A Xanthomonas campestris pv. campestris virulence factor modulates stomatal movements by preventing ROS elicitation in Arabidopsis thaliana guard cells.

LAILA TOUM; ADRIAN VOJNOV; GUSTAVO GUDESBLAT

Buenos Aires

Simposio; New Phytologist Symposium; 2013

Stomatal closure induced by microbes associated molecular patterns (PMAMs) is one of the mechanisms of the immediate immune response of plants against pathogens. Pathogens have developed mechanisms through which they can evade this first line of defense. We previously described the existence of a compound secreted by Xanthomonas campestris pv. campestris (Xcc) that can interfere with stomatal closure induced by this bacterium in Arabidopsis thaliana (Plant Physiol. 2009: 1017-1027). This molecule also partially abolish abscisic acid (ABA) induced stomatal closure, and its action is dependent on the presence of MAP kinase 3 (MPK3). In order to elucidate its molecular structure, we performed the purification of the virulence factor through a Biogel P2 size exclusion chromatography and HPLC. To shed light on the mechanism of action of this molecule we determined that Xcc virulence prevents stomatal closure induced by flg22, chitosan and MeJA but not by SA, suggesting that this compound could be inhibiting in a specific manner NADPH oxidases D/F. This would be consistent with a SA-induced generation of ROS independent from NADPH oxidases D/F. Our results reveal that this compound interferes with ABA, flg22 and MeJA induced-stomatal closure by preventing ROS elicitation in guard cells.