Low specificity and high variability of ectomycorrhizal association in Salix humboldtiana along its southern latitudinal distribution

Abstract

The preference in the ectomycorrhizal (ECM) - plant association exhibits a wide degree of variation and depends on the identity of the plant but also of the fungal species. Evaluating the degree of specificity of the plant species toward ECM symbionts is an important clue for understanding the functioning of the ECM symbiosis itself. In this work we set out to investigate the patterns of association and specificity of Salix humboldtiana in a wide range of distribution. To do this, we evaluated in a greenhouse experiment if this species establishes symbiosis with ECM fungi belonging to its own rhizosphere (using soil from three provenances of S. humboldtiana distribution in: north, center and south of Argentina) and the rhizosphere of Alnus acuminata and Nothofagaceae species, with which share distribution in the north and the south of Argentina, respectively. Trees of S. humboldtiana associate with ECM fungi belonging to its rhizosphere in the north, center and south of Argentina and from the A. acuminata rhizosphere, but not with those belonging to the Nothofagaceae rhizosphere. Furthermore, PERMANOVA showed that the composition of the associated ECM fungi differed between inoculum provenances. Our results suggest that S. humboldtiana shows low specificity on ECM symbiosis, associating with a small group of fungi that differ in abundance and composition throughout their distribution in Argentina.