Highly predictive SNP markers for efficient selection of the wheat leaf rust resistance gene Lr16

Leaf rust is an important foliar disease of wheat in Canada that reduces grain yield. Leaf rust can be controlled by growing leaf rust resistant wheat varieties. In this study, researchers developed DNA markers that are predictive of the presence of a leaf rust resistance gene called Lr16. This gene is common in Canadian wheat varieties and provides a high level of leaf rust resistance when a variety carries both Lr16 and another common leaf rust resistance gene called Lr34. These DNA markers will enable wheat breeders to accurately determine whether Lr16 is present in a wheat variety. Similar DNA markers already exist for Lr34. There is some evidence that the combination of Lr16 and Lr34 may provide a so-called ‘durable’ leaf rust resistance, which would be a major breakthrough. Disease resistance frequently becomes ineffective after long term use of specific resistance genes in farmers’ fields. This phenomenon is similar to the buildup of antibiotic resistance in bacteria after prolonged use of a specific antibiotic. The researchers also precisely located Lr16 on a single wheat chromosome, which will lead to DNA sequencing of Lr16 in the future. The chromosomal location also provides wheat breeders with knowledge needed to develop wheat varieties with Lr16 and other genes of interest found on the same wheat chromosome, such as the wheat midge resistance gene Sm1. The DNA markers from this study will facilitate the development of leaf rust resistant wheat varieties, which is important to farmers, the wheat industry, and consumers.