玉米对氮素形态的反应及机制研究进展

Research progress on the response and mechanism of maize(Zea mays L.)to nitrogen forms

【目的】硝态氮(NO_(3)^(−)-N)和铵态氮(NH_(4)^(+)-N)是植物从土壤中吸收的两种主要无机氮形态。玉米属于典型的旱地作物,通常认为NO_(3)^(−)-N是其主要的氮素吸收形态。然而,也有研究表明,与供应NO_(3)^(−)-N相比,供应NH_(4)^(+)-N更有利于玉米的生长。因此,目前为止对于玉米氮源偏好并无一致的结论。本文总结了不同环境下玉米的氮源偏好表现,以及其控制NO_(3)^(−)-N和NH_(4)^(+)-N吸收的基因家族。阐明玉米根系发育、碳氮代谢、光合作用、矿质元素吸收和抗逆性等生理过程对两种氮素形态的响应,以期为玉米的氮素高效利用与氮肥优化管理提供指导。【主要进展】玉米氮源偏好受外界环境的影响,土壤pH被认为是主要的影响因素之一。玉米在酸性环境下喜NO_(3)^(−)-N,碱性环境下更喜NH_(4)^(+)-N。相比单一氮素形态,适宜的铵硝配比更有利于玉米氮素的吸收和产量的提高。在玉米基因组中,负责编码高亲和力硝酸盐转运系统基因NRT2有4个,低亲和力硝酸盐转运系统基因NPF有79个,高亲和力铵盐转运系统基因AMT有8个,低亲和力铵盐转运系统基因AMF1有两个。NO_(3)^(−)-N和NH_(4)^(+)-N不仅作为养分资源,同时作为信号因子参与调控玉米的根系发育、碳氮代谢、光合作用、矿质元素吸收及抗逆性。【展望】为进一步提高玉米氮肥利用效率,明确氮素形态影响玉米生长发育和生理过程的机制,需要在以下几方面重点展开研究:深入挖掘玉米吸收、转运NO_(3)^(−)-N和NH_(4)^(+)-N的分子机制;探索NH_(4)^(+)-N与NO_(3)^(−)-N混合施用促进玉米生长的机理;开展氮素形态对玉米生长及产量影响的大田验证试验。

【Objectives】Nitrate(NO_(3)^(−)-N)and ammonium(NH_(4)^(+)-N)are the two main forms of inorganic nitrogen(N)absorbed by plants from soil.Maize(Zea mays L.)is a typical dry-land crop,some studies proved that NO_(3)^(−)-N was the major form for maize absorption,however,there were a fewer of studies showing that supplying NH_(4)^(+)-N was more beneficial for the growth of maize than supplying NO_(3)^(−)-N.In this paper,we summarized the N source preference of maize in different environments,and the gene families related to the absorption and transportation of NO_(3)^(−)-N or NH_(4)^(+)-N in maize,aiming to clarify the response of physiological processes such as root development,carbon and nitrogen metabolism,photosynthesis,mineral element absorption,and stress resistance to the two N forms,in order to provide a basis for efficient N utilization and optimized N fertilizer management in maize.【Major advances】The N source preference of maize varied depending on the external environmental factors,among which the medium pH was considered as one of important factors.Maize grown in acidic soils preferred NO_(3)^(−)-N,while in alkaline soils it preferred NH_(4)^(+)-N.Compared to the single N form,appropriate NO_(3)^(−)-N/NH_(4)^(+)-N ratios were more conducive to N absorption and yield improvement in maize.In the maize genome,4 NRT2 is responsible for encoding high affinity nitrate transport system,79 NPF for low affinity nitrate transport system,8 AMT for high affinity ammonium transport system,and 2 AMF1 for low affinity ammonium transport system.Nitrate and NH_(4)^(+)-N not only serve as important nutrient resources,but also as signaling factors that participate in and regulate maize root development,carbon and nitrogen metabolism,photosynthesis,mineral element absorption,and stress resistance.【Expectations】In order to improve the N-fertilizer utilization efficiency of maize and clarify the mechanism of N forms affecting maize growth,development,and physiological processes,further researches should focus on the molecular mechanisms of absorbing and transporting NO_(3)^(−)-N and NH_(4)^(+)-N by maize,the mechanism of promoting maize growth by the mixed application of NH_(4)^(+)-N and NO_(3)^(−)-N,and field validation experiments on the impact of N form on maize growth and yield.