Is the ability of biocontrol fluorescent pseudomonads to produce the antifungal metabolite 2,4-diacetylphloroglucinol really synonymous with higher plant protection?
The antifungal compound 2,4-diacetylphloroglucinol (Phl) contributes to biocontrol in pseudomonads, but whether or not Phl(+) biocontrol pseudomonads display higher plant-protecting activity than Phl(-) biocontrol pseudomonads remains to be demonstrated. This issue was addressed by assessing 230 biocontrol fluorescent pseudomonads selected from a collection of 3132 bacterial isolates obtained from 63 soils worldwide. One-third of the biocontrol pseudomonads were Phl(+) and almost all Phl(+) isolates also produced hydrogen cyanide (HCN). The only Phl(+) HCN(-) strain did harbor hcn genes, but with the deletion of a 134 bp hcnC fragment corresponding to an ADP-binding motif. Statistical analysis of biocontrol isolate distributions indicated that Phl production ability was associated with superior disease suppression activity in the Pythium-cucumber and Fusarium-tomato pathosystems, but this was also the case with HCN production ability. However, HCN significance was not as strong, as indicated both by the comparison of Phl(-) HCN(+) and Phl(-) HCN(-) strains and by correlation analyses. This is the first population-level demonstration of the higher plant-protecting activity of Phl(+) biocontrol pseudomonads in comparison with Phl(-) biocontrol pseudomonads.
Rezzonico
Fabio
F
Phytopathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, CH-8092 Zürich, Switzerland.|SafeCrop Center, c/o Agroscope ACW Changins-Wädenswil, CH-8820 Wädenswil, Switzerland.
Zala
Marcello
M
Phytopathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, CH-8092 Zürich, Switzerland.
Keel
Christoph
C
Phytopathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, CH-8092 Zürich, Switzerland.|Département de Microbiologie Fondamentale, Université de Lausanne, CH-1015 Lausanne, Switzerland.
Duffy
Brion
B
Phytopathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, CH-8092 Zürich, Switzerland.|Agroscope ACW Changins-Wädenswil, CH-8820 Wädenswil, Switzerland.
Moënne-Loccoz
Yvan
Y
Université de Lyon, Lyon, F-69003, France; Université Lyon 1, Lyon, F-69003, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, F-69622, France; IFR 41, Villeurbanne, F-69622, France.
Défago
Geneviève
G
Phytopathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, CH-8092 Zürich, Switzerland.
D000898:Antibiosis; D000935:Antifungal Agents / Q000378:metabolism*; D018553:Cucumis sativus / Q000382:microbiology; D005658:Fungi / Q000254:growth & development*; D005670:Fusarium / Q000254:growth & development; D006856:Hydrogen Cyanide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology; D010696:Phloroglucinol / Q000031:analogs & derivatives / Q000378:metabolism; D018517:Plant Roots / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D011551:Pseudomonas fluorescens / Q000302:isolation & purification* / Q000378:metabolism*; D011775:Pythium / Q000254:growth & development; D012988:Soil Microbiology
D000935:Antifungal Agents; D006856:Hydrogen Cyanide; C059817:2,4-diacetylphloroglucinol; D010696:Phloroglucinol