General polyamine metabolism is activated in Pseudomonas syringae during plant colonization.

VILAS, JUAN M.; ROSSI, FRANCO R; MARINA, MARÍA; PIECKENSTAIN, FERNANDO L; GÁRRIZ, ANDRÉS

Chascomús

Congreso; XV JORNADAS ANUALES DE LA SOCIEDAD ARGENTINA DE BIOLOGIA; 2013

SAB

Polyamines are important for bacterial virulence and its levels are modulated by the regulation of its biosynthetic as well as catabolic pathways. The aim of this work was to explore the regulation of polyamine metabolism genes in the plant pathogen P. syringae. Our analysis demonstrated the existence of two genes encoding the polyamine biosynthetic enzymes arginine and ornithine decarboxylase. In turn, several genes involved in three catabolic routes were also identified. qRT-PCR studies showed that the catabolism is induced in media with polyamines as the sole nitrogen source, even though this regulation is absent when media are amended with inorganic nitrogen. Further experiments demonstrated that biosynthesis and catabolism are activated after contact with Arabidopsis leaves, suggesting that this regulation might be a key step in plant colonization. Moreover, some of the catabolic genes maintain high expression levels during later stages. Interestingly, growth of bacteria in virulence gene-inducing media provoked only a mild activation of polyamine catabolism, indicating that polyamine metabolism is regulated by a different mechanism than pathogenesis.