Uptake, metabolism and distribution of nitrogen in crop plants traced by enriched and natural 15N: Progress over the last 30 years
Uptake, metabolism and distribution of nitrogen in crop plants traced by enriched and natural 15N: Progress over the last 30 years
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DOI：
10.1023/b:phyt.0000004198.95836.ad
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发表时间：
2004
影响因子：
7.7
通讯作者：
T. Yoneyama;O. Ito;W. Engelaar
中科院分区：
文献类型：
--
作者：
T. Yoneyama;O. Ito;W. Engelaar
本文综述了多年来植物氮循环研究的主要结果，首先是15 N富集方法的研究结果，其次是植物及其代谢产物中天然15 N丰度（δ 15 N）的研究结果。这项工作主要是在农业背景下完成的。由于许多研究小组特别试图将δ 15 N与N循环、大气N沉降以及N与碳收支的相互作用联系起来，我们认为综合这些主要发现是有用的。用~（15）N标记化合物对氮素进行标记后，通过测定~（15）N在植物各器官和各氨基酸中的富集程度，研究了氮素在植物体内的初级同化和分配。在根和叶中，NH4+和NO3 −主要通过谷氨酰胺合成酶（GS）和谷氨酸合成酶（GOGAT）的结合被同化为氨基酸。在叶片中，谷氨酰胺（酰胺）N转移到谷氨酸加速在光下，和一些氨基酸中的氨基N脱氨氨为氨，然后将其纳入谷氨酰胺在黑暗中。生长期叶片、灌浆期籽粒和生长期根系中的氮素主要来源于两个方面：一个是贮藏态氮（氨基酸）的再分配（韧皮部供给），另一个是当前吸收的氮。成熟部位的代谢产物可能充当植物生长的底物和基因表达的信号。植物/土壤和植物代谢产物（无机氮、氨基酸、多胺）的δ 15 N值与植物对氮的吸收、代谢和分配有关。在N2和NO3-的获取过程中，15N/14N分馏较小，而在NH4+的吸收过程中，15N/14N分馏较大，地上部和籽粒的δ 15N值在很大程度上反映了氮素的主要来源。在某些豆科植物中，15 N在根瘤中富集，其中一种极富集15 N的化合物是高甲脒。硝酸盐还原为氨（NR）和氨同化为谷氨酰胺（GS）的过程中，15N/14N比例较大。特别注意的是，δ 15 N值的木质部和韧皮部分泌物相比，植物器官。
The major findings of many years of research into plant N cycling are summarised in this review, firstly as revealed by15N-enriched methods and secondly, in relation to natural15N abundance (δ15N) in plants and their metabolites. This work has mainly been done in an agricultural context. As many groups especially attempt to relate δ15N to N cycling, atmospheric N deposition and the interactions of N with carbon budgets, we deem it useful to synthesize these major findings. Primary assimilation and distribution of N within plants were investigated from the15N enrichment in individual plant organs and in individual amino acids after feeding them15N-labelled compounds. In both roots and leaves, NH4+and NO3−were assimilated into amino acids, largely by a combination of glutamine synthetase (GS) and glutamate synthase (GOGAT). In the leaves, the transfer of glutamine (amide) N to glutamic acid was accelerated in the light, and amino N in some amino acids was deaminated to ammonia in the dark, followed by its incorporation into glutamine. The N in the growing parts such as growing leaves, filling grains and growing root parts were from two sources: re-allocation (phloem supply) of reserved N (amino acids), and currently-absorbed N. The metabolites from the mature parts may perform the roles of substrates for plant growth and signals for gene expression. δ15N values, measured for plants/soils and plant metabolites (inorganic N, amino acids, polyamines) were related with the acquisition, metabolism and distribution of N in plants. Small15N/14N fractionation in the acquisition of N2and NO3−and large15N/14N fractionation in NH4+uptake were found. The δ15N values of whole shoots or grains from field-grown crops were largely reflected major sources of N. In some legumes,15N was enriched in their nodules and an extremely15N-enriched compound was homospermidine. Nitrate reduction to ammonia (NR) and ammonia assimilation to glutamine (GS) showed large15N/14N fractionations. Specific attention was paid to the δ15N values in xylem and phloem exudates compared to those of plant organs.