Isolation and Molecular Characterization of the Fire Blight Pathogen, Erwinia amylovora, Isolated from Apple and Pear Orchards in Egypt

摘要

Eleven Erwinia amylovora isolates, the causal agent of the fire blight disease, were isolated from apple orchards adjacent to those of pears showing fire blight disease symptoms. Initial characterization concerning morphological and biochemical traitsrevealed that all isolates were typical to those of E. amylovora. Furthermore, all bacterial isolates showed typical symptoms of the fire blight disease upon infection of unripe pear fruits. Molecular characterization of these isolates via PCR utilizingspecific primers based on a region of plasmid pEA29 and chromosomal DNA a/ws-region was performed. PCR products were positive and represented the expected length 1.1 and 1.6 kb, respectively. Moreover, PCR reactions utilizing the 16S rRNA universal primers were carried out. DNA sequence of PCR products and analysis via blast and Genbank data showed that, the bacterial isolates actually belonging to E. amylovora. Moreover, there are interference between these Erwinia isolates and identified E. amylovorastrains based on constructed phylogenetic analysis. To the best of our knowledge this is the first report of fire blight of apples caused by E. amylovora in Egypt.