|Kolmer, James - Jim|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2006
Publication Date: 5/1/2007
Citation: Ordonez, M.E., Kolmer, J.A. 2007. Simple Sequence Repeat Diversity of a World-Wide Collection of Puccinia triticina from Durum Wheat. Phytopathology. 97:574-583. Interpretive Summary: Leaf rust is a disease of wheat caused by the fungus Puccinia triticina. Wheat cultivars in the U.S. are attacked yearly by this fungus. One type of leaf rust attacks bread wheat cultivars, which are commonly grown in the U.S. Another type of leaf rust attacks durum wheat, which is mostly grown in North Dakota, Arizona, California, Mexico, and other countries in Europe, South America, and North Africa. In 2001 durum wheats in Mexico were attacked by a new type of leaf rust. In recent years durum wheats in Europe and South America have also suffered yield losses due to increased leaf rust infections. In this study, we examined leaf rust from durum wheats in Europe, South America, Mexico, California, and North Africa, to see if these collections were similar for DNA variation, using a set of markers called microsatellites or simple sequence repeats. We found that the durum leaf rust collections from Europe, South America, Mexico, and California were very similar for DNA variation with the simple sequence markers. This indicated that a single group of leaf rust with virulence to durum wheat has most likely been spread from a single region to many different wheat -growing regions of the world.
Technical Abstract: Isolates of Puccinia triticina collected from durum wheat from Argentina, Chile, Ethiopia, France, Mexico, Spain, and the USA were analyzed with eleven SSR markers in order to determine the genetic relationship between isolates. These isolates were also compared with P. triticina from bread wheat from North America, and an isolate virulent on Aegilops speltoides from Israel, to determine genetic relationships among groups of P. triticina found on different telial hosts. The large majority of durum leaf rust isolates were identical for SSR markers or had less than 8% genetic dissimilarity, except for isolates from Ethiopia that had 55% dissimilarity with respect to the other durum leaf rust collections. Isolates from bread wheat had over 70% genetic dissimilarity from the durum wheat leaf rust population, and the isolate from A. speltoides was over 90% dissimilar from all isolates tested. AMOVA tests showed significant levels (p= 0.001) of genetic differentiation between regions and between isolates within countries. Isolates of P. triticina from durum wheat from South America, North America and Europe were closely related based on SSR genotypes, suggesting a recent common ancestor, while P. triticina from Ethiopia, bread wheat, and A. speltoides, each had distinct SSR genotypes, which suggested different origins.