A grapevine by-product extract enriched in oligomerised stilbenes to control downy mildews: focus on its modes of action towards <i>Plasmopara viticola</i>

Abstract

Natural extracts, and particularly plant by-product extracts, can represent an eco-friendly alternative to synthetic pesticides to control crop diseases. We produced an extract from a mix of grapevine trunk and roots that contain a high amount of complex stilbenes (grapevine phytoalexins), especially ε- and r-viniferins. This extract conferred protection to grapevines against Plasmopara viticola (the causal agent of downy mildew) by displaying antimicrobial activities towards zoospore mobility and sporulation and by stimulating plant defences. From the perspective of its application in the field, a formulated preparation of the extract was proposed using polysorbate and sophorolipids. The formulated extract reduced the development of various oomycetes impacting grapevine, potato, tomato and melon in semi-controlled conditions. Thus, such grapevine extract constitutes a promising strategy to protect major cultivated plants against downy mildews.

Antifungal Activities of a Grapevine Byproduct Extract Enriched in Complex Stilbenes and Stilbenes Metabolization by Botrytis cinerea

“…Vineyard co-products, such as canes, trunks, and roots, represent an important biomass that can be used as antifungal products to control plant diseases. From these grapevine perennial organs, extracts enriched in stilbenes, which are antimicrobial molecules, have been produced and reported to inhibit several grapevine pathogens as P. viticola (downy mildew), Erysiphe necator (powdery mildew), and B. cinerea . ,,− , These antifungal extracts were obtained from a particular organ (canes, trunks, or roots), but extracts obtained from a combination of perennial organs aiming to be highly enriched in stilbenes with the strongest inhibitory activity have never been studied previously. In this work, we produced an extract obtained by combining grapevine trunk and roots.…”

“…A mix with 70% trunks and 30% roots (w/w) was prepared to maintain the original ratio of these two organs on a grapevine plant in a vineyard. The extract was obtained as previously described . In brief, 1 g of powdered material was extracted twice by 10 mL of solvent (2 successive extractions, at 100 and 85% of ethyl acetate (100:0 ethyl acetate:water and 85:15 ethyl acetate:water, respectively) at 60 °C during 2 h. After a liquid–liquid extraction, the SE extract (the resulting organic extract) was obtained.…”

“…Stilbenes analysis was performed on an Agilent 1290 LC system series from Agilent Technologies (Santa Clara, CA, USA) as described before. 21 Briefly, samples at 1 mg/mL and calibration standards (pure stilbenes) were solubilized in 50% MeOH and filtrated through a 0.45 μm PTFE membrane before analysis. Stilbenes were separated using a reversedphase Agilent Zorbax SB-C18 (100 mm × 2.1 mm, 1.8 μm) column.…”

“…18−21 Canes, trunks, and roots are grapevine organs particularly rich in stilbenes, especially in their oligomerized forms. 19−21 The efficiency of extracts obtained from these grapevine organs to protect the vines from diseases was reported, 21,22 but few studies have evaluated their antimicrobial effect against the causal agent of the gray mold disease. 23 Trunks and roots constitute an important biomass of byproducts of viticulture activity within France, for instance around 0.4 million tons generated each year through the grubbing up of vines.…”

“…Phenolic compounds and extracts enriched in these molecules are able to reduce B. cinerea development. , Regarding grapevine stilbenes, resveratrol and pterostilbene, two monomers, are toxic to B. cinerea . Oligomerized compounds have been reported to display a strong antimicrobial activity against other major phytopathogens, such as the oomycete Plasmopara viticola and the fungi responsible for trunk diseases. − Canes, trunks, and roots are grapevine organs particularly rich in stilbenes, especially in their oligomerized forms. − The efficiency of extracts obtained from these grapevine organs to protect the vines from diseases was reported, , but few studies have evaluated their antimicrobial effect against the causal agent of the gray mold disease . Trunks and roots constitute an important biomass of byproducts of viticulture activity within France, for instance around 0.4 million tons generated each year through the grubbing up of vines .…”