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RESEARCH PRODUCT

Artificial selection of root microbiota associated to plant phenotype changes

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International audience; Artificial selection applied at community level is an important, but still growing topic in the field of ecology andexperimental evolution [1-3]. Its recent implementation to microbial communities holds not only appealingpromises in terms of fundamental knowledge about selection itself [3], but also in terms of relevant applicationsto our society, including bioremediation [4] and plant traits enhancement [5]. Here we transposed the conceptof artificial selection of communities to perform experimental evolution of root microbiota inducing relevantphenotypic changes in plants. We grew ten successive generations of four weeks old Brachypodiumdistachyon inoculated with artificially selected root microbiota from the previous generation, corresponding to~3700 plants. Depending on experiment goals, selection was applied based on specific plant phenotypic traitsof interest such as aboveground biomass or leaves color nuances as a proxy of nitrogen content, using anautomated high-throughput plant phenotyping platform. We orientated evolution in different directions byrespectively selecting plants within several lineages displaying the lowest and the highest values for targetedtraits against random selection controls. Root microbiota were characterized during the selection experimentby means of 16S rRNA gene amplicon sequencing. Despite challenges associated with ensuring efficientheredity of selected communities and plant phenotypic changes, results obtained showed rapid response ofplants to artificial root microbiota selection, with significant divergence for targeted traits after few generations.Our results support the fundamental notion that plant phenotypic changes may be rapidly acquired via artificialselection of root microbiota, which could potentially contribute to rethink the way we select for desired plantfunctions.