Characterization of Monilinia spp. populations in south Italy and determination of their sexual behavior

Monilinia species are responsible of brown rot decay of stone and pome-fruits in orchards as well as in postharvest. Monilinia laxa and Monilinia fructigena are common in Europe, while Monilinia fructicola is a quarantine pathogen, included in the EPPO A2 List. In Italy, it was first reported in 2009 in Piemonte (North Italy). The results of a monitoring program on the occurrence of M. fructicola, M. fructigena and M. laxa in South Italy are reported along with a comparative characterization of the three fungal species. Out of the tested 513 isolates from 24 orchards located in South Italy, 388 were identified as M. fructicola, 98 were M. laxa and 10 M. fructigena. A direct PCR assay was set up to identify the Monilinia species on rotted fruits. M. fructicola colonies grew faster and showed an optimum temperature higher than those of the other two species. Responses to different classes of fungicides in a colony growth assay revealed high sensitivity to fludioxonil, tebuconazole and SBI-III fungicides. The three species showed different responses to cyflufenamid and M. fructicola was the species more sensitive to the fungicide. A PCR-based protocol was set up to investigate on the sexual behavior of the three species. All the three species proved heterothallic, and both the MAT1-1 and MAT1-2 idiomorphs were detected in samples of their populations suggesting that sexual process is a potential source of genetic variability in Monilinia species.