Kelybin, Vasiliy Nikolevich

Skolotneva E.S., Kosman E., Kelbin V.N., Morozova E.V., Laprina Y.V., Baranova O.A., Kolomiets T.M., Kiseleva M.I., Sergeeva E.M., Salina E.A.

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, which used to be a harmful disease of winter wheat in the southern part of Russia, has been largely affecting the yield of spring bread wheat in the territories of the temperate climate zone since 2009. In total, 222 P. graminis f. sp. tritici isolates were obtained from samples of susceptible cultivars of spring bread wheat in Central and Volga regions and Omsk and Novosibirsk provinces in 2019. Genotyping of the isolates was carried out at 16 simple-sequence repeat (SSR) loci. Number of alleles, proportion of heterozygotes, and deviation from Hardy-Weinberg equilibrium were determined at each SSR locus. Based on genetic variability of SSR genotypes, it was shown that the P. graminis f. sp. tritici population is subdivided into two large clusters in the territory of the Russian temperate climate zone: the “European” population (the Central region) and the “Asian” one (the Volga region and two main wheat provinces of Western Siberia). Both of the P. graminis f. sp. tritici populations are characterized by a mixed mode of reproduction (sexual and clonal) but different sources of inoculum seem to shape a genotype structure within them. A group of P. graminis f. sp. tritici genotypes with high variability, the inbreeding coefficient closed to zero, and low observed heterozygosity was revealed among samples from Omsk. Moreover, two singular SSR genotypes identified among the Asian samples of P. graminis f. sp. tritici isolates should attract special attention in the monitoring of stem rust in order to disclose unexpected rapid changes of the pathogen in the corresponding regions and to prevent disease outbreak.

Kelbin V.N., Skolotneva E.S., Shamanin V.P., Salina E.A.

Stem rust disease caused by the obligate biotrophic fungus Puccinia graminis f. sp. tritici significantly reduces the yield and quality of wheat grain. A total of 92 entries of new Siberian agricultural wheat germplasm were studied with an integrated approach: phenotyping in the field and seedling stage reactions and using molecular markers to identify stem rust resistance genes. Among the tested germplasm, 38% were highly or moderately sensitive to stem rust, and 56% were resistant or moderately resistant. In total, 10 out of 16 molecular markers were positive in 92 entries of the new Siberian germplasm: specific or major genes Sr15, Sr22, Sr23, Sr24, Sr25, Sr31, Sr38 and Sr44 and nonspecific or minor genes Sr2 and Sr57, singly or combined. The Sr31 + Sr44, Sr31 + Sr24 and Sr31 + Sr25 gene pyramids provided effective resistance to natural infection. Since a substantial number of gene pyramids with various degrees of genetic resistance were identified, this wheat germplasm could be useful to pursue a strategy of durable resistance to stem rust in Western Siberia.

Skolotneva E.S., Kelbin V.N., Shamanin V.P., Boyko N.I., Aparina V.A., Salina E.A.

Present-day wheat breeding for immunity exploits extensively closely related species from the family Triticeae as gene donors. The 2NS/2AS translocation has been introduced into the genome of the cultivated cereal Triticum aestivum from the wild relative T. ventricosum. It contains the Lr37, Yr17, and Sr38 genes, which support seedling resistance to the pathogens Puccinia triticina Eriks., P. striiformis West. f. sp. tritici, and P. graminis Pers. f. sp. tritici Eriks. & E. Henn, which cause brown, yellow, and stem rust of wheat, respectively. This translocation is present in the varieties Trident, Madsen, and Rendezvous grown worldwide and in the Russian varieties Morozko, Svarog, Graf, Marquis, and Homer bred in southern regions. However, the Sr38 gene has not yet been introduced into commercial varieties in West Siberia; thus, it remains of practical importance for breeding in areas where populations of P. graminis f. sp. tritici are represented by avirulent clones. The main goal of this work was to analyze the frequency of clones (a)virulent to the Sr38 gene in an extended West Siberian collection of stem rust agent isolates. In 2019–2020, 139 single pustule isolates of P. graminis f. sp. tritici were obtained on seedlings of the standard susceptible cultivar Khakasskaya in an environmentally controlled laboratory (Institute of Cytology and Genetics SB RAS) from samples of urediniospores collected on commercial and experimental bread wheat fields in the Novosibirsk, Omsk, Altai, and Krasnoyarsk regions. By inoculating test wheat genotypes carrying Sr38 (VPM1 and Trident), variations in the purity of (a)virulent clones were detected in geographical samples of P. graminis f. sp. tritici. In general, clones avirulent to Sr38 constitute 60 % of the West Siberian fungus population, whereas not a single virulent isolate was detected in the Krasnoyarsk collection. The Russian breeding material was screened for sources of the stem rust resistance gene by using molecular markers specific to the 2NS/2AS translocation. A collection of hybrid lines and varieties of bread spring wheat adapted to West Siberia (Omsk SAU) was analyzed to identify accessions promising for the region. The presence of the gene was postulated by genotyping with specific primers (VENTRIUP-LN2) and phytopathological tests with avirulent clones of the fungus. Dominant Sr38 alleles were identified in Lutescens 12-18, Lutescens 81-17, Lutescens 66-16, Erythrospermum 79/07, 9-31, and 8-26. On the grounds of the composition of the West Siberian P. graminis f. sp. tritici population, the Sr38 gene can be considered a candidate for pyramiding genotypes promising for the Novosibirsk, Altai, and Krasnoyarsk regions. 

Kelbin V.N., Skolotneva E.S., Salina E.A.

Current studies on bread wheat resistance to stem rust have two main subjects: complex analysis for resistance of bread wheat germplasm using molecular markers, field screening and laboratory tests against samples of different fungal populations, and searching for sources and donors of new genes and gene loci, including cultivated and wild relatives of wheat. To achieve adequate genetic control of the disease, an integral approach is important, incorporating both data on sources of resistance and relevant information on pathogenic populations existing in the region, their race composition and dynamics of virulence genes. The analysis of experimental data on field screening of bread wheat varieties from the CIMMYT nursery germplasm for stem rust resistance in the Omsk and Novosibirsk regions, together with laboratory testing of infection samples on the international set of wheat differential lines, suggests that a separate “Asian” population of Puccinia graminis f. sp. tritici exists in Western Siberia and the Altai Territory. Wheat resistance genes Sr2, Sr6Ai#2, Sr24, Sr25, Sr26, Sr31, Sr39, Sr40, Sr44, and Sr57 are of practical interest for advanced wheat breeding programs for stem rust immunity in Western Siberia. This review provides an analysis of the gene sources that remain effective against the West Siberian population of P. graminis, in order to facilitate the initial stage of selection of breeding material to develop a stable genotype by gene pyramiding. The basic requirements for conducting a phytopathological test of breeding material are presented. A list of molecular markers for the mentioned resistance genes, both widely used in marker-assisted selection and requiring verification, has been compiled.

