Cultivable fungi associated with bryosphere of bipolar mosses Polytrichastrum alpinum and Polytrichum juniperinum in King George Island, South Shetland Islands, Maritime Antarctica

We characterized the diversity of cultivable fungal assemblages associated with the bryospheres of the bipolar mosses Polytrichastrum alpinum and Polytrichastrum juniperinum resident in King George Island, South Shetland Islands, Maritime Antarctica. From different parts of the mosses, 160 fungal isolates were obtained and identified using molecular biology methods as 43 taxa of 28 distinct genera. Antarctomyces psychrotrophicus, Mrakia gelida, Pseudogymnoascus sp., Melanodiplodia sp., and Vishniacozyma victoriae were the dominant taxa and displayed the highest values of frequency. Ecological diversity indices showed that the fungal assemblages were high but ranged among the mosses. Fungi of the bryospheres of both mosses showed different colonization patterns. Only A. psychrotrophicus, M. gelida, Pseudogymnoascus sp., and Leotiomycetidae sp. occurred as endophytes, epiphytes, and in the rhizoidosphere of P. alpinum. In contrast, the bryosphere of P. juniperinum did not show a single common fungus across its different portions. Our results show that the bryosphere of the bipolar Antarctic mosses seem to represent an interesting hostspot of fungal diversity dominated by cosmopolitan cold-adapted and endemic species recognized as symbionts and decomposer species. The high fungal diversity detected suggests that the Antarctic mosses may offer a protected microhabitat (bryosphere) favorable for the survival, dispersal, and colonization of symbionts and decomposer fungi in the different extreme environments of Antarctica.