Schematic model of the regulatory mechanism involving DSF and c‐di‐GMP for the virulence of Xanthomonas campestris pv. campestris. c‐di‐GMP, cyclic diguanosine monophosphate; DSF, diffusible signal factor; GMP, guanosine monophosphate; HK, histidine kinase domain; HPT, histidine transfer domain; IM, inner membrane; Pi, phosphate group; REC, receiver domain.