Growth of bacteria and migration along the root following inoculation 2.4 cm below the crown. (A) Migration of GFP-labeled E. coli O157:H7 (♦), S. enterica serovar Typhimurium SJW1103 (▵), S. enterica serovar Newport (⋄), S. enterica serovar Typhimurium SJW1368 (•), and S. enterica serovar Typhimurium SJW1809 (▴) above the region of inoculation was observed by stereo epifluorescence microscope. Migration distance is the extent of bacterial movement during the elapsed time and is the average of 10 measurements on different plants. (B) Growth of GFP-labeled S. enterica serovar Typhimurium SJW1103, S. enterica serovar Typhimurium SJW1368 and S. enterica serovar Typhimurium SJW1809 in the inoculated region of the root (○, ▪, and □, respectively) and above the inoculated region (▵, •, and ▴, respectively). Bacterial concentrations are averages of six samples. Error bars show standard errors.