Forty-two bacterial isolates were collected from soft-rotted potato tubers originating from four governorates in Egypt. Their phenotypic and genetic characteristics were studied. The phenotypic identification resulted in grouping the studied isolates into five different species and/or genera including Pectobacterium sp., Bacillus sp., Dickeya sp., Pseudomonas sp. (1), and Pseudomonas sp. (2). The molecular identification of the 10 isolates of them were pathogenic to potato tubers and other hosts. More specific identification of the later 10 isolates, using two specific primers for P. carotovorum subsp. carotovorum (Pcc) and the reference strain PccY46 (Acc. No. KP187511.1), revealed that all these isolates had yielded 220–272-bp DNA fragments identical to the 16S rRNA gene of PccY46. Phylogenetic analysis showed sequence similarity ranging from 87 to 98%, which confirmed the genetic variation among the 10 tested strains of Pcc. The isolates were distributed in four major clusters, each subdivided into a few sub-clusters. In another experiment, two different essential oils (peppermint and clove oils) plus a nano-Cu-based fungicide (Tango®), in comparison to the two different antibiotics and the two copper fungicides, were evaluated for their potential management on the three most severe bacterial isolates (Pcc1, Pcc5, and Pcc10). Results of in vivo experiment showed that clove oil was the most effective, where it caused a reduction of disease severity (0.0%) on potato tubers, 4 days post artificial inoculation. |
