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Population Genetic Analysis of a Global Collection of Pyrenophora tritici-repentis, Causal Agent of Tan Spot of Wheat

First author: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Cereal Crops Research Unit, Northern Crop Science Laboratory, Red River Valley Agricultural Research Center, Fargo, ND 58105; second and fourth authors: Department of Plant Pathology, North Dakota State University, Fargo 58105; and third author: Department of Biological Sciences, Minnesota State University, Mankato 56001

The work presented here is the first major study to analyze the genetic diversity within the worldwide population of the economically important wheat pathogen Pyrenophora tritici-repentis. The genetic structure of field populations of P. tritici-repentis was determined using amplified fragment length polymorphism markers along with sequence data from the internal transcribed spacer region of the ribosomal DNA. Ninetyseven fungal isolates were collected from naturally infected wheat and wild grass species. The collection of 97 P. tritici-repentis isolates included races 1, 2, 3, 4, 5, ND7, and ND8 and was collected from North America, South America, and Europe. Results show no genetic grouping of fungal races nor do results indicate grouping based on geographic location indicating that the population is preferentially outcrossing in nature and that the introduction and spread of this population is either relatively recent or that there has been a constant worldwide flow of this fungus possibly by seed movement between continents.

Additional keywords: ascomycete , Drechslera tritici-repentis .