Visual evidence of horizontal gene transfer between plants and bacteria in the phytosphere of transplastomic tobacco

Alessandra Pontiroli, Aurora Rizzi, Pascal Simonet, Daniele Daffonchio, Timothy M. Vogel, Jean Michel Monier

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Plant surfaces, colonized by numerous and diverse bacterial species, are often considered hot spots for horizontal gene transfer (HGT) between plants and bacteria. Plant DNA released during the degradation of plant tissues can persist and remain biologically active for significant periods of time, suggesting that soil or plant-associated bacteria could be in direct contact with plant DNA. In addition, nutrients released during the decaying process may provide a copiotrophic environment conducive for opportunistic microbial growth. Using Acinetobacter baylyi strain BD413 and transplastomic tobacco plants harboring the aadA gene as models, the objective of this study was to determine whether specific niches could be shown to foster bacterial growth on intact or decaying plant tissues, to develop a competence state, and to possibly acquire exogenous plant DNA by natural transformation. Visualization of HGT in situ was performed using A. baylyi strain BD413 (rbcL-APaadA::gfp) carrying a promoterless aadA::gfp fusion. Both antibiotic resistance and green fluorescence phenotypes were restored in recombinant bacterial cells after homologous recombination with transgenic plant DNA. Opportunistic growth occurred on decaying plant tissues, and a significant proportion of the bacteria developed a competence state. Quantification of transformants clearly supported the idea that the phytosphere constitutes a hot spot for HGT between plants and bacteria. The nondisruptive approach used to visualize transformants in situ provides new insights into environmental factors influencing HGT for plant tissues.

Original languageEnglish (US)
Pages (from-to)3314-3322
Number of pages9
JournalApplied and Environmental Microbiology
Volume75
Issue number10
DOIs
StatePublished - May 1 2009

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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