PUTRESCINE PARTICIPATES IN PLANT DEFENSE IN ARABIDOPSIS THALIANA BY REGULATING CELL DEATH AND THE OXIDATIVE BURST

GARRIZ A.; BACH-PAGES M.; SOLMI L.; ROMERO F.M.; RUIZ O.A.; PRESTON G.; ROSSI F.

SALTA

Congreso; Joint LV Annual SAIB Meeting-XIV PABMB Congress; 2019

SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUÍMICAS

Polyamines are a group of compounds with multiple physiological roles in all organisms. In plants, the metabolism of polyamines is altered upon pathogen invasion, which generally leads to an increment in its concentration and results in the activation of different defence mechanisms. In this trend, we previously showed that infection of Arabidopsis with virulent Pseudomonas syringae (Pst) provokes a marked increase in the concentration of the polyamine putrescine (Put) in the apoplastic space, which is explained mainly by the upregulation of its biosynthesis and the remobilization from the intracellular compartments. In the present work, we assessed the functions played by this polyamine in plant immunity. Interestingly, a mutant plant line with reduced levels of Put showed increased cell death upon infection and showed a higher susceptibility to virulent and non-virulent strains of Pst compared to wild-type plants, suggesting that the accumulation of Put is required for plant tolerance. Interestingly, a deeper exploration of the mechanistic role played by Put demonstrated that this polyamine inhibits the calcium influx and the oxidative burst mediated by NADPH oxidases that is induced during plant defence activation. On the other hand, we also demonstrated that Arabidopsis plants infected with non-virulent strains of Pst show higher Put accumulation compared to those infected by virulent strains, which is directly correlated with the induction of plant cell death. These results suggest that a fine-tuned spatio-temporal regulation of the metabolism of Put modulates different processes associated to the defence against pathogens in plants