The studies were conducted in the Lababoratory of plant immunity Agricultural Research Institute for South-East Regions Russia.  The samples of pathogen populations were collected from commercial and promising cultivars of spring and winter bread wheat at the end of their growing season at the maximum level of disease development in a field nursery. Then this inoculum's has been propagated on susceptible cultivars of bread wheat in the laboratory conditions. During three years of studies (2017-2019) 30 monopustules isolates has been  studied. These studied isolates were avirulent to Thatcher near isogenic lines with genes Lr41, Lr42, Lr43+24, Lr53 and virulent to Lr1, Lr2a, Lr2b, Lr2c, Lr3, Lr3bg, Lr3ka, Lr10, Lr11, Lr12, Lr13, Lr14a, Lr14b, Lr15, Lr16, Lr17, Lr18, Lr21, lr22a, lr22b, lr25, lr28, LR 30, Lr32, Lr33, Lr34, Lr35, lr36, lr37, LR 38, Lr40, LR44, Lr45, LR b, LR W, LR Erph, LR Kanred, Lr57, Lr67. The significant variation for virulence was observed in lines with the Lr20, Lr23, Lr24, Lr26, Lr29, and Lr47 genes.  The study of the P. triticina population structure in 2017-2019 revealed a partial loss of the effectiveness of the Lr47 gene. It was found that populations of P. triticina in 2017-2019 were characterized by high virulence.

Проведен анализ структуры образцов саратовских популяций возбудителя бурой ржавчины пшеницы по признакам вирулентности в течение 2013-2017 гг. Инфекционный материал собран с районированных и перспективных сортов озимой и яровой мягкой пшеницы, изучаемых в НИИСХ Юго-Востока, в разной степени пораженнных бурой ржавчиной: от умеренной (10-20 %) до высокой (70-90 %). Анализ вирулентности проводили с использованием серии почти изогенных линий сорта Thatcher, с 52 Lr-генами. Из ежегодно изучаемых образцов популяций патогена выделяли по десять монопустульных изолятов. Установлено, что популяции P. triticina в 2013-2017 гг. характеризовались высокой вирулентностью. Число генов вирулентности колебалось от 40 до 44, а авирулентности от 6 до 9. Существенное варьирование по вирулентности отмечено на линиях с генами Lr9, Lr19, Lr23, Lr24 и Lr29. Высокой эффективностью характеризовались гены Lr41, Lr42, Lr43+24, Lr47, Lr53. Использование этих генов в практической селекции позволит расширить генетическое разнообразие новых сортов и стабилизировать состав популяции патогена. Постоянный мониторинг популяционного состава возбудителя бурой ржавчины по вирулентности позволяет скорректировать стратегию селекции устойчивых сортов и размещения их в регионах возделывания.

The Volga region is one of the main grain-producing regions of Russia. Wheat stem rust caused by Puccinia graminis f. sp. tritici is among the most destructive fungal diseases of wheat. Recently, its harmfulness has increased in the Volga region. In this regard, an analysis of the resistance and diversity of the Sr genes in the Russian wheat cultivars is necessary. In this work, 126 wheat cultivars (including 23 durum wheat cultivars and 103 bread wheat cultivars) approved for use in the Volga region were evaluated for their resistance to two samples of P. graminis f. sp. tritici populations from different Volga region areas at the seedling stage. Specific DNA primers were used to identify resistance genes (Sr2, Sr24, Sr25, Sr26, Sr28, Sr31, Sr32, Sr36, Sr38, Sr39, and Sr57). Highly resistant cultivars (30 from 126) were identified. In bread wheat cultivars, the genes Sr31 (in 19 cultivars), Sr24 (in one cultivar), Sr25 (in 15 spring wheat cultivars), Sr28 (in six cultivars), Sr38 (in two cultivars), and Sr57 (in 15 cultivars) and their combinations—Sr31 + Sr25, Sr31 + Sr38, Sr31 + Sr28, Sr31 + Sr57, Sr31 + Sr28 + Sr57, and Sr31 + Sr24—were identified. The obtained results may be used to develop strategies for breeding rust-resistant cultivars.