Skolotneva E.S., Kosman E., Patpour M., Kelbin V.N., Morgounov A.I., Shamanin V.P., Salina E.A.

Management of wheat stem rust in Western Siberia has gained importance since the first outbreaks in 2007-2010 and 2016. The race composition and virulence patterns were investigated for the enlarged Puccinia graminis f. sp. tritici (Pgt) samples collected in three neighboring regions Omsk, Novosibirsk, and Altai during 2017-2018. Most of Pgt isolates were identified as virulent to wheat lines with genes Sr5, Sr9a, Sr10, Sr38, SrMcN and avirulent to Sr24, Sr31. Differentiation ability of genes Sr6, Sr7b, Sr8a, Sr9b, Sr9d, Sr9g, Sr9e, Sr11, Sr17, Sr21 Sr30, Sr36, and SrTmp to distinguish between the regional populations was established. A total of 33 virulence phenotypes or races were detected among 115 Pgt isolates tested. Based on virulence phenotypes, two different Pgt subpopulations were identified in the Altai and Omsk regions likely originating from asexual and sexual cycles, respectively. The Novosibirsk pathogen population seems to be a mixture of isolates originated from both neighboring regions with virulence phenotypes that developed in the west, Omsk (TKRPF, QHHSF, and MLLTF) and in the south, Altai (NFMSF, LKCSF, LKMSF, and PKCSF) of Western Siberia.

Сколотнева Е.С., Кельбин В.Н., Моргунов А.И., Бойко Н.И., Шаманин В.П., Салина Е.А.

Kazantsev F.V., Skolotneva E.S., Kelbin V.N., Salina E.A., Lashin S.A.

Population structure of fungal infections in wheat differs between wheat varieties and environments. Taking into account evolution of host-pathogen interactions, genetic diversity of both wheat and fungus must be a monitored. In order to catalogue information to support need of wheat pathologists and breeders, who use conventional methods and Molecular Assisted Selection (MAS) techniques, we have developed the Molecular Identification of Genes for Resistance in Wheat (MIGREW) database. The main goal of this database is to support wheat breeding efforts to develop immunity to rusts and powdery mildew. MIGREW is also focused on effectiveness of wheat resistance genes in different regions of Russia to provide users relevant information on the rapidly changing population structure of pathogens.

Klindworth D.L., Rouse M.N., Olivera P.D., Jin Y., Chu C., Friesen T.L., Zhong S., Faris J.D., Fiedler J.D., Haugrud A.R., Gu Y.Q., Elias E.M., Liu S., Cai X., Xu S.S.

AbstractFour durum wheat (Triticum turgidum ssp. durum) lines Rusty‐KLB (Reg. no. GP‐1098, PI 705448), Rusty‐14803 (Reg. no. GP‐1097, PI 705447), Rusty‐ST464C1 (Reg. no. GP‐1099, PI 705449), and CAT‐A1 (Reg. no. GP‐1096, PI 705446), which carry stem rust resistance gene Sr13 alleles Sr13a, Sr13b, Sr13c, and Sr13d, respectively, are released by USDA‐ARS. These alleles originated from cultivated emmer wheat (T. turgidum ssp. dicoccum) landrace Khapli (CItr 4013), T. turgidum ssp. polonicum accession CItr 14803, durum landrace ST464 (PI 191365), and durum line Camadi Abdu tipo #103 (PI 192168), respectively. Rusty‐KLB, Rusty‐14803, and Rusty‐ST464C1 are near‐isogenic lines with the pedigrees Rusty*7/KL‐B, Rusty*4/3/Rusty/CItr 14803//2*Rusty, and Rusty*7/ST464‐C1, respectively. KL‐B, ST464‐C1, and CAT‐A1 are monogenic lines with the pedigrees Marruecos 9623//Khapli/Marruecos 9623, Marruecos 9623*2/ST464, and Marruecos 9623*2/Camadi Abdu tipo #103, respectively. Sr13 can be detected by perfect markers including Kompetitive allele specific polymerase chain reaction (KASP) marker KASPSr13 and semi‐thermal asymmetric reverse polymerase chain reaction (STARP) markers rwgsnp37. Specific alleles can be identified via STARP markers rwgsnp38, rwgsnp39, and rwgsnp40. The Sr13 alleles provide a moderate level of resistance, typically an infection type 2, to a broad spectrum of stem rust races. Sr13c was effective against all 15 stem rust races tested while Sr13a was ineffective only against race TCMJC. Sr13b was ineffective against JRCQC, QCCJC, QFCSC, and TTRTF. Sr13d is notable in being the only Sr13 allele ineffective to TTKSK (Ug99) and TKTTF. These lines are useful for studying the host‐stem rust pathogen interactions, identifying new genes, and breeding durum and bread wheat cultivars with stem rust resistance.

Pirko Y.V., Kozub N.O., Rabokon A.M., Shysha O.M., Sozinov I.O., Karelov A.V., Sozinova O.I., Yemets A.I., Blume Y.B.

Introduction of genes conferring resistance to Puccinia graminis is considered as the best approach to protect common wheat against stem rust. To facilitate marker-assisted selection of common wheat breeding lines with the stem rust resistance genes Sr39 and Sr40, the testing of molecular markers for these genes was carried out. The markers used for the research were the following: BE500705, Xmag2090, Xmag464, Xcnl158, Xwmc25, Sr39#50, Sr39#22, BCD260, and Xwmc344. Among the simple sequence repeat markers, only Xmag2090, Xwmc25, and Xwmc344 proved to be polymorphic upon analysis of amplicons by polyacrylamide gel electrophoresis followed by silver staining. The markers Sr39#50 and Sr39#22 produced similar amplicons in the control lines RL5711 with Sr39 and RL6089 with Sr40, while amplified fragments were absent in the cultivars. Sr39#50 and Sr39#22 were used for marker-assisted selection of F2 lines from the cross Khutorianka × RL6089 (Sr40) and F4 lines from the cross Solomiia × RL5711 (Sr39). Using Sr39#50, the Sr40 resistance marker was found in 46% of the F2 offspring of the cross Khutorianka × RL6089. Among the F4 offspring of the cross Solomiia x RL5711, the frequency of genotypes with the combination of the Sr39#50 and Sr39#22 marker amplicons was only 11%. Additionally, 33% of the F4 lines showed the Sr39#22 amplicon of approximately 800 bp but lacked the Sr39#50 resistance markers. The reduced frequency of lines with the Sr39 and Sr40 genes may be due to the decreased survival of genotypes with the 2B chromosome introgression after fall planting. The winter wheat lines with the Sr39 or Sr40 gene may be used as the initial material in breeding programs.

