Plant genotype, immunity and soil composition control the rhizosphere microbiome

Tkacz, Andrzej (2013) Plant genotype, immunity and soil composition control the rhizosphere microbiome. Doctoral thesis, University of East Anglia.

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Three model plant and three crop plant species were grown for three generations in sand
and compost. Pots were inoculated with 10 % soil initially, and with 10% of growth medium
from the previous generation in generations 2 and 3, keeping replicates separate for all
three generations. The microbiome community structure of the plant rhizosphere in each
generation was characterised using ARISA DNA fingerprinting and 454 sequencing.
Rhizosphere bacterial and fungal communities are different from those in bulk soil and there
are also differences in the microbial community between different plant species. Plants both
select and suppress specific bacteria and fungi in the rhizosphere microbiome, presumably
via composition of their root exudates. Two out of three most abundant bacteria selected in
the rhizosphere were isolated. These isolates proved to possess plant growth promotion
properties. Plants are able to “farm” the soil in order to enrich it with plant growth
promoting rhizobacteria (PGPR) species. However, in some plant species rhizospheres,
invasions of opportunists and pathogens take place, mimicking events in plant
Other experiments using this multi-replicate system allowed for statistical analysis of the
influence of Arabidopsis and Medicago mutants on the rhizosphere microbiome. Three
groups of Arabidopsis mutants were tested: plants unable to produce aliphatic
glucosinolates, plants impaired in the PAMP-triggered immune response and plants unable
and over-expressed in methyl halides production and one group of Medicago mutants which
are impaired in the mycorrhization ability. All these plant genotypes, except those for
methyl-halide production and one genotype involved in PAMP response, significantly
altered the rhizosphere microbiome.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Users 2259 not found.
Date Deposited: 12 Mar 2014 14:40
Last Modified: 12 Mar 2014 14:40

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