title: Effects of rhizodeposition of non-transgenic and transplastomic tobaccos on the soil bacterial community.
abstract: The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil bacterial community structure, and their potential to support horizontal gene transfer (HGT) to bacteria have been studied. Soil microcosms were exposed to root-released compounds collected from transplastomic and non-transgenic tobacco cultivars. Cluster analysis of automated ribosomal intergenic spacer analysis (ARISA) profiles of the soil bacterial community after 48 h incubation grouped the transgenic cultivar apart from the non-transgenic, indicating that it had a rhizodeposition pattern different from the parental plants. However, these differences were less than between the two non-transgenic tobacco cultivars studied. NMR characterization of the root-released compounds showed some differences in chemical fingerprinting pattern between the transplastomic and the parental cultivar. However, the effect on bacterial community structure was transient, and tended to disappear after 96 h of incubation. The potential of root-released compounds as a source of transforming DNA for bacteria was investigated by using four potential recipient species. No transformants were obtained following exposure of all the recipients to the root-released compounds. Root-released compounds amended to transgene donor DNA decreased the transformation frequency of Acinetobacter baylyi strain ADP1200, while Azospirillum, Agrobacterium, and Sinorhizobium strains failed to develop competence also in the presence of an external added transgene source. Detection of plastid sequences by PCR suggested that a very low amount of fragmented plastid donor DNA was present in the root-released compounds.
authors.affiliation: Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche (DISTAM), Università degli Studi di Milano, via Celoria 2, 20133, Milano, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Brusetti
authors.forename: Aurora
authors.initials: A
authors.lastname: Rizzi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Abruzzese
authors.forename: Gian Attilio
authors.initials: GA
authors.lastname: Sacchi
authors.forename: Enzio
authors.initials: E
authors.lastname: Ragg
authors.forename: Marco
authors.initials: M
authors.lastname: Bazzicalupo
authors.forename: Claudia
authors.initials: C
authors.lastname: Sorlini
authors.forename: Daniele
authors.initials: D
authors.lastname: Daffonchio
mesh_terms: D001419:Bacteria / Q000235:genetics* / Q000254:growth & development; D002851:Chromatography, High Pressure Liquid; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D022761:Gene Transfer, Horizontal / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012988:Soil Microbiology; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014169:Transformation, Bacterial / Q000235:genetics; D019076:Transgenes / Q000235:genetics
chemical_list: D021903:DNA, Ribosomal Spacer