Nitrate-mediated maintenance of photosynthetic process by modulating hypoxic metabolism of common bean plants

• DOI: 10.1007/s11738-020-03107-y
• Publication Date: 2020-06-18T01:02:42Z
• Authors: Douglas Antônio P...; Junior Borella; Gabriela Niemeyer...; Luciano do Amarante; Marcos Antonio Ba...
• Keywords: Nitrogen Assimilation; Nitrogen Cycle; Plant Physiology

Nitrate has been reported to improve tolerance of plants under flooding by modulating carbon and nitrogen metabolism of root cells; however, the extent to which nitrate modulates the photosynthetic process is not well understood. This work aimed to evaluate the photosynthetic process by nitrate-mediated modulation of hypoxic metabolism in the root of common bean plants (Phaseolus vulgaris L.) under flooding and recovery conditions. Three groups of common beans [N2-fixing (N2)], N2-fixing pre-hypoxic nitrate-treated (N2 + NO3−), and nitrate (NO3−)-supplied plants] were grown in vermiculite and the root system was subjected to flooding for 48 h at the early reproductive stage. After flooding, plants returned to normoxic conditions per 24 and 72 h for recovery. Plants from N2 + NO3− and mainly NO3− groups maintained transpiration rate (E) and CO2 assimilation under root-flooding, which was not shown by N2-fixing plants. No changes in the dynamic dissipation of photosynthetic energy were evidenced in leaves of NO3− plants upon flooding, besides an increase in nitrate reductase (NR) activity and a decrease in fermentative enzymes in roots. Reactive oxygen species (ROS) and antioxidative enzymes increased in leaves and decreased in roots. Nitrate-mediated maintenance of the photosynthetic process may be related to induction in NR activity in roots to alleviate the toxic effects of fermentation through a decrease of fermentative enzyme activity.