Dissecting multiple resistance specificities at the Mla locus in barley
H. BRABHAM (1), I. Hernández-Pinzón (1), P. Green (1), M. Moscou (1), P. Hayes (2) (1) The Sainsbury Laboratory, United Kingdom; (2) Oregon State University, U.S.A.

In host-pathogen interactions, disease resistance is often conditioned in a gene-for-gene manner involving the direct or indirect interaction of a avirulence and R gene. In contrast, nonhost resistance is known to be broadly functional against a range of microbes. It remains unclear how a plant can be nonhost to the majority of pathogens but encode a finite number of immune receptors. We propose the model of multiple pathogen recognition specificity (MPRS) to explain the broad recognition of nonhost pathogens. Several examples are known, including Arabidopsis RPS4/RRS1 NB-LRR genes and tomato Mi-1 which confer resistance to taxonomically distinct plant pathogens. In our investigation of nonhost resistance in barley to wheat yellow rust, we found that resistance colocalises with Mla, which is a major resistance locus in barley to the host pathogen, barley powdery mildew (Blumeria graminis f. sp. hordei). Resistance to multiple pathogens has been associated with the Mla locus of barley, including B. graminis f. sp. hordei, Puccinia striiformis f. sp. tritici (Rpst1), and Magnaporthe oryzae (RMo1). Over 30 alleles of Mla have been identified to confer isolate specific B. graminis f. sp. hordei resistance, and these belong to the NB-LRR class of resistance genes. Current work is underway to elucidate the relationship of Mla3 and RMo1, including forward genetic (high-resolution recombination screens) and reverse genetic (transformation of Mla3) approaches.

Abstract Number: P17-499
Session Type: Poster