植物尿素代谢及稳态调节机制研究进展

尿素是农业生产中施用量最多的氮肥之一，也是植物体内重要的代谢中间产物。普遍认为，植物主要吸收土壤中经土壤微生物转化产生铵态氮和硝态氮，直接吸收尿素和内部水解作用并不显著， 但这一观点正受到挑战，因为植物拥有专用的尿素转运蛋白，能够利用尿素作为唯一氮源。本文通过概述尿素在不同生命系统中存在的基础生理意义及MIPs和DUR3系统在调控尿素吸收、转运以及库/源间氮循环过程的作用，讨论了脲酶在促进尿素氮的同化、信号传导，精氨酸途径和酰胺途径在维持C/N代谢平衡和激素信号网络调节机制，以及植物尿素代谢及稳态调节机制在农业运用方面的展望。通过阐述植物体内局部尿素浓度与整体的氮素状态信号的反馈调节调控氮素的吸收和再利用的复杂调控网络，为提高作物氮的吸收、利用及再分配和农作物遗传改良奠定理论基础。

Research progress on urea metabolism and regulation mechanism of homeostasis in plants

Urea is one of the most widely used nitrogen fertilizers in agricultural production, and it is also an important metabolic intermediate product in plant. A widespread opinion is that plants mainly take up ammonium and nitrate generated by microbial conversion of urea in the soil and direct urea uptake and internal hydrolysis by the plant are not significant, however, this view is now being challenged by the observation that plants possess dedicated urea transporters that can use urea as sole nitrogen source. This article summarized the basic physiological significance of urea in different life systems and the role of plant MIPs and DUR3 systems on urea absorption, transport and N cycle between library/source, discussed the role of urease on promoting the assimilation and signal transduction of urea nitrogen, the arginine pathway and the amide pathway maintaining the C/N metabolic balance and hormone signal network regulation mechanism, as well as the prospect of plant urea metabolism and homeostasis regulation mechanism in agricultural applications. By reviewing the feedback regulation of the local urea concentration in plants and the overall nitrogen status signal, the complex regulation network regulating the absorption and reuse of nitrogen is expected to lay a theoretical foundation for improving the absorption, utilization and redistribution of nitrogen in crops and the genetic improvement of crops.