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Poster: Biology & Disease Mgmt: Bacteriology


Bacteriophages: the over-looked component of the phyllosphere of Xanthomonas-diseased plants
D. RITCHIE (1), M. Munster (2), S. Butler (2) (1) North Carolina State University, U.S.A.; (2) North Carolina State University and Plant Disease & Insect Clinic, U.S.A.

Bacteriophages specifically infect and replicate within bacteria. Phages are the most numerous, diverse, and ubiquitous entities on earth, but little is known about their existence in the phytobiome, particularly the phyllosphere. Bacteria in the genus Xanthomonas cause foliar diseases in many plants. Our objective was to determine occurrence of phages on plants infected with Xanthomonas. Foliar samples from diseased Brassica spp., crape myrtle, Corylus sp., Nandina, pepper, poinsettia, Prunus spp., and Verbena were assayed. Diseased tissue was chopped/soaked in 1-3 ml sterile deionized water (SDW). Non-enrichment phage extraction used either filtering (0.22 um) and/or treating with 10% chloroform. Indicator/host bacteria were isolated from the same disease sample or bacteria that were isolated previously from similar samples. Bacteria isolated from samples were identified using Biolog, ITS region, and elicitation of HR in a non-host plant. Bacteria lysed by phages represented 4 Xanthomonas spp. and 5 pathovars (pv). Phage titers greater than 103 pfu/ml extraction SDW were detected representing all 8 plant genera. Plaque morphologies were hazy Xanthomonas-disease microbiota.