Oral Presentation Science Protecting Plant Health 2017

Development of markers to allow incorporation of complementary resistance genes to Rhynchosporium into elite barley varieties (4537)

Anna Avrova 1 , M Coulter 1 , L Griffe 1 , M Bayer 1 , B Buettner 2 , M Looseley 1
  1. The James HuttonInstitute, Dundee, ANGUS, United Kingdom
  2. Bavarian State Research Center for Agriculture, Freising, Germany

Rhynchosporium or leaf scald, caused by the fungal pathogen Rhynchosporium commune, is one of the most destructive and economically important diseases of barley. Current control practices for this and other foliar pathogens of barley rely heavily on fungicides, resulting in a significant cost to farmers. Additionally, high levels of fungicide use can lead to pathogen insensitivity to effective fungicide classes. The most sustainable and cost effective method of protecting against R. commune and other foliar pathogens is through the production of durably resistant barley cultivars. This requires the identification of tightly linked markers to a number of complementary resistance genes.

To address this demand, multiple collections of barley genotypes including 660 UK spring barley varieties, 480 Syrian and Jordanian landraces, and mapping populations for Rrs1 and horizontal resistance genes have been assessed for resistance to a complex natural population of R. commune in a field disease nursery at the James Hutton Institute in Dundee, Scotland. Application of a genome-wide association scan (GWAS) identified a number of QTL in genomic regions previously shown to contain major resistance genes against R. commune, in particular Rrs1 on chromosome 3H and Rrs2 on 7H.  In addition, novel QTL on 2H and 5H were detected. Phenotyping with individual R. commune strains differentiating Rrs1 and newly mapped Rrs18 resistances, combined with advanced barley genomics resources, allowed narrowing down of the physical intervals containing Rrs1 and Rrs18.

Our results indicate the importance of major resistance genes against R. commune, in particular Rrs1, in determining resistance in UK spring barley and their continued effectiveness against natural populations of R. commune.

The diagnostic markers for Rrs1Rrs18, and other resistance loci will facilitate the efficient production of new varieties with durable resistance to Rhynchosporium by barley breeders following incorporation into a marker assisted breeding programme.