Host- and tissue-specificity of moss-associated Galerina and Mycena determined from amplicon pyrosequencing data

The genetic diversity of two agaricoid saprotroph genera, Galerina and Mycena, and their distribution across bryophyte host species, and within bryophytes' photosynthetic and senescent tissues, was assessed using data from two pyrosequencing biodiversity inventories of bryophilous fungi. A total of 9 498 Galerina and 5 731 Mycena reads were mapped to branches broadly distributed throughout backbone trees, reflecting no obvious evolutionary specialization of particular fungal lineages to moss hosts/substrata. Although a few OTUs occurred with equal frequency across the hosts, most exhibited some degree of specialization to one or more bryophytes, indicating that the quality of different mosses as substratum varies between species. With one exception, all Galerina and Mycena OTUs were more frequent and abundant in senescent than photosynthetic tissues, likely reflecting saprotrophic nutritional modes in the fungi. A single Mycena OTU showed considerable colonization of both tissues, which may reflect an opportunistic parasitic or endophytic lifestyle.

► We assessed host- and tissue-specificity in bryophilous fungi using pyrosequencing.
► Some Galerina and Mycena species were generalists, some showed host specificity.
► Most Galerina and Mycena species are saprobic and colonize senescent moss tissues.
► One Mycena is a putative endophyte, colonizing both green and brown moss tissues.