Prevalence of LuxR- and LuxI-type quorum sensing circuits in members of the Populus deltoides microbiome

Journal Article · Tue Jan 01 04:00:00 EST 2013 · Applied and Environmental Microbiology

DOI:https://doi.org/10.1128/AEM.01417-13· OSTI ID:1090552

Schaefer, Amy L ^[1]; Lappala, Colin ^[1]; Morlen, Ryan ^[1]; Pelletier, Dale A ^[2]; Lu, Tse-Yuan ^[2]; Lankford, Patricia K ^[2]; Harwood, Caroline S ^[1]; Greenberg, E. Peter ^[1]

---

1. University of Washington, Seattle
2. ORNL

We are interested in the root microbiome of the fast-growing Eastern cottonwood tree, Populus 25 deltoides. There is a large bank of bacterial isolates from P. deltoides and there are 44 draft 26 genomes of bacterial endophyte and rhizosphere isolates. As a first step in efforts to understand 27 the roles of bacterial communication and plant-bacterial signaling in P. deltoides we focused on 28 the prevalence of acyl-homoserine lactone (AHL) quorum sensing signal production and 29 reception in members of the P. deltoides microbiome. We screened 129 bacterial isolates for 30 AHL production using a broad-spectrum bioassay that responds to many but not all AHLs, and 31 we queried the available genome sequences of microbiome isolates for homologs of AHL 32 synthase and receptor genes. AHL signal production was detected in 40% of 129 strains tested. 33 Positive isolates included -, - and -Proteobacteria. Members of the luxI family of AHL 34 synthases were identified in 18 of 39 Proteobacteria genomes including genomes of some 35 isolates that tested negative in the bioassay. Members of the luxR family of transcription factors, 36 that include AHL-responsive factors, were more abundant than luxI homologs. There were 72 in 37 the 39 Proteobacteria genomes. Some of the luxR homologs appear to be members of a 38 subfamily of LuxRs that respond to as yet unknown plant signals rather than bacterial AHLs. 39 Apparently, there is a substantial capacity for AHL cell-to-cell communication in Proteobacteria 40 of the P. deltoides microbiota and there are also Proteobacteria with LuxR homologs of the type 41 hypothesized to respond to plant signals or cues.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1090552
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 18 Vol. 79; ISSN 0099-2240
• Country of Publication: United States
• Language: English