Participation of Xanthomonas citri subsp. citri Type IV pilus in biofilm development

DUNGER, GERMÁN; GUZZO, CRISTIANE; FARAH, C.S.

Campinas

Workshop; Workshop on Recent Advances and Applications in Confocal and Widefield Microscopy; 2014

Laboratório Nacional de Biociências

Xanthomonas citri subsp. citri (Xac) is the causal agent of the citrus canker infecting plants worldwide. The pathogen enters host plant tissues through stomatal openings and wounds and then colonizes the apoplast. The infection is visualized as raised lesions on fruit, foliage and young stems. Bacterial type IV pilus (T4P) are long, flexible surface filaments involved in a variety of important bacterial behaviors, including twitching motility, surface adhesion, pathogenicity, natural transformation, immune escape and biofilm formation. The filament of the T4P is composed of a helical polymer of mostly pilin subunits. Cycles of polymerization, attachment and depolymerization mediate several pilus-dependent phenomena. Xac has a functional T4P. The sequenced Xac genome codes for a large set of genes involved in T4P biogenesis and regulation, including several pilin homologs. We produced a Xac knockout strain in the gene coding for the major pilin subunit (pilA). We analyzed the 3D structure of biofilm on biotic and abiotic surfaces by using confocal microscopy and where we observed critical differences in the biofilm structure among Xac strains.Microscopy analyses were performed for compare patterns of bacterial migration; for this purpose were designed special systems to observe microscopically the bacterial movement. The results of this study improve our understanding of how Xac T4P influences bacterial migration and biofilm.