Endophytic root colonization of gramineous plants by Herbaspirillum frisingense

Michael Rothballer, Barbara Eckert, Michael Schmid, Agnes Fekete, Michael Schloter, Angelika Lehner, Stephan Pollmann, Anton Hartmann

Research output: Contribution to journalArticlepeer-review

70 Scopus citations

Abstract

Herbaspirillum frisingense is a diazotrophic betaproteobacterium isolated from C4-energy plants, for example Miscanthus sinensis. To demonstrate endophytic colonization unequivocally, immunological labeling techniques using monospecific polyclonal antibodies against two H. frisingense strains and green fluorescent protein (GFP)-fluorescence tagging were applied. The polyclonal antibodies enabled specific in situ identification and very detailed localization of H. frisingense isolates Mb11 and GSF30T within roots of Miscanthus x giganteus seedlings. Three days after inoculation, cells were found inside root cortex cells and after 7 days they were colonizing the vascular tissue in the central cylinder. GFP-tagged H. frisingense strains could be detected and localized in uncut root material by confocal laser scanning microscopy and were found as endophytes in cortex cells, intercellular spaces and the central cylinder of barley roots. Concerning the production of potential plant effector molecules, H. frisingense strain GSF30T tested positive for the production of indole-3-acetic acid, while Mb11 was shown to produce N-acylhomoserine lactones, and both strains were able to utilize 1-aminocyclopropane-1-carboxylate (ACC), providing an indication of the activity of an ACC-deaminase. These results clearly present H. frisingense as a true plant endophyte and, although initial greenhouse experiments did not lead to clear plant growth stimulation, demonstrate the potential of this species for beneficial effects on the growth of crop plants.

Original languageEnglish
Pages (from-to)85-95
Number of pages11
JournalFEMS Microbiology Ecology
Volume66
Issue number1
DOIs
StatePublished - Oct 2008
Externally publishedYes

Keywords

  • AHL production
  • Barley
  • Endophytic colonization
  • Herbaspirillum frisingense
  • IAA production
  • Miscanthus

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