Bacterial Strains, Growth Media and Chemicals

The bacterial strains used in this study are listed in Table 1. CV026 is a mini-Tn5 mutant of the wild-type strain that lacks AHL synthase and can only produce violacein when the AHL signal molecules is supplied externally (McClean et al., 1997; Kothari et al., 2017). The E. coli strain pSB401 does not produce AHL and contains a plasmid based on LuxR of Vibrio fischeri and luxI promoter controlling luxCDABE expression (Winson et al., 1998). Transformation of DH5α/expI and SCC3065/expI was performed as described previously (Joshi et al., 2020). All strains were cultivated at 28°C in Luria-Bertani (LB) medium (Difco Laboratories, MI, United States). Strain pSB401 was cultivated at 37°C under continuous shaking at 150 rpm in a TU-400 incubator shaker (MRC, Holon, Israel). For the plant-inoculation assay, Murashige and Skoog minimal medium (MS; Duchefa, Haarlem, the Netherlands) was used. Solvents and chemicals were purchased from Sigma-Aldrich (Sigma-Aldrich), ciprofloxacin was purchased from Acros Organics. Phloretin was dissolved in DMSO to a concentration of 145 mM.

Strains used in this study.