Genome-wide association mapping analysis to identify genomic regions associated with virulence in Pyrenophora teres f. teres

Abstract

Net form of net blotch, caused by the fungal pathogen, Pyrenophora teres f. teres (Ptt), is an important foliar disease present in all barley (Hordeum vulgare) producing regions of the world. This fungus is a heterothallic haploid ascomycete and reproduces both sexually and asexually. Sexual recombination in Ptt can produce new combinations of pathogen virulences and lead to changes in disease expression in the host. Changes in virulence can be devastating to the barley industry especially if a limited number of barley varieties with common resistances are grown. Knowledge of the genetic structure and genes involved in virulence is vital to researchers and breeders to increase the durability of Ptt resistance in barley varieties. We have used a genome-wide association mapping approach to characterise genomic regions associated with virulence in Australian barley varieties. One hundred and eighty-seven Ptt isolates collected from five Australian states were genotyped using DArTseq (Diversity Arrays Technology Pty Ltd) markers and phenotyped across ten different barley genotypes. Association mapping analysis identified eleven unique genomic regions associated with virulence. The majority of these genomic regions were located on Ptt chromosomes 3 and 5. Four of the regions identified were confirmed via bi-parental quantitative trait loci mapping analysis in two different Ptt/Ptt populations. Knowledge of the virulence genes present in the Australian Ptt pathogen population will provide barley breeding programs with valuable information for future breeding of Ptt resistant barley varieties.