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Gewählte Doctoral Thesis:

Katharina Fallmann (2014): Bacterial rhizosphere communities and competitive plant colonization of the heavy metal accumulator plant Salix.
Doctoral Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 150. UB BOKU obvsg

Data Source: ZID Abstracts
Willows (Salix spp.) can accumulate heavy metals from contaminated soils in their shoot tissues. Therefore they are suitable plants for phytoextraction of polluted soils; however, the remediation takes several years or decades. Microbial rhizosphere processes play a role in heavy metal accumulation by plants and are a possible target for acceleration. In this work, the following questions are addressed: Does the rhizosphere bacterial community of Salix plants with different metal accumulation potential vary; and if so, what are the differences? Can bacteria be feasibly screened by mixed plant inoculation for their competitive plant colonization ability, and how reliable are the results? The bacterial rhizosphere community of differently metal accumulating Salix clones was analyzed by 16S rRNA gene amplicon pyrosequencing. The relation with the plants and with cadmium and zinc accumulation was statistically examined. Community diversity and structure were connected to the extent of heavy metal extraction as well as shaped by the Salix clone. Certain bacteria were indicative of S. smithiana. Furthermore, α-Proteobacteria of the genus Bauldia were correlated to high foliar cadmium uptake. Bacterial isolates were screened for competitive colonization ability by mixed strain inoculation of plants and subsequent re-isolation. Thus 14% of the strains were selected. The results were evaluated by single inoculation of the re-isolated strains and colonization assessment, demonstrating that most selected strains successfully colonized the plants under competitive conditions. This work showed that the degree of heavy metal accumulation by Salix is reflected in the bacterial rhizosphere community and identified specific bacteria associated with highly accumulating willows. The tested screening strategy can be considered feasible for the selection of competitive plant colonizing bacteria.

1. Berater: Puschenreiter Markus
2. Berater: Wenzel Walter

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