The potential of modern Russian winter and spring wheat (Triticum aestivum L.) varieties for genetic protection against leaf and yellow rust

Leaf and yellow rust are highly damaging diseases of soft wheat. Cultivation of resistant varieties is an environmentally friendly method of control. Successful genetic protection requires information on resistance of cultivated wheat varieties and their genetic diversity. Immunogenetic studies of new Russian varieties for resistance to leaf rust have been carried out at the All-Russian Research Institute of Plant Protection (VIZR) since 2000. In this work, new Russian cultivated wheat varieties were characterized for the first for seedling resistance to leaf and yellow rust and their genotyping was carried out using molecular markers of Lr and Yr genes. The aim of this study was to characterise seedling resistance to leaf and yellow rust in soft wheat varieties, first included in the State Register of Breeding Achievements of the Russian Federation in 2024, and to identify their Lr and Yr genes using molecular markers. Twenty-eight winter and 16 spring varieties of soft wheat were studied. The aim of the work is to characterize domestic varieties of winter and spring soft wheat, which were first included in the State Register of Breeding Achievements in 2024, in terms of resistance to leaf and yellow rust and the composition of Lr and Yr genes identified using molecular markers. The studied materials included 28 winter and 16 spring wheat varieties ( Triticum aestivum ). The experiments were conducted in the laboratory of Mycology and Phytopathology (VIZR) in 2024. For plant inoculation, 4 single pustule isolates of Puccinia triticina (test clones) with different virulence characteristics and geographical origin were used: Pt1 isolate was isolated from the Chelyabinsk P. triticina population in 2022 and assigned to the TLTTR race, Pt2 isolate was obtained from the Saratov population in 2022 and represented by the TGTTT race, Pt3 isolate was isolated from the Krasnodar The Pt4 isolate was obtained from the Dagestan population in 2023 and corresponds to the THTTR race. The test clones differed between in virulence/avirulence to lines with the Lr2a, Lr2b, Lr2c, Lr9, Lr15, Lr19 , and Lr26 genes. Resistance to yellow rust was studied by inoculation with five isolates of P. striiformis . The Pst1 isolate was isolated from the Dagestan pathogen population in 2023, the Pst2 isolate from Krasnodar in 2021, the Pst3 isolate from Leningrad in 2021, the Pst4 isolate from Saratov in 2023, and the Pst5 isolate from Novosibirsk in 2021. The isolates differed in virulence/avirulence to isogenic Av Yr lines 1, 7, 17, 27 and differentiator varieties Chinese 166, Strubes Dickkopf, Hybrid 46, Reichersberg 42, Nord Desprez, Carstens V, Heines VII. In experiments with P. triticina , 8-10-day-old seedlings were used for infection (first leaf stage), with P. striiformis - 11-14-day-old seedlings (second leaf appearance stage). The type of reaction to P. triticina infection was recorded after 9-10 days, P. striiformis - after 16-18 days. E.B. Mains and H.S. Jackson scale was used to determine the type of reaction to leaf rust; the scale of G. Gassner and W. Straib for yellow rust. Plants with scores of 0, 1, 2 were classified as resistant and those with scores of 3, 4 as susceptible. Molecular markers were used to identify 20 Lr genes ( Lr1 , Lr3 , Lr9 , Lr10 , Lr19 , Lr20 , Lr21 , Lr24 , Lr25 , Lr26 , Lr28 , Lr29 , Lr34 , Lr35, Lr37, Lr41(39), Lr47, Lr51, Lr66, Lr6Agi2 ), eight Yr genes ( Yr5 , Yr9 , Yr10 , Yr15 , Yr17 , Yr18 , Yr24, Yr60 ) and the wheat-rye translocation 1AL. 1 RS with unknown Lr and Yr genes. Seven (25 %) winter (Verochka, KVS Emil, Olshanka, Stavropolskaya 7, Emma, En Altais, En Isida) and five (37 %) spring varieties (Agronomichnaya 5, Zagora Novosibirskaya, KVS Karuzum, Kinelskaya Zvezda, Melnitsa) showed resistance to all P. triticina isolates. The number of varieties resistant to the yellow rust pathogen was much lower. Only one winter variety KWS Emil showed resistance to the used isolates of P. striiformis . The genes Lr24, Lr25 , Lr28 , Lr29 , Lr41(39) , Lr47 , Lr51 , LrSp , Lr6Agi2 were characterised as highly effective against leaf rust in Russia; against yellow rust the genes Yr5 , Yr10 , Yr15 , Yr24 . In molecular analysis, of these genes, only Lr24 was identified in varieties KWS Emil, KWS Carusum, Melnitsa (+ Lr20 , Lr34 ). The genes Lr9 and Lr19 belong to the group of partially effective genes. The Lr9 gene was determined in winter variety Vladimirskaya 9 (+ Lr1 ) and spring variety Agronomichnaya 5 (+ Lr26 ), the Lr19 gene in spring varieties - Zauralsky Prostor (+ Lr3 ) and Kinelskaya Zvezda (+ Lr10 ). Moderately effective adult plant resistance genes to leaf Lr37 and yellow rust Yr17 were identified in winter varieties Arena (+ Lr1 , Lr10 , Lr26 , Yr9 ) and Mezhdurechenka. The cluster of partial resistance genes Lr34 , Yr18 and Sr38 was identified in seven winter (Alamat, Aida, Antipovka, Verochka, Donskaya T20, Olshanka, Stavropolskaya 7) and two spring (Agros, Nitsa) varieties.