2005 Fiscal Year Final Research Report Summary
Development of practically applicable stress-tolerant plants by transformation of stress response genes identified and characterized from microalgae
| Project/Area Number |
15310054
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental technology/Environmental materials
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| Research Institution | Osaka University |
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Principal Investigator |
HIRATA Kazumasa Osaka University, Graduate School of Pharmaceutical Sciences, Associate Professor, 薬学研究科, 助教授 (30199062)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Green alga / Stress response / Phytochelatin / Abscisic acid / Heavy metal / Reactive oxygen / Stress-tolerant plant / Anti-oxidant enzyme |
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| Research Abstract |
Phytochelatins (PCs) are heavy-metal-binding peptides that play important roles in the detoxification of toxic heavy metals in higher plants. In this study, we investigated the regulation mechanism of PC biosynthesis in microalgae such as green algae and cyanobacteria. In higher plants, it is well known that Cd is a more effective inducer of PC synthesis than other heavy metals. On the other hand, we have observed PC synthesis is more strongly induced by zinc than Cd in a marine green alga, Dunaliella. This result suggests Dunaliella PC synthase gene may be applicable to develop practical hyperaccumulator for toxic heavy metals.
PC and PC synthase genes have never been identified in prokaryotes. In this study, however, we found a gene encoding a PC synthase-like protein in a prokaryote, Nostoc sp.PCC7120. This cyanobacterial protein contained the conserved N-terminal domain but not the variable C-terminal domain found in eukaryotic PC synthases. Furthermore, this protein strongly cataly
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zed the first step of PC synthesis but could not catalyze the second step, although eukaryotic enzymes can catalyze both reactions. These results suggest this prokaryotic PC synthase may be a more primitive form of the eukaryotic ones.
Abscisic acid (ABA) is a well known signal molecule for induction of various stress response reactions in higher plants. In this study, we investigated the function of ABA in microalgae. Although ABA biosynthesis is generally accelerated by exposure to various environmental stresses in higher plants, the biosynthesis was specifically accelerated by oxidative stress in freshwater green alga, Chlamydomonas. Furthermore, exogenously added ABA specifically induced anti-oxidant reactions. On the other hand, in a cyanobacterium, Synechocystis, ABA biosynthesis never occurred under exposure to any stresses and any response reactions were not induced by ABA. These results suggest the ABA biosynthetic pathway and ABA-dependent stress response systems found in higher plants also exist in green algae but do not exist in cyanobacteria. Less
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Research Products
(18 results)
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[Journal Article] Comparative analysis of the two-step reaction catalyzed by prokaryotic and eukaryotic phytochelatin synthase by an ion-pair liquid chromatography assay.2005
Author(s)
Tsuji, N., Nishikori, S., Iwabe, O., Matsumoto, S., Shiraki, K., Miyasaka, H., Takagi, M., Miyamoto, K., Hirata, K.
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Journal Title
Planta Vol.222
Pages: 181-191
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Characterization of phytochelatin synthase-like protein encoded by alr0975 from a prokaryote, Nostoc sp.PCC7120.2004
Author(s)
Tsuji, N., Nishikori, S., Iwabe, O., Shiraki, K., Miyasaka, H., Takagi, M., Hirata, K., Miyamoto, K.
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Journal Title
Biochem.Biophys.Res.Commun. Vol.315
Pages: 751-755
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Functional analysis of phytochelatin synthase from Arabidopsis thaliana and its expression in Escherichia coli and Saccharomyces cerevisiae.2004
Author(s)
Matsumoto, S., Shiraki, K., Tsuji, N., Hirata, K., Miyamoto, K., Takagi, M.
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Journal Title
Sci.Technol.Adv.Materials (STAM) Vol.5
Pages: 377-381
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Regulation of phytochelatin synthesis by zinc and cadmium in marine green alga, Dunaliella tertiolecta.2003
Author(s)
Tsuji, N., Hirayanagi, N., Iwabe, O., Namba, T., Tagawa, M., Miyamoto, S., Miyasaka, H., Takagi, M., Hirata, K., Miyamoto, K.
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Journal Title
Phytochemistry Vol.62
Pages: 453-456
Description
「研究成果報告書概要(欧文)」より
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