Diverse fungal communities associated with the roots of isoetid plants are structured by host plant identity

We examined fungi associated with roots of isoetid plants collected from six Norwegian lakes. The composition of the diverse fungal communities was shaped mainly by host identity, while abiotic factors had negligible effects. The communities associated with roots of Subularia aquatica, Isoetes echinospora and Isoetes lacustris were dominated by Ascomycota, Chytridiomycota, and Basidiomycota while Glomeromycota were infrequent and the proportion of unidentified fungal taxa was relatively high. In contrast, Lobelia dortmanna and Littorella uniflora roots associated mainly with Glomeromycota, Ascomycota, and Basidiomycota. Chytridiomycota and unidentified fungi were rare. Glomeromycota comprised 39 phylotypes spanning nine families, with the second most abundant phylotype belonging to a yet undescribed sister lineage to the family Archaeosporaceae, repeatedly reported from aquatic environments. Our results indicate that fungal communities in roots of aquatic plants might be diverse as in terrestrial plants, and that they comprise a high proportion of yet undescribed taxa. (C) 2020 Elsevier Ltd and British Mycological Society. All rights reserved.