| The bacterial wilt of tomato caused by Ralstonia solanacearum is a serious disease which distributes widely in the world. It is very difficult to control the disease for it's soilborne and vascular-harm. Plant endophytic bacteria have some superiority as biocontrol agents to control plant diseases. In this study, the antagonists of R. solanacearum were obtained from inner tomato plant, and the colonization and disease-control function of antagonist were clarified preliminary.1. Total 239 bacterial isolates were obtained from inner roots of heathy tomatos 'Hezuo 903' by the method of trituration and surface-disinfestation. In vitro antagonistic assay with the method of plate spray indicated that 18 strains could inhibit the growth of R. solanacearum Bs0l-05 obviously on PSA media plate. Only 7 of the 18 strains could show the inhibition on NA media plate. The zones of inhibition produced by the strains on plates were different in size and transparency. Strains 01-144, 01-182, 01-188, 01-191-1 and 01-191-2 could produce large and transparent zones of inhibition on both PSA and NA plates.2. Disease-control experiment in greenhouse with the 18 strains were conducted using tomato 'Hezuo903'. Two of them (01-144, 01-182) had good control effects with the values of 40%~50% in two duplicates tests.3. Strain 01-144 was marked with the method of antibiotic resistance. TheV 1 Ispontaneous mutant 01-144 which resistant Stre 200μg· mL-1 and Rif 100μg· mL-1 was obtained with the method of increacing antibiotic concentration step by step. The01-144K maintain the resistance and against Bs01 -05 in vitro or in vivo after 20 transfer of culture on NA or PSA slope. The marked strain 01-144 K could be used in the colonization studies of 01-144.4. Under the same condition of the tomato variety, soil and seedling incubation, the colonization study of 01-144 were carried out. In the course of experimenting,concentration of 01-144 K for dipping seeds was about 2 X 109cfu' mL-1 and for watering roots was about 6 X 108cfu· mL-1. The results as showed:CD The 01 -144 K could not only colonizate but also maitain a considerably populationon tomato roots-surface, inner roots, stems, cotyledon and euphylla tissues after dipping seeds or watering roots with suspension of the strain. So 01-144 had a good ability of colonizating and transferring inner tomato plant. The endophytic of 01-144 was also verified.(D After treated tomato with methods of dipping seeds, watering healthy roots orwounded roots with suspension of 01-144 K , respectively, the population fluctuation of the strain had the same development trend in the roots and stems(first increased then decreased). At the respect of the population density, roots > stems, lower stems >upperstems; for the changing range, roots < stems, lower stems < upper stems. Thecolonization ability of 01-144 was the strongest in inner roots, followed in lower stems and upper stmes. Comparison of the results of watering wounded and unwounded roots treaments, the colonization population of the former was greater than the later only in the early stage. Wounding roots could not be as a good measure to increase the amount of the bacterium inner tomato plant.(3) The experiment of dipping seeds and watering roots twice at the stage later withsuspensition of 01-144K indicated that the amount of 01-144K could increase obviously in roots, lower stems and upper stems after each watering roots treament. Therefore, watering roots could be as a measure to increase the number of 01-144 inner the plant.5. Disease-control experiment with different methods of 01-144 showed that only dipping seeds (concentration about 2 X 10 cfu· mL-1) could express some differendsin effectiveness. The effectiveness could be up to about 40% when watering roots (concentratio...
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