Post-harvest grape infection of Botrytis cinerea and its interactions with other moulds under withering conditions to produce noble-rotten grapes

ABSTRACT Aims: to investigate the interactions between Botrytis cinerea and other moulds during grape withering and post-harvest infection to obtain noble-rotten grapes. Methods and Results: Strains of Botrytis cinerea, Penicillium expansum, Penicillium crustosum, Aspergillus niger, Fusarium verticilloides and Alternaria alternata, isolated from naturally withered grapes and identified by molecular tools, were used to infect Garganega and Corvina grapes. Individually sterilized berries were infected by a single inoculation of each strain or a simultaneous inoculation of B. cinerea together with one of each of the other moulds. Withering kinetics, glycerol, gluconic acid, total polyphenols, total anthocyanins and laccase activity greatly varied among each strain and also in respect to untreated berries. Successful noble rot settlement was ascertained by an additional infection assay carried out on non-sterilized berries. Conclusions: The suitability of inducing noble rot infection during grape withering and the improvement of the health of noble-rotten grapes has been demonstrated. Significance and impact of the study: This study provides insights on the effects of mould interactions on withered grape quality. Implementing noble rot induction by post-harvest infection in winery drying fruit rooms to standardize the level of grape botrytization is encouraged.