CONICET | Buscador de Institutos y Recursos Humanos

Polyamines are low molecular weight aliphatic amines that play an essential role in different cellular processes and in response to abiotic and biotic stimuli. The main polyamines are the diamine putrescine, the triamine spermidine and the tetraamine spermine. It has been shown that polyamine catabolism is important in the plant defense response against pathogens, like hemibiotrophic bacteria of the genus Pseudomonas. Spermidine and spermine are oxidative deaminated by flavin-dependent polyamine oxidases (PAOs) producing hydrogen peroxide. Being the later an important signalling molecule that depending on the site where it is produced differentially modulates the plant response after pathogen recognition. In this work we studied the role of polyamine oxidase-mediated polyamine catabolism in Arabidopsis thaliana in response to Pseudomonas syringae pv. tomato DC3000 (Pst). In particular, we focused on the role of spermine catabolism mediated by AtPAO1. Therefore, a 35S::AtPAO1 overexpression line was generated and its phenotype was analyzed during plant-Pst interaction. In order to evaluate this phenotype, reactive oxygen species content, PAO and respiratory burst oxidase homologue (RBOH) activities were measured in presence or absence of Pst and spermine supplementation. Colony forming units were also estimated. The 35S::AtPAO1 overexpression line was more susceptible to Pst infection than wild type (WT) plants and this phenotype was alleviated with spermine supplementation. Differences among this 35S::AtPAO1 overexpression line, a previously characterized loss-of-function Atpao1 mutant line and WT plants are discussed to elucidated the role of AtPAO1 in plant defense.