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A current challenge in microbial pathogenesis is to identify biological control agents that may prevent and/or limit host invasion by microbial pathogens.

In the wild, hosts are often infected with several pathogens. However, most of the current studies are conducted under controlled laboratory conditions and consider only the interaction between a single commensal species and a single pathogen. The study of the relationships between the microbial communities of the host (named microbiota) and the procession of microbial species with potential pathogenic behavior (called pathobiota) in a realistic ecological context remains to be explored.

163 natural populations of Arabidopsis thaliana under the magnifying glass

The researchers described for two seasons (autumn and spring) the bacterial communities associated with the roots and leaves of 163 populations of Arabidopsis thaliana located in southwest of France.

The authors detected a negative relationship between microbiota diversity and pathobiota diversity, which is robust between the seasons and the organs of the plant. Thus, the more diversified the microbiota, the less the plant would be attacked by pathogenic bacteria.

It has also been found that in most natural populations, the composition of the microbiota largely difers between autumn and spring. This seasonal variation is much less marked for the pathobiota composition. These results suggest that biomarkers controlling invasion of pathogens can be very dynamic.

Future studies at the interface between molecular biology and ecology should make it possible to identify the molecular mechanisms underlying the control of pathogenic species by the microbiota, thus opening up the way for new alternatives for the prevention and management of diseases in species cultivated in an agro-ecological context.