Physiological and Molecular Mechanisms of Enhanced Nitrate Nutrition in Rice

Abstract: Previous researches on nitrogen nutrition of rice mainly focus more on ammonium (NH4+) than nitrate (NO3-). In fact, the roots of rice can excrete oxygen (O2) to surrounding soil and this can convert NH4+ to NO3- in the process of nitrification at root surface or in rhizosphere. Therefore, rice roots are actually always exposed to a mixture of NH4+ and NO3- even in flooded condition. This paper referred ecological significance of enhanced nitrate nutrition in rice and the nitrification process in the rhizosphere of rice, and then supposed that enhanced nitrate nutrition could improve the root growth, N absorption and assimilation by rice. Then, the molecular mechanisms of enhanced nitrate nutrition in rice from nitrate transporters, ammonium transporters and cDNA microarrays was discussed. At last, this paper suggested that there might be a relationship between enhanced nitrate nutrition and nitrogen us