How many fungi make sclerotia?

Most fungi produce some type of durable microscopic structure such as a spore that is important for dispersal and/or survival under adverse conditions, but many species also produce dense aggregations of tissue called sclerotia. These structures help fungi to survive challenging conditions such as freezing, desiccation, microbial attack, or the absence of a host. During studies of hypogeous fungi we encountered morphologically distinct sclerotia in nature that were not linked with a known fungus. These observations suggested that many unrelated fungi with diverse trophic modes may form sclerotia, but that these structures have been overlooked. To identify the phylogenetic affiliations and trophic modes of sclerotium-forming fungi, we conducted a literature review and sequenced DNA from fresh sclerotium collections. We found that sclerotium-forming fungi are ecologically diverse and phylogenetically dispersed among 85 genera in 20 orders of Dikarya, suggesting that the ability to form sclerotia probably evolved 14 different times in fungi. a 2014 Elsevier Ltd and The British Mycological Society. All rights reserved. Fungi are among the most diverse lineages of eukaryotes with an estimated 5.1million species (Blackwell, 2011). They are the principle saprotrophs in most terrestrial biomes and play important ecological and economic roles as plant pathogens and mutualists. Fungi are found in all terrestrial ecosystems and they use a variety of strategies to colonize appropriate substrata and survive unfavorable conditions (Blackwell, 2011). They have significant impacts on the biology of plants because they are the most economically significant plant pathogens, serve as mycorrhizal and endophytic symbionts, and act as key players in nutrient cycles (Schumann, 1991; Rodriguez et al., 2009; Hobbie and Hogberg, 2012). Two fungal phyla, Basidiomycota and Ascomycota, comprise the subkingdom Dikarya, a diverse group with ca. 100,000 described species (James et al., 2006). Most Dikarya share key 7; fax: þ1 352 392 6532. . Smith). h Mycological Society. Al h, et al., How many fun features such as a hyphal thallus, non-flagellated cells, and the production of spores (Stajich et al., 2009). However, because of their cryptic lifestyles within environments such as plants and soil, the ecology and evolutionary history of many fungi remains poorly understood. Almost all fungi produce some type of durable, quiescent microscopic structure such as a spore that is important for dispersal and/or survival under adverse conditions (Stajich et al., 2009). However, some fungi also produce dense aggregations of fungal tissue called sclerotia (Willetts, 1971). These persistent structures help fungi to survive challenging conditions such as freezing temperatures, desiccation, microbial attack, or the long-term absence of a host (Townsend and Willetts, 1954; Coley-Smith and Cooke, 1971). Sclerotia are highly variable in their morphology (Fig 1). Some have a hard,