FIG. 3.

R. solanacearum strain K60 was attracted to plant root exudates. Bacterial number per 0.01 mm² was determined by the agarose plug assay (see the legend to Fig. 2). (A) K60 responded to tomato and rice root exudates. NC, negative control (chemotaxis buffer); PC, positive control (0.1% yeast extract); TRE, tomato root exudates; RRE, rice root exudates. Root exudate concentrations are given as total protein concentrations. (B) Effects of different treatments on the ability of TRE to attract R. solanacearum K60 cells. NC-PrK and TRE-PrK, NC and TRE treated with 10 μg/ml proteinase K at 37°C for 1 h, respectively; TRE-Boiled, TRE boiled for 15 min. Numbers represent the means of three independent assays with two plugs per assay. Error bars represent standard errors of the means.