| Budget Amount *help |
¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥4,100,000 (Direct Cost: ¥4,100,000)
|
|---|
| Research Abstract |
In order to study adaptation mechanism of plants to high O_2 atomosphere, (1) C_3 (barley, rice, wheat) and C_4 (sorghum and maize) plants were grown for 3 weeks in 65% O_2 and 500 ppm CO_2 and the levels of photosynthetic and photorespiratory enzymes, as well as those of the enzymes and substrates involved in detoxification of active oxygen species, were compared with control plants grown in normal air containing 21% O_2 and 500 ppm CO_2. Although chlorophyll content declined considerably in high O_2 plants, soluble protein content was normal. Therefore, enzyme activities are compared on a protein basis. In C_3 plants grown in high O_2, FuBPase and NADP^+-GA3PDH increased, while the two activities of RuBP carboxylase/oxygenase and the ratio of the two activities were unchanged. Among the photorespiratory enzymes, glycolate oxidase and hydroxypyruvate reductase increased considerably. In C_4 plants, PEP carboxylase apparently increased. In both C_3 and C_4 plants. glutathione reductase increased dramatically. In addition, reduced glutathione content was doubled in barley leaves.
(2) In prospect of obtaining a high-O_2 resistant mutant, seeds of barley and sorghum were mutagenized by treatment with EMS and M2 seedlings were selected for plants which could survive in 75% O_2 over 2 weeks. In these three years, 2 Plants were selected out of 26,715 seeds of sorghum and 7 out of 35,650 seeds of barley, although the latter 7 were not fertile. Both species also yielded various types of mutants; namely, albino, xantha, viridis, and leaves of low and high starch content.
|