Bradshaw C.D., Hemming D.L., Mona T., Thurston W., Seier M.K., Hodson D.P., Smith J.W., Eyre D., Liu T., Taylor B., Davie J.C., Urhausen S., Crocker T., Millington S.C., Hort M.C., et. al.

Abstract After many decades of effective control of stem rust caused by the Puccinia graminis f.sp. tritici, (hereafter Pgt) the reported emergence of race TTKSK/Ug99 of Pgt in Uganda reignited concerns about epidemics worldwide because ∼90% of world wheat cultivars had no resistance to the new race. Since it was initially detected in Uganda in 1998, Ug99 variants have now been identified in thirteen countries in Africa and the Middle East. Stem rust has been a major problem in the past, and concern is increasing about the risk of return to Central and East Asia. Whilst control programs in North America and Europe relied on the use of resistant cultivars in combination with eradication of barberry (Berberis spp.), the alternate host required for the stem rust pathogen to complete its full lifecycle, the focus in East Asia was principally on the use of resistant wheat cultivars. Here, we investigate potential airborne transmission pathways for stem rust outbreaks in the Middle East to reach East Asia using an integrated modelling framework combining estimates of fungal spore deposition from an atmospheric dispersion model, environmental suitability for spore germination, and crop calendar information. We consider the role of mountain ranges in restricting transmission pathways, and we incorporate a representation of a generic barberry species into the lifecycle. We find viable transmission pathways to East Asia from the Middle East to the north via Central Asia and to the south via South Asia and that an initial infection in the Middle East could persist in East Asia for up to three years due to the presence of the alternate host. Our results indicate the need for further assessment of barberry species distributions in East Asia and appropriate methods for targeted surveillance and mitigation strategies should stem rust incidence increase in the Middle East region.

Gultyaeva E.I., Shaydayuk E.L.

Yellow rust (Puccinia striiformis f. sp. tritici, Pst) is a potentially dangerous disease of wheat. Genetic protection of wheat is an environmentally safe method of control. For its successful application, information on the structure of regional populations of the pathogen is needed. The purpose of these studies is to characterize the virulence and molecular polymorphism of Russian Pst populations in 2022. Wheat leaves with Pst urediniopustules were obtained from the North Caucasus (Krasnodar Territory, Dagestan, Kalmykia) and Northwestern (Leningrad region) regions. Virulence analysis was performed on 14 isogenic lines (AvocetNIL) and 15 differentiator varieties. The polymorphism of 20 microsatellite loci was evaluated in molecular analysis. We used SSR markers recommended by the Global Rust Reference Center. Virulence was studied in 74 monopustular isolates: 29 Dagestan, 10 Krasnodar, 5 Kalmyk, 30 northwestern. Resistance to all isolates was shown for lines with genes Yr5, Yr10, Yr15, Yr24, Yr26 and varieties Moro (Yr10, YrMor) and Nord Desprez (Yr3, YrND, Yr+). Isolates virulent to the AvYr17 line were detected for the first time in Dagestan and Krasnodar populations. They were moderately represented in the northwestern population (13%). Significant variation was observed in lines and varieties with the Yr1 and Yr3 genes. There was a decrease in virulence to Yr7 and YrSp compared to 2019–2021. 28 phenotypes (races) were determined in the virulence analysis (15 in Dagestan, 11 in North West, 3 in Krasnodar and 2 in Kalmyk). A common phenotype was noted for three North Caucasian Pst samples. The genetic distances between the identified phenotypes were estimated. In the multidimensional diagram, most of them combined together in a common group, with the exception of three Dagestan phenotypes with the fewest virulence alleles. According to the Fst index, Dagestan and Kalmyk Pst collections were characterized by high similarity; others differed moderately from them. The long-term virulence dynamics (2019–2022) of Pst populations in the Northwestern and North Caucasian regions was assessed. High similarity was determined between all regional population samples in 2019 and 2020. The northwestern and Dagestan populations differed slightly from them in 2021 and 2022. In 2022, the Krasnodar and Kalmyk populations were divided into separate groups, which differed from each other and from the main group. Long-term results of virulence analysis indicate a high dynamic of the structure of Pst populations in Russia. All North Caucasian isolates and 23 Northwestern isolates were used in the SSR analysis. Six loci (RYN3, RYN9, RYN12, WU6, RJO21, RJO24) were monomorphic. Three polymorphic alleles were identified in the RYN13 and RJO27 loci and two in the remaining studied ones. Significant deviations from the Hardy-Weinberg equilibrium are noted for most loci. The observed heterozygosity exceeded the expected one, which indicates an excess of heterozygotes and the clonal origin of the population. The studied collection of isolates was represented by 20 multilocus genotypes (MGs) (Dagestan and Northwestern – 11 each, Krasnodar – 3, Kalmyk – 1). Common genotypes were detected in Dagestan, Krasnodar and Northwestern populations (MG_1); Dagestan, Kalmyk and Northwestern (MG_2); Dagestan and Krasnodar (MG_3, MG_4). The genetic distances between MGs were estimated. In the multidimensional diagram, they are divided into 4 groups. The main group included 80% of MGs. One Dagestan MG, two Northwestern MG and MG_3 common for Dagestan and Krasnodar collections, significantly differentiated from the main group and among themselves. According to the Fst index, most regional Pst collections were moderately differentiated among themselves, with the exception of Dagestan and Kalmyk, which is consistent with the virulence analysis. According to the Mantel test, a moderate correlation was found between the results of virulence analysis and SSR (r = 0.6). This indicates that both analyses can be used in assessing the genetic polymorphism of Pst. The high variability of Russian populations based on virulence and microsatellite loci determines the need for annual monitoring of regional Pst populations in Russia.

Gultyaeva E.I., Shaydayuk E.L.

