Baig, D. I.; Moeller, M.; Tam, R.; Pereira, E. C.; Rodriguez-Algaba, J.; Mojerlou, S.; Hovmoller, M. S.; Fejer Justesen, A.; Nha Ho, T.; Zhang, J.; Ding, Y.; Li, J.; Wu, J.; Periyannan, S.; Zhang, X.; Rathjen, J.; Schwessinger, B.

Wheat diseases, including wheat stripe (yellow) rust, significantly impact wheat production and lead to several billions of dollars in economic losses each year. Wheat stripe rust is caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst) which is best controlled via integrated disease management including growing disease resistant wheat cultivars. To-date, there are over 80 catalogued and more than 10 cloned stripe rust resistance genes (Yr genes). Yet our knowledge of corresponding avirulence (Avr) genes lags far behind which contrasts with other important wheat pathogens. The absence of cloned Pst's Avrs reflects long-standing challenges associated with Pst complex, highly heterozygous genome and the lack of robust transformation and map-based cloning systems. Recent advances in high-quality genome assemblies and wheat defense reporter assays have now made Avr gene identification more feasible. Building on these step-change advancements, we identify and characterize AvrYr7 which is specifically recognized by Yr7. We further identify six additional alleles of avrYr7 that escape recognition due to non-synonymous genetic variations, transposable element activity, missense mutation, and expression polymorphism. These findings provide critical insights into virulence evolution in one of the world's most important wheat pathogens.