Ectomycorrhizal (EcM) fungi are essential for the establishment of woody perennial plants in the European Alps. From continental to local scales, environmental conditions and plant host characteristics can predict EcM community structure and composition. However, it is unclear whether EcM communities of congeneric host species and their hybrids are differentially structured at local scales. We aimed to i) characterize EcM communities of Salix helvetica, Salix purpurea and their hybrids and ii) elucidate the abiotic and biotic factors affecting EcM communities in hybrid zones. We analysed the EcM communities associated with willows in a glacier valley by combining molecular identification of fungi from individual ectomycorrhizas and from soil. We detected diverse EcM fungi forming non-modular and unnested networks, but we did not find significant differences in the overall EcM fungal community richness or composition among parental species and hybrids. Nevertheless, individual fungi differed regarding host preference. Our results demonstrate that in a sub-alpine hybrid zone with heterogeneous geomorphology, host genotype was not a strong predictor of overall EcM fungal community, but it influenced the occurrence of particular fungi.

外生菌根（EcM）真菌对于在欧洲阿尔卑斯山建立多年生木本植物至关重要。从大陆到地方尺度，环境条件和植物寄主特征都可以预测EcM群落的结构和组成。但是，尚不清楚同类宿主物种的EcM群落及其杂种在地方尺度上是否存在差异性结构。我们的目标是：i）表征黑柳（Salix helvetica），紫柳（Salix purpurea）的ECM社区ii）阐明影响杂交区EcM群落的非生物和生物因素。我们通过结合来自单个外生菌根和土壤真菌的分子鉴定，分析了冰川谷中与柳树相关的EcM群落。我们检测到了形成非模块化和非嵌套网络的多种EcM真菌，但在亲本物种和杂种之间，总体EcM真菌群落的丰富度或组成没有发现显着差异。然而，个体真菌在宿主偏好方面有所不同。我们的结果表明，在具有异质地貌的亚高山杂交带中，宿主基因型不是整体EcM真菌群落的强力预测指标，但它会影响特定真菌的发生。