Pantoea agglomerans N J07 and its GFP tagged strains(NJ07-GFP)were tested under greenhouse condition to explore its rhizocompetence and colonization pattern during control of tomato Ralstonia wilt.The biocontrol efficacy of NJ07-GFP was 78.3%,while that of wild type strain was-71.3%,implicating that wild type N J07 might help the survival or infection into tomato of Ralstonia solanacearum,therefore be deleterious to tomato.Concentration of NJ07-GFP had a sharp reduction during 21 days after inoculation,while R.solanacearum biovar 2 strain B3B in this treatment decreased slightly quicker than that of wild type NJ07 and control groups according to the result of CFU count.DGGE(denaturing gradient gel electrophoresis)profile of 16S rRNA gene fragments amplified from total community DNA indicated that the wild type N J07 dominated in the tomato rhizosphere longer than strain NJ07-GFP.We deduced that GFP labeling destroyed wild type N J07 with the deleterious gene which might have some relationship with bacterial rhizocompetence,and displayed the positive biocontrol efficacy against Ralstonia wilt,probably by resistance inducing.PCR-DGGE analysis also showed that there was no obvious difference of the bacterial community in the rhizosphere among N J07,NJ07-GFP treatments and control group,except for inoculated bacteria themselves.Confocal laser scanning microscopy(CLSM)results showed that NJ07-GFP was found maily onto the surface of tomato root system,and frequently found at the conjunctions of roots,sometimes inside the cells of roots which probably because of the injury.This is the first report to employ Pantoea agglomerans in the biocontrol study of Ralstonia wilt.