PUTRESCINE PARTICIPATES IN PLANT DEFENSE IN Arabidopsis thaliana BY REGULATING CELL DEATH AND THE OXIDATIVE BURST

ANDRÉS GÁRRIZ; MARCEL BACH-PAGÉS; LEANDRO SOLMI; FERNANDO M ROMERO; OSCAR A RUÍZ; GAIL PRESTON; FRANCO R ROSSI

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Polyamines are a group of compounds withmultiple physiological roles in all organisms. In plants, the metabolism of polyaminesis altered upon pathogen invasion, which generally leads to an increment in itsconcentration and results in the activation of different defence mechanisms. Inthis trend, we previously showed that infection of Arabidopsis with virulent Pseudomonassyringae (Pst) provokes a marked increase in the concentration of thepolyamine putrescine (Put) in the apoplastic space, which is explained mainlyby the upregulation of its biosynthesis and the remobilization from theintracellular compartments. In the present work, we assessed the functionsplayed by this polyamine in plant immunity. Interestingly, a mutant plant line withreduced levels of Put showed increased cell death upon infection and showed ahigher susceptibility to virulent and non-virulent strains of Pst compared towild-type plants, suggesting that the accumulation of Put is required for planttolerance. Interestingly, a deeper exploration of the mechanistic role playedby Put demonstrated that this polyamine inhibits the calcium influx and theoxidative burst mediated by NADPH oxidases that is induced during plant defenceactivation. On the other hand, we also demonstrated that Arabidopsis plantsinfected with non-virulent strains of Pst show higher Put accumulation comparedto those infected by virulent strains, which is directly correlated with theinduction of plant cell death. These results suggest that a fine-tunedspatio-temporal regulation of the metabolism of Put modulates different processesassociated to the defence against pathogens in plants.