Polyphasic identification of decay agents of lemon fruits in Serbia

Abstract

Lemon fruits are an important source of vitamin C, potassium, folate, carotenoids, polyphenols, coumarins and terpenes. These lemon compounds have antioxidant and anti-inflammatory properties which have beneficial effects on human health. This research aimed to elucidate the etiology of blue and green molds detected on lemon fruits in Serbia. Using integrative identification approach, the obtained isolates were characterized from morphological, physiological, molecular, phylogenetic and pathological aspects. Colony growth and morphology were examined on Czapek yeast autolysate agar (CYA), Malt extract agar (MEA) and Creatine sucrose agar (CREA), and on CYA at two additional incubation temperatures (5 and 37 °C). For molecular identification, ITS and partial β-tubulin (BenA) genes were sequenced. Phylogenetic relationships were investigated using maximum-likelihood method. A pathogenicity test was carried out and the possible difference in pathogenicity among isolates was assessed with analysis of variance (ANOVA) and subsequent Tukey’s test. Four species were identified: Penicillium expansum, Penicillium digitatum, Penicillium polonicum and Talaromyces rugulosus. All four species proved to be pathogenic on lemon fruits, producing symptoms similar to those observed on naturally infected fruits. The results of this study are the first records of the beforementioned Penicillium/ Talaromyces species as postharvest pathogens on lemon fruits in Serbia and the first world report of T. rugulosus as phytopathogenic on the same host.

Keywords

• citrus limon
• morphological analysis
• molecular characterization
• multilocus phylogeny
• pathogenicity
• penicillium
• talaromyces