Efficacy of Stilbenoid-Enriched Vine Root Extracts in Controlling Aspergillus carbonarius Growth and Ochratoxin A Production in Grapes.

With increased mycotoxin contamination, the search for eco-friendly biocontrol strategies has become increasingly important. This study aimed to evaluate the efficiency of stilbenoid-enriched Merlot (Me) and Tannat (Ta) vine root extracts, and their major active molecule, vitisin B (VIT), against Aspergillus carbonarius growth and its ochratoxin A (OTA) production using in vitro liquid and solid, and ex vivo grape-berry assays. In liquid assay, Me and Ta (125 mg/L) and VIT (36 mg/L) significantly inhibited extracellular OTA. Additionally, VIT temporarily reduced both fungal growth and total OTA. Transcriptomics showed that VIT and Me slightly induced OTA biosynthesis genes. In solid and ex vivo assays, doses above 1 g/L decreased OTA production by up to 48% without impacting fungal growth. This lack of correlation suggested a distinct regulatory response to extract-induced stress. Importantly, the fungicide tebuconazole showed method-dependent effects. On in vitro solid medium, it significantly inhibited the fungal growth without affecting OTA yield, whereas in ex vivo berry assays, it significantly inhibited both. Our findings emphasize the potential of stilbenoid-enriched extracts as biocontrol agents targeting OTA production, highlighting the value of multi-assay evaluations. Future studies should elucidate their modes of action and optimize their efficacy.