Over 1000-Fold Synergistic Boost in Viniferin Levels by Elicitation of Vitis vinifera cv. Gamay Red Cell Cultures over Accumulating Phenylalanine

Elicitation treatments of grape cell cultures with methyl jasmonate (MeJA), ultraviolet-C (UV-C) irradiation, and sucrose induce mild production of stilbenes and flavonoids due to limited substrate availability. However, these treatments cause a synergistic boost of stilbenes production when applied to two phenylalanine (Phe)-enriched transgenic grape cell lines, AroG∗ + STS and AroG∗ + FLS. The combined treatment of UV-C elicitation on the Phe-fed AroG∗ + STS line resulted in the highest content of stilbenes (37.8-fold increase, 17.39 mg/g dry weight (DW)) mainly due to resveratrol (64-fold, 3.23 mg/g DW) and viniferin (1343-fold, 13.43 mg/g DW). The synergistic increase following either UV-C or MeJA elicitation was due to the induction of stilbene-related genes, while sucrose treatment had no effect on gene expression levels and served as an additional carbon source for phenylpropanoids. The combined strategy presented may enable future usage of grape cell cultures for the production of stilbenes and in particular viniferin.