UV-B light enhances antimicrobial activity of postharvest lemon peel against Penicillium digitatum

CERIONI, L.; RUIZ V.; ISLA MI; BOUZO C; RAPISARDA V. A; ZAMPINI IC; HILAL M.

Congreso; SAIB 2016; 2016

UV-B radiation treatment previously standardized in our laboratory contributes to prevent green mold on postharvestlemons, caused by Penicillium digitatum. The aim of this workwas to assess in vitro the effect of flavedo extracts from UV-Bexposed lemons (UV-BFEx) and from control lemons (CFEx) onP. digitatum conidia. Several parameters of conidia viabilitywere evaluated after treatments. Moreover, HPLC and HPLCMS/MS analysis of phenolic compounds were carried out on both flavedo extracts. Conidia viability was markedly affected byUV-BFEx in respect to CFEx, in assays using the same concentrations. Conidia treated with UV-BFEx showed an inhibition of germination and oxygen consumption, an increased membrane permeability and ROS and TBARS production. On the other hand, two fractions of the flavedo extracts were detected and isolated by HPLC, due to a stablechromatographic behavior of two peaks in response to the UV-B exposure. The different phenolic composition in those fractions could explain the differential antifungal activities of the extracts. In conclusion, UV-B exposure increases lemon peel natural defenses, by activating the differential synthesis of phenolic compounds and thereby raising the resistance against the phytopathogen