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Poster: Biology & Disease Mgmt: Bacteriology


Development of green fluorescent protein-expressing Xanthomonas gardneri strains to study tomato infection processes
F. ROTONDO (1) (1) The Ohio State University, U.S.A.

Bacterial leaf spot (BLS) is a serious disease of tomato, causing millions of dollars in losses worldwide. While BLS is associated with several species of Xanthomonas, X. gardneri is the predominant species in Ohio where it causes severe damage to processing and fresh market tomatoes. To improve our understanding of BLS disease development, two green fluorescent protein (GFP)-labeled X. gardneri strains were developed to study colonization in planta. Wild-type X. gardneri strains SM605-2011 and SM775-2012 were isolated from tomatoes produced in Ohio. Each strain was transformed by electroporation utilizing a GFP-expressing kanamycin/tetracycline-resistant plasmid, CGT46339. Overall, transformation efficiency for this system was low, approaching 102 CFU/ug DNA. Two GFP-expressing transformants, SM605-2011gfp and SM775-2012gfp, were evaluated against their wild-type counterparts for growth in vitro. No significant differences were observed based on optical density measurements (Permutation test, p>0.05), and both reached the stationary phase at 1.8 OD600 and 109 CFU/ml. Stability of the GFP marker and virulence of the transformed strains will be determined. These strains will be used to study leaf, fruit and seed infection using confocal microscopy (Leica TCS SP5). The transformed strains will be a powerful tool to visualize infection processes and provide critical information for disease management.