Rearrangement of carbon metabolism in Arabidopsis thaliana subjected to oxidative stress condition:: an emergency survival strategy

Studies of oxidative stress in plants began several years ago, although many aspects of the antioxidant response are still unknown. In this work, we analyze the transcription profile of Arabidopsis thaliana leaves under oxidative and control conditions. Plants were challenged with methyl viologen (MV), a redox cycling herbicide that produces superoxide anion (O-2(center dot-)) in the light and in the chloroplasts, generating inhibition of photosynthesis. Gas exchange measurements and starch and soluble sugars were assayed to test the status of primary metabolism of Arabidopsis leaves. Within the first 2 h of 50 mu M MV treatment, several genes were differentially expressed, among them were proteins implicated in photosynthesis, respiration, and carbon metabolism. Soluble sugars and starch markedly dropped after 3 h MV treatment, while respiration rate showed a steady increase after 4 h oxidative treatment. It was observed that the anabolic pathways were repressed while catabolic pathways were induced after the oxidative treatment. Overall, results suggest a rearrangement of carbon metabolism in the leaves, which could reflect a short-term mechanism of survival of Arabidopsis seedlings subjected to severe oxidative stress conditions.