Quorum-sensing effects in the antagonistic rhizosphere bacterium Serratia plymuthica HRO-C48.
The rhizosphere-associated bacterium Serratia plymuthica HRO-C48 is not only able to suppress symptoms caused by soil-borne pathogens but is also able to stimulate growth of plants. Detailed knowledge about the underlying mechanisms and regulation are crucial for the application in biocontrol strategies. To analyse the influence of N-acyl homoserine lactone (AHL)-mediated communication on the biocontrol activity, the AHL-degrading lactonase AiiA was heterologously expressed in the strain, resulting in abolished AHL production. The comparative analysis of the wild type and AHL negative mutants led to the identification of new AHL-regulated phenotypes. In the pathosystem Verticillium dahliae-oilseed rape, the essential role of AHL-mediated signaling for disease suppression was demonstrated. In vitro, the regulatory function of AHLs in the synthesis of the plant growth hormone indole-3-acetic acid is shown for the first time. Additionally, swimming motility was found to be negatively AHL regulated. In contrast, production of extracellular hydrolytic enzymes is shown to be positively AHL-regulated. HRO-C48 emits a broad spectrum of volatile organic compounds that are involved in antifungal activity and, interestingly, whose relative abundances are influenced by quorum sensing (QS). This study shows that QS is crucial for biocontrol activity of S. plymuthica and discusses the impact for the application of the strain as a biocontrol agent.
Müller
Henry
H
Department of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
Westendorf
Christian
C
Leitner
Erich
E
Chernin
Leonid
L
Riedel
Kathrin
K
Schmidt
Silvia
S
Eberl
Leo
L
Berg
Gabriele
G
D054742:Acyl-Butyrolactones / Q000378:metabolism*; D000898:Antibiosis; D018441:Biofilms; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D010641:Phenotype; D053038:Quorum Sensing; D012705:Serratia / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D017262:Siderophores / Q000378:metabolism; D012988:Soil Microbiology; D020172:Verticillium / Q000254:growth & development; D055549:Volatile Organic Compounds / Q000378:metabolism
D054742:Acyl-Butyrolactones; D007210:Indoleacetic Acids; D017262:Siderophores; D055549:Volatile Organic Compounds; C030737:indoleacetic acid; D002265:Carboxylic Ester Hydrolases; C432003:N-acyl homoserine lactonase