ARS | Publication request: GENETICS OF LEAF RUST RESISTANCE IN THREE AMERICANO LANDRACE DERIVED WHEAT CULTIVARS FROM URUGUAY

Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 2006
Publication Date: April 1, 2007
Citation: Kolmer, J.A., Oelke, L.M., Liu, J.Q. 2007. Genetics of Leaf Rust Resistance in Three Americano Landrace Derived Wheat Cultivars from Uruguay. Plant Breeding. 126:152-157.

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 disease. New genes for leaf rust resistance are critical to control this disease. The wheat lines Americano 25e, Americano 26n, and Americano 44d, are early cultivars from Uruguay that have been used as sources of leaf rust resistance for wheats grown in South America. The purpose of this study was to determine if these early wheat cultivars had new genes for leaf rust resistance. Americano 25e was determined to have genes Lr3, Lr16, and two new genes for leaf rust resistance. Americano 26n was determined to have genes Lr1, Lr12, Lr13, and Lr14a. Americano 44d was determined to have either one or two new genes for leaf rust resistance. The new genes in these wheat cultivars provided effective resistance to leaf rust and can be used to improve leaf rust resistance in U.S. wheat cultivars.

Technical Abstract: A genetic analysis of the landrace derived wheat accessions Americano 25e, Americano 26n, and Americano 44d from Uruguay was conducted to identify the leaf rust resistance genes present in these early wheat cultivars. The three cultivars were crossed with the leaf rust susceptible cultivar Thatcher and approximately 80 backcross (BC) F2 families were derived for each cross. The BCF2 families and selected BCF4 lines were tested for seedling and adult plant leaf rust resistance with selected isolates of leaf rust, Puccinia triticina. The segregation and infection type data indicated that Americano 25e had seedling resistance genes Lr3, Lr16, an additional unidentified seedling gene, and one adult plant resistance gene that was not either Lr12 or Lr13 and did not phenotypically resemble Lr34. Americano 26n was postulated to have genes Lr11, Lr12, Lr13, and Lr14a. Americano 44d appeared to have two possibly unique adult plant leaf rust resistance genes.