Isolation and Identification of Bacterial Soft Rot Disease Agent Pectobacterium Isolates on Potato Tubers Delivered for Consumption in Yozgat and Kirsehir Provinces

Pectobacterium spp. are ubiquitous bacterial plant pathogens with a wide host range which cause soft rot disease on the invaded plant tissue. This study aimed to isolate the bacterial soft rot disease agents belonging to Pectobacterium spp. on potato tubers delivered for consumption in the local bazaar, grocery and markets in the Center district of Yozgat province and Kaman district of Kirsehir province of Turkey between 2018 and 2019. Local bazaar, market and grocery stores were surveyed and 168 potato tubers were collected. The humidity cell test was performed to investigate the presence of pectinolytic bacteria in asymptomatic and soft rotted potato tubers. Bacterial isolation from 54 different soft rotted tuber slices was performed on Crystal Violet Pectate (CVP) medium. A total of 42 bacterial isolates, that formed pits on CVP medium, were obtained following isolation. Among these, 27 isolates were observed to have shiny, transparent, irregular, crater-shaped colony morphology on Nutrient Agar (NA) plates. All isolates were gram and oxidase negative, catalase-positive, facultative anaerobe, non-fluorescent morphological characteristics and caused soft rot on potato tuber slices. Following PCR analysis, 19 of 54 symptomatic tuber samples were determined as infected by P. carotovorum subsp. carotovorum (9 isolates), P. atrosepticum (6 isolates) and Pectobacterium spp. (4 isolates). In 8 of 114 asymptomatic tuber samples, P. carotovorum subsp. carotovorum (5 isolates), P. atrosepticum (2 isolates) and P. carotovorum subsp. brasiliense (1 isolate) were determined as responsible agents of latent infections. The presence of Pectobacterium isolates in the stored potato tubers brought for consumption suggests the pathogen can be transferred to different regions. Potato tubers offered for sale for consumption are thought to be an important inoculum source for the transfer of Pectobacterium isolates to disease-free areas.