| 論文英文摘要 |
Soft rot bacteria of the genera Pectobacterium and Dickeya are important pathogens that cause the soft rot diseases in plants. They can infect a variety of economic crops and cause severe losses. Soft rot bacteria were originally classified to the genus Erwinia. With the progress of molecular taxonomy, their taxonomic status has been revised and new species continue to be discovered. Thus, it is necessary to understand the soft rot bacteria in Taiwan again. Based on 16S rDNA, dnaX, leuS and recA gene sequences, we analyzed the phylogenetic placement 9 strains of the original Erwinia genus and 2 unknown strains of soft rot bacteria of vegetables. Results showed that the original E. carotovora subsp. carotovora strains were classified as P. aroidearum, P. brasiliense, P. colocasium, and Pectobacterium spp. and the original E. chrysanthemi strain was identified as D. fangzhongdai. The unknown strains were P. brasiliense and P. versatile. Almost all tested strains were able to induce soft rot symptoms on potato and onion. Only strains belonging to P. brasiliense did not induce symptoms on onion. There were significant differences among the symptom severities caused by different strains. All tested strains can produce pectolytic enzymes, but only the D. fangzhongdai strain can produce blue pigment. Tested strains were able to grow in nutrient broth adjusted to pH5 to pH10, but not in those adjusted to pH4. There were significant different among the OD600 values of different strains. This study revealed the species diversity of soft rot bacteria causing vegetable diseases in Taiwan. The results will help to understand the current status of bacterial soft rot in Taiwan. |