The effect of indole-3-acetic acid (IAA) treatment on PtoDC3000 virulence-related gene expression in culture. A, Expression of virulence-related genes avrPto, B, hrpL, C, cmaA, D, tvrR, E, hcp1, and F, PSPTO_5415 1.5 h after being transferred from nutrient yeast gycerol (NYG) to hrp/hrc de-repressing media (HDM) or HDM containing 100 μM IAA (HDM+IAA). Expression levels in cells growing in NYG was used as the calibrator of relative expression. The relative expression was calculated using the reference genes rpoD and gyrB. Data from two independent experiments, carried out on different days, were combined, with each datapoint representing the average of six biological replicates and error bars representing the standard error of the mean between biological replicates. Results were analyzed using analysis of variation, followed by a Tukey’s post hoc test. Different letters indicate significant difference between samples with P < 0.05. This experiment was repeated a third time with similar results.