Fig. 5.
A lipopeptide-associated quorum-sensing in divergent Pseudomonas spp. a Gene tree showing the phylogenetic relationship of the six acyl-homoserine lactone (AHL) synthase homology groups identified by PyParanoid. Light gray squares indicate the absence of a gene and dark gray or purple squares show the presence of a gene. Group 22008 contains the LuxILPQ protein sequence from N2C3 as well as protein sequences from other LPQ+ strains (PdfI, PcoI, and PmeI) [41, 42, 45]. b Correlation coefficients between each AHL synthase homology group and the 14 other LPQ island homology groups across the entire Pseudomonas clade showing that the presence of LuxILPQ is correlated with the capacity for lipopeptide biosynthesis across the entire Pseudomonas genus. c Fresh weight of seedlings inoculated with 10 mM MgSO4, wild-type N2C3, wild-type DF41, the AHL synthase deletion mutant N2C3∆luxILPQ alone or co-inoculated with DF41, and the AHL-binding transcriptional regulator mutant N2C3∆luxRLPQ alone or co-inoculated with DF41. Lowercase letters indicate statistically significant (p < 0.01, 23 > n > 12) differences as determined by a two-sided unpaired Student’s T-test. Data shown are from one of two independent experiments performed with similar results. Boxplots are quartile plots of the observed data. d Species tree based on 217 housekeeping genes showing the distribution of six AHL synthase homology groups identified using PyParanoid. All strains with an asterisk were tested in a visual screen for induction of pigment production in the C. violaceum CV026 AHL biosensor strain, but only strains in the bcm clade with the LPQ island resulted in visible pigment production. Within the bcm clade, purple and brown taxon names show strains that were confirmed to induce or have no effect, respectively, on violacein production in a quantitative assay. e Barplot showing quantitative violacein production by C. violaceum CV026 by specified strains in the bcm clade. Data are the average of three biological replicates and error bars indicate the standard deviation (n = 3). Violacein production was normalized to total bacterial growth by calculating the ratio of OD585/OD764