SAITO Kazuki Chiba University, Faculty of Pharmaceutical Sciences, Professor, 薬学部・薬用資源センター, 教授 (00146705)
SANO Hiroshi Nara Institute for Science and Technology, Research and Education Center for Genetic Information, Professor, 遺伝子教育研究センター, 教授 (20178809)
MIZUNO Takeshi Nagoya University, Graduate School of Bioagricultural Sciences, Professor, 大学院・生命農学研究科, 教授 (10174038)
HAYASHI Hiroaki The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (60180973)
YAMAYA Tomoyuki Tohoku University, Graduate School of Agricultural Science, Professor, 大学院・農学研究科, 教授 (30144778)
1. Cytokinin was shown to act as the organ-to-organ signal, transmitted from the root to shoot, for the presence of nitrate in the soil. The sensor kinase responsive to cytokinin was indentified. Other components of the His-Asp phosphorelay system (i. e. response regulators and His-containing phophotransmitters), implicated in transduction of the cytokinin signal, were also identified and characterized. In addition, pseudo-response regulators, implicated in generation of circadian rhythm in plants, were identified and characterized.
2. The genes encoding adenylate isopentenyltransferase, a cytokinin biosynthesis enzyme, were identified in Arabidopsis thaliana, demonstrating that the plant hormone is synthesized by the plant and not by symbiotic microorganisms.
3. Phloem sap of rice was shown to contain certain proteins, including thioredoxin h, and several mRNA species. It was further shown that at least some of these macromolecules are synthesized in the companion cell and transferred to the sieve element via plasmodesmata.
4. A particular set of glutamine synthetase and glutamate synthease isozymes, which are localized in the vascular bundle of leaf blade and maturing grains, respectively, was found to play an important role in mobilization of leaf nitrogen and its transfer to rice grains.
5. Genes encoding sulfate transporters and sulfate assimilating enzymes were identified in A. thaliana and other plants. Regulatory links between the sulfur- and nitrogen-assimilating pathways were found.