title: Rhizosphere bacteria affected by transgenic potatoes with antibacterial activities compared with the effects of soil, wild-type potatoes, vegetation stage and pathogen exposure.
abstract: A greenhouse experiment was performed to analyze a potential effect of genetically modified potatoes expressing antibacterial compounds (attacin/cecropin, T4 lysozyme) and their nearly isogenic, nontransformed parental wild types on rhizosphere bacterial communities. To compare plant transformation-related variations with commonly accepted impacts caused by altered environmental conditions, potatoes were cultivated under different environmental conditions, for example using contrasting soil types. Further, plants were challenged with the blackleg pathogen Erwinia carotovora ssp. atroseptica. Rhizosphere soil samples were obtained at the stem elongation and early flowering stages. The activities of various extracellular rhizosphere enzymes involved in the C-, P- and N-nutrient cycles were determined as the rates of fluorescence of enzymatically hydrolyzed substrates containing the highly fluorescent compounds 4-methylumbelliferone or 7-amino-4-methyl coumarin. The structural diversity of the bacterial communities was assessed by 16S rRNA-based terminal restriction fragment length polymorphism analysis, and 16S rRNA gene clone libraries were established for the flowering conventional and T4 lysozyme-expressing Desirée lines grown on the chernozem soil, each line treated with and without E. carotovora ssp. atroseptica. Both genetic transformation events induced a differentiation in the activity rates and structures of associated bacterial communities. In general, T4 lysozyme had a stronger effect than attacin/cecropin. In comparison with the other factors, the impact of the genetic modification was only transient and minor, or comparable to the dominant variations caused by soil type, plant genotype, vegetation stage and pathogen exposure.
authors.affiliation: Department of Bioresources, ARC Seibersdorf Research GmbH, Seibersdorf, Austria.
authors.forename: Frank
authors.initials: F
authors.lastname: Rasche
authors.forename: Verania
authors.initials: V
authors.lastname: Hödl
authors.forename: Christian
authors.initials: C
authors.lastname: Poll
authors.forename: Ellen
authors.initials: E
authors.lastname: Kandeler
authors.forename: Martin H
authors.initials: MH
authors.lastname: Gerzabek
authors.forename: Jan D
authors.initials: JD
authors.lastname: van Elsas
authors.forename: Angela
authors.initials: A
authors.lastname: Sessitsch
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D003001:Cloning, Molecular; D004798:Enzymes / Q000378:metabolism; D015723:Gene Library; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D009113:Muramidase / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology; D012150:Polymorphism, Restriction Fragment Length; D012335:RNA, Ribosomal / Q000032:analysis; D017423:Sequence Analysis, RNA; D012988:Soil Microbiology; D011198:Solanum tuberosum / Q000235:genetics* / Q000382:microbiology / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D004798:Enzymes; D019476:Insect Proteins; D012335:RNA, Ribosomal; C039711:attacin antibacterial protein, insect; C031162:cecropin B protein, Insecta; D009113:Muramidase