Elevated Atmospheric CO sub(2) Alters Microbial Population Structure in a Pasture Ecosystem

An increase in concentration of atmospheric CO sub(2) is one major factor influencing global climate change. Among the consequences of such an increase is the stimulation of plant growth and productivity. Below-ground microbial processes are also likely to be affected indirectly by rising atmospheri...

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Bibliographic Details
Published in:Global change biology 2000-06, Vol.6 (5), p.475-482
Main Authors: Montealegre, C M, Van Kessel, C, Blumenthal, J M, Hur, H, Hartwig, U A, Sadowsky, MJ
Format: Article
Language:English
Subjects:
Rhizobium leguminosarum
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Summary:An increase in concentration of atmospheric CO sub(2) is one major factor influencing global climate change. Among the consequences of such an increase is the stimulation of plant growth and productivity. Below-ground microbial processes are also likely to be affected indirectly by rising atmospheric CO sub(2) levels, through increased root growth and rhizodeposition rates. Because changes in microbial community composition might have an impact on symbiotic interactions with plants, the response of root nodule symbionts to elevated atmospheric CO sub(2) was investigated. In this study we determined the genetic structure of 120 Rhizobium leguminosarum bv. trifolii isolates from white clover plants exposed to ambient (350 mu mol mol super(-1)) or elevated (600 mu mol mol super(-1)) atmospheric CO sub(2) concentrations in the Swiss FACE (Free-Air-Carbon-Dioxide-Enrichment) facility. Polymerase Chain Reaction (PCR) fingerprinting of genomic DNA showed that the isolates from plants grown under elevated CO sub(2) were genetically different from those isolates obtained from plants grown under ambient conditions. Moreover, there was a 17% increase in nodule occupancy under conditions of elevated atmospheric CO sub(2) when strains of R. leguminosarum bv. trifolii isolated from plots exposed to CO sub(2) enrichment were evaluated for their ability to compete for nodulation with those strains isolated from ambient conditions. These results indicate that a shift in the community composition of R. leguminosarum bv. trifolii occurred as a result of an increased atmospheric CO sub(2) concentration, and that elevated atmospheric CO sub(2) affects the competitive ability of root nodule symbionts, most likely leading to a selection of these particular strains to nodulate white clover.
ISSN:1354-1013
DOI:10.1046/j.1365-2486.2000.00326.x