Polyclonal antisera to epacrid mycorrhizae and to Hymenoscyphus ericae display specificity

Abstract

Three polyclonal antisera produced in mice were used to investigate specificity and cross-reactivity between ericaceous and epacridaceous mycorrhizal fungi. One antiserum was to a culture of Hymenoscyphus ericae (Read) Korf and Kernan, the fungal endophyte of Calluna vulgaris (L.) Hull (Ericaceae). The other two were to peloton preparations from roots of Epacris impressa Labill. (Epacridaceae) from two sites (Cranbourne and Grampians) in Victoria, Australia. By immunofluorescence, all three antisera recognised H. ericae but not Oidiodendron griseum Roback, suggesting a serological relationship with the former endophyte. They also recognised 10 of the 12 fungal isolates tested, from mycorrhizal roots of E. impressa (Cranbourne), and all 4 isolates from Astroloma pinifolium (R. Br.) Benth. (Epacridaceae) (Grampians). Furthermore, none of the antisera recognised any of the nine common soil-inhabiting fungi selected for screening. Antisera recognised only unmelanized hyphae on epacrid and other plant roots taken from the wild. With plants from Cranbourne, all antisera except the Grampians antiserum recognised hyphae only on epacrid roots, demonstrating specificity. Hyphae on other plant roots were not recognised by any of the antisera. With plants from the Grampians, all antisera recognised some hyphae on both epacrid and other plant roots, except in two instances. The immunogold labelling indicates that the antisera are specific for fungi and do not recognise the plant. Since the fungal isolate forms true mycorrhizal structures, this suggests that there is a serological similarity between fungi forming epacrid mycorrhiza and those (H. ericae) forming ericoid mycorrhiza.Key words: ericoid mycorrhizae, Epacridaceae, polyclonal antibodies, immunofluorescence, immunogold.