Yellow rust (Puccinia striiformis f. sp. tritici (Pst)) is a potentially dangerous disease of wheat. Genetic protection of wheat is an environmentally safe method to control the disease, but its successful application requires information on the structure of regional populations of the pathogen. Virulence and molecular polymorphism were characterized in two Russian Pst populations in 2022. Wheat leaves with Pst urediniopustules were collected from the North Caucasus (Krasnodar Krai, Dagestan, and Kalmykia) and Northwestern Russia (Leningrad Oblast). Virulence was tested on 14 isogenic lines (AvocetNIL) and 15 differentiator cultivars. Polymorphism at 20 microsatellite loci was evaluated in molecular analyses. The SSR markers were as recommended by the Global Rust Reference Center. Virulence was assessed in 74 monopustular isolates, including 29 Dagestan, 10 Krasnodar, 5 Kalmyk, and 30 Northwestern ones. Resistance to all isolates was observed in lines with the genes Yr5, Yr10, Yr15, Yr24, and Yr26 and the cultivars Moro (Yr10, YrMor) and Nord Desprez (Yr3, YrND, Yr+). Isolates virulent to the AvYr17 line were detected for the first time in the Dagestan and Krasnodar populations. Their occurrence was moderate (13%) in the Northwestern population. A significant variation was observed in lines and cultivars with the Yr1 and Yr3 genes. Virulence to Yr7 and YrSp was found to be lower than in 2019 to 2021. In total, 28 phenotypes (races) were determined in the virulence analysis (15 in Dagestan, 11 in the Northwestern region, 3 in Krasnodar, and 2 in Kalmykia). A common phenotype was detected in three North Caucasian Pst samples. Genetic distances between the phenotypes were estimated. Most phenotypes grouped together in a multidimensional diagram, with the exception of three Dagestan phenotypes with the fewest virulence alleles. Based on the Fst index, the Dagestan and Kalmyk Pst collections were high similar to each other and differed moderately from the other collections. Long-term trends in virulence (from 2019 to 2022) were assessed in the Pst populations. A high similarity was observed between all regional population samples in 2019 and 2020. The Northwestern and Dagestan populations slightly differed from the other populations in 2021 and 2022. In 2022, the Krasnodar and Kalmyk populations formed separate groups, which differed from each other and from the main group. The long-term virulence analysis indicated that the structure of Pst populations is highly dynamic in Russia. All North Caucasian isolates and 23 Northwestern isolates were used in the SSR analysis. Six loci (RYN3, RYN9, RYN12, WU6, RJO21, and RJO24) were monomorphic. Three polymorphic alleles were identified in each of the RYN13 and RJO27 loci; two alleles, in each of the remaining loci examined. Significant deviations from Hardy–Weinberg equilibrium were observed for most loci. The observed heterozygosity exceeded the expected one, suggesting a clonal origin of the Pst population. Twenty multilocus genotypes (MGs) were found in the total isolate collection (11 in Dagestan, 11 in the Northwestern region, 3 in Krasnodar, and 1 in Kalmykia). Common MGs were detected in the Dagestan, Krasnodar, and Northwestern populations (MG_1); Dagestan, Kalmyk, and Northwestern populations (MG_2); and Dagestan and Krasnodar populations (MG_3 and MG_4). Genetic distances between MGs were estimated. MGs formed four groups in a multidimensional diagram. A major group included 80% of MGs. One Dagestan MG, two Northwestern MGs, and MG_3 common for the Dagestan and Krasnodar collections were significantly differentiated from the major group and differed from each other. Based on Fst, most regional Pst collections were moderately differentiated from each other, with the exception of the Dagestan and Kalmyk collections. The finding was consistent with the virulence analysis results. The Mantel test detected a moderate correlation between the virulence and SSR data (r = 0.6). This indicates that both analyses can be used to assess genetic polymorphism in Pst. The high variability of the virulence and microsatellite loci warrants annual monitoring of regional Pst populations in Russia.

Volkova G., Gladkova E., Kudinova O., Ignateva O.

ABSTRACTWheat stem rust (caused by Puccinia graminis f.sp. tritici) is a damaging disease widespread in all grain‐producing regions of the world. In this work, the effectiveness of Sr genes was analysed under field conditions in the southern region of Russia (Krasnodar Krai, Stavropol Krai and Rostov Oblast) during 2016‐2021. The data were obtained using a set of 46 isogenic lines and varieties with artificial inoculation. The Sr31 gene proved absolute effectiveness in the field. Effective (1R–10R) Sr genes were the following: 5, 12, 35 and 37; moderately effective (10MR–30MR) Sr genes: 1, 6, 9g, 10, 11, 13, 14, 15, 20, 22, 23, 24, 25, 32, 33, 38 and WLD. Lines with Sr genes 7a, 7b, 8a, 8b, 9a, 9b, 9d, 9e, 9f, 16, 17, 19, 21, 26, 27, 29, 30, 36, 39, 40, 44, Dp2, Gt and Tmp were ineffective in the adult plant phase (30MS–70S). Polymorphism of infection types and disease severity was noted for most of these lines in different years. Ongoing analysis of the efficiency of Sr genes in the region is important to prevent the risk of epidemics, and lines with stem rust resistance genes that have shown efficiency can be used as donors in breeding programmes.

Kosman E., Anikster Y., Ben-Yehuda P., Manisterski J., Sela H.

AbstractThis paper is dedicated to the memory of the APS Fellow Prof. Yehoshua Anikster (1934 -2023). A total of 336 urediniospore isolates of Puccinia graminis f. sp. tritici (Pgt) were derived from samples collected in Israel from 2009 to 2019 and analyzed for virulence with the standard set of 20 differentials. Seventy-four virulence phenotypes were identified during the survey. Two Pgt phenotypes (TKTTF, TTTTF) were found in nine annual populations while 57 appeared in only one year, in most of the cases (51) only once. The yearly pathogen collections of 2009 – 2014 differed from the collections of 2015-2018, and the 2019 collection diverged from all others. No virulence to Sr24 and Sr31 indicators of UG99 was detected. When comparing the 2009 – 2014 and 2015 – 2018 periods, virulence frequencies declined for Sr17, 30, and 38 genes from 0.85—0.98 to 0.31 – 0.59, while the frequency for Sr36 rose (0.42 vs. 0.87). The average relative virulence complexity of Pgt phenotypes decreased from 0.83 (2009—2014) and 0.79 (2015 – 2018) to 0.67 in 2019. Variability within the annual populations gradually increased over time. The Pgt collections of isolates in 2009 – 2014 and 2015 – 2018 were significantly different (p = 0.01). The effective number of different annual populations in 2009 – 2018 was 2.04 (β-variation = 0.12). Since Pgt does not over-summer in Israel, the northern source of inoculum from Turkey and Russia seems the most probable.

Baranova O.A., Adonina I.G., Sibikeev S.N.

Anticipatory wheat breeding for pathogen resistance is key to preventing economically significant crop losses caused by diseases. Recently, the harmfulness of a dangerous wheat disease, stem rust, caused by Puccinia graminis f. sp. tritici, was increased in the main grain-producing regions of the Russian Federation. At the same time, importation of the Ug99 race (TTKSK) is still a possibility. In this regard, the transfer of effective resistance genes from related species to the bread wheat breeding material followed by the chromosomal localization of the introgressions and a marker analysis to identify known resistance genes is of great importance. In this work, a comprehensive analysis of ten spring bread wheat introgressive lines of the Federal Center of Agricultural Research of the South-East Region (L657, L664, L758, L935, L960, L968, L971, L995/1, L997 and L1110) was carried out. These lines were obtained with the participation of Triticum dicoccum, T. timopheevii, T. kiharae, Aegilops speltoides, Agropyron elongatum and Secale cereale. In this study, the lines were evaluated for resistance to the Ug99 race (TTKSK) in the Njoro, Kenya. Evaluation of introgression lines in the field for resistance to the Ug99 race (TTKSK) showed that four lines were immune, two were resistant, three were moderately resistant, and one had an intermediate type of response to infection. By cytogenetic analysis of these lines using fluorescent (FISH) and genomic (GISH) in situ hybridization, introgressions from Ae. speltoides (line L664), T. timopheevii (lines L758, L971, L995/1, L997 and L1110), Thinopyrum ponticum = Ag. elongatum (2n = 70) (L664, L758, L960, L971, L997 and L1110), as well as introgressions from T. dicoccum (L657 and L664), T. kiharae (L960) and S. cereale (L935 and L968) were detected. Molecular markers recommended for marker-oriented breeding were used to identify known resistance genes (Sr2, Sr25, Sr32, Sr1A.1R, Sr36, Sr38, Sr39 and Sr47). The Sr36 and Sr25 genes were observed in lines L997 and L1110, while line L664 had the Sr39+Sr47+Sr25 gene combination. In lines L935 and L968 with 3R(3D) substitution from S. cereale, gene resistance was presumably identified as SrSatu. Thus, highly resistant to both local populations of P. graminis and the Ug99 race, bread wheat lines are promising donors for the production of new varieties resistant to stem rust.

