Abstract:
Pseudomonas syringae pv. actinidae (Psa) is the causal agent of kiwifruit canker disease. This pathogen has decimated the kiwifruit industry particularly plantings of kiwifruit of Actinidia chinensis throughout the world. Methods of control are limited to antibiotics and copper-based compounds. The genomes of many Psa isolates have been sequenced. Sequences of two isolates of Psa ICMP18884 and the ICMP 9617 were previously assembled into pseudo molecules and recently new assemblies of ICMP18884 plasmid and chromosome were generated using the Pac-Bio platform. Previous work showed many rearrangements between the genomes of two the circularized genomes and some differences between the Pac-Bio assemblies for Psa ICMP18884were more recently observed. The aim of the project was to develop methods for fingerprinting both plasmid and chromosomal DNA from different Psa isolates. In-gel extraction and digestion of Psa chromosomal DNA was optimized, DNA from this procedure and plasmid DNA could be routinely analyzed using pulse-field gel electrophoresis. Techniques for improving pulse-field results were also developed during this study. Results from this work verified the Pac-Bio assembly for both plasmid and chromosome of Psa ICMP18884. Plasmid DNA from Psa Biovar 2 from Korea was analyzed for the first time. Enzyme digest of the plasmid showed that there were differences between the strains within the biovar. Estimates of the size of the biovar 2 plasmid were made using restriction digests.
