Mapping and Candidate Gene Analysis of an All-Stage Stem Rust Resistance Gene in Durum Wheat Landrace PI 94701.

f. sp. (), the causal agent of wheat stem rust, poses a significant threat to global wheat production. Genetic resistance offers a cost-effective and sustainable solution. The durum wheat landrace PI 94701 was previously hypothesized to carry two stem rust resistance () genes, but their chromosomal locations were unknown. In this study, we mapped and characterized an all-stage gene in PI 94701, temporarily designated as . In seedling tests, was effective against all six races tested. Using a large segregating population, we mapped on chromosome arm 5BL within a 0.17-cM region flanked by markers and , corresponding to 1.04 and 2.15 Mb genomic regions in the Svevo and Chinese Spring reference genomes. Within the candidate region, eight genes exhibited differential expression between the -inoculated resistant and susceptible plants. Among them, two nucleotide-binding leucine-rich repeat (NLR) genes, and , showed high polymorphism between the parental lines and were upregulated in -inoculated resistant plants. However, the flanking and completely linked markers developed in this study could not accurately predict the presence of in a survey of 104 wheat accessions. is a promising resource for enhancing stem rust resistance in wheat breeding programs.