Genome-Wide Association Studies of Stripe Rust Resistance in Spring Wheat Landraces from Northwest China

Stripe rust is an important disease affecting wheat production around the world and poses a constant threat to yield. Discovery of new resistance genes is essential for long-term maintenance of resistance. This study used a group of 273 spring wheat landraces collected in northwest China to identify better sources of resistance to stripe rust. The landrace population was planted in five environments to assess adult plant resistance. Both genetic and environmental factors were associated with resistance variation. Several varieties, including Banjiemang, Gezanmai, and Datangsanyuemai, were found to be highly resistant in all environments. Population structure analysis divided the population into six subgroups, and there were significant differences in stripe rust resistance responses between these subgroups. A genome-wide association study (GWAS) was performed using two algorithms to balance the false negative and false positive rates. Eight reliable quantitative trait loci (QTL) and their candidate genes were detected on chromosomes 1B, 2B, 3B, 5A, 6D, and 7A. To determine the resistance of the identified QTL, we evaluated the seedling-stage infection responses of different genotypes to the stripe rust races CYR32 and CYR34. The pyramid effects of favorable alleles have been validated to improve resistance. The identified resistant varieties and QTL will be useful for further improving stripe rust resistance in wheat breeding.