Analysis of signal transduction system involved in cytosolic ascorbate peroxidase responce under the high light stress

Abstract

We studied the signal transduction system of cytosolic ascorbate peroxidase (APX) in spinach. When the detached spinach leaves were treated with 3-aminotriazol and methyl viologen, the cellular H₂O₂ levels and the transcript level of cytosolic APX (cAPX) were increased. The H₂O₂ treatment also increased the transcript level of cAPX.
The treatment of DCMU inhibited the induction of cAPX transcript level under high light intensity. In contrast, the treatment with DBMIB increased the transcript level of cAPX under low light intensity. These results indicate that cAPX is regulated by the redox status of plastquinone pool or cellular H₂O₂ level. Currently, we are analyzing the effects of the production of H₂O₂ and the over-reduction of plastquinone pool on cAPX induction under high light intensity using transgenic tobacco plants expressing the E. coli catalase (T43-1) or thylakoid-membrane bound APX (TpTAP-12) in chloroplasts.