植物生理学与病理学杂志

Molecular and Biological Identification of Erwinia amylovora Egyptian Isolates Compared with Other German Strains

Shoeib AA, Nader A Ashmawy, Saad M Hammad and Elsayed E. Hafez

Molecular and Biological Identification of Erwinia amylovora Egyptian Isolates Compared with Other German Strains

Thirty one isolates of the enterobacterium Erwinia amylovora the causal agent of the fire blight disease were collected from different locations in Egypt and Germany. The E. amylovora (Ea) isolates were identified by biochemical tests and the obtained results were confirmed by polymerase chain reaction (PCR) using 16S universal primers. The results showed that, all the examined isolates are E. amylovora with different percentage of similarity. The phylogenetic tree constructed based on the DNA nucleotide sequences of the 16S rRNA gene revealed that the Egyptian isolates have specific roots and they are close similar to Italian isolate (AJ746202). Two specific genes Amsb1 and PEA29 plasmid were detected in all the examined isolates and amplicons with 1600 and 1200 bp were observed. Moreover, the pathogenicity for virulence using the immature pear fruits (IPF) test was carried out and results divided the 31 isolates into 3 virulent groups, it was evident that twelve isolates were highly virulent whereas three were moderately virulent and sixteen were weakly virulent. These isolates were also fingerprinted using RAPD-PCR, the constructed phylogenetic tree based on RAPD data divided the isolates into two major clusters; cluster 1 includes all Egyptian isolates whenever cluster 2 includes all German isolates. It can conclude that more specific genes are still need to discover to differentiate between the closely related Erwinia amylovora bacterial isolates.