Glomeromycetes from the Magdalen Islands archipelago: analyzing diversity and meta-community structure in a sand-dune ecosystem

This report presents the first survey and analysis of the arbuscular mycorrhizal fungi community associated with Ammophila breviligulata Fernald (American beachgrass), of the Magdalen Islands archipelago, Quebec. Of the 36 selected harvesting sites, a total of 180 sand samples were collected from the rhizosphere of American beachgrass. Analyses were performed on the original sand samples and root and sand trap cultures. Of the 34 spore-morphotypes found, 31 belonged to glomoid spore species. Of the field sand samples, 72% contained the spores of Glomeromycetes and subsequent trap cultures increased this percentage to 84%. Of the 34 species, 29 were found sporulating in indigenous sand samples at harvest time, and only five additional species were recovered from root and sand trap pot culturing. Among the more generalist species were Rhizoglomus irregulare and G. sp4, which were found in 19 sites, Rhizoglomus aggregatum and Corymbiglomus tortuosum (found in 17 sites), Funneliformis mosseae and G. sp3 (found in 15 sites). This meta-community of Glomeromycetes is shown to have significant nestedness, indicating that fungal taxa that are more frequent in the whole archipelago are also more abundant locally. Some species pairs are shown to display significant negative associations in their patterns of co-occurrence. The relevance of these results for arbuscular mycorrhizal fungal community assembly and dynamics is discussed.