Involvement of Plasma Membrane H+-ATPase in Adaption of Rice to Ammonium Nutrient

The preference of paddy rice for NH4+ rather than NO3ˉ is associated with its tolerance to low pH since a rhizosphere acidification occurs during NH4+ absorption. However, the adaptation of rice root to low pH has not been fully elucidated. The plasma membrane H+-ATPase is a universal electronic H+ pump, which uses ATP as energy source to pump H+ across the plasma membranes into the apoplast. The key function of this enzyme is to keep pH homeostasis of plant cells and generate a H+ electrochemical gradient, thereby providing the driving force for the active influx and efflux of ions and metabolites across the plasma membrane. This study investigated the acclimation of plasma membrane H+-ATPase of rice root to low pH. This mechanism might be partly responsible for the preference of rice plants to NH4+ nutrition. Key words: rice; ammonium nutrient; plasma membrane H+-ATPase