NDVB PROTEIN GENE IS INVOLVED IN XANTHOMONAS CAMPESTRIS (XC) GLUCAN BIOSYNTHESIS AND PATHOGENICITY

RIGANO, L.A.; TORRES, P.S.; MALAMUD, F.; MARANO, M.R.; CASTAGNARO, A.P.; VOJNOV, A.A

Rosario, Santa Fe, Argentina

Congreso; XLII Reunion Anual, Sociedad Argentina de Investigaciones en Bioquimica y Biologia Molecular; 2006

Xc is a major bacterial pathogen of cruciferous plants worldwide. The ability of Xc to incite disease in plants depends in part of the production of extracellular factors such as degradative enzymes, exopolysacharide, etc. An extracellular molecule also produced by Xc, the cyclic glucans, have been shown to be important for a number of plant-microbe interactions. We have identified a gene involved in cyclic beta glucan biosynthesis of in Xc. The orf YP245226 (identified as NdvB protein, an smaller version of the Sinorhizobium NdvB gene) was disrupted through a cassete in a site directed mutagenesis, and the insertion was confirmed by PCR and Southern blot. The insertional inactivation 1,2 glucan, assayedâof NdvB protein compromised the production of the cyclic by size exclusion cromatography and TLC. The mutant strain shows a significative impairment in the bacterial growth in plant respect to the wild type strain.When the plant was inoculated with the mutant it showed an exacerbated defense response (PR1 transcript accumulation, callose deposition) compared with the wild type inoculated plants. The production of cyclic glucan and pathogenicity were fully restored by complementation of the mutant with the Xc NdvB protein gene. This results suggest an important role of the YP245226 orf in xanthomonas glucan biosynthesis and pathogenicity.