Xiaochun Sun, Agronomy, Kansas State University, 2004 Throckmorton Hall, Manhattan, KS 66506, Guihua Bai, Plant Science and Entomology Research Unit, USDA-ARS/Kansas State University, 4008 Throckmorton Hall, Manhattan, KS 66506, and Brett Carver, Plant and Soil Science, Oklahoma State University, Stillwater, OK 74078.
Leaf rust, caused by Puccinia triticina (Eriks. and E. Henn), is an important foliar disease of wheat (Triticum aestivum) worldwide. Pyramiding of major rust-resistant genes into a single cultivar is an effective solution to this problem. Molecular markers linked to the genes are essential tool for gene pyramiding. Two major leaf rust resistance genes, Lr41 and Lr42, were identified from chromosome 1D of T. tauschii, and the genes have been transferred into wheat germplasm for breeding application. Recent mapping work has relocated the L41 on 2DS, but the markers linked to Lr42 have not been identified. In this study, two sets of near-isogenic lines (NIL) were developed by backcrossing the two T. tauschii accessions TA2460 (Lr41) and TA2450 (Lr42), respectively, to a susceptible hard winter wheat cultivar Century. To identify new markers for Lr42 and verify the markers for Lr41, two populations of 95 Bc3F2:6 lines were analyzed with microsatellite markers on both 1DS and 2DS. Four markers from chromosome 2DS were identified to link to Lr41, and two markers on short arm of chromosome 1D were tightly linked to Lr42. The marker Xarc124 on 2DS was located on 0.3 cM proximal to Lr41 and the marker Xwmc432 on 1DS was located on 0.6 cM proximal to the Lr42. Physical mapping of the markers using Chinese Spring nullitetrasomic and ditelosomic genetic stocks confirmed that markers linked to Lr41 and Lr42 were on 1DS and 2DS, respectively. Markers for these genes can be used for marker-assisted selection in breeding programs.
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