Wild barley (Hordeum spontaneum) and landraces (Hordeum vulgare) from Turkey contain an abundance of novel Rhynchosporium commune resistance loci

Abstract

Rhynchosporium commune, the causal agent of the disease scald or leaf blotch of barley is a hemibiotrophic fungal pathogen of global importance, responsible for yield losses ranging from 30-40% on susceptible varieties. To date, over 150 resistance loci have been characterized in barley. However, due to the suspected location of the R. commune host jump in Europe, European germplasm has been the primary source used to screen for R. commune resistance leaving wild (Hordeum spontaneum) and landrace (H. vulgare) barley populations from the center of origin largely underutilized. A diverse population consisting of 94 wild and 188 barley landraces from Turkey were genotyped using PCR-GBS amplicon sequencing and screened with six Turkish R. commune isolates. The isolates were collected from distinct geographic regions of Turkey with two from the Aegean region, two from central Turkey and two from the Fertile Crescent region. The data was utilized for association mapping analysis with a total of 21 loci identi ed, of which 13 were novel, indicating that these diverse primary barley gene pools contain an abundance of novel R. commune resistances that could be utilized for resistance breeding. Key MessageRhychosporium commune is a globally devastating pathogen of barley. Wild and landrace barley are underutilized; however, contain an abundance of loci that can be used as potential sources of resistance.

An Island of Receptor-Like Genes at the Rrs13 Locus on Barley Chromosome 6HS Co-locate with Three Novel Sources of Scald Resistance

“…It was interesting to note that both accessions were sourced from Jordan. Clare et al (2023) identified an abundance of scald resistance genes in wild barley accessions from Turkey, but none of the resistances were mapped to the Rrs13 locus. One Rrs13 resistance was derived from a wild barley collected from Bar Giyyora, Israel (Brown et al 1988), not far from the Israel-Jordan border.…”

“…Approximately 50 resistance loci have been discovered on all seven barley chromosomes, with a prevalence to chromosomes 3H and 7H (as comprehensively reviewed by Zhang et al 2020). Sources of resistance have not only originated from H. vulgare (Looseley et al 2012;Schweizer et al 1995), but also from wild relatives such as H. spontaneum and H. bulbosum (Clare et al 2023). For example, Rrs12 on chromosome 7H (Abbott et al 1991), Rrs14 on 1H (Garvin et al 1997) and Rrs15 on 7HL (Genger et al 2005) all originated from H. spontaneum, while Rrs16 Hb on 4HS originated from H. bulbosum (Pickering et al 2006).…”