Journal des maladies végétales et des biomarqueurs


Mapping Lr18: A leaf rust resistance gene widely deployed in soft red winter wheat.

Neal R Carpenter, Carl A Griffey, Luciana Rosso, Subas Malla, Shiaoman Chao and Gina L Brown Guedira

Leaf rust caused by Puccinia triticina is a destructive pathogen of wheat (Triticum aestivum) in a majority of the world’s wheat producing areas. Host resistance is the most economical solution for providing full season control and reducing damage due to leaf rust as opposed to use of multiple fungicide applications. The soft red winter wheat cultivar Jamestown is productive in the deep south, southern Corn Belt, and mid-atlantic regions, and this can be attributed in part to its resistance to multiple diseases including leaf rust. Jamestown is postulated to contain gene Lr18. Seedlings of 186 F5:9 recombinant inbred lines (RILs) from a cross of Pioneer ‘25R47’/Jamestown and 200 F2 seedlings from eight other crosses including Jamestown and/or the Lr18 host differential line RL6009 (Thatcher*6/Africa 43) were screened with P. triticina race TNRJJ. Genetic analysis of the populations was conducted to validate the presence of Lr18 in Jamestown. Linkage analysis conducted with SNP markers in the Pioneer 25R47/Jamestown population identified markers that were closely linked with Lr18, and these were validated in Jamestown/VA10W-21 and RL6009/VA10W21 F2 populations. Results of linkage analysis identified SNP maker IWB41960 linked within 5 cM of gene Lr18 in all three populations.