INTERSPECIFIC AND INTRASPECIFIC VARIATION WITHIN THE MORPHOLOGICALLY SIMILAR ARBUSCULAR MYCORRHIZAL FUNGI GLOMUS-MOSSEAE AND GLOMUS-CORONATUM

This collaborative investigation was aimed at using morphological and molecular characters to study inter- and intraspecific variation withi n isolates of Glomus mosseae and Glomus coronatum from different parts of the world. A secondary aim was to assess whether any divergence fo und was genetically based and/or correlated with the biogeographic ori gin of isolates. Morphological evaluations of various possible taxonom ic characters including spore colour, size, sporocarp architecture and hyphal attachment morphology, showed that only spore colour could dis criminate the two groups. Isozyme analysis of malate dehydrogenase and esterase loci clearly confirmed this grouping of the two species comp lexes. SDS profiles and cluster analysis showed the same separation on a selection of isolates from the two groups. A comparison of a repres entative isolate from the G. coronatum group (BEG 49) with other arbus cular mycorrhizal fungi using G. mosseae-specific primers also provide d evidence for separation of the two species complexes. The data and m ethodology employed provide a blueprint for future multimodal and mult idisciplinary approaches to the unravelling of taxonomic problems with in this ancient group of symbiotic fungi.