title: Bacterial populations in the rhizosphere of tobacco plants producing the quorum-sensing signals hexanoyl-homoserine lactone and 3-oxo-hexanoyl-homoserine lactone.
abstract: A tobacco line genetically modified to produce two N-acyl homoserine lactones and its non-transformed parental line were grown in non-sterile soil. Microbial populations inhabiting the bulk soil, and those colonizing the root system of the two tobacco lines, were analyzed using cultivation-independent (phospholipid fatty acid and denaturing gradient gel electrophoresis) and cultivation-based assays. The cell density of total cultivable bacteria, fluorescent pseudomonads, sporulated, and thermotolerant bacteria was also determined in a time-course experiment (15 weeks). A possible "rhizosphere effect" related to the development of the plant was seen. However, no dissimilarities in cell population densities or population ratios of the microbial groups were detected in the rhizosphere of the two plant lines. Similarly, bacterial communities that either produced N-acyl homoserine lactone or degraded the signal hexanoyl homoserine lactone were enumerated from the two plant lines. No noticeable differences were evidenced from one plant genotype to the other. Whilst the transgenic plants released detectable amounts of the quorum-sensing signal molecules and efficiently cross-talked with the surrounding microbial populations, the bias generated by these signals in the reported experimental conditions therefore appears to remain weak, if not non-existent.
authors.affiliation: Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, UPR2355, Bâtiment 23, F-91198, Gif-sur-Yvette, France.
authors.forename: Cathy
authors.initials: C
authors.lastname: d'Angelo-Picard
authors.forename: Denis
authors.initials: D
authors.lastname: Faure
authors.forename: Aurélien
authors.initials: A
authors.lastname: Carlier
authors.forename: Stéphane
authors.initials: S
authors.lastname: Uroz
authors.forename: Aurélie
authors.initials: A
authors.lastname: Raffoux
authors.forename: Rupert
authors.initials: R
authors.lastname: Fray
authors.forename: Yves
authors.initials: Y
authors.lastname: Dessaux
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000737:chemistry / Q000235:genetics*; D005838:Genotype; D018517:Plant Roots / Q000382:microbiology; D030821:Plants, Genetically Modified; D011156:Population Density; D012988:Soil Microbiology; D014026:Nicotiana / Q000235:genetics* / Q000382:microbiology*; D015534:Trans-Activators / Q000032:analysis
chemical_list: D015534:Trans-Activators; C088386:homoserine lactone; D015107:4-Butyrolactone