Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2005
Publication Date: 10/26/2005
Citation: Castlebury, L.A., Carris, K. Vanky, 2005. Phylogenetic analysis of Tilletia and allied genera in order Tilletiales (Ustilaginomycetes; Exobasidiomycetidae) based on large submit nuclear RDNA sequences. Mycologia 97(4):888-900. Interpretive Summary: Bunt fungi cause a number of serious diseases of cereal crops in the United States of which some are of dire quarantine importance. Knowledge of the relationships among bunt fungi is essential for their accurate identification and controlling the diseases they cause. At present, disagreement exists about how to define species of bunt fungi and how they are related to each other. In this paper molecular sequence data are used to determine which morphological characteristics can be used to accurately identify these fungi and how closely related they are to each other. This research will be used to ensure that bunt fungi especially those of plant quarantine significance are accurately identified.
Technical Abstract: Bunt fungi in Tilletia and related genera parasitizing members of the Poaceae are distinguished by teliospore ornamentation and host. A number of non-reticulate-spored species in Tilletia have been placed in segregate genera including Conidiosporomyces, Ingoldiomyces, Neovossia, and Oberwinkleria. Two economically important species, T. indica (Karnal bunt) and T. horrida (rice kernel smut) have been placed in Neovossia on the basis of tuberculate teliospore ornamentation, floret infection and the production of large number of non-conjugating basidiospores. Phylogenetic analysis of large subunit nuclear rDNA sequences shows that reticulate-spored taxa with hosts in the Pooideae form a well-supported monophyletic group. Also on members of the Poodieae, Tilletia indica and T. walkeri form another well-supported group (100%) and are more closely related to reticulate-spored Pooid-infecting taxa than to other tuberculate-spored taxa. A few reticulate-spored taxa and other tuberculate-spored taxa on non-Pooideae hosts, including T. horrida, fall in a separate, unsupported group although a number of well-supported lineages exist within this group. Conidiosporomyces ayresii groups strongly with T. vittata. Results suggest that host subfamily may be more phylogenetically informative than morphological characters and that these data do not support the segregation of Conidiosporomyces, Ingoldiomyces, and Neovossia, from Tilletia.