可用的形式。在农业豆类中，这是一个重要的机制，为人类和牲畜的饮食提供氮，同时限制氮肥。在大豆和相关豆类中，固定氮以酰脲的形式从根瘤转移到叶子、豆荚和种子，然后酰脲被分解并被利用。当水分变得有限时，酰脲形成，固氮作用停止。这个过程是非常敏感的水分限制，我们已经表明，酰亚胺也积累反应活性氧（ROS），可能是一个一般的非生物胁迫反应。我的长期研究课题是氮代谢的分子和生化调控，重点是酰脲代谢和非生物胁迫。具体目标包括测试突变体缺乏酰脲代谢的敏感性，非生物胁迫，确定何时何地这些基因表达的ROS和其他压力和解决他们的影响固氮。我的研究计划继续整合植物生理学，生物化学和分子生物学，以增加我们对酰脲代谢的理解。

Biological nitrogen fixation is integral to the global nitrogen cycle. Legumes form symbioses with soil bacteria resulting in specialized root structures called nodules. The plant supplies carbon, derived from photosynthesis, to the bacteria and the bacteria convert atmospheric nitrogen, a fundamental component of protein, DNA and other biomolecules, to a form usable by the plant. In agricultural legumes, this is an important mechanism to supply nitrogen to the diets of humans and livestock while limiting nitrogen fertilization. In soybean and related legumes fixed nitrogen moves from the nodules to leaves, pods and seeds as ureides, which are then broken down and the nitrogen utilized. When water becomes limiting, ureides build up and nitrogen fixation ceases. This process is extremely sensitive to water limitation, and we have shown that ureides also accumulate in response to reactive oxygen species (ROS), likely a general abiotic stress response. The long term theme of my research program is molecular and biochemical regulation of nitrogen metabolism, with a focus on ureide metabolism and abiotic stress. Specific objectives include testing mutants deficient in ureide metabolism for sensitivity to abiotic stress, identifying when and where these genes are expressed in response to ROS and other stressors and addressing their impact on nitrogen fixation. My research program continues to integrate plant physiology, biochemistry and molecular biology to augment our understanding of ureide metabolism.