CONICET | Buscador de Institutos y Recursos Humanos

Plant production of reactive oxygen species (ROS) in various cellular compartments is a hallmark of pathogen recognition. Above all, chloroplast-generated ROS are implicated in initiation, propagation and limitation of the spread of the complex responses deployed by plants [1]. The contribution of this organelle to plant immunity is further underscored by the fact that plant immunity networks have been linked to the mechanisms of light perception [2].The role of chloroplast-generated ROS in plant defence is evaluated using transgenic tobacco lines expressing a plastid-targeted flavodoxin, which showed increased tolerance to multiple adverse environmental conditions and lower ROS accumulation in chloroplasts [3]. These plants are employed to study the light requirements for ROS production in chloroplasts during interactions with pathogens.We report herein the phenotypic and biochemical characterization of the interaction between these plants and pathovars of Pseudomonas syringae that display compatible or incompatible interactions; in the presence or absence of light. ROS assessment by fluorescent microscopy and quantification of their reaction products indicate that transgenic plants accumulated fewer ROS and suffered less damage than wild-type siblings only if light was present. We also analysed sugar levels taking into account their role as signal molecules contributing to plant immune defence [4]. The results provide insights into the role of light and ROS on the succession of events that follow pathogen recognition. [1] A. Shapiguzov, J. Vainonen, M. Wrzaczek and J. Kangasjärvi, Front. Plant Sci., 2012, 3, 292. [2] S. Karpinski, H. Gabrys, A. Mateo, B. Karpinska and P.M. Mullineaux, Curr. Op. Plant Biol., 2003, 6, 390. [3] V.B. Tognetti, J.F. Palatnik, M.F. Fillat, M. Melzer, M.R. Hajirezaei, E.M. Valle and N. Carrillo, Plant Cell, 2006, 18, 2035. [4] M.R. Bolouri-Moghaddam and W. Van den Ende, J. Exp Bot., 2012, 63, 3989.