Former Land Use and Host Genotype Influence the Mycorrhizal Colonization of Poplar Roots

The present paper analyses the community structure of ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM) fungi associated with seven different poplar clone types growing in a patch system on soil from four different former land use types, originating from spruce forest, poplar stand, grassland and cornfield. We determined the extent to which ECM and AM play a role on the studied factors (genotype, former land use type and host growth). The diversity of ECM and AM fungal communities was estimated by morphological and molecular analyses of the 18S and ITS of the rDNA genes. Fifteen ECM fungal taxa and four AM groups were distinguished in the roots of the poplars grown for 18 months on soil originating from the respective land use types. The poplar clones showed significantly different rates of shoot length and AM colonization, especially concerning the occurrence of Glomus intraradices and Scutellospora sp. Populus deltoides had significantly higher Scutellospora sp. abundance. Although ECM abundance and diversity was high, no significant differences between the different land use types was found. However, some ECM fungi like Paxillus involutus, Laccaria proxima and Laccaria tortilis showed significant preferences for specific land use types. Our findings suggest that both factors, former land use type and poplar genotype, are important determinants of mycorrhizal colonization of the host plants