Data for: Foraging speed and precision of arbuscular mycorrhizal fungi under field conditions: An experimental approach

To better understand the ecology of arbuscular mycorrhizal (AM) symbiosis, we need to measure functional traits of individual fungal virtual taxa under field conditions. The efficiency of AM fungi in locating nutrient-rich patches in soil space is one of their central traits in this symbiotic relationship. We used plots of a long-term field experiment in grassland with manipulated functional group composition of host plant community to establish ingrowth patches with substrate free of roots and fungi and with varying nutrient availability. Comparison of the original AM fungal community before patch creation with that present 9 weeks after patch establishment enabled us to estimate relative hyphal foraging speed for 41 fungal taxa, and a comparison of the fungal community in neighbouring patches differing in nutrient availability provided estimates of hyphal foraging precision for 22 taxa. Members of two dominant fungal families, Glomeraceae and Claroideoglomeraceae, differed in their foraging speed and precision. Glomeraceae taxa responded more slowly, but with a higher focus on enriched patches. We further demonstrated the usefulness of obtained fungal functional traits by testing the differences between grass and dicotyledonous plant hosts using a dataset obtained in another experiment at the same plots. Grass species hosted AM fungal communities with higher foraging speed, but lower foraging precision than the dicotyledonous species. Our study results support the use of field experiments for measuring comparative characteristics of AM fungi, which are highly elusive (or mis-represented) under controlled conditions.

Methods
We collected soil cores, separated roots from soil and used these two fractions for independent NGS. Further, we filled the cores with zeolite-based substrate and let the AMF hyphae to growth into them. After 9 weeks of exposure, the substrate was again used for NGS.

为深入解析丛枝菌根（arbuscular mycorrhizal, AM）共生体系的生态学特征，我们需在田间条件下测定单个真菌虚拟分类单元的功能性状。丛枝菌根真菌在土壤空间中定位富营养斑块的能力，是该共生关系中的核心功能性状之一。
本研究依托一处长期草地田间试验样地，该样地的宿主植物群落功能群组成已被人为调控，以此构建了无根系与真菌定殖、且养分有效性存在梯度差异的内生生长斑块。通过对比斑块构建前的原始丛枝菌根真菌群落与斑块定植9周后的群落组成，我们可估算41个真菌分类单元的相对菌丝觅食速率；通过对比相邻不同养分有效性斑块内的真菌群落差异，我们还获得了22个分类单元的菌丝觅食精度数据。
两个优势真菌科——球囊霉科（Glomeraceae）与近明球囊霉科（Claroideoglomeraceae）——在觅食速率与精度上存在显著分化：球囊霉科类群的响应速度较慢，但对富营养斑块的靶向聚集性更强。
我们进一步整合同一样地另一项试验的数据集，检验草本植物与双子叶植物宿主间的群落差异，以此验证所获取真菌功能性状的实用性。结果显示，相较于双子叶植物宿主，草本植物所关联的丛枝菌根真菌群落具备更高的觅食速率，但觅食精度更低。
本研究结果证实，田间试验可用于测定丛枝菌根真菌的比较性特征——这类特征在受控培养条件下往往难以被准确观测，或存在严重的表征偏差。

研究方法
我们采集土壤岩芯样品，将根系与土壤分离后，分别对这两个组分开展独立的二代测序（next-generation sequencing, NGS）。随后，我们向岩芯中填充以沸石为基质的培养基质，引导丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）菌丝侵入其中。经过9周的培养后，再次对该基质样品进行二代测序。