High-resolution mapping ofRym14^Hb, a wild relative resistance gene to barley yellow mosaic disease

Abstract

Barley yellow mosaic disease is caused by Barley yellow mosaic virus and Barley mild mosaic virus, and leads to severe yield losses in barley (Hordeum vulgare) in Central Europe and East-Asia. Several resistance loci are used in barley breeding. However, cases of resistance-breaking viral strains are known, raising concerns about the durability of those genes. Rym14Hb is a dominant major resistance gene on chromosome 6HS, originating from barley’s secondary genepool wild relative Hordeum bulbosum. As such, the resistance mechanism may represent a case of non-host resistance, which could enhance its durability. A susceptible barley variety and a resistant H. bulbosum introgression line were crossed to produce a large F2 mapping population (n=7,500), to compensate for a ten-fold reduction in recombination rate compared to intraspecific barley crosses. After high-throughput genotyping, the Rym14Hb locus was assigned to a 2Mbp telomeric interval on chromosome 6HS. The co-segregating markers developed in this study can be used for marker-assisted introgression of this locus into barley elite germplasm with a minimum of linkage drag.

Rapid evolution of an RNA virus to escape recognition by a rice nucleotide‐binding and leucine‐rich repeat domain immune receptor

“…Dominant resistance to viruses is frequent in cereals. The corresponding genes have been in many cases genetically characterized and NLRs have been frequently identified as candidate genes suggesting that, also in cereals, they are a major class among dominant virus R genes (Wu et al, 2007;Zhao et al, 2010;Lu et al, 2011;Okada et al, 2020;Pidon et al, 2021). Our study lends strong support to this hypothesis and suggests that monocot immunity to viruses also largely relies on the intracellular recognition of viral proteins by NLRs.…”