Ectomycorrhizal types and endobacteria associated with ectomycorrhizas of Morchella elata (Fr.) Boudier with Picea abies (L.) Karst

Subterranean morel sclerotia connected with ascomata of Morchella elata (Fr.) Boudier were found to surround 155 ectomycorrhizal root tips of Picea abies (L.) Karst, belonging to seven different types. Based upon anatomical and cytological studies, three ectomycorrhizal types could be attributed to types already described, whereas four types appeared to be undescribed. The nature of the association between the morel and the mycorrhizal types was dependent on the type and was not related to their vitality. In particular, morel ectomycorrhizas formed secondarily and exclusively by succeeding to primary mycorrhizas of a heterobasidiomycete. In addition to this triple association, an endobacterium was observed growing within the Hartig net of this heterobasidiomycete mycorrhiza. The significance of this complex of associations for the formation of ectomycorrhizas by the morel is discussed.