ENVIRONMENTALLY SUSTAINABLE TOOLS FOR GRAPEVINE PROTECTION AGAINST FUNGAL AND OOMYCETES DISEASES Activity of peptaibol analogs and a grape chitinase against the grape pathogens B. cinerea and P. viticola

Grapevine productions is worldwide affected by fungal pathogens both in the field and during post-harvest storage. In addition to yield losses, even the quality of grape and wine is affected. The management of these pathogens mainly relies on chemicals and agronomical practices. The majority of the plant protection products (PPPs) distributed in the vineyard are directed to control Botrytis cinerea and Plasmopara viticola, causal agents of gray mold and downy mildew disease, respectively. However, pathogens can develop resistance to synthetic fungicides. Moreover, the high use of PPPs poses serious risks to the environment and the health of operators and consumers. In this regard, European Union (UE) policies foresee a 50% reduction in the use of chemical pesticides by 2030 and the implementation of integrated approaches for crop protection. The research studies presented in this thesis share the final purpose to find out new alternative strategies and molecules to counteract grapevine pathogens. To this aim, a deep knowledge of the pathogenic mechanism is fundamental. Therefore, in the first part of the thesis the interaction between B. cinerea and grapevine was investigated by characterizing the ability of this fungus to detoxify plant defense proteins. During ripening, grape berries accumulate a class IV chitinase, a pathogenesis related (PR) protein with antifungal activity. However, the protease activity of B. cinerea is able to cleave this chitinase impairing its antifungal activity. This research could represent a first step into the identification of new fungal virulence factors to be counteracted. The second part of the thesis focused on the development of new biopesticides active against P. viticola and B. cinerea. The effectiveness of several water-soluble analogs produced by targeted amino acid substitutions of an antimicrobial peptide (peptaibol) naturally produced by Trichoderma longibrachiatum, was evaluated against the two pathogens. The assays allowed to identify a peptide highly effective against both pathogens that may be developed as biopesticide.