Occurrence, identification, and host range of Pectobacterium brasiliense causing soft rot on seed potato tubers in Turkey

摘要

Pectobacterium brasiliense is an important bacterial species that causes soft rot disease in a wide range of host plants including potatoes worldwide. In 2018, seed potato tubers were collected to verify the presence and characterize strains of P. brasiliense in Turkey. Bacterial isolation from soft-rotted seed tubers was performed on a CVP medium, and we found that 18 of 34 strains (55%) belonged to the P. brasiliense species. All of them produced 322 bp products with Br1f/L1r primers in the PCR assay. Partial nucleotide sequences of the housekeeping genes mdh and recA confirmed the result obtained with the species-specific primers. Phylogenetic analysis of the recA gene sequences allowed the strains to be grouped into a cluster divided into two clades distinct from other Pectobacterium species. There was a difference between the tested strains for their ability to macerate potato tubers tissue. Four Turkish P. brasiliense strains were determined to be highly virulent on potato tubers, which caused soft rot symptoms on plants of 17 species of 8 families. Multiple strains also caused soft rot on harvested plant organs (leaves, head, and bulb) and necrosis on sugar beet roots and eggplant fruits, except strain Pbr5, whose pathogenicity was limited. This is the first isolation of P. brasiliense from infected seed potato tubers in Turkey and the first detailed report showing the host range of domestic strains.