Quorum sensing in Pseudomonas savastanoi pv. savastanoi and Erwinia toletana: role in virulence and interspecies interactions in the olive knot

Caballo-Ponce, Eloy, Meng, Xianfa, Uzelac, Gordana, Halliday, Nigel, Cámara, Miguel, Licastro, Danilo, Passos da Silva, Daniel, Ramos, Cayo, Venturi, Vittorio and Kivisaar, Maia (2018) Quorum sensing in Pseudomonas savastanoi pv. savastanoi and Erwinia toletana: role in virulence and interspecies interactions in the olive knot. Applied and Environmental Microbiology, 84 (18). ISSN 0099-2240

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The olive-knot disease (Olea europea L.) is caused by the bacterium Pseudomonas savastanoi pv. savastanoi (PSV). PSV in the olive-knot undergoes interspecies interactions with the harmless endophyte Erwina toletana (ET); PSV and ET co-localize and form a stable community resulting in a more aggressive disease. PSV and ET produce the same type of the N-acylhomoserine lactone (AHL) quorum sensing (QS) signal and they share AHLs in planta. In this work we have further studied the AHL QS systems of PSV and ET in order to determine possible molecular mechanism(s) involved in this bacterial inter-species interaction/cooperation. The AHL QS regulons of PSV and ET were determined allowing the identification of several QS-regulated genes. Surprisingly, the PSV QS regulon consisted of only a few loci whereas in ET many putative metabolic genes were regulated by QS among which several involved in carbohydrate metabolism. One of these loci was the aldolase-encoding gene garL, which resulted to be essential for both co-localization of PSV and ET cells inside olive knots as well as knot development. This study further highlighted that pathogens can cooperate with commensal members of the plant microbiome.

SIGNIFICANCE OF THIS STUDY: This is a report on studies of the quorum sensing (QS) systems of olive knot pathogen Pseudomonas savastanoi pv. savastanoi and olive-knot cooperator Erwinia toletana. These two bacterial species form a stable community in the olive knot, share QS signals and cooperate resulting in a more aggressive disease. In this work we further studied the QS systems by determining their regulons as well studying QS-regulated genes which might play a role in this cooperation. This represents a unique in vivo interspecies bacterial virulence model and highlights the importance of bacterial interspecies interaction in disease.

Item Type: Article
Schools/Departments: University of Nottingham, UK > Faculty of Medicine and Health Sciences > School of Life Sciences
Identification Number: https://doi.org/10.1128/AEM.00950-18
Depositing User: Eprints, Support
Date Deposited: 18 Sep 2018 14:56
Last Modified: 13 Jan 2019 04:30
URI: https://eprints.nottingham.ac.uk/id/eprint/55041

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