Effect of cytosolic APX expression levels on photo-oxidative stress response in Arabidopsis

Abstract

Among ascorbate peroxidase (APX) isoenzymes, cytosolic APX plays an important role to control cellular redox conditions in response to photooxidative stress. In this study, we have evaluated the effect of cytosolic APX overexpression (cAPX-OE) or suppression (cAPX-KO) on cellular H₂O₂ accumulation and gene expression levels under photo-oxidative stress conditions. We obtained 7 independent Arabidopsis plants transformed with pBI/cAPX1 and one cAPX-KO line from TAIR. The APX activities in cAPX-OE and cAPX-KO plants were approximately 300-600 % and 30%, respectively, compared with that in wild-type plants. When exposed to high-light stress at 1,000 μmol m^-2 s^-1, the H₂O₂ levels in both wild-type and cAPX-KO transiently increased within 1 h, but the level was almost constant in cAPX-OE. The results of comprehensive gene analysis in these plants will be reported.