title: Survival of gfp-tagged antagonistic bacteria in the rhizosphere of tomato plants and their effects on the indigenous bacterial community.
abstract: The survival and colonization patterns of Pseudomonas putida PRD16 and Enterobacter cowanii PRF116 in the rhizosphere of greenhouse-grown tomato plants and the effects of their inoculation on the indigenous bacterial community were followed by selective plating, molecular fingerprinting, and confocal laser scanning microscopy (CLSM) over 3 weeks. Both strains, which showed in vitro antagonistic activity against Ralstonia solanacearum, were previously tagged with gfp. Seed and root inoculation were compared. Although plate counts decreased for both gfp-tagged antagonists, PRD16 showed a better survival in the rhizosphere of tomato roots independent of the inoculation method. Analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and CLSM confirmed the decrease in the relative abundance of the inoculant strains. Pronounced differences in the Pseudomonas community patterns for plants inoculated with PRD16 compared to the control were detected 3 weeks after root inoculation, indicating a longer-lasting effect. Analysis by CLSM showed rather heterogeneous colonization patterns for both inoculant strains. In comparison with seed inoculation, root inoculation led to a much better colonization as evidenced by all three methods. The colonization patterns observed by CLSM provide important information on the sampling strategy required for monitoring inoculant strains in the rhizosphere.
authors.affiliation: Institute for Plant Virology, Microbiology and Biosafety, Federal Biological Research Centre for Agriculture and Forestry, Braunschweig, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Götz
authors.forename: Newton C M
authors.initials: NC
authors.lastname: Gomes
authors.forename: Albert
authors.initials: A
authors.lastname: Dratwinski
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Costa
authors.forename: Gabriele
authors.initials: G
authors.lastname: Berg
authors.forename: Raquel
authors.initials: R
authors.lastname: Peixoto
authors.forename: Leda
authors.initials: L
authors.lastname: Mendonça-Hagler
authors.forename: Kornelia
authors.initials: K
authors.lastname: Smalla
mesh_terms: D000898:Antibiosis; D001431:Bacteriological Techniques; D004754:Enterobacter / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000032:analysis; D018551:Solanum lycopersicum / Q000382:microbiology*; D018613:Microscopy, Confocal; D018517:Plant Roots / Q000382:microbiology; D016958:Pseudomonas putida / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D012335:RNA, Ribosomal / Q000032:analysis; D012988:Soil Microbiology
chemical_list: D012335:RNA, Ribosomal; D049452:Green Fluorescent Proteins