Abstract

RIGANO, Luciano A. et al. Role of xanthan in biofilm formation during Xanthomonas citri subsp. citri epiphytic life and its relationship to canker development. Rev. ind. agric. Tucumán [online]. 2014, vol.91, n.1, pp.1-9. ISSN 1851-3018.

Almost all phytopathogenic bacteria have an epiphytic life before invading the host plant. These bacteria survive on the surface of the host tissue through biofilm formation. The ability to produce exopolysaccharides is critical for biofilm formation in several phytopathogenic bacteria. In this work, biofilm formation by Xanthomonas citri subsp. citri (bacterium responsible for citrus canker disease), and its relationship to epiphytic survival and canker development on lemon leaves were studied. Through crystal violet staining and confocal laser scanning microscopy analysis, it was observed that X. citri subsp. citri forms biofilm structures on lemon leaves. Furthermore, a X. citri subsp. citri gumB mutant strain, defective in production of exopolysaccharide xanthan, did not form a structured biofilm and showed reduced growth and survival on leaf surfaces, and reduced disease symptoms. These results suggest that biofilm formation has an important role in X. citri subsp. citri epiphytic survival prior to canker development.

Keywords : Citrus limon; Exopolysaccharides; Citrus canker; Confocal laser scanning microscopy; GumB gene.

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