The Rrs1 resistance locus against scald in barley
Abstract
Rhynchosporium commune causes leaf scald, one of the most important diseases of barley. Yield losses attributed to this pathogen commonly range around 5-10%, though losses of up to 40% have been reported. To date, four major scald resistance genes have been mapped in cultivated barley Hordeum vulgare ssp. vulgare, and another four in wild barley Hv. spontaneum or Hv. bulbosum. The most abundant and effective one is the Rrs1 resistance locus. It was mapped to the centromeric region of chromosome 3H.
Rrs1 resistance was detected in the landrace SBCC145 and SBCC154 of the Spanish Barley Core Collection (SBCC). Two large DH mapping populations were developed crossing each donor line with cv. Beatrix. A QTL-analysis was conducted in both populations phenotyped for scald resistance in greenhouse test and in the field. Single QTL was detected on chromosome 3H close to the centromere in both populations and, therefore, confirmed this locus as the only resistance locus in both populations.
The “Rrs1 region” has been saturated with all available SSR and SNP-markers and a consensus map was constructed. New markers for this region are developed based on the llumina iSelect custom 9K barley chip, the barley genome zipper and a BSA analysis with AFLP. The genome zipper identified 64 candidate genes. Sequence analysis and mapping of the candidates is in progress. For fine mapping and haplotyping of all the genes around the Rrs1 loci a mapping population comprising >10,000 F2 from the cross SBCC145 x Beatrix has been constructed. F2 screening has identified around 385 verified recombinant plants. The development of diagnostic markers for Rrs1 will be the basis to incorporate scald resistance in modern barley varieties and the haplotype analysis will help to get more information to discuss the evolution of the Rrs1 locus.
Biography
