Figure 5

Abscisic acid (ABA) promotes swimming of XKK12 WT (pPIP122) via the LuxR solo OryR. (A), Effect of different ABA concentrations on swimming motility of XKK12 WT (pPIP122). Equivalent volumes of the ABA solvent ethanol (EtOH) were added to control (Ctrl) treatments. Data are means ± SE. Different letters indicate statistically significant differences (LSD: n ≥ 9; α = 0.05). (B), Phenotype of XKK12 WT (pPIP122) on swimming plates containing 0 (left) or 50 μM ABA (right). (C), Effect of 50 μM ABA on the swimming of XKK12 WT, oryR ⁻ and the complemented stain oryR ^-+. Data are means ± SE of three independent experiments. Different letters indicate statistically significant differences (Mann-Whitney: n ≥ 18; α = 0.05). (D), Expression of oryR in XKK12 WT (pPIP122) grown in PY broth with or without 50 μM ABA. Data are means ± SE of two technical replicates and two biological replicates. There were no significant differences between control (Ctrl) and ABA treatments. (T-test: n = 4; α = 0.05). (E), oryR gene promoter activity in XKK12 WT harboring the pORYR122 reporter plasmid and grown in PY broth supplemented or not with 50 μM ABA. Data are means ± SE of three replicates from a representative experiment. There were no significant differences between control (Ctrl) and ABA treatments (T-test: n = 3; α = 0.05). Repetition of experiments led to results very similar to those shown. (F), Expression of OryR-regulated flagellar genes in XKK12 WT (pPIP122) grown in PY broth in response to 50 μM ABA. Data are means ± SE of two technical and two biological replicates. There were no significant differences between control (Ctrl) and ABA treatments. (T-test: n = 4; α = 0.05).