Grass Rhizosheaths: Associated Bacterial Communities and Potential for Nitrogen Fixation

Rhizosheaths are structures composed of mucilage secreted from plants and adherent soil particles that form a cylinder around the root. Using scanning electron microscopy (SEM), we observed bacteria associated with rhizosheaths of the grasses Achnatherum hymenoides, Calamovilfa longifolia, Hesperost...

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Bibliographic Details
Published in:Western North American naturalist 2009-04, Vol.69 (1), p.105-114
Main Authors: Bergmann, David, Zehfus, Mike, Zierer, Linda, Smith, Brian, Gabel, Mark
Format: Article
Language:English
Subjects:
Alkynes
Bacteria
Bacteriology
Calamovilfa longifolia
Grasses
Grassland soils
Lotus
nifH
Nitrogen
Nitrogen fixation
Plant growth
Plants
Poaceae
Polymerase chain reaction
rhizosheath
Soil bacteria
Soil microorganisms
Soil samples
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Summary:Rhizosheaths are structures composed of mucilage secreted from plants and adherent soil particles that form a cylinder around the root. Using scanning electron microscopy (SEM), we observed bacteria associated with rhizosheaths of the grasses Achnatherum hymenoides, Calamovilfa longifolia, Hesperostipa comata, and Pascopyrum smithii from a sand dune area in Harding County in northwestern South Dakota. The greatest numbers of bacteria, observed with SEM (529 mm-2), and the greatest number of culturable bacteria (9.9 × 107 CFU · g-1 or 5178 CFU · mm-2) were on rhizosheaths of C. longifolia. Rhizosheaths of all the grasses examined contained a higher density of bacteria than the surrounding soil. Nitrogen fixation, as assayed by reduction of acetylene to ethylene, was present in some rhizosheaths. Bacterial nifH gene sequences amplified from bacteria associated with rhizosheaths were most similar to those from Alcaligenes latus and Mesorhizobium loti.
ISSN:1527-0904
1944-8341
DOI:10.3398/064.069.0102