Burkholderia phytofirmans PsJN protects Arabidopsis thaliana against a virulent strain of Pseudomonas syringae DC3000 through additive mechanisms of biocontrol
T. TIMMERMANN (1), G. Armijo (2), R. Donoso (1), A. Seguel (2), L. Holuigue (2), B. Gonzalez (1) (1) Universidad Adolfo Ibanez, Chile; (2) Pontificia Universidad Catolica de Chile, Chile

Improvement of plant resistance to pathogens using plant-growth promoting rhizobacteria (PGPR) is a promising strategy in agriculture. Burkholderia phytofirmans PsJN is a PGPR that induces plant growth and abiotic/biotic stress tolerance. This study analyzed whether strain PsJN induced systemic resistance (ISR) to a virulent strain of Pseudomonas syringae in Arabidopsis, showing that A. thaliana plants previously exposed to strain PsJN, display a reduction in disease severity and pathogen density in leaves compared with non-inoculated plants. After the infection, defense genes related with salicylic acid, jasmonate and ethylene signaling pathways were expressed, faster and stronger, in PsJN-treated plants than in the non-inoculated plants, suggesting that resistance to P. syringae in plants treated with strain PsJN requires these hormone-signaling pathways. Additionally, a B. phytofirmans mutant without flagellum and with lower levels of biofilm production, conferred reduced protection to Arabidopsis against pathogen infection. This suggests that the protection granted to P. syringae, induced by PsJN strain, is not due to the activation of ISR, but also by an alternative mechanism. This study provides the first report of the mechanisms used by the PGPR B. phytofirmans PsJN to protect A. thaliana against a common virulent pathogen. Acknowledgments: CONICYT Ph.D. fellowship, BASAL-CAPES FB-0002-2014 and Millennium Nucleus Center for Plant Systems and Synthetic Biology.

Abstract Number: P9-313
Session Type: Poster