First report of Pectobacterium punjabense causing potato soft rot and blackleg in Serbia

Abstract

Soft rot and blackleg are common diseases of potato (Solanum tuberosum) in Serbia. Opportunistic pectinolytic plant pathogens in the genus Pectobacterium cause soft rot and wilt diseases by cell wall degradation. They cause major economic losses in potato crops worldwide and are among the top 10 plant pathogenic bacteria (Mansfield et al. 2012). Potato plants (‘VR808’) with symptoms of wilting, slow growth, stem blackening, and tuber softening were collected from a commercial field in Zobnatica, Serbia, in July 2019 and analyzed. All symptoms occurred in the same field, and ~5% of plants were symptomatic. Isolation was performed from 10 randomly chosen symptomatic plants and tubers. Plant tissue was surface disinfected, and 1-cm sections from the margins of lesions were macerated in sterile distilled water (SDW) for 25 min and streaked on nutrient agar. After 48 h of incubation at 26C, predominant shiny, cream-colored, round colonies were obtained from all samples. Three representative isolates (MMZKVR1, MMZCVR2, and MMZKVR3) from independent samples were selected randomly for biochemical and pathogenicity tests. Isolates were gram-negative, nonfluorescent facultative anaerobes exhibiting pectinolytic activity on potato tuber slices and hypersensitive response on tobacco leaves. They expressed catalase activity but did not express oxidase or acid phosphatase activity or produce indole.