Mitochondrial regulation of nitrogen metabolism under hypoxic conditions

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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.