Barley doubled haploid (DH) lines, from a wide cross between landrace Eth069 and cv Baudin, are used to filter gene expression changes from heterogeneous backgrounds during powdery mildew.

Barley powdery mildew is a globally significant disease, responsible for reduced grain yield and quality. A major effect adult plant resistance gene, RBgh2, was previously found in a landrace from Azerbaijan, and mapped to barley chromosome 7HS. To investigate the genetic basis for the resistance, genome-wide gene expression was compared between sets of heterogeneous doubled haploids.