Markers Linked to Stem Rust Resistance Genes Sr39 and Sr40 for Selecting Wheat Breeding Lines

Introduction of genes conferring resistance to Puccinia graminis is considered as the best approach to protect common wheat against stem rust. To facilitate marker-assisted selection of common wheat breeding lines with the stem rust resistance genes Sr39 and Sr40, the testing of molecular markers for these genes was carried out. The markers used for the research were the following: BE500705, Xmag2090, Xmag464, Xcnl158, Xwmc25, Sr39#50, Sr39#22, BCD260, and Xwmc344. Among the simple sequence repeat markers, only Xmag2090, Xwmc25, and Xwmc344 proved to be polymorphic upon analysis of amplicons by polyacrylamide gel electrophoresis followed by silver staining. The markers Sr39#50 and Sr39#22 produced similar amplicons in the control lines RL5711 with Sr39 and RL6089 with Sr40, while amplified fragments were absent in the cultivars. Sr39#50 and Sr39#22 were used for marker-assisted selection of F2 lines from the cross Khutorianka × RL6089 (Sr40) and F4 lines from the cross Solomiia × RL5711 (Sr39). Using Sr39#50, the Sr40 resistance marker was found in 46% of the F2 offspring of the cross Khutorianka × RL6089. Among the F4 offspring of the cross Solomiia x RL5711, the frequency of genotypes with the combination of the Sr39#50 and Sr39#22 marker amplicons was only 11%. Additionally, 33% of the F4 lines showed the Sr39#22 amplicon of approximately 800 bp but lacked the Sr39#50 resistance markers. The reduced frequency of lines with the Sr39 and Sr40 genes may be due to the decreased survival of genotypes with the 2B chromosome introgression after fall planting. The winter wheat lines with the Sr39 or Sr40 gene may be used as the initial material in breeding programs.