Identification of New Sources of Resistance to Septoria Tritici Blotch Caused by Zymoseptoria tritici

Twenty‐nine synthetic hexaploid wheats (SHWs) were evaluated for resistance to five isolates of Zymoseptoria tritici, a devastating wheat pathogen worldwide. The five Z. tritici isolates varied in their virulence spectra towards wheat genotypes, indicating that they have distinct set of avirulence genes. New isolate‐specific resistances were identified that could be used in wheat breeding programmes. Comparing with the previous studies, the number of specific resistances identified in this study is considerable. Among 150 interactions, 78 isolate‐specific resistances were identified. Interestingly, 21 wheat genotypes showed specific responses to one or more isolates tested. Of these, 12 genotypes were highly resistant to all isolates, indicating that they possess known or novel effective resistance genes. The Stb15 and Stb16/Stb17 are effective resistance genes towards isolates used in this study, indicating that the conferred resistance in these genotypes is due to the presence of either of these genes in combination or individually. Alternatively, they may carry novel broad‐spectrum resistance gene(s) that their identification is of interest. Our data suggest that the presence of complete resistance to various Z. tritici isolates in SHWs justifies the need for more in‐depth research to characterize the likely novel genes.