Differential colonization by ecto-, arbuscular and ericoid mycorrhizal fungi in forested wetland plants

Abstract

The roots of most land plants are colonized by mycorrhizal fungi under normal soil conditions, yet the influence of soil moisture on different types of mycorrhizal symbioses is poorly understood. In wet soils, colonization of woody plants by ectomycorrhizal (ECM) fungi tends to be poor, and colonization of herbaceous plants by arbuscular mycorrhizal (AM) is highly variable. However, little information is available on the influence of soil moisture on the colonization of ericaceous roots by ericoid mycorrhizal (ErM) fungi. Colonization was assessed microscopically in the ECM plant Pinus strobus, two AM plants (Cornus canadensis and Lysimachia borealis) and two ErM plants (Kalmia angustifolia and Gaultheria hispidula) along two upland to wetland gradients in Southwestern Nova Scotia. For the ErM plants, fungal ITS sequencing was used to assess community structure. The data indicate that ErM colonization increases with soil moisture in forested wetlands and is associated with distinctive fungal communities.