First report of Pectobacterium odoriferum causing bacterial soft rot of cabbage in Serbia

Abstract

In August 2021, symptoms of soft rot appeared on cabbage in Futog (Bačka, Vojvodina) locality known for traditional cabbage cultivation in Serbia. Symptoms appeared in the form of sunken and soft lesions on outer head leaves, while interior tissue was macerated, with cream to black discoloration. A strong, specific odor followed the breakdown of the affected tissue. From the 1 ha field, a total of 5 heads were collected for the isolation of causing pathogen. Margins of healthy and dead tissues were macerated and plated on Crystal Violet Pectate medium. Five creamy-white colonies forming pits in the medium were purified. These bacterial isolates were positive for pectinolytic activity on cabbage heads and potato slices. They were all facultative anaerobic, Gram-negative, catalase-positive, and oxidase-negative; unable to produce diffusible fluorescent pigments. Multilocus sequence typing of cabbage isolates was performed by sequencing of four housekeeping genes (proA, dnaX, icdA, mdh). Based on the nucleotide BLAST (National Center for Biotechnology Information, NCBI) analysis of the sequences of genes icdA and mdh, Serbian cabbage isolates were 100% identical with Pectobacterium carotovorum subsp. odoriferum strain BC S7. Based on the dnaX gene, identity with the same strain was 99.79% and 99.57% based on the proA gene. Serbian cabbage isolates also showed 100% identity with other NCBI deposited P. odoriferum strains CFBP1878 and ATCC 25272 based on the icdA gene, as well as ICMP 11533 based on mdh gene. Therefore, this first report of P. odoriferum indicates a wider range of Pectobacterium spp. recently described in Serbia.