Root–fungus interactions observed on initial stages of mantle formation and Hartig net establishment in mycorrhizas of Amanita muscaria on Picea abies in pure culture

Abstract

Initial stages of mantle formation and Hartig net establishment of Amanita muscaria (L. ex Fr.) Hooker on roots of Picea abies (L.) Karst. in pure culture were observed. Decomposition of root cap cells seems to be a common feature and facilitates contact to living cortical cells. Both processes seem to stimulate mantle formation, since hyphae become enlarged and form a pseudoparenchymatic structure. Remnants of root cap cell walls remain as a boundary structure in the differentiated mantle. Wall ingrowths were observed on cortical cells in contact with the hyphal sheath and intercellular penetrating hyphae, which may be interpreted as transfer cell structures. A stimulating effect of nutrient supply on mantle formation in early stages of mycorrhizal development is supported by these observations.