Ericoid mycorrhizas and rhizoid‐ascomycete associations in liverworts share the same mycobiont: isolation of the partners and resynthesis of the associations in vitro

Abstract

The hypothesis was tested that rhizoids of leafy liverworts of the families Lepidoziaceae, Calypogeiaceae, Cephaloziaceae and Cephaloziellaceae can be infected by the aseomycetous fungal endophyte Hymenoicyphus ericae which forms ericoid mycorrhiza with the major ericaceous genera Calluna, Erica, Rhododendron and Vaccinium. The extent of the specificity of any such association was also examined by growing the liverworts with pure cultures of the putative ascomycetous ericoid endophyte Oidiodendron, with the basidiomycetous endophyte of orchids, Ceratobasidium cornigerum, and with several ectomycorrhizal fungi. It was confirmed that the members of these liverwort families tested, most of which are associated in nature with ericaceous plants, were readily infected by H. ericae, as well as by isolates obtained from the liverworts themselves. The latter, when used to challenge aseptically grown seedlings of the ericaceous genera on water agar, produced typical ericoid mycorrhiza. Neither the Oidiodendron isolates nor the orchid or ectomycorrhizal fungi infected the liverworts, and all failed to reproduce the characteristic swelling of the rhizoid tips which is seen in nature and in plants inoculated with H. ericae. The results provide a major extension of the likely host range of H. ericae and may have considerable significance for both groups of plants which, as a consequence of sharing the same endophyte, have the potential to act as sources of inoculum for each other in nature. The possible physiological and ecological impacts of the association for both liverwort and ericaceous hosts are discussed. Copyright © 1995, Wiley Blackwell. All rights reserved