Effects Of Different Elicitations On The Biosynthesis Of Stilbene In Grape Berry Skins, Calli And Cell Suspension Cultures

Stilbenes are important secondary metabolites of grapevine and act as phytoalexins in plant defense mechanism against phytopathogens. Grapes and grape products are main sources of polyphenols for human diet. In recent years, much attention has been devoted to stilbenes because of their biological benefits on human health. The aim of the present research was to investigate the effects of different elicitors (i.e., a environmental stress factor, two signal molecules, three poly-or oligosaccharides and three fungal elicitors) on the biosynthesis of stilbene in grape berry skins, calli and cell suspension cultures.Stilbene composition and content was analyzed in the skins of ’Beihong’(Vitis vinifera×V. amurensis),’Beixiang’(V. thunbergii x V. vinifera),’Beizi’(V. thunbergii×V. vinifera) and V. vinifera L. cv. Cabernet Sauvignon berries at different developmental stages. The results show that the biosynthesis of stilbene varied from grape cultivars and berry developmental stages.Vitis vinifera L. cv. Cabernet Sauvignon berries, calli and cell suspension cultures were treated with ultraviolet C (UV-C) irradiation to investigate the effects on the biosynthesis of stilbene. The results showed that stilbene production was significantly enhanced after UV-C irradiation, and the results depended on berry developmental stages and UV-C dosages. The strongest induction of stilbene production occurred at the beginning of verasion, followed by the end of veraison. UV-C irradiation for20min (output10W m-2) was the most efficient for the induction of stilbene production in grape calli and cell suspension cultures. UV-C irradiation significantly enhanced total phenolics and total flavonoids contents, and increased the expression levels of genes involved in stilbene and flavonoid biosynthesis.Vitis vinifera L. cv. Cabernet Sauvignon cell suspension cultures were treated with different concentrations of two signal molecules (methyl jasmonate and salicylic acid) and three poly-or oligosaccharides (chitosan, sodium alginate and oligochitosan) to investigate the time-course influences on the biosynthesis of stilbene. The optimal concentrations of these elicitors for the induction of stilbene production were:methyl jasmonate at100μM, salicylic acid at100μM, chitosan at50mg l-1, sodium alginate at100mg l-1and oligochitosan at100mg l-1. The combined elicitation of UV-C irradiation together with methyl jasmonate, salicylic acid or chitosan, highly enhanced stilbene production in V. vinifera cell cultures, more than each elicitor used alone. Total phenolics and total flavonoids contents significantly increased after treatments. The expression levels of genes involved in stilbene and flavonoid biosynthesis were significantly up-regulated, and the combined elicitations showed a synergistic effect on the expression levels of stilbene synthase. When V. vinifera cell suspension cultures were treated with UV-C irradiation, chitosan, sodium alginate, oligochitosan, or a combination of UV-C irradiation and chitosan, the expression levels and enzyme activities of two pathogenesis-related proteins, chitinase and β-1,3-glucanase significantly increased.Vitis vinifera L. cv. Cabernet Sauvignon cell suspension cultures were treated with three fungal elicitors (a Saccharomyces cerevisiae elicitor, a Botrytis cinerea mycelium homogenate elicitor and a B. cinerea culture filtrate elicitor) to investigate the effects on the biosynthesis of stilbene. The results showed that fungal elicitors significantly enhanced stilbene production inside the cells and trans-resveratrol accumulation in the culture medium. Total phenolics and total flavonoids production significantly increased after treatments. The expression levels of genes involved in stilbene and flavonoid biosynthesis significantly increased in the presence of fungal elicitors. Moreover, fungal elicitors significantly induced the expression levels of seven pathogenesis-related genes and the enzyme activities of chitinase and β-1,3-glucanase.These results suggest that V. vinifera cell suspension cultures responded to different elicitors (environmental stress factor, signal molecule, poly-or oligosaccharide and fungal elicitor) by the accumulation of secondary metabolites such as stilbene and the synthesis of pathogenesis-related proteins.