Functions for Glutamine-Metabolizing Enzymes, Expressed in Vascular Tissues, in the Remobilization and Utilization of Nitrogen in Rice Plants

免疫细胞学研究了水稻叶片维管束中胞质谷氨酰胺合成酶（GS1）蛋白和nadh依赖性谷氨酸合成酶（NADH-GOGAT）的细胞定位。衰老叶片中GS1蛋白主要分布在伴生细胞和维管薄壁细胞中，说明GS1对谷氨酰胺的合成和叶片氮的输出具有重要作用。NADH-GOGAT蛋白在未膨大的非绿色叶片的韧皮部和木质部的溶质运输中被认为具有活性。这一结果表明GOGAT对于谷氨酰胺的转化是重要的，通过血管系统运输，谷氨酸在生物合成过程中进一步使用。根内NADH-GOGAT mRNA和蛋白质的表达在氮的供应下受到极大的刺激。为了研究诱导增加的分子机制，获得了包含预期启动子区域的约14kb长的基因组克隆并对其进行了测序。农杆菌介导的水稻植物转化为我的栽培品种，Sasanishiki，研究表达调控。

Cellular localization of cytosolic glutamine synthetase (GS1) protein, as well as NADH-dependent glutamate synthase (NADH-GOGAT), in vascular bundles of rice leaves have been investigated immunocytologically. The GS1 protein in senescing leaf blade was located in companion cells and vascular parenchyma cells, suggesting that the GS1 is important for the synthesis of glutamine for export of leaf nitrogen.NADH-GOGAT protein was detected in cells, which are considered to be active in the transport of solutes from phloem and xylem, in unexpanden, non-green leaf blade. This results indicates this GOGAT is important for the conversion of glutamine, transported via vascular system, to glutamate for the further use in the biosynthetic processes.In the roots, the expression of NADH-GOGAT mRNA and that of protein were greatly stimulated by the supply of nitrogen. To investigate the molecular mechanisms for the inducible increase, about 14-kb long genomic clones containing the expected promoter-region were obtained and sequenced. Agrobacterium-mediated transformation of rice plants is developed for my cultivar, Sasanishiki, to investigate the regulation of the expression.