Cat A.

Wheat stem rust, which is caused by Puccinia graminis f. sp. tritici (Pgt), is a highly destructive disease that affects wheat crops on a global scale. In this study, the reactions of 150 bread wheat varieties were evaluated for natural Pgt infection at the adult-plant stage in the 2019–2020 and 2020–2021 growing seasons, and they were analyzed using specific molecular markers to detect stem rust resistance genes (Sr22, Sr24, Sr25, Sr26, Sr31, Sr38, Sr50, and Sr57). Based on phenotypic data, the majority of the varieties (62%) were resistant or moderately resistant to natural Pgt infection. According to molecular results, it was identified that Sr57 was present in 103 varieties, Sr50 in nine varieties, Sr25 in six varieties, and Sr22, Sr31, and Sr38 in one variety each. Additionally, their combinations Sr25 + Sr50, Sr31 + Sr57, Sr38 + Sr50, and Sr38 + Sr57 were detected in these varieties. On the other hand, Sr24 and Sr26 were not identified. In addition, many varieties had low stem rust scores, including a large minority that lacked Sr57. These varieties must have useful resistance to stem rust and could be the basis for selecting greater, possibly durable resistance.

Hekimhan H., Aydoğdu M.

Wheat (Triticum aestivum L.) is the main staple crop and primary source of starch and energy in human diet. It is grown in over 120 countries in the world. However, global wheat production is adversely affected by biotic stress factors including fungal and bacterial diseases. In the presence of sufficient inoculum, favorable environmental conditions, and susceptible cultivar, the causal agents of wheat diseases can cause yield losses up to 100% and epidemics in wheat-growing areas. Therefore, establishing the most efficient and sustainable management practices against these diseases is of prime importance. In this context, host resistance is the most suitable approach to control the diseases of wheat. In this chapter, diseases causing economically significant damage to wheat are considered and categorized as fungal and bacterial. The diseases are presented based on the latest studies and their descriptive symptoms on plant tissues.

Gultyaeva E.I., Shaydayuk E.L., Kosman E.G.

AbstractThe importance of monitoring and management of yellow rust, caused by Puccinia striiformis f. sp. tritici (Pst), has markedly increased in Russia over recent years because of intensifying negative effects of this destructive disease on wheat production. The Pst virulence survey was conducted in 2019–2021 in the European (North‐West, Volga, North Caucasus) and Asian (Siberia) parts of Russia, and the same 109 isolates have been genotyped here with 20 SSR markers. Fifty‐three multilocus genotypes (MLGs) were detected, seven of which occurred in two or more regions. The most frequent MLG was found in three European Pst collections (except Dagestan) and Siberia. SSR‐based variation within the regional collections was low because many MLGs were closely related. Nevertheless, each collection contained relatively different small genotype groups. No clear geographic structure of the Russian Pst population was observed because the five studied regional collections shared groups of similar genotypes. The most singular SSR genotype was identified in the North‐West collection, but genotypes of four invasive isolates belonging to the PstS2 temperature‐adapted aggressive strain did not considerably differ from others. The observed heterozygosity at all SSR loci exceeded the expected one in all regional Pst collections, which could imply asexual reproduction of the pathogen. Both the SSR and virulence analyses demonstrated similar patterns of relationships between the regional Pst collections, although the magnitude of differences between the collections was larger for virulence pathotypes. However, no significant association was established between the virulence pathotypes and SSR genotypes because multiple pathotypes had the same genotype and vice versa.

Kosman E.G., Anikster Y., Ben-Yehuda P., Manisterski J., Sela H.

Abstract This paper is dedicated to the memory of the APS Fellow Prof. Yehoshua Anikster (1934 -2023). A total of 336 urediniospore isolates of Pucciniagraminis f. sp. tritici (Pgt) were derived from samples collected in Israel from 2009 to 2019 and analyzed for virulence with the standard set of 20 differentials. Seventy-two virulence phenotypes were identified during the survey. Two Pgt phenotypes (TKTTF, TTTTF) were found in nine annual populations while 49 appeared in only one year. The yearly pathogen collections of 2009 – 2014 differed from the collections of 2015-2018, and the 2019 collection diverged from all others. No virulence to Sr24 and Sr31 indicators of UG99 was detected. Comparing the 2009 – 2014 and 2015 – 2018 periods, virulence frequencies declined on Sr17, 30, and 38 genes from 0.853 - 0.973 to 0.308 – 0.587, whereas the frequency on Sr36 rose (0.418 vs. 0.865). The average relative virulence complexity of the Pgt phenotypes decreased from 0.833 (2009 - 2014) and 0.786 (2015 – 2018) to 0.671 in 2019. Variability within the annual populations gradually increased over time. The Pgt collections of isolates in 2009 – 2014 and 2015 – 2018 were significantly different (p = 0.01). The effective number of different annual populations in 2009 – 2018 was 2.04 (β-variation = 0.116). Since Pgt does not over-summer in Israel, the northern source of inoculum from Turkey and Russia seems the most probable.

Erreguerena I.A., Hoebe P.N., Carmona M.A., Guillín E., Havis N.D.

AbstractRamularia collo‐cygni (Rcc) is a major barley pathogen that causes yield and grain quality losses worldwide. The main sources of Rcc inoculum are the seed and asexual airborne spores. In Argentina, Rcc is considered to be an emerging threat to barley crops, especially as most varieties are susceptible to Rcc and have a European genetic background. Here, we describe the population genetic diversity and structure of the Argentinian Rcc population, based on 10 simple‐sequence repeat (SSR) markers, in order to compare it with Rcc populations from the Czech Republic and Scotland. The Argentinian Rcc population showed lower genetic diversity, higher level of structuring and higher number of clonal isolates than European populations. Significant differentiation at population origin (country) and region (Europe and South America) level suggests the occurrence of a genetic bottleneck and/or a founder effect on Rcc entry to Argentina and that this population could still be in a state of establishment and emergence. Further research on Rcc genetic structure at local and global scale will be crucial for the understanding of Rcc population dynamics for disease management.

