Transformation of Xanthomonas axonopodis pv. citri by Electroporation

This study describes the use of electroporation for transforming Xanthomonas axonopodis pv. citri (Xac), the causal agent of citrus (Citrus spp.) canker. It also evaluates the methodology used for this species under different electrical parameters. The bacterium used in the study (Xac 306) was the same strain used for recent complete sequencing of the organism. The use of a plasmid (pUFR047, gentamycin) is reported here to be able to replicate in cells of Xac. Following the preparation and resuspension of competent cells of Xac at a density of ~4 x 10 cfu/ml, in 10% glycerol, and the addition of the replicative plasmid, an electrical pulse was applied to each treatment. Selection of transformants showed a high efficiency of transformation (1.1 x 10 transformants/μg DNA), which indicates an effective, and inverse, combination between electrical resistance (50 Ω) and capacitance (50 μF) for this species, with an electrical field strength of 12.5 kV.cm and 2.7-ms pulse duration. Besides the description of a method for electroporation of Xac 306, this study provides additional information for the use of the technique on studies for production of mutants of this species. Additional key words: citrus canker, mutant, Citrus spp.