Virulence Associations and Global Context of Genetic Diversity in Iranian Populations of Zymoseptoria tritici

Managing pathogen damage in wheat production is important for sustaining yields. Fungal plant pathogen genomes encode many small secreted proteins acting as effectors that play key roles in the successful colonization of host tissue and triggering host defenses. is the first described avirulence effector, which triggers -mediated immunity in the wheat host in a gene-for-gene manner. Evasion of major resistance factors such as challenges deployment decisions on wheat cultivars. In this study, we analyzed the evolution of the effector in Iranian isolates of . In total, 78 isolates were isolated and purified from 30 infected wheat specimens collected from the East Azerbaijan and Ardabil provinces of Iran. The pathogenicity of all isolates was evaluated on the susceptible wheat cultivar 'Tajan'. A subset of 40 isolates were also tested for pathogenicity on the resistant cultivar 'Shafir' carrying . Genetic diversity at the locus was analyzed for 14 isolates covering the breadth of the observed disease severity. The sequence variation was high, with virulent isolates carrying highly diverse haplotypes. In an analysis including more than 1,000 additional sequences from a global set of isolates, we found that virulent isolates carried haplotypes either clustering with known virulent haplotypes on different continents or constituting previously unknown haplotypes. Furthermore, we found that variants from avirulent isolates clustered with known avirulent genotypes from Europe. Our study highlights the relevance of for virulence and the exceptional global diversity patterns of this effector.