| Budget Amount *help |
¥13,800,000 (Direct Cost: ¥13,800,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2003: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Research Abstract |
1)The influence of H_2O_2 accumulation and redox status of the photosynthetic electron transport on the expression of cytosolic ascorbate peroxidase (cAPX).
Transgenic tobacco plants expressing catalase and thylakoid-membrane bound APX in chloroplasts, both of which had increased tolerance to photooxidative stress, were utilized for evaluation of the relationship between H_2O_2 accumulation or change of redox status of the PET and cAPX induction under photooxidative stress condition. These results suggest that the induction of cAPX expression is caused by a redox change in the PET, probable PQ pool at an early stage and-thereafter by an increase in the cellular H_2O_2 level.
Next, to clarify the mechanism of the decline in oxidative stress tolerance of leaves during the course of senescence, we studied the differences in the levels of various antioxidants and antioxidant enzymes in leaves of different ages.
The data suggest that the decline in the levels of antioxidants and antioxidant en
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zymes associated with leaf senescence lead to lower photooxidative-stress tolerance, which might in turn accelerate the propagation of senescence.
2)The effect of AOS, signal molecules on the regulation of many physiological processes, including environmental stress responses.
We investigated the effect of lowered cAPX activity in transgenic tobacco BY-2 cells, using two transformed BY-2 cell lines, cAPX-S2 and cAPX-S3. Interestingly, the APX-suppressed cells showed different responses and tolerances to environmental stresses, such as heat and salinity. Suppression subtractive hybridization revealed that several heat and salt-stress inducible genes were upregulated in cAPX-S3 cells. HSP70, DnaJ-like protein and purple acid phosphatase were among the constitutively induced genes.
3)Molecular breeding of transgenic plants introducing the genes involved in the redox regulation.
To identify the genes involved in the the redox regulation in higher plants, we are trying to generate transgenic plants expressing a redox regulatory factor. Less
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