| Project/Area Number |
14360089
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
林学
|
|---|
| Research Institution | KYUSHU UNIVERSITY |
|---|
Principal Investigator |
KOBAYASHI Yoshichika Kyushu University, Graduate School of Agriculture, Professor, 農学研究院, 教授 (90087594)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
三宅 親弘 九州大学, 農学研究院, 助教授 (80294289)
|
|---|
| Project Period (FY) |
2002 – 2004
|
| Project Status |
Completed (Fiscal Year 2004)
|
| Budget Amount *help |
¥14,800,000 (Direct Cost: ¥14,800,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2003: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥8,500,000 (Direct Cost: ¥8,500,000)
|
|---|
| Keywords | Photosynthesis / CO_2 fixation / Electron Transport / Tree plants / Rate-limitting step / Carbon dooxide / 脂肪酸 / FAD遺伝子 / クスノキ / タバコ / 光呼吸 / トコフェロール / 生体膜 |
|---|
| Research Abstract |
Leaves of evergreen trees are characterized by the low activity of CO_2 uptake compared with leaves of deciduous trees and herbaceous plants. However, we found that there are no substantial differences among leaves of these plant species in the activities of electron transport (Je) and CO_2 assimilation (JCO_2), when the activities (Je and JCO_2) were compared with leaves containing similar levels of CO_2 at the carboxylation site in stroma (Cc). The results suggest that chloroplasts of evergreen tree leaves have high abilities of electron transport and CO_2 assimilation in spite of their very low activities of leaf photosynthesis evaluated as the activity of CO_2 uptake under illumination with saturating light in air containing 350 ppm CO_2.
We, therefore, measured the photosynthetic parameters of attached leaves such as the stomatal and mesophyll conductance to CO_2 diffusion (gs and gm), the CO_2 concentrations in intercellular spaces and stroma (Ci and Cc), and the fluxes of electrons consumed by photosynthesis and photorespiration (JCO_2 and JPR). After the measurement, membrane lipids were isolated from the same leaves as used for the experiments, and the fatty acid composition was determined. A linear relationship was observed between the net activity of photosynthesis (JCO_2) and the mesophyll conductance, indicating that leaf photosynthesis depends on the mesophyll conductance (gm). A good correlation was also found between gm and the relative content of α-linolenic acid (18:3), and between gm and the relative content of palmitic acid (16:0). On the basis of these observations, several possible factors limiting the diffusion of CO_2 in leaf tissue of evergreen trees including Eucalyptus plants were determined.
|