Morgounov A., Babkenov A., Ben C., Chudinov V., Dolinny Y., Dreisigacker S., Fedorenko E., Gentzbittel L., Rasheed A., Savin T., Shepelev S., Zhapayev R., Shamanin V.

The Kazakhstan-Siberia Network for Spring Wheat Improvement (KASIB) was established in 2000, forming a collaboration between breeding and research programs through biannual yield trials. A core set of 142 genotypes from 15 breeding programs was selected, genotyped for 81 DNA functional markers and phenotyped for 10 agronomic traits at three sites in Kazakhstan (Karabalyk, Shortandy and Shagalaly) and one site in Russia (Omsk) in 2020–2022. The study aim was to identify markers demonstrating significant effects on agronomic traits. The average grain yield of individual trials varied from 118 to 569 g/m2. Grain yield was positively associated with the number of days to heading, plant height, number of grains per spike and 1000-kernel weight. Eight DNA markers demonstrated significant effects. The spring-type allele of the Vrn-A1 gene accelerated heading by two days (5.6%) and was present in 80% of the germplasm. The winter allele of the Vrn-A1 gene significantly increased grain yield by 2.7%. The late allele of the earliness marker per se, TaMOT1-D1, delayed development by 1.9% and increased yield by 4.5%. Translocation of 1B.1R was present in 21.8% of the material, which resulted in a 6.2% yield advantage compared to 1B.1B germplasm and a reduction in stem rust severity from 27.6 to 6.6%. The favorable allele of TaGS-D1 increased both kernel weight and yield by 2–3%. Four markers identified in ICARDA germplasm, ISBW2-GY (Kukri_c3243_1065, 3B), ISBW3-BM (TA004946-0577, 1B), ISBW10-SM2 (BS00076246_51, 5A), ISBW11-GY (wsnp_Ex_c12812_20324622, 4A), showed an improved yield in this study of 3–4%. The study recommends simultaneous validation and use of selected markers in KASIB’s network.

CAT A.

Abstract Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is more destructive disease of wheat on a global scale. In this study, reactions of the 150 bread wheat cultivars were evaluated on the natural Pgt infection at adult-plant stage in 2020 and 2021 and they were also analyzed by using the specific molecular markers to detect resistance genes (Sr22, Sr24, Sr25, Sr26, Sr31, Sr38, Sr50 and Sr57). Based on the phenotypic data, the majority of the cultivars (62%) showed resistance/moderate resistance reactions to natural Pgt infection. According to the molecular findings, the genes Sr57 (in 103 cultivars), Sr50 (in nine cultivars), Sr25 (in six cultivars) and Sr22, Sr31 and Sr38 (in one cultivar) and their combinations Sr25 + Sr50, Sr31 + Sr57, Sr38 + Sr50, Sr38 + Sr57 were detected in these cultivars. However, Sr24 and Sr26 were determined none of them. These resistance genes were identified for the first time during this study. In addition, the findings may be used to develop resistant cultivars in rust disease breeding programs.

Patpour M., Hovmøller M.S., Rodriguez-Algaba J., Randazzo B., Villegas D., Shamanin V.P., Berlin A., Flath K., Czembor P., Hanzalova A., Sliková S., Skolotneva E.S., Jin Y., Szabo L., Meyer K.J., et. al.

The objective of this study was to investigate the re-emergence of a previously important crop pathogen in Europe, Puccinia graminis f.sp. tritici, causing wheat stem rust. The pathogen has been insignificant in Europe for more than 60 years, but since 2016 it has caused epidemics on both durum wheat and bread wheat in local areas in southern Europe, and additional outbreaks in Central- and West Europe. The prevalence of three distinct genotypes/races in many areas, Clade III-B (TTRTF), Clade IV-B (TKTTF) and Clade IV-F (TKKTF), suggested clonal reproduction and evolution by mutation within these. None of these genetic groups and races, which likely originated from exotic incursions, were detected in Europe prior to 2016. A fourth genetic group, Clade VIII, detected in Germany (2013), was observed in several years in Central- and East Europe. Tests of representative European wheat varieties with prevalent races revealed high level of susceptibility. In contrast, high diversity with respect to virulence and Simple Sequence Repeat (SSR) markers were detected in local populations on cereals and grasses in proximity to Berberis species in Spain and Sweden, indicating that the alternate host may return as functional component of the epidemiology of wheat stem rust in Europe. A geographically distant population from Omsk and Novosibirsk in western Siberia (Russia) also revealed high genetic diversity, but clearly different from current European populations. The presence of Sr31-virulence in multiple and highly diverse races in local populations in Spain and Siberia stress that virulence may emerge independently when large geographical areas and time spans are considered and that Sr31-virulence is not unique to Ug99. All isolates of the Spanish populations, collected from wheat, rye and grass species, were succesfully recovered on wheat, which underline the plasticity of host barriers within P. graminis. The study demonstrated successful alignment of two genotyping approaches and race phenotyping methodologies employed by different laboratories, which also allowed us to line up with previous European and international studies of wheat stem rust. Our results suggest new initiatives within disease surveillance, epidemiological research and resistance breeding to meet current and future challenges by wheat stem rust in Europe and beyond.

Gultyaeva E.I., Shaydayuk E.L.

Background. Wheat leaf rust caused by Puccinia triticina Erikss. is a significant wheat disease in all regions of the Russian Federation. The genetic diversity of the cultivated wheat varieties regarding the type of resistance and genes that control it ensures reliable protection of this crop against the pathogen. The aim of this work was to characterize the diversity of new Russian varieties of winter and spring common wheat for leaf rust resistance genes (Lr-genes).Materials and Methods. The research material was represented by 43 varieties of winter and 25 of spring wheat included in the State Register of Selection Achievements of the Russian Federation in 2018-2020.Results. Using molecular markers, 18 Lr genes were identified: Lr1, Lr3, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr25, Lr26, Lr28, Lr29, Lr34, Lr35, Lr37, Lr41 (39), Lr47 and Lr66. A phytopathological test was used to clarify the results of molecular analysis. Ninety-three percent of the studied wheat varieties were found to contain Lr genes, either separately or in combinations. These were the highly and partially effective genes Lr24, Lr9, and Lr19, adult plant resistance genes Lr34 and Lr37, and ineffective genes Lr1, Lr3, Lr10, Lr20, and Lr26. The Lr24 gene has been identified for the first time in Russian varieties. The spring variety ‘Leader 80’, harboring this gene, is recommended for cultivation in the West Siberian and East Siberian regions. An effective combination of Lr9 + Lr26 genes, individually overcome by the pathogen, was determined in the spring cultivar ‘Silach’, highly resistant to leaf rust. The Lr9 gene was found in the winter variety ‘Gerda’, which is recommended for cultivation in the North Caucasus region. Previously, the varieties with Lr9 were not grown in the North Caucasus. An increase in the number of leaf rust resistant accessions protected by the effective adult plant resistance gene Lr37 is noted among wheat varieties undergoing regional adaptation testing. Many of the identified Lr genes (Lr19, Lr24, Lr26, Lr34, Lr37) are linked with effective Sr genes (Sr25, Sr24, Sr31, Sr57, and Sr38), which additionally ensures stable genetic protection of wheat against stem rust.Conclusions. The obtained information about representation of Lr genes in wheat varieties should be used in regional breeding programs. A timely replacement of genetically protected varieties allows stabilizing the populational composition of the phytopathogen and reducing the likelihood of epiphytotics.

