Hélène Pidon, Neele Wendler, Antje Habekuβ, Anja Maasberg, Brigitte Ruge-Wehling, Dragan Perovic, Frank Ordon & Nils Stein

Theoretical and Applied Genetics March 2021; vol. 134:  823–833

Key message

We mapped the Rym14^Hb resistance locus to barley yellow mosaic disease in a 2Mbp interval. The co-segregating markers will be instrumental for marker-assisted selection in barley breeding.

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. Rym14^Hb 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 = 7500), to compensate for a ten-fold reduction in recombination rate compared to intraspecific barley crosses. After high-throughput genotyping, the Rym14^Hb 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.

See: https://link.springer.com/article/10.1007/s00122-020-03733-7

Figure 1: Physical map of the Rym14^Hb locus. a Low-resolution mapping of the Rym14^Hb locus. Graphical genotype and phenotype of the four recombinant F₆ lines. H. vulgare, H. bulbosum, and heterozygous allelic states are represented as orange, blue, and yellow bars, respectively. Coordinates on ‘Morex’ reference genome (Monat et al. 2019) of strategic markers are displayed. Names of the haplotypes are displayed on the left, and phenotypes deduced from the phenotyped F₇ progenies are shown on the right (R resistant, S susceptible, seg segregation of resistance). b High-resolution mapping of the Rym14^Hb locus. KASP and PACE markers are represented as black and blue vertical lines, respectively, and the 11 recombinant haplotypes found in F₂ plants are indicated by horizontal bars: blue = H. bulbosum homozygous; orange = H. vulgare homozygous; yellow = heterogygous. The haplotype name is indicated on the left while the phenotypes of their progeny are shown on the right (R resistant, S susceptible, seg segregation of resistance)