AHL Signals Induce Rubrifacine Production in a bruI Mutant of Brenneria rubrifaciens

Ali E. McClean, Breck A. Duerkop, E. Peter Greenberg, Daniel A. Kluepfel

Research output: Contribution to journalArticle

2 Scopus citations


Several members of the bacterial genus Brenneria are pathogenic on different tree species. Cell-free extracts from the bacterial phytopathogens Brenneria rubrifaciens, B. salicis, and B. nigrifluens induced production of the red pigment rubrifacine in the B. rubrifaciens bruI insertional mutant Br-212. Analysis of the bruI locus identified an adjacent open reading frame, designated bruR, with homology to luxR. High-performance liquid chromatography and mass spectrometry analysis of ethyl acetate extracts from wild-type B. rubrifaciens and Escherichia coli expressing the bruI gene identified two acyl homoserine lactone (AHL) peaks, N-(3-oxohexanoyl)-homoserine lactone (3OC6HSL) and Nhexanoyl- homoserine lactone (C6HSL). Addition of synthetic 3OC6HSL and C6HSL at 10 μM to the bruI mutant, strain Br-212, induced rubrifacine production and the ability to elicit a hypersensitive reaction (HR) in tobacco leaves. Synthetic C6HSL was less effective at inducing pigment production than 3OC6HSL at 10 μM. The bruI mutant Br-212 did not produce detectable AHLs, indicating that C6HSL and 3OC6HSL are the major AHLs produced by this species. The AHLs N-heptanoyl-DLhomoserine lactone (C7HSL), N-octanoyl-DL-homoserine lactone (C8HSL), and N-(3-oxooctanoyl)-DL-homoserine lactone (3OC8HSL) also induced pigment production in Br-212 and restored its ability to elicit an HR in tobacco, suggesting that cross-talk with other bacterial species may be possible.

Original languageEnglish (US)
Pages (from-to)195-203
Number of pages9
Issue number2
StatePublished - Feb 1 2012


ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

Cite this

McClean, A. E., Duerkop, B. A., Greenberg, E. P., & Kluepfel, D. A. (2012). AHL Signals Induce Rubrifacine Production in a bruI Mutant of Brenneria rubrifaciens. Phytopathology, 102(2), 195-203. https://doi.org/10.1094/PHYTO-04-11-0111