Ontogeny of Early Stages of Ectomycorrhizae Synthesized between Dryas integrifolia and Hebeloma cylindrosporum

Abstract

Ectomycorrhizae between Dryas integrifolia and Hebeloma cylindrosporum were synthesized in plastic growth pouches. Structural modifications in the mycorrhizal root were observed at different stages in the development of the symbionts using light microscopy. These included radial expansion of infected root apices, plant cell contortion, Hartig net formation, and production of phi thickenings in the inner cortical layers of the infection zone. Division of epidermal cells occurred in the proximal region of roots colonized by surface hyphae. Modified meristem activity resulted in the production of additional cortical cell layers and an accumulation of root cap cells beneath the mantle. Plant cells in the older Hartig net were reduced in size. Nonmycorrhizal control roots were used as a reference for all mycorrhizal samples.