2001 Fiscal Year Final Research Report Summary
Factors affecting the abilities of photosynthesis, photorespiration and heat tolerance of plant leaves
| Project/Area Number |
11460072
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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 |
林学
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| Research Institution | KYUSHU UNIVETRSITY |
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Principal Investigator |
KOBAYASHI Yoshichika Faculty of Agriculture, Kyushu University, Prof., 大学院・農学研究院, 教授 (90087594)
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| Project Period (FY) |
1999 – 2001
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| Keywords | photosynthesis / photorespiration / electron transport / fatty acids |
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| Research Abstract |
The aim of this study was to determine the physiological factors affecting the abilities of photosynthesis, photorespiration and temperature-stress tolerance of herbaceous plants and woody plants.
Photosynthesis is one of the most heat-sensitive functions of plant cells. Temperatures in the range of 35 ℃ to 45 ℃ tend to inhibit photosynthesis. In order to assess the effect of high temperature on the photosynthetic machinery, the level of photosynthetic activity was measured in transgenic tobacco plants in which the expression of the chloroplast trienoic fatty acid synthetase gene was inhibited. The transgenic plants contained a lower level of trienoic fatty acids than wild-type plants and were better able to acclimate to higher temperature. The ω-3 fatty acid desaturase enzyme, which is expressed in nearly all plant species, may be widely useful in engineering temperature tolerance in plants.
Photosynthetic electron transport is damaged when strong illumination causes either excessive reduction on the acceptor side or oxidation on the donor side of photosystem II (PS II). Plants have protective mechanisms such as photorespiration and down regulation of PS II to prevent the damage. The relationship between photorespiration and the down regulation of PS II was investigated. It was found that the down regulation of PS II is increased with acceleration of photorespiration when the limiting factor of photosynthesis was changed from light to CO_2. From these results, it was concluded that the most important factor affecting photorespiration is the diffusivity of CO_2 in leaf tissue.
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