The structure of the culturable root bacterial endophyte community of Nicotiana attenuata is organized by soil composition and host plant ethylene production and perception

New Phytol. 2010 Jan;185(2):554-67. doi: 10.1111/j.1469-8137.2009.03079.x. Epub 2009 Nov 10.

Abstract

*A plant's bacterial endophyte community is thought to be recruited from the rhizosphere, but how this recruitment is influenced by the plant's phytohormone signaling is unknown. Ethylene regulates plant-microbe interactions; here, we assess the role of ethylene in the recruitment of culturable endophytic bacteria from native soils. *We grew wild-type Nicotiana attenuata plants and isogenic transformed plants deficient in ethylene biosynthesis (ir-aco1) or perception (35S-etr1) in four native soils and quantified the extent of culturable bacterial endophyte colonization (by plate counting) and diversity (by amplified rDNA restriction analysis and 16S rDNA sequencing). *The endophyte community composition was influenced by soil type and ethylene signaling. Plants grown in organic (vs mineral) soils harbored a more diverse community and plants impaired in ethylene homeostasis harbored a less diverse community than wild-type plants. Wild-type and ethylene signaling-impaired plants fostered distinct bacteria in addition to common ones. In vitro re-colonization by common and genotype-specific isolates demonstrated the specificity of some associations and the susceptibility of 35S-etr1 seedlings to all tested bacterial isolates, suggesting an active process of colonization driven by plant- and microbe-specific genes. *We propose that soil composition and ethylene homeostasis play central roles in structuring the bacterial endophyte community in N. attenuata roots.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / genetics*
  • Biodiversity*
  • Colony Count, Microbial
  • DNA, Bacterial
  • DNA, Ribosomal
  • Ecosystem
  • Ethylenes / biosynthesis*
  • Genotype
  • Mycorrhizae* / genetics
  • Mycorrhizae* / metabolism
  • Nicotiana / genetics
  • Nicotiana / metabolism
  • Nicotiana / microbiology*
  • Plant Growth Regulators
  • Plant Roots / metabolism
  • Plant Roots / microbiology*
  • Plants, Genetically Modified
  • RNA, Ribosomal, 16S
  • Seedlings / physiology
  • Signal Transduction
  • Soil / analysis*

Substances

  • DNA, Bacterial
  • DNA, Ribosomal
  • Ethylenes
  • Plant Growth Regulators
  • RNA, Ribosomal, 16S
  • Soil
  • ethylene