title: Host jumping onto close relatives and across kingdoms by Tyrannicordyceps (Clavicipitaceae) gen. nov. and Ustilaginoidea_(Clavicipitaceae).
abstract: OBJECTIVE
  This research seeks to advance understanding of conditions allowing movement of fungal pathogens among hosts. The family Clavicipitaceae contains fungal pathogens exploiting hosts across three kingdoms of life in a pattern that features multiple interkingdom host shifts among plants, animals, and fungi. The tribe Ustilaginoideae potentially represents a third origin of plant pathogenesis, although these species remain understudied. Fungal pathogens that cause ergot are linked morphologically with Clavicipitaceae, but are not yet included in phylogenetic studies. The placement of Ustilaginoideae and ergot pathogens will allow differentiation between the host habitat and host relatedness hypotheses as mechanisms of phylogenetic diversification of Clavicipitaceae.
  
  
  METHODS
  A multigene data set was assembled for Clavicipitaceae to test phylogenetic placement and ancestral character-state reconstructions for Ustilaginoidea virens and U. dichromonae as well as the ergot mycoparasite Cordyceps fratricida. Microscopic morphological observations of sexual and asexual states were also performed.
  
  
  RESULTS
  Phylogenetic placement of U. virens and U. dichromonae represents a third acquisition of the plant pathogenic lifestyle in Clavicipitaceae. Cordyceps fratricida was also placed in Clavicipitaceae and recognized as a new genus Tyrannicordyceps. Ancestral character state reconstructions indicate initially infecting hemipteran insect hosts facilitates subsequent changes to a plant pathogenic lifestyle. The ancestor of T. fratricida is inferred to have jumped from grasses to pathogens of grasses.
  
  
  CONCLUSIONS
  The host habitat hypothesis best explains the dynamic evolution of host affiliations seen in Clavicipitaceae and throughout Hypocreales. Co-occurrence in the same habitat has allowed for host shifts from animals to plants, and from plants to fungi.
authors.affiliation: Department of Entomology, 6124 Comstock Hall, Cornell University, Ithaca, New York 14853, USA. rmk272@cornell.edu
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Kepler
authors.forename: Gi-Ho
authors.initials: GH
authors.lastname: Sung
authors.forename: Yukio
authors.initials: Y
authors.lastname: Harada
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Tanaka
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Hosoya
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Bischoff
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Spatafora
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000502:physiology*; D010802:Phylogeny