The influence of host genotype and soil conditions on ectomycorrhizal community of poplar clones

• Site and soil depth had significant effects on the structure of ECM communities.
• Host genotype plays a minor role related to adaptation to stressful conditions.
• The diversity of ECM communities decreased with increasing soil depth.
• The evenness indexes were stable across all soil strata.
• The abundance of Ascomycota appeared to increase in response to heavy-metal stress.

Poplar species and their hybrids are known to be very diverse in terms of their physiological characteristics but little is known about how host genotype influences fungal communities associated with poplar roots. In the present paper we focused on a detailed analysis of the community structure of ectomycorrhizal (ECM) fungi associated with four poplar clones growing at three sites (one heavy-metal polluted and two unpolluted sites differing in environmental characteristics). We determined the extent to which the studied factors (genotype, site, and soil depth) play a role in structuring the fungal communities. Twenty seven fungal taxa were distinguished at the three experimental sites. Overall, 94.6% of the identified ectomycorrhizae belonged to Basidiomycota and 3.9% to Ascomycota. The abundance of Ascomycota in fungal communities appeared to increase in response to heavy-metal stress. The diversity of ECM communities decreased with increasing soil depth, whereas the evenness indexes were stable across all soil strata studied. The results revealed the dominant role of site characteristics and soil depth in determining the structure and composition of fungal symbionts associated with the roots of poplar clones. Host genotype plays a minor role related to adaptation to stressful conditions.