1. Floral nectar harbours a diverse microbiome of yeasts and bacteria that depend predominantly on animal visitors for their dispersal. Since pollinators visit specific sets of flowers and carry their own unique microbiota, we hypothesize that plant species visited by the same set of pollinators may support non-random nectar microbial communities linked together by the type of pollinator.
2. Here we explore the importance of plant–pollinator interactions in the assembly of nectar microbiome and study the role of plant geographic location as a determinant of microbial community composition. We intensively sampled the nectar of 282 flowers of 48 plant species with beetles, birds, long-tongued and short-tongued insects as pollinators in wild populations in South Africa, one of the world's biodiversity hotspots, and using molecular techniques we identified nectar yeast and bacteria taxa. The analyses provided new insights into the richness, geographic structure and phylogenetic characterization of nectar microbiome, and compared patterns of composition of bacteria and yeast communities in relation to plant and pollinator guild.
3. Our results showed that plant–pollinator interactions played a crucial role in shaping nectar microbial communities. Plants visited by different pollinator guilds supported significantly different yeast and bacterial communities. The pollinator guild also contributed to the maintenance of beta diversity and phylogenetic microbial segregation. The results revealed different patterns for yeast and bacteria; whereas plants visited by beetles supported the highest richness and phylogenetic diversity of yeasts, bacteria communities were significantly more diverse in plants visited by other insect groups. We found no clear microbial spatial segregation at different geographical scales for bacteria, and only the phylogenetic similarity of yeast composition was correlated significantly with geography.
4. Synthesis. Interactions of animal vector, plant host traits and microbe physiology contribute to microbial community assemblages in nectar. Our results suggest that plants visited by the same pollinator guild have a characteristic nectar microbiota signature that may transcends the geographic region they are in. Contrasted patterns for yeast and bacteria stress the need for future work aimed at better understanding the causes and consequences of the importance of plants and pollinators in shaping nectar microbial communities in nature.

中文翻译：

---

植物传粉者相互作用在构建花蜜微生物群落中的作用

1. 花蜜含有多种酵母菌和细菌微生物群，主要依靠动物访客进行传播。由于传粉者访问特定的花朵并携带自己独特的微生物群，我们假设同一组传粉者访问的植物物种可能支持通过传粉者类型连接在一起的非随机花蜜微生物群落。
2. 在这里，我们探讨了植物 - 传粉媒介相互作用在花蜜微生物组组装中的重要性，并研究了植物地理位置作为微生物群落组成决定因素的作用。我们在世界生物多样性热点之一南非的野生种群中以甲虫、鸟类、长舌和短舌昆虫为传粉媒介，对 48 种植物的 282 朵花的花蜜进行了密集采样，并利用分子技术鉴定了花蜜酵母和细菌分类群。这些分析为花蜜微生物组的丰富度、地理结构和系统发育特征提供了新的见解，并比较了与植物和传粉者行会相关的细菌和酵母群落的组成模式。
3. 我们的研究结果表明，植物 - 传粉媒介的相互作用在塑造花蜜微生物群落中起着至关重要的作用。不同传粉者行会访问的植物支持显着不同的酵母和细菌群落。传粉者协会还有助于维持β多样性和系统发育微生物的分离。结果揭示了酵母和细菌的不同模式；虽然甲虫访问的植物支持酵母的最高丰富度和系统发育多样性，但其他昆虫群体访问的植物中的细菌群落更加多样化。我们发现细菌在不同地理尺度上没有明显的微生物空间分离，只有酵母组成的系统发育相似性与地理显着相关。
4. 合成。动物载体、植物宿主性状和微生物生理学的相互作用有助于花蜜中的微生物群落组合。我们的结果表明，同一传粉者协会访问过的植物具有特征性的花蜜微生物群特征，可能超越它们所处的地理区域。酵母和细菌的对比模式强调了未来工作的必要性，旨在更好地了解重要性的原因和后果植物和传粉者在塑造自然界中的花蜜微生物群落中的作用。