| Research Abstract |
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.
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