Assessing short-term responses of prokaryotic communities in bulk and rhizosphere soils to tall fescue endophyte infection

• Published in: Plant and soil 2006-11, Vol.289 (1-2), p.309-320
• Main Authors: Jenkins, Michael B, Franzluebbers, Alan J, Humayoun, Shaheen B
• Format: Article
• Language: English
• Subjects: Agricultural soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Archaea; Bacteria; Biological and medical sciences; bulk soil; Carbon; Carbon sequestration; Clay loam; Clay loam soils; Endophytes; Eubacteria; forage grasses; Fundamental and applied biological sciences. Psychology; Grasses; Infection; loamy sand; Lolium perenne; Microbial activity; Microbiology; Neotyphodium coenophialum; Oligonucleotide probes; Organic carbon; Pasture; Planctomycetes; Proteobacteria; Rhizosphere; Soil; Soil bacteria; Soil density; Soil microorganisms; soil organic carbon; soil organic matter; soil organic nitrogen; Soil samples; Soil treatment; Soil types; Soils; turf grasses
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-006-9141-0

In contrast to endophyte-free (E-) tall fescue, endophyte-infected (E+) tall fescue pastures appear to enhance soil carbon sequestration. A hypothetical mechanism that may account for the enhanced carbon sequestration is that the E+ tall fescue affects the soil microbial community or components of it that are involved in organic carbon turnover. A 60-week mesocosm study with a factorial arrangement of soil type, loamy sand (LS) and clay loam (CL), and E+ and E- tall fescue was conducted to determine if the soil microbial communities were affected by the presence of the endophyte. Bulk and rhizosphere soil samples were fixed in paraformaldehyde, and prepared for total direct microbial counts, and with a combination of one of a domain or subdivision fluorescent oligonucleotide probe for enumerating metabolically active Eubacteria, bacterial subdivisions, and Archaea. E+ tall fescue suppressed the archaeal and high G+C gram-positive bacterial communities of the bulk CL, the delta-proteobacterial community in the rhizosphere CL, and the Planctomycetes community of the rhizosphere LS. In the long-term, suppression of these microbial communities may be a factor in enhanced soil carbon sequestration associated with E+ tall fescue.