Study of leaf metabolome modifications induced by UV-C radiations in representative Vitis, Cissus and Cannabis species by LC-MS based metabolomics and antioxidant assays.

UV-C radiation is known to induce metabolic modifications in plants, particularly to secondary metabolite biosynthesis. To assess these modifications from a global and untargeted perspective, the effects of the UV-C radiation of the leaves of three different model plant species, Cissus antarctica Vent. (Vitaceae), Vitis vinifera L. (Vitaceae) and Cannabis sativa L. (Cannabaceae), were evaluated by an LC-HRMS-based metabolomic approach. The approach enabled the detection of significant metabolite modifications in the three species studied. For all species, clear modifications of phenylpropanoid metabolism were detected that led to an increased level of stilbene derivatives. Interestingly, resveratrol and piceid levels were strongly induced by the UV-C treatment of C. antarctica leaves. In contrast, both flavonoids and stilbene polymers were upregulated in UV-C-treated Vitis leaves. In Cannabis, important changes in cinnamic acid amides and stilbene-related compounds were also detected. Overall, our results highlighted phytoalexin induction upon UV-C radiation. To evaluate whether UV-C stress radiation could enhance the biosynthesis of bioactive compounds, the antioxidant activity of extracts from control and UV-C-treated leaves was measured. The results showed increased antioxidant activity in UV-C-treated V. vinifera extracts.

Vitis vinifera canes, a new source of antifungal compounds against Plasmopara viticola, Erysiphe necator, and Botrytis cinerea.

Methanolic and ethanolic crude extracts of Vitis vinifera canes exhibited significant antifungal activity against the three major fungal pathogens affecting grapevines, Plasmopara viticola, Erysiphe necator and Botrytis cinerea. The active extracts were analyzed by LC-PDA-ESI-MS, and selected compounds were identified. Efficient targeted isolation using medium-pressure liquid chromatography afforded six pure constituents in one step. The structures of the isolated compounds were elucidated by NMR and HRMS. Six identified compounds (ampelopsin A, hopeaphenol, trans-resveratrol, ampelopsin H, ε-viniferin, and E-vitisin B) presented antifungal activities against P. viticola. ε-Viniferin also exhibited a low antifungal activity against B. cinerea. None of the identified compounds inhibited the germination of E. necator. The potential to develop a novel natural fungicide against the three major fungal pathogens affecting V. vinifera from viticulture waste material is discussed.