Figure 1: Quantitative assessment of cell-to-cell aggregation and biofilm formation of wild type X. fastidiosa, XfΔpopP and complement XfΔpopP-C. A) The percentages of aggregated cells of X. fastidiosa strains in PD2 broth [63]. B) Quantitative assessment of biofilm formation of all tested X. fastidiosa strains. Averages and standard deviations of three independent experiments are shown for all assessment experiments. Error bars indicate standard deviation. Letters indicate groups assigned by significant difference test (t test, P<0.05).