Identification and Molecular Marker Detection of Leaf Rust Resistance Genes in Wheat Lines from China: Development of an Efficient Software for Gene Postulation

Wheat leaf rust, caused by Puccinia triticina, is one of the most devastating diseases in common wheat (Triticum aestivum) globally. Using resistant lines is the most cost-effective and safe disease control method. Eighty-three wheat lines from China and 36 differential lines, mainly near-isogenic lines with known leaf rust resistance (Lr) genes in the Thatcher background, were inoculated with 17 P. triticina races at the seedling stage to postulate Lr gene(s) in the greenhouse. Field tests conducted during the 2020-2021 and 2021-2022 cropping seasons assessed adult-plant resistance to leaf rust. Moreover, we developed a graphical user interface bioinformatics toolkit platform called WEKits v1.0, which integrates a gene postulation submodule based on the gene-for-gene hypothesis, providing accurate and efficient analysis. Through gene postulation, molecular marker detection, and pedigree analysis, we identified the presence of nine Lr genes (Lr1, Lr10, Lr14a, Lr21, Lr26, Lr34, Lr37, Lr44, and Lr13/LrZH22) either individually or in combination in 30 wheat lines. Furthermore, 19 lines exhibited slow rusting resistance in both growing seasons. The development of the WEKits software significantly enhanced the efficiency and accuracy of the gene postulation process, providing a valuable tool for rapid identification of known resistance genes in the wheat lines. This could create a vital input to wheat rust resistance breeding. The results identified in this study and the WEKits platform are valuable for selecting lines with effective Lr genes and breeding rust-resistant wheat.