Development of a High-resolution Melt (HRM) Marker Diagnostic to the Wheat (Triticum aestivum L.) Leaf Rust Resistance Gene Lr34.

The wheat leaf rust and multi-pathogen resistance gene Lr34 has been used in many breeding programs throughout the world as it confers durable resistance and is known to enhance the resistance of other leaf rust resistance genes and conditions resistance to stripe rust (Yr18), stem rust (Sr57), and powdery mildew (Pm38). Lr34 is mapped on chromosome 7D and numerous molecular markers associated with the gene have been identified by different studies. However, some of the identified diagnostic markers are not codominant and are based on gel electrophoresis or fail to show effectiveness in Canadian wheat germplasm. We recently developed a fast and scalable codominant marker assay effective in Canadian wheat germplasm and diagnostic to the adenosine triphosphate binding cassette (ABC) transporter gene, identified as the sole candidate for Lr34, to provide an alternative to existing markers. Here we describe the method that could similarly be used in developing a high-resolution melt (HRM) marker diagnostic to other resistance genes.