Antifungal activity of hop extracts and compounds against the wheat pathogen Zymoseptoria tritici

International audienceSearching for alternative methods to conventional pesticides against crop pathogens is a huge challenge. Here, we tested the potential of hop extracts and compounds to be used as biofungicides towards Zymoseptoria tritici, the most frequently-occurring and damaging pathogen on wheat crops. Hop (Humulus lupulus L.) is known for its benefits on human health conferred by its antifungal, antiviral and antibacterial properties. However, this species has never been examined for its ability to biocontrol phytopathogens. Hydro-alcoholic crude extracts from different parts of hop (leaves, stems, rhizomes, and female cones also called hops), as well as hops essential oil, were assessed for their activity against Z. tritici using spotting bioassays on PDA medium. Moreover, the major phenolic compounds purified from the hydro-alcoholic extract of hops following a bioguided fractionation and the three major terpenes of hops essential oil, previously characterized by GC-MS, were also tested using a microdilution method. Furthermore, checkerboard method was used to assess the potential co-action of hops essential oil and the synthetic fungicide bixafen. Dose-response-curves revealed that only the crude extract and the essential oil from hops significantly decreased fungal growth. Among the purified prenylated chalcones and acylphloroglucinol derivatives, only des-methylxanthohumol and co-humulone showed an antifungal activity against Z. tritici with a half-maximal inhibitory concentration of 0.2 and 0.11 g L-1 respectively. The three major terpenes of hops essential oil were not active but an additive to synergistic effect was observed when the essential oil is combined to bixafen. This study provides new insights into the valorization of antimicrobial properties of hop in crop protection