The Effect Of UV-C Irradiation And Soil Drought On Flavanols Accumulation, LAR Activity And Tissue Localization

Flavanols and anthocyanins are the most abundant flavonoids in grape berries, and they are not only contribute to fruit quality, but also to the quality of wine, such as the color, taste, clarity and astringency. To study the effects of soil drought and UV-C irriadiation on the accumulation of flavanols, the acitivity as well as the tissue localization of leucoanthocyanidins reductase (LAR) during grape berry development, the5-year old grapevines (Vitis vinifera L. cv. Cabernet Sauvignon) were used as materials, and were subjected to soil drought stress simulated by the controlling irrigation and UV-C irradiation during grape berry development. The main results were showed as bellow:1. The content of total phenol in the skin was significantly higher than the flesh. An accumulation of total phenol in skin was significantly induced by soil drought. While, the induced effects was only founded in flesh in young fruit period. The accumulation of total phenol was significantly promoted by UV-C irradiation in skin and flesh.2. The content of flavanols in skin was higher than in flesh. An accumulation of flavanols was induced by both soil drought and UV-C irradiation in skin and flesh.3.The flavan-3-ols mainly accumulated in the skin, and the highest content was observed in young fruit period. The accumulation of flavan-3-ols was significantly induced by soil drought in skin. But in flesh, the induced effects was founded before veraison. The accumulation of flavan-3-ols was significantly induced by UV-C irradiation in skin and flesh only before veraison.4. The accumulation of proanthocyanidins in skin and flesh was complex during grape berry development. The accumulation of proanthocyanidins in skin and flesh was significantly induced by soil drought. The accumulation of proanthocyanidins was significantly inhibited by UV-C in skin. The accumulation of proanthocyanidins was induced before veraison, but inhibited after veraison by UV-C irradiation in the flesh.5. The highest LAR enzyme activity was observed in young fruit period in both skin and flesh. And the enzyme activity reduced trend was observed during the growth of berry. LAR enzyme activity was significantly induced by soil drought. And the role was showed more pronounced in flesh than in skin. LAR enzyme activity also was significantly induced by UV-C irradiation in skin and flesh.6. During the berry development, both LAR1and LAR2enzyme were distributed in the skin and flesh, and the stronger signals were observed in vascular bundle. The accumulation of LAR1and LAR2protein were induced by soil drought and UV-C irradiation during grape berry development.