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United States Department of Agriculture

Agricultural Research Service

Title: Powdery Mildew Resistance and Lr34/yr18 Genes for Durable Resistance to Leaf and Stripe Rust Cosegregate at a Locus on the Short Arm of Chromosome 7d of Wheat

item Mcintosh, R - UNIV. SYDNEY, AUSTRALIA
item Kolmer, James

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 5, 2005
Publication Date: August 1, 2005
Citation: Spielmeyer, W., McIntosh, R.A., Kolmer, J.A., Lagudah, E.S. 2005. Powdery mildew resistance and Lr34/Yr18 genes for durable resistance to leaf and stripe rust cosegregate at a locus on the short arm of chromosome 7d of wheat. Journal of Theoretical and Applied Genetics. 111:731-735.

Interpretive Summary: A gene in wheat called Lr34 gives resistance to the wheat leaf rust disease which is caused by the fungus Puccinia triticina. The same gene, called by another designation, Yr18, also gives resistance to a different disease, wheat stripe rust, which is caused by Puccinia striiformis. The gene Lr34/Yr18 was determined to also give resistance to the powdery mildew disease, which is caused by Blumeria graminis. This gene is very important in wheat because it gives resistance to three different diseases. The gene was located on the short arm of chromosome 7DS in wheat using biotechnology techniques. This research will assist in the development of molecular markers that can be used to select wheat lines with the Lr34/Yr18 gene.

Technical Abstract: The incorporation of effective and durable disease resistance is an important breeding objective for wheat improvement. The leaf rust resistance gene Lr34 and stripe rust resistance gene Yr18 are effective at the adult plant stage and have provided durable resistance to leaf rust, caused by Puccinia triticina, and stripe rust, caused by Puccinia striiformis, respectively. These genes have not been separated by recombination and map to chromosome 7DS in wheat. In a population of 110 F7 lines of Thatcher x Thatcher isogenic line with Lr34/Yr18, field resistance to leaf rust conferred by Lr34 and stripe rust resistance conferred by Yr18 cosegregated with adult plant resistance to powdery mildew caused by Blumeria graminis var. tritici. The genes Lr34 and Yr18 were previously shown to be associated with enhanced stem rust resistance and tolerance to barley yellow dwarf virus infection. This chromosomal region in wheat has now been linked with resistance to five different pathogens. The Lr34/Yr18 phenotypes and associated powdery mildew resistance were mapped to a single locus flanked by microsatellite loci Xgwm 1220 and Xgwm 295 on chromosome 7DS.

Last Modified: 4/22/2015
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