Ectomycorrhizal fungal communities differ among parental and hybrid Populus cross types within a natural riparian habitat

Plant hybridization is common and important in ecological and economic contexts, however little is known about the impact of plant hybridization on ectomycorrhizal fungal (EMF) communities in natural habitats. We used a Populus hybrid system (P. angustifolia x P. fremontii) in a heterogeneous riparian landscape to address the hypothesis that EMF communities differ among hybrids and their parental species (cross types). Several key results emerged. (1) Cross type influenced EMF composition, with communities on hybrids being distinct from their parents. (2) Cross type influenced the composition of hyphal exploration types important for soil resource foraging, although contact and short distance exploration types were dominant on all cross types. (3) Cross type had a marginal influence on EMF colonization, with P. angustifolia highest and P. fremontii lowest. These results highlight the potential for tree hybridization to structure belowground communities in heterogeneous natural ecosystems.