title: Pseudomonas protegens CS1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent.
abstract: Citrus canker is a worldwide-distributed disease caused by Xanthomonas citri subsp. citri. One of the most used strategies to control the disease is centred 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 the opportunistic human pathogen Pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including X. citri subsp. citri. The action mechanism, addressed with the model bacterium Escherichia coli, was connected to the generation of reactive oxygen species (ROS). 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 colonise the lemon phyllosphere and inhibit X. citri subsp. citri was selected and characterised as Pseudomonas protegens CS1. From a liquid culture of this strain, the active compound was purified and identified as the pyochelin enantiomer, enantio-pyochelin. Using the producing strain and the pure compound, both in vitro and in vivo, we determined that the action mechanism of X. citri subsp. citri inhibition also involved the generation of ROS. 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 reduce canker formation makes this strain an interesting candidate as a biocontrol agent.
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Michavila
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: C
authors.initials: C
authors.lastname: Adler
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: P R
authors.initials: PR
authors.lastname: De Gregorio
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lami
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Caram Di Santo
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Zenoff
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: R E
authors.initials: RE
authors.lastname: de Cristobal
authors.affiliation: Facultad de Bioquímica, Química y Farmacia, UNT, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT and Instituto de Química Biológica "Dr. Bernabé Bloj", San Miguel de Tucumán, Argentina.
authors.forename: P A
authors.initials: PA
authors.lastname: Vincent
mesh_terms: D002957:Citrus / Q000382:microbiology*; D010636:Phenols / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D011549:Pseudomonas / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D014974:Xanthomonas / Q000187:drug effects
chemical_list: D010636:Phenols; D017382:Reactive Oxygen Species; D013844:Thiazoles; C025316:pyochelin
keywords: 
  Pseudomonas
  ; Biological control; citrus canker disease; enantio-pyochelin; indigenous; lemon