An optimized disease resistance gene cloning workflow for wheat

The cloning of disease resistance genes in wheat has been disproportionately slow, tedious and costly because of the large and complex genome. Wheat gene cloning projects in the late 1990s and early 2000s were multi-year endeavors, often spanning a decade or longer. The development of genomics-assisted gene cloning tools and speed breeding have significantly accelerated gene cloning in wheat over the past years. Here, we present an optimized high-throughput disease resistance gene cloning workflow that allows to identify causal genes in less than six months. As a proof-of-principle, we clone the stem rust resistance gene Sr6, which has been a historically relevant source of resistance to confine a major stem rust outbreak in North America in the mid-20th century. Sr6 encodes a CC-BED-domain-containing nucleotide-binding and leucine-rich repeat (NLR) immune receptor. The workflow provides a basis to tackle the systematic cloning of all the genetically described disease resistance genes by the wheat community, which will facilitate knowledge-guided deployment of resistance genes in wheat breeding.