The bacteriophytochrome protein increase virulence in Xanthomonas campestris pv. campestris.

FLORENCIA MALAMUD; HERNAN R. BONOMI; LAILA TOUM; GUSTAVO GUDESBLAT; FERNANDO A GOLDBAUM; ADRIAN A VOJNOV; CARLOS L. BALLARÉ

CABA

Congreso; 32nd New Phytologist Symposium section. Plant interactions with other organisms: molecules, ecology and evolution; 2013

Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot of crucifers is a biotrophic-necrotrophic phytopathogen of worldwide economic relevance. In previous work we have shown that although Xcc is a non photosynthetic bacteria, it possesses a functional bacteriophytochrome (phy). Phy mutation leads to altered production of xanthan, the principal exopolysaccharide produced by these bacteria that functions as a virulence factor. Our results also showed that the phy mutant is more virulent in Arabidopsis than the wild-type strain. Preliminary experiments showed that when inoculated on npr1 mutant Arabidopsis plants, the differences in virulence between the Xcc wild-type and phy mutant strains were no longer apparent. Since NPR1 is involved in the majority of the plant defense responses controlled by salicylic acid (SA), or results suggest that the phy mutation increases Xcc virulence by circumventing SA-mediated plant immunity.