ROLE OF THE MYCOTOXIN PATULIN IN BLUE MOULD OF APPLES.

Patulin is a mycotoxin produced by a variety of molds but mainly associated to Penicillium expansum, the causal agent of blue mould of pome fruit, particularly apples. Its amount in juices, purees, and baby food is considered a quality parameter, since a number of studies have shown patulin toxicity to humans and animals. However, to date, the role of this mycotoxin in the post-harvest decay of apples remains elusive. In the present investigation a disruption construct was used to alter patulin production in P. expansum. The transformation of a wildtype strain was carried out against the biosynthetic gene 6 methyl-salicylic acid synthase, using hygromycin B resistance as a selectable marker. By the end of sub-cultural and molecular confirmation tests two mutants were selected, namely M5 and M21. In vitro tests showed that the disruption event did not alter the physiological characteristics, such as pigmentation or growth rate, although mutants proved to produce 33-41% less patulin than their wild-type strain. In vivo tests on cv. Golden Delicious apples confirmed that impairment of patulin production in the mutants correlated with a loss of pathogenicity and virulence. In particular, a 33-34% and 47-54% reduction in disease incidence and severity were recorded for M5 and M21, respectively. These findings suggest a possible role for patulin not only as a food contaminant but also in blue mould development on apples.