Influence of terroir on the fungal assemblages associated to common bean seed

Plants have evolved in association with microbial assemblages, also known as microbiota, which can affect plant growth and health. In contrast with other plant habitats, microbiota associated to seeds have only recently become an object of research. First surveys reveal that seed-associated microbial assemblages are composed of 50 to 1000 bacterial and fungal operational taxonomic units (OTUs) (Barret et al., 2015), including plant pathogens. Common bean (Phaseolus vulgaris L.) is affected by several seed-borne pathogens representing a phytosanitary challenge for common bean seed production. In a participatory research project (Farm Seed Opportunities, a European FP6 project), small scale organic seed producers emitted the hypothesis that seed microbiota in their integrity, including pathogens, play a role in shaping the crop as it adapts to local environments, leading to more resilience (Döring et al., 2014). As a first step to investigating this hypothesis, we analyzed 27 bean seed samples to assess whether the seed microbiota are indeed site-dependant or in contrary transmitted from on plant generation to the next within each cultivar.Plant adaptation and plant health in a context of on-farm breeding of common bean (Phaseolus vulgaris) in European organic farm