The purpose of the current work was to study the development of tan spot, the causative agent of yellow leaf spot Pyrenophora tritici-repentis (Died) Drechsler on winter bread wheat in the conditions of the Saratov region of Russia. In 2018–2019 there was carried out an estimation of the resistance of 33 winter bread wheat samples to the causative agent of yellow leaf spot. It was established that the varieties “Gostianum 237” and “Levoberezhnaya 1” were characterized by a high level of resistance in the fields. There were identified such weak susceptible varieties as “Victoria 95”, “Gubernia”, “Mironovskaya 808”, “Donskaya bezostaya”, “Smuglyanka”, “Kalach 60”, “111-96 / Zhemchuzhina Povolzhiya”, “L 329 / Urozhaynaya”, “Gubernia / Zhemchuzhina Povolzhiya”, “Saratovskaya 90/ Ukraina”, “L 503 / M Freeman”, “81-93 / (Saratovskaya 11 / Kharkov 82)”. There was identified a moderate damage in the varieties “Lutenscens 230”, “Saratovskaya 80”, “Saratovskaya 90 / 14431 M”, “Sozvesdie”, “Anastasia”, “Saratovskaya 8 / Yubilyar”. The varieties “Zhemchuzhina Povolzhiya”, “Saratovskaya 17”, “Elvira”, “Saratovskaya 8 / B.Z.D.”, “(26-72 / N 49)/(L 15 / Pia)/Sar. 8)”, “Saratovskaya 8 / Yubilyar”, “L 503 / M Freeman”, “30-99/(Saratovskaya 11 / Kharkovskaya 82)”, “Sharada / L 31-98”, “346-06 / L 1334-5”, “Saratovskaya 90”, “L 329 / Saratovskaya ubileynaya”, “Istok/(Saratovskaya 90 / L 503)”, “Brigantina / Don 74” were found susceptible to the pathogen. It was identified that the proportion of winter soft wheat samples resistant to Pyrenophora tritici-repentis was 42% of the total number of varieties studied. There was studied dynamics of Pyrenophora tritici-repentis development in the winter soft wheat variety “Saratovskaya90”. It was found out that the damage degree of the winter bread wheat variety “Saratovskaya90” greatly depended upon the remoteness of the sowings from the source of infection.

The current paper has presented the study results of collection winter bread wheat samples. The purpose of the study was to screen the world collection of winter bread wheat for disease resistance in the Nizhnevolzhsky region. The study was carried out on the basis of the FSBSI “Federal Agricultural Research Center of the South-East” (Saratov). In 2017–2021 there was conducted an estimation of the resistance of 152 winter bread wheat samples to the main pathogens. The samples were sown at the optimal time with the SSFC-8 seeder on plots of 3 m2 in a single repetition. The seeding rate was 450 germinating seeds per m2 . There have been studied the world collection varietal samples of winter bread wheat VIR (from breeding centers of the USA, Canada, Ukraine, Slovakia, Latvia, Hungary, etc.), as well as the samples of domestic breeding (FANC of the South-East, NTsZ named after P.P. Lukyanenko, Severokavkazsky FNATS, etc.). There have been identified the most harmful leaf-stem diseases, such as brown rust (Puccinia triticina Erikss.) and stem rust (Puccinia graminis f. sp. Tritici), septoria (Septoria tritici Rob. et Desm.) and yellow leaf blotch (Pyrenophora tritici-repentis (Died) Drechsler). There has been characterized the resistance of the winter bread wheat collection to the complex of leaf-stem diseases. There have been identified two samples with group resistance to brown and stem rusts, septoria and pyrenophorosis; one sample resistant to leaf rust and stem rust; three samples resistant to stem rust and septoria; one sample resistant to leaf and stem rust and septoria; six samples resistant to septoria and pyrenophorosis.