Mitochondrial regulation of nitrogen metabolism under hypoxic conditions

厌氧病是一种广泛存在的有害应激。植物在占据加拿大大片地区的淹水和致密的土壤上经历了它。由于其溶解度低，在水中扩散速率低，导致缺氧，主要损害根和种子。多年来，人们已经知道硝酸盐对淹水作物有改善作用，但这一现象的确切机制至今尚不清楚。该提案旨在通过增加参与氮代谢，特别是硝酸盐/亚硝酸盐/一氧化氮的转换，为植物线粒体建立与缺氧条件下功能相关的新功能。通过这个研究项目，我试图了解植物线粒体从使用氧气到减少亚硝酸盐然后产生一氧化氮的分子机制。我将探讨线粒体在低氧环境中对ATP合成的贡献的可能性，从而在缺氧时维持细胞能量状态，并减少乙醇和乳酸的产生。通过缺氧诱导血红蛋白的反应去除有毒一氧化氮的途径将被研究。我的研究项目将对植物适应的基本过程产生直接而深远的影响。线粒体作为低氧防御系统的主要组成部分，为提高植物的抗逆性提供了新的潜在靶点。证明厌氧线粒体ATP合成作为经典发酵途径的替代方法，将有可能制定策略来应对植物系统中厌氧事件的负面后果，并选择耐涝作物。

Anaerobiosis is one of the widespread and damaging stresses. Plants experience it on flooded and compact soils which occupy large areas in Canada. Oxygen deficiency arises due to its low solubility and low diffusion rate in water and damages mostly roots and seeds. It has been known for many years that nitrate has ameliorating effect on flooded crops but the exact mechanism of this phenomenon is not understood to date. The proposal aims to establish novel functions for plant mitochondria connected with their functionality under hypoxic conditions via increased involvement in nitrogen metabolism and in particular in nitrate/nitrite/nitric oxide turnover. Through this research program, I seek to understand the molecular mechanism by which plant mitochondria switch from the use of oxygen to the reduction of nitrite followed by nitric oxide production. I will explore the possibility of mitochondrial contribution to ATP synthesis in low oxygen environments, leading to the maintenance of cell energy status during hypoxia and to the decreased production of ethanol and lactic acid. The pathway of removal of toxic nitric oxide via reactions involving the hypoxically induced hemoglobin will be studied. My research program will have immediate and far-reaching impacts on fundamental processes of plant adaptation. Mitochondria as major components of the defense system under hypoxia represent a new potential target for improving resistance to stress in plants. Proving the operation of anaerobic mitochondrial ATP synthesis as an alternative to classic fermentation pathways will make it possible to develop strategies to cope with negative consequences of anaerobic events in plant systems and select flood-tolerant crops.