Species composition of septoria blotch of cereal crops and identification of effector genes in populations of <i>Parastagonospora</i> spp. on the territory of Krasnodar and Leningrad regions of the Russian Federation

Abstract

The studies were conducted in Krasnodar and Leningrad Oblast s in order to clarify the species composition of wheat septoriosis pathogens and further characterize the populations of Parastagonospora nodorum and P. pseudonodorum for the presence of effector genes Tox1, Tox3, ToxA and Tox267 using associated molecular markers to create artificial infection backgrounds to identify sources and donors of leaf spot resistance. The material for the study was represented by samples of affected plants collected in 2023. In the Leningrad Oblast and Krasnodar Krai the species of Zymoseptoria tritici demonstrated predominance. It was detected on all of the examined plant samples (100 % occurrence). P. nodorum and P. pseudonodorum were noticed less frequently in the Leningrad Oblast, the occurrence of P. nodorum was 80 %, while P. pseudonodorum – 60 %. In Krasnodar Krai, the occurrence of P. pseudonodorum comprised 35.29 %, while P. nodorum – 11.76 %. In the present study the primer pair SnTox2DONRF/SnTox2DONRS was applied for the first time to test Russian populations of Parastagonospora spp. for the presence of the Tox267 gene. Molecular screening revealed the ToxA and Tox1 genes in P. nodorum and P. pseudonodorum, while the Tox3 and Tox267 genes were identified only in P. nodorum. Of the 28 P. nodorum isolates studied, the presence of the ToxA gene was found in 29 % (8 isolates from the Krasnodar Krai). The Tox1 gene was noted in 32 % (5 isolates from the Leningrad Oblast and 4 from the Krasnodar Krai). The Tox3 gene was identified in 64 % of 28 (8 isolates from the Krasnodar Krai and 10 from the Leningrad Oblast). The Tox276 gene was found only in the genotype of 8 isolates from the Krasnodar Krai, which amounted to 29 % of those studied. The study also included 87 isolates of P. pseudonodorum. Of these, 5 % had ToxA in the genotype (4 isolates from the Krasnodar Krai) and 23 % Tox1 (17 isolates from Leningrad Oblast; 3 from the Krasnodar Krai).