Ecology of the core microbiome in natural Lotus corniculatus populations

01/12/2018 to 30/11/2021

Understanding the diversity and dynamics of plant-inhabiting microbiota is one of the key challenges in current plant science. From which microbial sources are plants colonized? What are the mechanisms that structure and maintain microbial communities? What explains microbiome variation among plant organs, genotypes and species, as well as between different environments? Recent studies on microbial communities of the model species Arabidopsis thaliana have identified a small subset of ‘hub’ microbes that are strongly interconnected and have large impact on microbiota structure and diversity. They have also shown that such hub species can link host genotype and environmental factors to microbiome diversity. However, our understanding of the origin and stability of the core microbiome, and in particular to what degree it is variable in natural plant populations, is still very limited. To address these gaps in our knowledge, we need to study more different plant species that are widespread and occur across a broad range of natural environments, and we need to study them also in situ. We propose to study the common legume Lotus corniculatus, an important species in Central European grasslands. We will take advantage of the research platform Biodiversity Exploratories where L. corniculatus occurs on a range of different soils and under different land use regimes. The unique metadata available for these populations will allow us to incorporate various ecological factors into our microbial network analyses of L. corniculatus rhizospheres, shoots, flowers and seeds, and thus to disentangle different drivers of natural microbiome variation. A particular focus will be on the two fundamental modes of microbe transmission: vertical transmissiom through seeds, and horizontal transmission through pollinators or other vectors and shared environmental conditions. We will also link our microbiota analyses to host fitness and host genotype effects. Our study will combine extensive field surveys with advanced microbial network analyses, and a series of controlled-environment experiments. It will thus provide a uniquely comprehensive study of plant-inhabiting microbiota in ecological context.