title: Comparative analysis of defence responses induced by the endophytic plant growth-promoting rhizobacterium Burkholderia phytofirmans strain PsJN and the non-host bacterium Pseudomonas syringae pv. pisi in grapevine cell suspensions.
abstract: Plant growth-promoting rhizobacteria (PGPR) are beneficial microorganisms that colonize the rhizosphere of many plant species and confer beneficial effects, such as an increase in plant growth. PGPR are also well known as inducers of systemic resistance to pathogens in plants. However, the molecular mechanisms involved locally after direct perception of these bacteria by plant cells still remain largely unknown. Burkholderia phytofirmans strain PsJN is an endophytic PGPR that colonizes grapevine and protects the plant against the grey mould disease caused by Botrytis cinerea. This report focuses on local defence events induced by B. phytofirmans PsJN after perception by the grapevine cells. It is demonstrated that, after addition to cell suspension cultures, the bacteria were tightly attaching to plant cells in a way similar to the grapevine non-host bacteria Pseudomonas syringae pv. pisi. B. phytofirmans PsJN perception led to a transient and monophasic extracellular alkalinization but no accumulation of reactive oxygen species or cell death were detected. By contrast, challenge with P. syringae pv. pisi induced a sustained and biphasic extracellular alkalinization, a two phases oxidative burst, and a HR-like response. Perception of the PGPR also led to the production of salicylic acid (SA) and the expression of a battery of defence genes that was, however, weaker in intensity compared with defence gene expression triggered by the non-host bacteria. Some defence genes up-regulated after B. phytofirmans PsJN challenge are specifically induced by exogenous treatment with SA or jasmonic acid, suggesting that both signalling pathways are activated by the PGPR in grapevine.
authors.affiliation: Université de Reims Champagne-Ardenne, URVVC-SE-EA 2069, Laboratoire Stress, Défense et Reproduction des Plantes, BP 1039, F-51687 Reims cedex 2, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Bordiec
authors.forename: Sandra
authors.initials: S
authors.lastname: Paquis
authors.forename: Hélène
authors.initials: H
authors.lastname: Lacroix
authors.forename: Sandrine
authors.initials: S
authors.lastname: Dhondt
authors.forename: Essaïd
authors.initials: E
authors.lastname: Ait Barka
authors.forename: Serge
authors.initials: S
authors.lastname: Kauffmann
authors.forename: Philippe
authors.initials: P
authors.lastname: Jeandet
authors.forename: Florence
authors.initials: F
authors.lastname: Mazeyrat-Gourbeyre
authors.forename: Christophe
authors.initials: C
authors.lastname: Clément
authors.forename: Fabienne
authors.initials: F
authors.lastname: Baillieul
authors.forename: Stéphan
authors.initials: S
authors.lastname: Dorey
mesh_terms: D001422:Bacterial Adhesion; D019117:Burkholderia / Q000502:physiology*; D002478:Cells, Cultured; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D018384:Oxidative Stress; D010935:Plant Diseases / Q000382:microbiology; D044224:Pseudomonas syringae / Q000502:physiology*; D058441:Rhizosphere; D012988:Soil Microbiology; D013559:Symbiosis; D027843:Vitis / Q000235:genetics / Q000254:growth & development* / Q000382:microbiology* / Q000502:physiology