Genetic identification, pathogenicity and patulin production of Penicillium species from apple blue mold in China

Abstract Objectives Blue mold is a common postharvest disease that leads to severe rot and patulin (PAT) contamination in fruits, which is a key factor endangering the storage and quality of apple products. However, the Penicillium species from apple blue mold in China and their pathogenicity and PAT production ability have not been well studied. Materials and Methods In this study, 62 strains of pathogenic Penicillium species were isolated from blue mold apples collected from different regions of China. The ITS, BenA, and CaM genes were sequenced for molecular identification. Results Penicillium strains were identified as three species, 57 P. expansum, 3 P. crustosum, and 2 P. polonicum. Twelve variants of the ITS sequence, 61 variants of BenA and 67 variants of CiaM genes were identified between Penicillium species. Fungal morphology was observed on potato dextrose agar (PDA). After 10 d of cultivation, P. expansum cultures were detected with PAT concentrations ranging from 457.98 to 1333.85 mg/kg, and two P. polonicum strains were 6.02 mg/kg and 6.30 mg/kg. The three P. crustosum strains could not produce PAT on PDA. In apple inoculation, P. expansum strains showed significantly faster infection rates than P. crustosum and P. polonicum strains. All P. expansum strains can produce PAT during infection, and the concentrations in the rot apple tissues were 2.31–88.67 mg/kg. The P. crustosum and P. polonicum strains could not produce PAT during infection. Conclusions This study provides data and information regarding the morphology, virulence and PAT production of Penicillium pathogens that will improve the understanding of apple blue mold and postharvest disease control.