In vitro interactions between ectomycorrhizal fungi and ericaceous plants

In view of the close association between ericaceous shrubs and ectomycorrhizal trees in forest ecosystems, the interaction between ectomycorrhizal basidiomycetes and the hair roots of four typical ericoid mycorrhizal hosts was investigated in vitro. Seedlings of , , and were inoculated with each of four ectomycorrhizal basidiomycetes from different phylogenetic groups ( and ) in a low carbon and nutrient agar-cellophane culture system. Two ericoid mycorrhizal Helotiales ascomycetes ( in the aggregate and a mycobiont out of the aggregate) were included for comparison. Interactions between fungi and hair roots ranged from neutral to surface attachment, and the formation of intracellular hyphal coils. Root and shoot responses to inoculation were different between the host/fungus combinations. The ectomycorrhizal fungus formed extensive intracellular colonization, spreading cell-to-cell with multiple hyphal entry points and intracellular hyphal coils with single entry points in and epidermal cells respectively, however, no significant effects on plant growth were detected. formed intracellular hyphal coils in the epidermal cells of and but not the other host spp. The isolate stimulate root length about 2.5 times. Interestingly, although the unknown ascomycete strain out of the aggregate formed intracellular hyphal coils in epidermal cells of all host plants, it suppressed the growth of , , and . but not to . Further and more detailed experimentation under more ecological realistic conditions for a longer period of time is needed.