Submitted to: Mycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2003
Publication Date: 6/30/2003
Citation: Castlebury, L.A., Rossman, A.Y., Farr, D.F. Phylogenetic placement of the anamorph genus sirococcus. Mycological Society of America.Inoculum Vol.54 P.15,2003.
Technical Abstract: The anamorph genus Sirococcus contains the causal agents of Sirococcus shoot blight of conifers (S. conigenus) and butternut canker (S. clavigignenti-juglandacearum). The butternut canker fungus was recently introduced into North America and threatens the extinction of the butternut tree (Juglans cinerea). Sirococcus is characterized by the production of fusiform, hyaline, mostly 1-sepate conidia from globose or flattened, simple to multilocular pycnidia. Teleomorphs for these fungi, if they exist, have not been reported. Internal transcribed spacer region sequences indicate that the type species S. conigenus is most closely related to diaporthalean fungi. Approximately 1200 bp of LSU nrDNA were sequenced to determine a more exact placement in the Diaporthales. Parsimony and Bayesian analyses firmly placed both species in the Gnomoniaceae. Sirococcus conigenus is most closely related to isolates of Discula destructiva, while S. clavigignenti-juglandacearum is closest to an isolate Gnomonia padicola. These data suggest that the butternut canker fungus does not belong in the genus Sirococcus. Correct placement of S. clavigignenti-juglandacearum may help to determine the origin of this devastating disease.