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Burkholderia sp are major inhabitants of white lupin cluster roots

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2011
Author Weisskopf Laure Heller Stefanie and Eberl Leo,
Project Dominance of Burkholderia sp. in low pH Environments: from Biogeography to Tolerance Mechanisms
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Original article (peer-reviewed)

Journal Applied and Environmental Microbiology
Volume (Issue) 77(21)
Page(s) 7715 - 7720
Title of proceedings Applied and Environmental Microbiology
DOI 10.1128/AEM.05845-11

Abstract

The formation of cluster roots by plants represents a highly efficient strategy for acquisition of sparingly available phosphate. This particular root type is characterized by a densely branched structure and high exudation of organic acids and protons, which are likely to influence the resident bacterial community. Until now, the identity of the bacterial populations living in cluster roots has not been investigated. We applied cultivation-dependent and cultivation-independent methods to characterize the dominant bacterial genera inhabiting the growing cluster roots of white lupin. We observed a high relative abundance of Burkholderia species (up to 58 % of all isolated strains and 44% of all retrieved 16S rRNA sequences) and a significant enrichment with increasing cluster root age. Most of the sequences retrieved clustered together with known plant- or fungi-associated Burkholderia species, while only one of 98 sequences was affiliated with the Burkholderia cepacia complex. In vitro assays revealed that Burkholderia strains were much more tolerant to low pH than non-Burkholderia strains. Moreover, many strains produced large amounts of siderophores and were able to utilize citrate and oxalate as carbon source. These features seem to represent important traits for the successful colonization and maintenance of Burkholderia species in white lupin cluster roots.
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