Data from: Tracking plant preference for higher-quality mycorrhizal symbionts under varying CO conditions over multiple generations

The symbiosis between plants and root-colonizing arbuscular mycorrhizal (AM) fungi is one of the most ecologically important examples of interspecific cooperation in the world. AM fungi provide benefits to plants; in return plants allocate carbon resources to fungi, preferentially allocating more resources to higher-quality fungi. However, preferential allocations from plants to symbionts may vary with environmental context, particularly when resource availability affects the relative value of symbiotic services. We ask how differences in atmospheric CO2-levels influence root colonization dynamics between AMF species that differ in their quality as symbiotic partners. We find that with increasing CO2-conditions and over multiple plant generations, the more beneficial fungal species is able to achieve a relatively higher abundance. This suggests that increasing atmospheric carbon supply enables plants to more effectively allocate carbon to higher-quality mutualists, and over time helps reduce lower-quality AM abundance. Our results illustrate how environmental context may affect the extent to which organisms structure interactions with their mutualistic partners and have potential implications for mutualism stability and persistence under global change.

植物与定殖于根系的丛枝菌根（AM）真菌之间的共生关系，是全球范围内生态重要性最为突出的种间合作范例之一。AM真菌可为植物提供有益共生服务；作为回报，植物会向真菌分配碳源资源，且优先将更多碳源分配给品质更优的真菌类群。然而，植物对共生伙伴的优先分配策略可能随环境背景发生改变，尤其当资源可获得性影响共生服务的相对价值时。本研究旨在探究大气二氧化碳水平的差异，如何对共生品质存在分化的AM真菌物种间的根系定殖动态产生影响。研究结果显示，在二氧化碳浓度升高的环境条件下，经过多代植物种植周期后，更具有益性的真菌物种能够获得相对更高的种群丰度。这表明大气碳供应的增加可使植物更高效地将碳资源分配给品质更优的互惠共生伙伴，且随着时间推移，有助于降低低品质AM真菌的种群丰度。本研究结果阐明了环境背景如何影响生物构建与互惠共生伙伴互动关系的程度，并对全球变化背景下共生关系的稳定性与存续性具有潜在的科学启示意义。