Agricultural practices and pollinators modulate the anthosphere microbiome

The flower microbiome is pivotal in plant health, influencing reproductive success, fruit quality, and pathogen vulnerability. However, the impact of intensified agricultural practices on these microbial communities remains to be understood. This study examines how specific agricultural practices influence the bacterial composition of the strawberry anthosphere, focusing on cultivation intensification. Intensified systems were defined by practices such as indoor glasshouse substrate-based cultivation, increased use of plant protection products, larger cultivation areas, and reliance on managed pollinators. Using citizen science and V4 16S rRNA gene sequencing, we found that flowers in these more intensively managed systems had lower bacterial diversity, more variable microbiomes, and loss of core taxa such as Sphingomonas and Pseudomonas. To determine if pollinators could help mitigate these effects, we conducted exclusion experiments. In a tunnel system, we observed that foraging pollinators facilitated the dispersal of specific bacteria, such as Staphylococcus and Pseudomonas, and increased flower bacterial richness. However, in an open field, foraging pollinators had no significant impact. Our findings highlight the significant impact of cultivation intensification on the anthosphere microbiome and suggest that pollinators may play a role in restoring microbiome diversity. This research fills a critical gap in understanding how agricultural practices shape plant microbiomes and underscores the potential for microbe-based strategies to improve plant health in intensively managed systems.