Identification of virulence genes of the septoria pathogen Zimoseptoria tritici in Russia

The studies aimed to determine the frequency of occurrence of virulence genes of the wheat septoria pathogen Z. tritici and to evaluate the effectiveness of resistance to Stb-genes against regional populations of this septoria species. The work was carried out in 2009-2022. Eight wheat varieties with known resistance genes were used in the experiments: Bulgaria 88 (Stb1), Veranopolis (Stb2), Israel 493 (Stb3), Tadinia (Stb4), CS/Synthetic 7D (Stb5), Flame (Stb6), Estanzuela Federal (Stb7) and W7984 (Stb8). A total of 412 monosporic isolates of Z. tritici were tested, isolated in 23 regions of 8 regions of the Russian Federation: North Caucasus, Central Black Earth, Central, Volga, Northwestern, Volga-Vyatka, West Siberian, and Kaliningrad regions. Experiments were carried out in artificial climate chambers and in a greenhouse on plants in the seedling phase. The highest virulence of Z. tritici isolates was observed for varieties carrying the Stb1, Stb2, Stb5 and Stb7 genes, especially in the North Caucasus, Central Black Earth, Volga regions and the Kaliningrad region. Almost no virulent isolates were observed for varieties carrying the Stb3, Stb6 and Stb8 genes. Isolates with a wide range of virulence genes, virulent for more than 3 varieties, prevailed in the population of Z. tritici from the Kaliningrad region, accounting for 55.6%. In the North Caucasus, Central Black Earth and Volga regions, widely virulent isolates were found with a frequency of 16.7-23.3%. In the Central, North-Western and Volga-Vyatka regions, the value of this indicator was 5.9-10%; in the West Siberian region there were no widely virulent isolates. Today, the Stb3, Stb6 and Stb8 genes can be recommended for use in breeding and genetic programmes to create forms resistant to Septoria leaf spot, as they are highly effective against Z. tritici in the Russian Federation. The Stb1, Stb2 and Stb4 genes are effective only against certain regional populations of Z. tritici. The Stb5 and Stb7 genes turned out to be ineffective.

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