Dual specificity at the Mla locus confers resistance to barley powdery mildew and wheat stripe rust
M. MOSCOU (1), I. Hernandez-Pinzon (1) (1) The Sainsbury Laboratory, United Kingdom

Resistance to biotrophic pathogens is often controlled by a gene-for-gene interaction, wherein the product of a plant resistance (R) genes recognize the corresponding effector encoded by an avirulence gene in the pathogen. However, there are several R loci that confer resistance to multiple diverse pathogens. We initiated an investigation to define the genetic architecture of the host species specificity of Puccinia striiformis f. sp. tritici (PST; wheat stripe rust). Mapping resistance from 16 diverse accessions of barley identified a major locus conditioning resistance to PST that mapped to the barley powdery mildew resistance locus, Mla. Fine-mapping established that these two resistance specificities are in complete coupling. To define the gene content in the region, we developed a BAC library from a near-isogenic line containing Mla7. Sequencing of the minimal tiling path using PacBio sequencing showed that suppressed recombination was defined by a completely distinct genomic structure as compared to the reference genome. Expression analysis using RNAseq showed the Mla7 is the primary candidate for the resistance to wheat stripe rust. Current work is underway to determine the functionality of Mla against wheat stripe rust based on transformation and targeted mutagenesis. The observation of dual specificity at Mla broadens our understanding of multiple pathogen resistance and the positive and negative consequences of selection in plant breeding.

Abstract Number: P17-573
Session Type: Poster