作物硝态氮转运利用与氮素利用效率的关系

【目的】 铵态氮（NH₄+）和硝态氮（NO₃-）是作物氮素吸收利用的主要形态，旱作作物NO₃-的累积与利用是氮素营养研究的主要组成部分，关系到理解作物NO₃-的转运和利用关系及作物体内NO₃-含量和氮素利用效率（nitrogen utilization efficiency，NUE）高低的问题。主要进展 作物吸收的NO₃-分为被作物直接利用、分泌到根外、储存在液泡和向地上部分运输四种途径。其中NO₃-短途分配（液泡NO₃-分配）和长途转运（地上、地下部NO₃-的转运）共同调控着NO₃-的利用效率，进而影响作物的NUE。液泡NO₃-不能被作物直接利用，只有分配到液泡外细胞质中的NO₃-才能被作物迅速代谢和利用；同时有更大比例的NO₃-分配到地上部分，使得作物可以充分利用太阳光能进行NO₃-代谢和能量转换，从而提高了作物的NUE。此外，液泡对NO₃-起到分隔作用，储存在液泡中的NO₃-并不能对NO₃-转运相关基因（如NR、NO₃-长途转运基因NRT1.5和NRT1.8）起到诱导效果；只有分配在液泡外原生质体中的NO₃-才能对NO₃-诱导基因产生强烈的诱导。因此，作物细胞原生质体中液泡内、外NO₃-的分配不仅影响了NO₃-的同化利用，而且直接影响了NO₃-的长途转运。展望 本文对植物原生质体中液泡内、外NO₃-的短途分配和地上、地下部间NO₃-的长途转运机制进行了总结，为进一步深入研究作物地上、地下部NO₃-长途转运和液泡NO₃-短途分配的关系，以及更好地揭示作物NUE对NO₃-转运和利用的响应机理提供参考。

The relationship between nitrate transport and utilization in crop and nitrogen utilization efficiency

[Objectives] Ammonia (NH4+) and nitrate (NO3-) are the primary forms for crop nitrogen (N) absorption and utilization.NO3-accumulation and utilization in plant tissues of dry land crops are the main components of N nutrient study,which are related to the NO3 content and N utilization efficiency (NUE) in plant tissues.[Main advances] Absorbed NO3-in crop can be assimilated into organic N directly,secreted to the root,accumulated into vacuolar space and transported from roots to shoots.NO3-utilization efficiency and NUE were regulated by NO3-short distribution (vacuole NO3-distribution) and NO3-long transportation (between roots and shoots).Vacuole NO3-can not be assimilated into organic N,but the NO3-outside of the vacuole in protoplast can be utilized by crop directly.The higher proportion of NO3-in shoots has higher NUE,because the NO3-assimilation in shoots will take full advantage of the solar energy.In addition,NO3-is separated by vacuole,NO3-assimilation genes (NR) and transportation genes (NRT1.5 and NRT1.8 for long transport of NO3-) can not be induced by vacuole NO3-,but can be stimulated by the cytosolic NO3-.Consequently,not only NO3-assimilation is regulated by NO3-short distribution,but also affected the NO3-long transport between roots and shoots.[Prospective] We summarized the mechanisms of NO3-short distribution and long transportation in this review,and provided some implications for further study on the relationship between NO3-long transportation and vacuole NO3-short distribution,and the response of crop NUE to NO3-transportation and utilization.