Abstract
Despite the large morphological and physiological changes that plants have undergone through domestication, little is known about their impact on their microbiome. Here we characterized rhizospheric bacterial and fungal communities as well as the abundance of N-cycling microbial guilds across thirty-nine accessions of tetraploid wheat, Triticum turgidum, from four domestication groups ranging from the wild subspecies to the semi dwarf elite cultivars. We identified several microbial phylotypes displaying significant variation in their relative abundance depending on the wheat domestication group with a stronger impact of domestication on fungi. The relative abundance of potential fungal plant pathogens belonging to the Sordariomycetes class decreased in domesticated compared to wild emmer while the opposite was found for members of the Glomeromycetes, which are obligate plant symbionts. The depletion of nitrifiers and of arbuscular mycorrhizal fungi in elite wheat cultivars compared to primitive domesticated forms suggests that the Green Revolution has decreased the coupling between plant and rhizosphere microbes that are potentially important for plant nutrient availability. Both plant diameter and fine root percentage exhibited the highest number of associations with microbial taxa, highlighting their putative role in shaping the rhizosphere microbiota during domestication. Aside from domestication, significant variation of bacterial and fungal community composition was found among accessions within each domestication group. In particular, the relative abundances of Ophiostomataceae and of Rhizobiales were strongly dependent on the host accession, with heritability estimates of ~ 27% and ~ 25%, indicating that there might be room for genetic improvement via introgression of ancestral plant rhizosphere-beneficial microbe associations.
Highlights
Despite the large morphological and physiological changes that plants have undergone through domestication, little is known about their impact on their microbiome
In a more comprehensive study based on 33 sunflower genotypes that varied in their extent of domestication, Leff et al demonstrated that domestication affected only rhizosphere and seed associated fungal communities and neither root nor rhizosphere bacterial c ommunities[23]
We characterized the rhizosphere microbiota of 39 selected accessions, homogeneously divided in four representative accession subsets corresponding to four main steps of the evolutionary history of Triticum turgidum i.e. wild, first domesticated, free threshing landraces and post Green Revolution elite lines respectively
Summary
Despite the large morphological and physiological changes that plants have undergone through domestication, little is known about their impact on their microbiome. The depletion of nitrifiers and of arbuscular mycorrhizal fungi in elite wheat cultivars compared to primitive domesticated forms suggests that the Green Revolution has decreased the coupling between plant and rhizosphere microbes that are potentially important for plant nutrient availability. Both plant diameter and fine root percentage exhibited the highest number of associations with microbial taxa, highlighting their putative role in shaping the rhizosphere microbiota during domestication. We characterized the rhizosphere microbiota of 39 selected accessions, homogeneously divided in four representative accession subsets corresponding to four main steps of the evolutionary history of Triticum turgidum i.e. wild, first domesticated, free threshing landraces and post Green Revolution elite lines respectively. We hypothesized that wheat domestication, by modifying key crop traits, might have weakened the association between wheat and its rhizosphere microbiota, and led to significant changes in rhizosphere bacterial and fungal communities
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