Poster Session: Disease Control and Pest Management - Regulatory Plant Pathology

322-P

Genome-informed identification of diagnostic sequences in non-pathogenic Pseudomonas syringae.
G. BUSOT (1), M. Arif (1), J. P. Stack (1)
(1) Kansas State Univ, Manhattan, KS, U.S.A.

Specific populations of the kiwi fruit pathogen, P. syringae pathovar actinidiae (Psa), have been identified as quarantine pathogens in some countries. Next-generation sequencing was used to identify Psa-specific DNA sequences with which to develop accurate diagnostic tools. Non-pathogenic plant-associated P. syringae strains may be a potential source of false positives in some sample matrices and with some diagnostic tools. Two commercially available non-pathogenic strains of P. syringae (ESC10 & ESC11) were used to explore genomic differences among pathogenic and nonpathogenic populations of P. syringae and to determine the potential of false positive interference in Psa diagnostics. Genomic DNA was isolated and paired end libraries prepared and sequenced using Illumina MiSeq platform (2X300bp). De novo assembly was performed using MiSeq Reporter. The genome assembly of the two non-pathogenic strains resulted in 6.1 Mb and 5.8 Mb represented by 413 and 562 contigs respectively. Unique and core regions were identified by comparison to published genomes. In one of the non-pathogenic P. syringae strains (ESC11), the pathogenicity island (PAI) reported in P. syringae pv. syringae B728a was absent. In the other non-pathogenic strain (ESC10), the PAI is present but six genes within the island were absent. The potential for false positive diagnostic tests with some nonpathogenic populations of P. syringae may exist.