Generation of Hydrogen Peroxide in Chloroplasts of Arabidopsis Overexpressing Glycolate Oxidase as an Inducible System to Study Oxidative Stress1[W]

Arabidopsis (Arabidopsis thaliana) overexpressing glycolate oxidase (GO) in chloroplasts accumulates both hydrogen peroxide (H2O2) and glyoxylate. GO-overexpressing lines (GO plants) grown at 75 μmol quanta m−2 s−1 show retarded development, yellowish rosettes, and impaired photosynthetic performance, while at 30 μmol quanta m−2 s−1, this phenotype virtually disappears. The GO plants develop oxidative stress lesions under photorespiratory conditions but grow like wild-type plants under nonphotorespiratory conditions. GO plants coexpressing enzymes that further metabolize glyoxylate but still accumulate H2O2 show all features of the GO phenotype, indicating that H2O2 is responsible for the GO phenotype. The GO plants can complete their life cycle, showing that they are able to adapt to the stress conditions imposed by the accumulation of H2O2 during the light period. Moreover, the data demonstrate that a response to oxidative stress is installed, with increased expression and/or activity of known oxidative stress-responsive components. Hence, the GO plants are an ideal noninvasive model system in which to study the effects of H2O2 directly in the chloroplasts, because H2O2 accumulation is inducible and sustained perturbations can reproducibly be provoked by exposing the plants to different ambient conditions