Structure and function of the bacterial root microbiota in wild and domesticated barley.
Bottom Line: The microbial communities inhabiting the root interior of healthy plants, as well as the rhizosphere, which consists of soil particles firmly attached to roots, engage in symbiotic associations with their host.Host genotype has a small, but significant, effect on the diversity of root-associated bacterial communities, possibly representing a footprint of barley domestication.Strikingly, protein families assigned to these same traits showed evidence of positive selection.
Affiliation: Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany; Division of Plant Sciences, College of Life Sciences, University of Dundee at The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK.Show MeSH
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Mentions: Taxonomic classification of the OTU-representative sequences to phylum level highlighted that Actinobacteria, Bacteroidetes, and Proteobacteria largely dominate the barley rhizosphere and root communities, where 88% and 96% of the pyrosequencing reads, respectively, were assigned to these three phyla. Of note, other members of the soil biota, such as Firmicutes and Chloroflexi, were virtually excluded from the plant-associated assemblages (Figure 1). The enrichment of members of the phylum Bacteroidetes significantly discriminated rhizosphere and root samples from bulk soil samples irrespective of the accession tested (moderated t test, false discovery rate-adjusted [FDR], p value < 0.05; Figure 1) At family level, Comamonadaceae, Flavobacteriaceae, and Rhizobiaceae designated a conserved barley microbiota whose enrichment differentiated the rhizosphere and root communities from bulk soil irrespective of the accessions tested (moderated t test, FDR, p < 0.05; Figure 1). Of note, the enrichment of a fourth family, Oxalobacteraceae, also significantly discriminated between root samples and unplanted soil in wild, landrace, and modern accessions (moderated t test, FDR < 0.05; Figure 1). Taken together, these results highlight a shift in community composition at the barley root-soil interface, which progressively differentiated the rhizosphere and root bacterial assemblages from the surrounding soil biota.
Affiliation: Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany; Division of Plant Sciences, College of Life Sciences, University of Dundee at The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK.