Molecular analysis of the role of the bacteriophytochrome protein in the virulence of the plant pathogen Xanthomonas campestris pv. campestris.

FLORENCIA MALAMUD; HERNAN R. BONOMI; LAILA TOUM; ANDRES M TOSCANI; FEDERICO COLUCCIO LESKOW; FERNANDO A GOLDBAUM; ADRIAN A VOJNOV

Angers

Conferencia; 4th Xanthomonas genomics conference, Angers, France; 2012

Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot of crucifers is a phytopathogen of worldwide economic relevance. Light is an important source of information for many different organisms. In plants and other photosynthetic organisms, photoreceptor proteins called phytochromes regulate functions contributing to growth and development. Surprisingly photoreceptors called bacteriophytochromes are also found in non-photosynthetic bacteria (including pathogens), although their role is poorly understood. The Xcc genome encodes one putative bacteriophytochrome (phy). Recent results from our laboratory suggest that light modulates biofilm formation. Furthermore we have established that mutation of phy leads to altered level of xanthan polysaccharide, which is a virulence factor also involved in biofilm formation. Moreover the absence of this protein in Xcc results in an increase of the production of secreted protein, such as amylase. Our results also show that Xccphy is more virulent that wild type strain, this is in part due because the mutant is able to keep the stomata open. On the other hand when we studied the callose synthesis during the infection with this mutant we observed a significant reduction compared with wild type strain.