Medium alkalinization by tobacco BY2 suspension cells upon addition of ultrashort lipopeptides. A 3.1-nmol (A) or a 6.25-nmol (B) sample of lipopeptide P1, P2, or P3 or 5 μl of water (control [C]) was added to 1 ml of cells, and the pH was measured every 5 min. The results shown are averages (± standard deviations) of three independent experiments with six repeats for each time point. A three-way factorial ANOVA of time, concentration, and peptide revealed significance for all three factors. a, significantly different from the control. b, not significantly different from the control.