2005 Fiscal Year Final Research Report Summary
Research on novel inhibitor that regulates photosynthesis and photosynthetic source-sink regulatory mechanism
| Project/Area Number |
16370009
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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 |
Ecology/Environment
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| Research Institution | Hirosaki University |
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Principal Investigator |
KASAI Minobu Hirosaki University, Faculty of Agriculture and Life Science, Professor, 農学生命科学部, 教授 (10221871)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKAWA Osamu Hirosaki University, Faculty of Agriculture and Life Science, Professor, 農学生命科学部, 教授 (70184265)
USUDA Hideaki Teikyo University, School of Medicine, Associate Professor, 医学部, 助教授 (90112755)
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| Project Period (FY) |
2004 – 2005
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| Keywords | photosynthetic rate / source-sink / sink-limit / Rubisco inhibitor |
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| Research Abstract |
When, in plants, source capacity exceeds sink capacity, leaf photosynthetic carbohydrates accumulate and photosynthetic rate declines. Research using sweet potato plants suggested that the decline of photosynthesis under sink limitation involved the binding of a novel inhibitor to Rubisco. The aim of this research is to identify the inhibitor and to investigate the universality of the inhibitor, the process of dissociation of the inhibitor from Rubisco and in addition, whether the inhibitor is a main cause of the decline of photosynthesis under sink-limitation.
1.Research on the novel Rubisco inhibitor that causes decline of photosynthesis under sink-limitation. In the first year of this research, we could obtain the solution of the novel Rubisco inhibitor that gave one peak in a HPLC from the extract of leaves of steam-girdled, sink-limited sweet potato plants. However, the inhibitor solution still contained a lot of polysaccharides. In the second (final) year of this research, membran
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e filtration technique could not remove the polysaccharides. To raise the purity of the novel Rubisco inhibitor, sweet potato plants were placed for a longer time under sink limitation after steam-girdling. However, we could not obtain the leaves which were suited to purify the novel Rubisco inhibitor, because the leaves showed senescence such as a significant decrease in Rubisco content.
2.Research on Rubisco inhibitor, universality of the inhibitor, dissociation of the inhibitor from Rubisco, and influence of the inhibitor on photosynthesis in soybean. In the first year of this research, it was shown that in soybean plants, two sink-limit conditions resulted in the decline of photosynthesis and that the binding of a substrate to Rubisco could be the cause of the decline of photosynthesis. In the second (final) year of this research, it was shown that different sink-limit conditions in soybean plants also resulted in the decline of photosynthesis and that the binding of the same substrate to Rubisco could be the cause of the decline of photosynthesis. In addition, there was the relationship between leaf photosynthetic rate, amount of the substrate bound to Rubisco and source-to-sink ratio of the plants, suggesting that plants might have a photosynthetic source-sink regulatory mechanism via the binding of a substrate to Rubisco. Less
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