| Ultraviolet radiation (UV-C) is one of the most commonly used non-biological factors to induce the synthesis resveratrol (Res) in plants. Resveratrol, a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi, has been extensively studied in a variety of plants, especially in the common grapes and peanuts. Some resveratrol derivatives possessing strong biological activity have also been discovered in certain plants with the development of improved experimental techniques and the further research on Res. However, the effect of elicitor, especially the UV-C, on inducing the synthesis of resveratrol has rarely been reported.In the present study, UV-induced Cabernet Sauvignon grapes (Vitis vinifera L.cv.Cabernet Sauvignon) and peanut (Arachis hypogaea L.) seedlings were used in this experiment to investigated the underlying mechanisms involved in the changes of resveratrol and its derivatives and the factors affecting the metabolic activity of related enzymes. The main results are as follows:UV-induced resevratrol in grapes seedlings has a role in rapid protective responses to diverse environmental stresses. Also, significantly high levels of endogenous resveratrol and its derivatives occurred rapidly in response to UV-C irradiation. Moreover, the contents of resveratrol and its derivatives change over time in different tissues and locations in grape, there were two peaks of resveratrol after 18-36h in the dark, the peaks of irradiation leaves were at 24 and 36h, and the first peak was higher than the second peak, while the opposite leaves, upside leaves, lunder leaves and stems at 30 and 48h, and the closer of irradiation leaves, the greater the peak of its resveratrol, suggesting that there exists the possibility that UV-induced plant defense response are correlated with resveratrol and its derivatives and some kind of resveratrol transport mechanism in plants.The activity of peroxidase (POD),the major metabolic enzyme of resveratrol, was significantly enhanced by UV-C treatment, indicating that the enhancement of the inducement of resveratrol and its derivatives might also be related to the number of POD. Moreover, there was no new POD enzyme found before and after UV-C treatment at the isozyme level, and POD activity was not significantly changed before and after UV-C treatment.Different inhibitors and scavengers had dramatic effects on the production of H2O2, with corresponding changes in the activity of POD Therefore, we could suppose that H2O2 may act as a signal molecule for resveratrol and its derivatives in response to UV-C irradiation. Thus the levels of resveratrol and its derivatives could be further regulated through the regulation of H2O2 in a plant.To test the generality of UV-induce in plants, this study used the peanuts to further investigate the biological character of resveratrol. It could be seen that the research on peanut seedlings provided the same results as we obtained in grape seedlings. Firstly, both of the contents of resveratrol and its derivatives were significantly increased by UV-induced in peanut-seedlings. Additionally, the sensitivity to UV irradiation changed as tissues and loactions differ in peanut plant:the sensitivity was much higher in roots than in stem and leaves,at the 42h after UV-treatwith over a period of 30min and then stored in the dark at 25℃, Resveratrol in peanut roots level up to 124.47μg/g. All these conclusions could provide theoretical evidence for employing the UV-C treatment in peanut roots to enhance the disease resistance in peanuts.
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