title: Revisiting the Life Cycle of Dung Fungi, Including Sordaria fimicola.
abstract: Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem to challenge the view that they are obligate to dung. However, endophyte status is controversial because surface-sterilization protocols could fail to kill dung fungus ascospores stuck to the plant surface. Thus, we first tested the ability of representative isolates of three common genera of dung fungi to affect plant growth and fecundity given that significant effects on plant fitness could not result from ascospores merely stuck to the plant surface. Isolates of S. fimicola, Preussia sp., and Sporormiella sp. reduced growth and fecundity of two of three populations of Bromus tectorum, the host from which they had been isolated. In further work with S. fimicola we showed that inoculations of roots of B. tectorum led to some colonization of aboveground tissues. The same isolate of S. fimicola reproduced sexually on inoculated host plant tissues as well as in dung after passage through sheep, thus demonstrating a facultative rather than an obligate life cycle. Finally, plants inoculated with S. fimicola were not preferred by sheep; preference had been expected if the fungus were obligate to dung. Overall, these findings make us question the assumption that these fungi are obligate to dung.
authors.affiliation: Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: George
authors.initials: G
authors.lastname: Newcombe
authors.affiliation: Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, Idaho, United States of America.|Palouse Research, Education and Extension Center, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Jason
authors.initials: J
authors.lastname: Campbell
authors.affiliation: Environmental Sciences Program, University of Idaho, Moscow, Idaho, United States of America.|Center for Resilient Communities, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Griffith
authors.affiliation: Environmental Sciences Program, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Baynes
authors.affiliation: Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Karen
authors.initials: K
authors.lastname: Launchbaugh
authors.affiliation: US Forest Service, Rocky Mountain Research Station, Albuquerque, New Mexico, United States of America.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Pendleton
mesh_terms: D005243:Feces / Q000382:microbiology*; D008018:Life Cycle Stages / Q000502:physiology*; D063245:Plant Development / Q000502:physiology; D018515:Plant Leaves / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D020037:Sordariales / Q000254:growth & development* / Q000302:isolation & purification; D013172:Spores, Fungal
references.citation: Mycologia. 1975 Jan-Feb;67(1):63-74
references.pmid: 1167620
references.citation: Can J Res. 1948 Oct;26(5):486-95
references.pmid: 18892116
references.citation: J Nat Prod. 2009 Sep;72(9):1712-5
references.pmid: 19708679
references.citation: Eur J Cell Biol. 2010 Dec;89(12):864-72
references.pmid: 20739093
references.citation: Microb Ecol. 2011 Feb;61(2):239-44
references.pmid: 20842497
references.citation: Fungal Biol. 2012 Jan;116(1):133-44
references.pmid: 22208608
references.citation: PLoS One. 2012;7(4):e34847
references.pmid: 22536336
references.citation: Oecologia. 1996 Oct;108(1):159-166
references.pmid: 28307746
references.citation: Genetics. 1998 May;149(1):87-99
references.pmid: 9584088