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Outer membrane protein OmpA is required for disease symptom development and colonization of sugarcane by Xanthomonas albilineans

Fleites L., Rott P., Zhang S., Gabriel D.W.. 2012. Phytopathology, 102 (7) : S4.39. 2012 APS Annual Meeting, 2012-08-04/2012-08-08, Providence (Etats-Unis).

DOI: 10.1094/PHYTO-102-7-S4.1

Xanthomonas albilineans (Xa) is a systemic, xylem-invading pathogen that causes sugarcane leaf scald. Xa produces albicidin, the only known pathogenicity factor in Xa. To identify additional pathogenicity factors, 1,216 independent Tn5 insertions in Xa strain XaFL07-1 were screened for reduced pathogenic symptoms and reduced capacity to multiply in stalks of cultivar CP80-1743. Five (8.2%) independent insertions with reduced symptoms and capacity to multiply in stalks were found in XaompA1 (XALc_0557), predicted to encode an OmpA family outer membrane protein. One mutant, M768, was able to consistently colonize stalk tissue but at severely reduced levels. Additional studies showed that all 5 mutants 1) produced albicidin, 2) were less motile (except M768), 3) were unable to grow in the presence of SDS (except M768), and 4) were slower growing than the wild type in vitro. Complementation was confirmed by two constructs; one carrying only the OmpA domain of XALc_0557, which provided partial complementation and the other carrying the entire XaompA1 gene, which provided full complementation. This work shows that ompA is required for disease symptom development and colonization of sugarcane by Xa.

Mots-clés : xanthomonas albilineans; protéine microbienne; toxine bactérienne; saccharum officinarum; albicidine

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