Peptaibols as naturally-based fungicides against grapevine pathogens

Fungi belonging to the genus Trichoderma are widespread and have been used successfully in protection against many crop pathogens. Among the secondary metabolites secreted against dangerous plant pathogens, Trichoderma species produce peptaibols, a peculiar family of peptides that significantly contribute to their attack arsenal against other microorganisms. Such secondary metabolites are known for their plant-protection properties: they (i) possess antimicrobial activity, (ii) act as stimulants of plant defences and growth (iii) elicit plant production of volatiles to attract natural enemies of herbivorous insects. Moreover, peptides are ecofriendly compounds that can be degraded by enzymes to nontoxic amino acids. We present our progress towards the exploitation of analogs of the peptaibols family as fungicides. These peptides have been screened against Plasmopara viticola and Botrytis cinerea, two of the most important grapevine pathogens in the temperate regions including Italy. We found that treatments with selected peptaibols on grapevine leaves inhibit sporangia production by the downy mildew pathogen P. viticola and decrease the incidence of leaf rot by the grey mould fungus B. cinerea. Experiments are in progress to assay the effectiveness of peptaibols against Colletotrichum gleosporioides and C. acutatum, two of the most dangerous ripe rot fungi in sub-tropical climate including the south regions of Brazil. Additional experiments showed a low level of toxicity against the yeast Saccharomyces cerevisiae. Such compounds can match the demand of environmental safe fungicides and circumvent the unreliable effectiveness of antagonistic microorganisms used as biological control agents in open field.