Pathogen genetics identifies avirulence/virulence loci associated with barley chromosome 6H resistance in thePyrenophora teresf.teres– barley interaction

Abstract

AbstractBarley net form net blotch (NFNB) is a foliar disease caused byPyrenophora teresf.teres. Barley line CIho5791, which harbors the chromosome 6H broad spectrum resistance geneRpt5, displays dominant resistance toP. teresf.teres. To genetically characterizeP. teresf.teresavirulence/virulence on the barley line CIho5791, we generated aP. teresf.teresmapping population using a cross between the Moroccan CIho5791-virulent isolate MorSM40-3, and the avirulent reference isolate 0-1. Genetic maps were generated for all 12 chromosomes (Ch) and quantitative trait locus (QTL) mapping identified two significant QTL associated withP. teresf.teresavirulence/virulence on CIho5791. The most significant QTL mapped toP. teresf.teresCh1 where the virulent allele was contributed by MorSM40-3. A second QTL mapped to Ch8, however, this virulent allele was contributed by 0-1. The Ch1 and Ch8 loci accounted for 27 and 15% of the disease variation, respectively and the avirulent allele at the Ch1 locus was shown to be epistatic over the virulent allele at the Ch8 locus. Additionally, we used 177 sequencedP. teresf.teresisolates in a genome wide association study that identified the same Ch1 and Ch8 loci as the two most significant associations. Within the identified genomic regions, we identified several genes that encoded small secreted proteins, one or more of which may be responsible for overcoming the CIho5791 resistance. Results presented here demonstrate the complexity of avirulence/virulence in theP. teresf.teres- barley interaction.