The effects of host species and sexual dimorphism differ among root, leaf and flower microbiomes of wild strawberries in situ

Abstract

Plant-associated microbiomes profoundly influence host interactions with below- and aboveground environments. Characterizing plant-associated microbiomes in experimental settings have revealed important drivers of microbiota assemblies within host species. However, it remains unclear how important these individual drivers (e.g., organ type, host species, host sexual phenotype) are in structuring the patterns of plant-microbiota association in the wild.\n\nUsing 16s rRNA sequencing, we characterized root, leaf and flower microbiomes in three closely related, sexually polymorphic Fragaria species, in the broadly sympatric portion of their native ranges in Oregon, USA. Taking into account the potential influence of broad-scale abiotic environments, we quantified the relative effects of organ type, host species and sex on the - and {beta}-diversity of bacterial communities in these wild populations. Our statistical models showed that organ type explained the largest variation of compositional and phylogenetic - and {beta}-diversity of plant microbiomes, and its overall effect exceeded that of host plant species. Yet, the influence of host species increased from root to leaf to flower microbiomes. We found strong sexual dimorphism in flower and leaf microbiomes, especially in host species with the most complete separation of sexes. Our results provide the first demonstration of enhanced effects of host species and sexual dimorphism from root to flower microbiomes. While these findings await manipulative experiments to disentangle contributions of micro-environment and the residing microbiota from host genetic effects, we anticipate that such phenotypic patterns of host species-microbiota association may be broadly applicable to other plants in the wild.