Shaydayuk E.L., Yakovleva D.R., Abdullaev K.M., Pyukkenen V.P., Gultyaeva E.I.

Nazari K., Al-Maaroof E.M., Kurtulus E., Kavaz H., Hodson D., Ozseven I.

Baranova* O.A., Sibikeev S.N., Druzhin A.E., Sozina I.D.

Wheat is one of the most important food crops in Russia. Rust diseases (leaf, yellow and stem rusts) are particularly dangerous diseases of wheat that threaten food security. The stem rust (the causative agent is a biotrophic fungus Puccinia graminis f. sp. tritici) is the most damaging; crop losses can reach 50 to 80% and more. The paper presents the results of the analysis of resistance to stem rust of 189 introgressive lines of spring soft wheat breeding ARISER and 11 varieties cultivated in the Lower Volga region in the growing season 2016-2020. The results of phytopathological assessment of virulence of Saratov pathogen population 2016-2020 are also presented. It is shown that Sr13, Sr26, Sr31, Sr35 and combinations of Sr24+31, Sr36+31 and Sr26+9g genes are effective for Saratov populations of P. graminis 2016 - 2020. No isolates virulent to the line with the Sr31 gene have been identified in all years of research. Analysis of resistance in wheat varieties and lines showed a loss of Sr6Agi gene efficacy from 2016 and a gradual loss of Sr25 efficacy by 2020. In 2020, varieties carrying the Sr25 gene (Lebedushka and Dobrynya) and lines with this gene affected the Saratov population of stem rust, both under laboratory conditions and in the field on a natural infection background. In the analyzed 189 introgressed lines, Sr25/Lr19 (77.2%) and Sr31/Lr26 (22.2%) genes were mainly identified, Sr22, Sr35, Sr28, Sr38/Lr37 and Sr57/Lr34 genes were also identified. Fifty lines carrying the combination of Sr31 with Sr25/Lr19 and Sr6Agi have been identified as highly resistant to stem rust. Thus, it was shown that Sr31 gene was effective against P. graminis populations in Volga region, while Sr6Agi and Sr25 genes lost their effectiveness in Volga region.

Czajowski G., Kosman E., Słowacki P., Park R.F., Czembor P.

The aim of the present study was to validate new simple-sequence repeat (SSR) markers and use them to assess genetic variability among 24 isolates of Puccinia triticina collected from wheat (Pt-wheat) and triticale (Pt-triticale), and 15 isolates of P. recondita f. sp. secalis (Prs) collected from rye. The Pt and Prs isolates were tested for virulence on a set of 35 Thatcher wheat near-isogenic lines, eight rye lines with known resistance genes, and 53 triticale cultivars with uncharacterized leaf rust resistance. Molecular genotypes were determined using a newly developed set of 34 SSR microsatellite primer pairs. All SSR markers tested on Pt isolates successfully amplified fragments of appropriate size. When tested on the Prs isolates, 21 out of the 34 Pt SSRs amplified expected fragments. Sixteen of these 21 SSRs were polymorphic, providing for the first time microsatellite markers to study genetic variation in Prs. Based on virulence data, variation among Prs isolates was low, probably due to the small number of rye differential lines available. Much higher variation for virulence was observed within the collection of Pt isolates from wheat and triticale, and two separate groups were established with mixed host origin. Substantial genetic variation was detected among the isolates studied with the SSR markers, assuming two different models of SSR evolution (infinite alleles model and stepwise mutation model). The newly developed set of SSR markers proved their effectiveness in detecting genetic variation and should be useful in further population genetics investigations of the two pathogens.

Rsaliyev A., Yskakova G., Maulenbay A., Zakarya K., Rsaliyev S.

Hanzalová A., Dumalasová V., Zelba O.

Skolotneva E.S., Kosman E., Patpour M., Kelbin V.N., Morgounov A.I., Shamanin V.P., Salina E.A.

Management of wheat stem rust in Western Siberia has gained importance since the first outbreaks in 2007-2010 and 2016. The race composition and virulence patterns were investigated for the enlarged Puccinia graminis f. sp. tritici (Pgt) samples collected in three neighboring regions Omsk, Novosibirsk, and Altai during 2017-2018. Most of Pgt isolates were identified as virulent to wheat lines with genes Sr5, Sr9a, Sr10, Sr38, SrMcN and avirulent to Sr24, Sr31. Differentiation ability of genes Sr6, Sr7b, Sr8a, Sr9b, Sr9d, Sr9g, Sr9e, Sr11, Sr17, Sr21 Sr30, Sr36, and SrTmp to distinguish between the regional populations was established. A total of 33 virulence phenotypes or races were detected among 115 Pgt isolates tested. Based on virulence phenotypes, two different Pgt subpopulations were identified in the Altai and Omsk regions likely originating from asexual and sexual cycles, respectively. The Novosibirsk pathogen population seems to be a mixture of isolates originated from both neighboring regions with virulence phenotypes that developed in the west, Omsk (TKRPF, QHHSF, and MLLTF) and in the south, Altai (NFMSF, LKCSF, LKMSF, and PKCSF) of Western Siberia.

Leonova I.N., Skolotneva E.S., Orlova E.A., Orlovskaya O.A., Salina E.A.

