水稻增硝营养的生理与分子生物学机制

 前人对水稻氮（N）营养的研究主要侧重在铵（NH4+）营养而忽略了对硝（NO3－）营养的研究。但值得注意的是，水稻根系能分泌氧气（O2），这些O2能被硝化微生物利用，从而将NH4+氧化成NO3－。因此，即便是完全淹水，水稻根系也是处于铵、硝混合营养中。本文首先论述了水稻根际的硝化作用及增硝营养的可行性，然后提出增硝营养可促进水稻根系生长、氮素吸收和同化，并阐述了目前增硝营养条件下硝酸盐转运蛋白、铵转运蛋白和基因芯片的分子生物学研究进展，并提出水稻对增硝营养的响应度强弱可能是水稻品种氮素效率差异性的因子之一，最后提出了今后在水稻增硝营养方面的研究方向。

Physiological and Molecular Mechanisms of Enhanced Nitrate Nutrition in Rice

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 discusses the physiological and molecular mechanisms of enhanced nitrate nutrition in rice from root growth, nitrogen absorption and assimilation. Finally some issues on enhanced nitrate nutrition of rice are proposed to be further studied.