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Poster Session: Diseases of Plants - Disease Detection and Diagnosis


What is flag smut of wheat?.
K. G. SAVCHENKO (1), L. M. Carris (1), J. Demers (2), L. A. Castlebury (3)
(1) Department of Plant Pathology, Washington State University, Pullman, WA, U.S.A.; (2) Systematic Mycology & Microbiology Laboratory, USDA-ARS, Beltsville, MD, U.S.A.; (3) Systematic Mycology and Microbiology Laboratory, USDA-ARS, Beltsville, MD, U.S.A.

Urocystis agropyri, causal agent of flag smut of wheat, is a quarantine-regulated pathogen of wild and cultivated grasses with a wide host range and worldwide distribution. Currently U. agropyri is subject to strict quarantine regulations in countries that prohibit the entry of wheat from any region where the pathogen is known to occur. The fungus was first described from Elymus repens; however, using a morphological concept G.W. Fischer in 1953 placed a large number of species in synonymy with U. agropyri, including U. tritici from wheat. The present study is a first attempt to clarify the taxonomy and phylogeny of flag smut of grasses using molecular analyses. Internal transcribed spacer rDNA and translation elongation factor 1 alpha loci were amplified from 22 fresh and herbarium specimens of infected Alopecurus, Beckmannia, Bromus, Calamagrostis, Elymus, Lolium, Phleum, Secale and Triticum. Results indicate that there are several distinct lineages of flag smut, with U. hispanica from Aegilops being the closest relative of flag smut of wheat. The specimens from Elymus repens grouped in a clade distinct from the specimens from wheat and rye. Recognition that U. tritici is genetically distinct from U. agropyri s. str. will impact regulatory policy and facilitate the development of diagnostic tests.