Analysis of the signal transduction system involved in cytosolic ascorbate peroxidase response under the high light stress using transgenic tobacco plants

Abstract

We studied the signal transduction system of the expression of cytosolic ascorbate peroxidase (cAPX) in tobacco plants. The levels of cellular H₂O₂ and the cAPX transcript were increased by the treatment with 3-aminotriazol or paraquat in the tobacco plants. The treatment with DBMIB also increased the transcript level of cAPX under low-light intensity. These results indicate that the cAPX expression is regulated by the redox status of plastquinone pool and/or cellular H₂O₂ level. Next, we used transgenic tobacco plants expressing the E.coli catalase or thylakoid-membrane bound APX in chloroplasts, which showed the increased tolerance to photooxidative stress. There was no difference in increase in the transcript level of cAPX at the first 1 h under the high-light irradiation between the wild-type and both transgenic plants. We report the effects of the enhancement of H₂O₂-scavenging capacity in chloroplasts on the induction of cAPX expression under high-light intensity in the transgenic plants.