Stem rust caused by Puccinia graminis f. sp. tritici Eriks. is a dangerous disease of common wheat worldwide. Development and cultivation of the varieties with genetic resistance is one of the most effective and environmentally important ways for protection of wheat against fungal pathogens. Field phytopathological screening and genome-wide association study (GWAS) were used for assessment of the genetic diversity of a collection of spring wheat genotypes on stem rust resistance loci. The collection consisting of Russian varieties of spring wheat and introgression lines with alien genetic materials was evaluated over three seasons (2016, 2017 and 2018) for resistance to the native population of stem rust specific to the West Siberian region of Russia. The results indicate that most varieties displayed from moderate to high levels of susceptibility to P. graminis; 16% of genotypes had resistance or immune response. In total, 13,006 single-nucleotide polymorphism (SNP) markers obtained from the Infinium 15K array were used to perform genome-wide association analysis. GWAS detected 35 significant marker-trait associations (MTAs) with SNPs located on chromosomes 1A, 2A, 2B, 3B, 5A, 5B, 6A, 7A and 7B. The most significant associations were found on chromosomes 7A and 6A where known resistance genes Sr25 and Sr6Ai = 2 originated from Thinopyrum ssp. are located. Common wheat lines containing introgressed fragments from Triticum timopheevii and Triticum kiharae were found to carry Sr36 gene on 2B chromosome. It has been suggested that the quantitative trait loci (QTL) mapped to the chromosome 5BL may be new loci inherited from the T. timopheevii. It can be inferred that a number of Russian wheat varieties may contain the Sr17 gene, which does not currently provide effective protection against pathogen. This is the first report describing the results of analysis of the genetic factors conferring resistance of Russian spring wheat varieties to stem rust.

Sun X., Kosman E., Sharon O., Ezrati S., Sharon A.

Endophytic fungi compose a significant part of plant microbiomes. However, while a small number of fungal taxa have proven beneficial impact, the vast majority of fungal endophytes remain uncharacterized, and the drivers of fungal endophyte community (FEC) assembly are not well understood. Here, we analysed FECs in three cereal crops-related wild grasses - Avena sterilis, Hordeum spontaneum and Aegilops peregrina - that grow in mixed populations in natural habitats. Taxa in Ascomycota class Dothideomycetes, particularly the genera Alternaria and Cladosporium, were the most abundant and prevalent across all populations, but there was also high incidence of basidiomyceteous yeasts of the class Tremellomycetes. The fungal community was shaped to large extent by stochastic processes, as indicated by high level of variation even between individuals from local populations of the same plant species, and confirmed by the neutral community model and Raup-Crick index. Nevertheless, we still found strong determinism in FEC assembly with both incidence and abundance data sets. Substantial differences in community composition across host species and locations were revealed. Our research demonstrated that assembly of FECs is affected by stochastic as well as deterministic processes and suggests strong effects of environment heterogeneity and plant species on community composition. In addition, a small number of taxa had high incidence and abundance in all of the 15 populations. These taxa represent an important part of the core FEC and might be of general functional importance.

Сколотнева Е.С., Кельбин В.Н., Моргунов А.И., Бойко Н.И., Шаманин В.П., Салина Е.А.

Shamanin V.P., Pototskaya I.V., Shepelev S.S., Pozherukova V.E., Salina E.A., Skolotneva E.S., Hodson D., Hovmøller M., Patpour M., Morgounov A.I.

Stem rust in recent years has acquired an epiphytotic character, causing significant economic damage  for wheat production in some parts of Western Siberia. On the basis of a race composition study of the stem rust  populations collected in 2016–2017 in Omsk region and Altai Krai, 13 pathotypes in Omsk population and 10 in  Altai population were identified. The race differentiation of stem rust using a tester set of 20 North American  Sr genes differentiator lines was carried out. The genes of stem rust pathotypes of the Omsk population are avirulent only to the resistance gene Sr31, Altai isolates are avirulent not only to Sr31, but also to Sr24, and Sr30. A low  frequency of virulence (10–25 %) of the Omsk population pathotypes was found for Sr11, Sr24,Sr30, and for Altai  population – Sr7b,Sr9b,Sr11,SrTmp, which are ineffective in Omsk region. Field evaluations of resistance to stem  rust were made in 2016–2018 in Omsk region in the varieties and spring wheat lines from three different sources.  The first set included 58 lines and spring bread wheat varieties with identified Sr genes – the so-called trap nursery  (ISRTN – International Stem Rust Trap Nursery). The second set included spring wheat lines from the Arsenal collection, that were previously selected according to a complex of economically valuable traits, with genes for resistance  to stem rust, including genes introgressed into the common wheat genome from wild cereal species. The third  set included spring bread wheat varieties created in the Omsk State Agrarian University within the framework of  a shuttle breeding program, with a synthetic wheat with the Ae. tauschiigenome in their pedigrees. It was established that the resistance genes Sr31, Sr40,Sr2 complexare effective against stem rust in the conditions of Western  Siberia. The following sources with effective Srgenes were selected: (Benno)/6*LMPG-6 DK42, Seri 82, Cham 10,  Bacanora (Sr31), RL 6087 Dyck (Sr40), Amigo (Sr24,1RS-Am), Siouxland (Sr24,Sr31), Roughrider (Sr6, Sr36), Sisson  (Sr6,Sr31,Sr36), and Fleming (Sr6,Sr24,Sr36,1RS-Am), Pavon 76 (Sr2 complex) from the ISRTN nursery; No. 1 BC 1F2 (96 × 113) × 145 × 113 (Sr2,Sr36,Sr44), No. 14а F 3(96 × 113) × 145 (Sr36,Sr44), No. 19 BC 2F3(96 × 113) × 113 (Sr2, Sr36, Sr44), and No. 20 F 3 (96 × 113) × 145  (Sr2,Sr36,Sr40, Sr44) from the Arsenal collection; and the Omsk State Agrarian  University varieties Element 22 (Sr31,Sr35), Lutescens 27-12, Lutescens 87-12 (Sr23,Sr36), Lutescens 70-13, and  Lutescens 87-13 (Sr23,Sr31,Sr36). These sources are recommended for inclusion in the breeding process for developing stem rust resistant varieties in the region.  

Gultyaeva E.I., Shaydayuk E.L., Kosman E.G.

Leaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north‐west and south‐west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.

Nemati Z., Mostowfizadeh-Ghalamfarsa R., Dadkhodaie A., Mehrabi R., Steffenson B.J.

The wheat leaf rust fungus, Puccinia triticina, has widespread geographical distribution in Iran within the Fertile Crescent region of the Middle East where wheat was domesticated and P. triticina originated. Therefore, it is of great importance to identify the prevalence and distribution of P. triticina pathotypes in this area. From 2010 to 2017, 241 single-uredinium isolates of P. triticina were purified from 175 collections of P. triticina made from various hosts in 14 provinces of Iran, and they were tested on 20 Thatcher near-isogenic lines carrying single-leaf rust resistance genes. In total, 86 pathotypes were identified, of which the pathotypes FDTTQ, FDKPQ, FDKTQ, and FDTNQ were most prevalent. No virulence for Lr2a was detected, whereas virulence for Lr1 was found only on bread wheat in a few provinces in 2016. Only isolates from durum wheat and wild barley were virulent to Lr28. Although virulence for Lr9, Lr20, and Lr26 was observed in some years, the virulence frequency for these genes was lower than that of the other Lr genes. P. triticina collections from host plants with different ploidy levels or genetically dissimilar backgrounds were grouped individually according to genetic distance. Based on these results, collections from barley, durum wheat, oat, triticale, and wild barley were different from those of bread wheat.