Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2007
Publication Date: March 1, 2008
Citation: Carris, L.M., Castlebury, L.A. 2008. Is Tilletia contraversa the causal agent of dwarf bunt of wheat?. Inoculum 59(2):10 2008
Tilletia contraversa is accepted as the valid name for the dwarf bunt pathogen of wheat. This species is a quarantine status pathogen with a host range including 45 grass hosts in 13 genera. In 1952, G.W. Fischer erected T. brevifaciens for the dwarf bunt pathogen, which had previously been considered a variant of T. caries, and designated a type on Agropyron intermedium (now Thinopyrum intermedium). T. brevifaciens was then synonymized with T. contraversa, described by Kühn (1874) for a smut on Triticum repens (now Elymus repens). There are no valid species described for the dwarf bunt pathogen based on a type from wheat. We have noted differences in spore germination, and morphology of teliospores and sterile cells among specimens of T. contraversa from different host genera. A phylogenetic analysis was conducted using sequence data from rDNA ITS, RPB2 and translation elongation factor 1 alpha to test conspecificity of specimens from Triticum and other grass genera. Collections from Hordeum, Secalis, Thinopyrum and other genera were found to represent species distinct from a complex of wheat bunt pathogens consisting of T. caries, T. contraversa, and T. laevis. This indicates that the broad synonymies proposed by various authors may not accurately reflect phylogenetic or morphological species and that the species status of T. contraversa needs further investigation.