Penicillium expansum as a postharvest pathogen of tomato fruit in Serbia

Abstract

Tomato (Solanum lycopersicum, L.) is one of the most widely cultivated crops with high content of vitamins and antioxidant lycopene, which are very important for human health. During the growing season and postharvest storage tomato is susceptible to various diseases caused by pathogenic fungi. In July 2019, tomato (cv. Balkan) with symptoms of blue mold decay were collected from market in Belgrade, Serbia. Macroscopic morphology of three obtained monosporic isolates were observed after growth on Czapek yeast autolysate agar (CYA), creatine sucrose agar (CREA), and malt extract agar (MEA) for seven days at 25ºC. Also, selected isolates were incubated at 5, 25, and 37°C for one week on CYA to monitor the effect of different temperature incubation conditions. Colony characteristics and micromorphology of the fungi agreed with the literature descriptions of Penicillium expansum. The conidiophores of isolates were hyaline, mainly terverticillate; stipes usually smooth-walled; metulae and phialides cylindrical; conidia ellipsoidal (3-3,86-4 × 3-3,13-4 μm), greenish, smooth-walled. Total DNA was extracted using DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and partial β-tubulin (BenA) sequence was amplified with primers Bt2a/Bt2b. BenA sequence of representative isolate ParP/1 was deposited in NCBI GenBank (Accession No. ON186699). Phylogenetic analysis clustered our isolate with other isolates of P. expansum. Pathogenicity test was conducted on symptomless, detached tomato fruits. All tested isolates caused typical blue mold symptoms on tomato fruits after seven days of incubation. To our knowledge, this is the first report of P. expansum causing postharvest fruit decay on tomato in Serbia.