Genetic improvement of nitrogen use efficiency in crops.

Nitrogen (N) is an essential mineral nutrient for plant growth and development. N deficiency is the major factor limiting plant growth and crop production in most natural and agricultural soils. The green revolution of the 1960's boosted crop yields through cultivation of semi-dwarf plant varieties. However, green revolution wheat and rice varieties have relatively poor nitrogen use efficiency (NUE), require a high N fertilizer supply to achieve maximum yield potential, and this leads to an increase in production costs and environmental problem. Therefore, a major challenge for sustainable agriculture is whether improvement of NUE through the reduction of N fertilizer supply can be achieved without yield penalty. In this review, we summarize the recent advances in understanding of molecular mechanisms underlying the regulation of N-responsive plant growth, utilization and possibility for improvements of NUE in crops, and new breeding strategies through modulation of N-responsive growth-metabolism coordination for future sustainable agriculture.氮素是植物生长发育所需的大量元素之一,施用氮肥是农业生产中提高农作物产量的重要手段。自20世纪60年代以来,“绿色革命”半矮秆农作物品种的育成和大面积推广有效地解决了“高产与倒伏”之间的矛盾,提高了农作物的收获指数和产量。然而半矮秆水稻和小麦品种也表现出生长发育对氮肥响应减弱、根系对铵态氮和硝态氮的吸收能力下降以及氮肥利用效率(nitrogen use efficiency, NUE)低的弊病,其产量增加依赖于氮肥的大量投入,这不仅提高了种植成本还导致了严重的环境污染问题。因此,提高农作物氮肥利用效率对于保障国家粮食安全和农业可持续发展具有重要战略意义。本文概述了“绿色革命”与赤霉素的作用机理,系统总结了植物氮素吸收、同化和代谢调控方面的研究进展,并介绍了提高作物氮肥利用效率的最新研究发现,以期为作物氮肥高效利用的遗传改良提供参考。.