Pseudomonas protegens CS1 from the lemon phyllosphere inhibits canker formation

MICHAVILA G; ADLER C; DE GREGORIO PR; LAMI MJ; CARAM DI SANTO MC; ZENOFF A; DE CRISTOBAL RE; VINCENT PA

PLANT BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017

1435-8603

Citrus canker is a worldwide-distributed disease caused by Xanthomonas citri subsp. citri. One of the most used strategies to control the disease is centered on copper-based compounds that cause environmental problems. Therefore, it is of interest to develop new strategies to manage the disease. Previously, we reported the ability of the siderophore pyochelin, produced by opportunistic human pathogen Pseudomonas aeruginosa, to inhibit in vitro several bacterial species including X. citri subsp. citri. The action mechanism was addressed with the model bacterium Escherichia coli and defined that was mediated by oxidative stress. This work aimed to find a non-pathogenic strain from the lemon phyllosphere that would produce pyochelin and therefore serve in canker biocontrol. An isolate that retained its capacity to colonize the lemon phyllosphere and inhibit X. citri subsp. citri was selected and characterized as Pseudomonas protegens CS1. From liquid culture of this strain, the active compound was purified and identified as the pyochelin enantiomer, enantio-pyochelin. Using the pure compound and the producing strain, in both in vitro and in vivo studies, we determined that the action mechanism on X. citri subsp. citri inhibition also involved the generation of reactive oxygen species. Finally, the potential application of P. protegens CS1 was evaluated by spraying the bacterium in a model that mimics the natural X. citri subsp. citri infection. The ability of P. protegens CS1 to diminish canker formation turns this strain into an interesting candidate for a biocontrol agent.