Leaf Rust Resistance Evaluation and Identification of Lr Genes in 48 Selected Common Wheat Cultivars in China

To elucidate the leaf rust resistance and distribution of Lr genes in major wheat-producing regions of China, 48 common wheat cultivars newly registered at the national level between 2020 and 2022 were phenotyped via multi-race field resistance assays and gene postulation. Parallel molecular marker genotyping was performed on the entire panel to detect the presence of nine documented Lr genes (Lr1, Lr9, Lr10, Lr19, Lr20, Lr24, Lr26, Lr28, and Lr34), and the resistance gene profiles of all accessions were further validated by integrating genotyping results with pedigree tracing analysis. The present study systematically characterizes this uniformly assembled panel of 48 recently registered national wheat cultivars, offering an updated, comprehensive overview of Lr gene distribution patterns in current Chinese commercial wheat breeding programs. The results indicated that nine formally catalogued Lr resistance genes were present in the tested wheat cultivars, predominantly occurring in diverse pyramidal combination patterns. The Lr1 and Lr26 exhibited the highest detection frequency across the entire cultivar panel. Furthermore, Lr10, Lr11, Lr14a, Lr15, Lr28, Lr33 and Lr39 genes were putatively identified in a small subset of the tested accessions. None of the cultivars carried Lr9, Lr19, Lr20, or Lr24. Seven cultivars were susceptible to all tested pathogen races. Two of the assessed wheat cultivars were confirmed to carry effective adult plant resistance, whereas an additional two cultivars were classified as carrying the characteristic slow rusting resistance phenotype.. Collectively, these results provide critical empirical evidence and actionable theoretical references for targeted regional cultivar deployment, durable leaf rust resistance breeding, and novel resistance gene discovery in Chinese wheat production systems.