Changes of resveratrol and antioxidant enzymes during UV-induced plant defense response in peanut seedlings

Plants have evolved mechanisms to avoid and repair UV radiation damage, and the free radicals caused by UV tend to be involved in the induction of antioxidant defense systems. In this study, changes in resveratrol and antioxidant enzymes were investigated in relation to UV damage in peanut seedlings. Accumulation of endogenous resveratrol and stilbene synthase mRNA occurred rapidly and significantly in response to UV-C irradiation. Applying resveratrol before UV-C irradiation mitigated rusty spots and wilting of peanut leaves, and inhibition of resveratrol by applying 3,4-methylenedioxycinnamic acid worsened UV-C damage, an effect that was found to be concentration dependent. Correspondingly, the effect of resveratrol on malondialdehyde was similar to changes in the apparent morphology of seedling leaves. Changes in H2O2, O2–, and antioxidant enzymes showed some similarities after either UV-C irradiation or resveratrol treatment. Activities of superoxide dismutases, glutathione reductase, and catalase were more than 2-fold higher during the first 1 h after treatments. Ascorbate peroxidase activity increased to more than 3-fold higher 24 h after irradiation, whereas it was more than 2-fold higher 8 h after resveratrol treatment. Activities of dehydroascorbate reductase and monodehydroascorbate reductase increased by 40% during 8–24 h after treatments. Consequently, we proposed that changes in endogenous resveratrol and in antioxidant enzymes may have been involved in oxidative stress induced by UV-C exposure in peanut seedlings.