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Leaf rust, caused by Puccinia triticina (Pt), is a widely occurring disease of wheat in the North-Western Region of Russia. Annual Pt surveys of wheat in this region have been conducted between 2001 and 2021. In total, 740 single urediniospore isolates were analyzed over 20 years. Virulence to Lr9, Lr19 and Lr24 were rare in 2001–2010 and was not detected after 2010. Temporal variation in virulence was determined on Thatcher lines with Lr1, Lr2a, Lr2b and Lr2c genes and was found to be relatively high. Virulence to Lr1 increased to 100% from 2001 to 2014. Until 2010, most northwestern Pt isolates were avirulent to Lr2a and virulent to Lr2b and Lr2c. In the middle of 2010, avirulence to Lr2a, Lr2b, Lr2c and Lr15 began to increase. Strong variability between years was revealed for virulence to Lr20 and Lr26. Based on a set of 20 differential lines, 122 virulence pathotypes were detected. More than half of those were observed only once across all years. Pathotypes were divided into groups of B-, C-, D- and F-, virulent to Lr1 and Lr2a, dominating until 2009. From 2010 pathotype groups M- and P-, virulent to Lr1 and avirulent to Lr2a, began to dominate. Temporal differentiation of northwestern Pt population for virulence was determined. High similarity was observed for Pt accessions in 2001–2009 and 2010–2015 and these two groups differed moderately from each other. Pt accessions from 2016–2019 and 2020–2021 differed from each other and from accessions from the previous collection period. Field response of Lr differential lines was studied in the North-Western Region during 1998–2022. Wheat genotypes with genes Lr9, Lr19, Lr23, Lr24, Lr25, Lr28, Lr29, Lr35, Lr39, Lr42, Lr43, Lr45, Lr47, Lr48, Lr49, Lr50, Lr51, Lr53 and Lr57 remained resistant throughout the period of the study. Leaf rust severity in lines TcLr12, TcLr21, TcLr22a, Gatcher (Lr27+31), TcLr44 and Pavon (Lr46) varied from 1% to 30% before 2014 and significantly decreased after 2014. A general trend of decreasing virulence of the Pt pathogen has been observed in the North-Western Region over the recent years.

Background. One of the promising sources for enrichment of the common wheat (Triticum aestivum L.) gene pool with new alleles is synthetic hexaploid wheat (SHW), or allopolyploids from crossing tetraploid wheats (2n = 4x = 28, BBAA) with accessions of Aegilops tauschii Coss. (2n = 2x = 14, DD), and subsequent doubling of the chromosome number in the hybrids. Objectives of the study were to evaluate the SHW accessions from the VIR collection for resistance to Puccinia triticina Erikss. populations collected in Russia; genotype the accessions; and summarize information from the published sources concerning the resistance of the studied accessions to other harmful diseases and pests.Materials and methods. Resistance of 36 SHW accessions from the VIR collection to the populations of P. triticina was assessed in the laboratory and in the field, under artificial infection pressure, using the techniques developed by the Institute of Plant Protection. A phytopathological test and PCR markers were used to identify the Lr genes.Results and conclusion. The SHW accessions were characterized according to their resistance to the Russian populations of the wheat leaf rust pathogen. The sources of resistance in the phase of emergence and in adult plants were identified. The phytopathological test isolated three accessions with Lr23; the PCR marker of Lr21=Lr40 was found in 11 accessions, Lr39=Lr41 in 19, and Lr22a in 3. At the same time, k-65496, k-65515 and k-65517 had si multaneously Lr21=Lr40 and Lr39=Lr41, while k-65497, k-65503 and k-65508 had Lr22a and Lr39=Lr41. The analysis of published data showed that many of the studied SHW accessions were also resistant to other harmful diseases and insect pests, so they are of interest for further studying and possible use in domestic breeding.

A collection of 482 tetraploid wheat accessions from the CIMMYT Germplasm Bank was screened in the greenhouse for resistance to leaf rust disease caused by the fungus Puccinia triticina E. The accessions were screened against two races CBG/BP and BBG/BP in the field at two locations: against race CBG/BP at the Norman E. Borlaug Experimental Station (CENEB) located in the Yaqui Valley in the northern state of Sonora in Mexico during the 2014–2015 growing season; and against race BBG/BP at CIMMYT headquarters in El Batan, Texcoco, in the state of Mexico in the summer of 2015. Among the accessions, 79 durum genotypes were identified, of which 68 continued demonstrating their resistance in the field (past the seedling stage) against the two leaf rust races. An additional set of 41 genotypes was susceptible at the seedling stage, but adult plant race-specific resistance was identified in the field. The 79 seedling-resistant genotypes were tested against 15 different leaf rust races at the seedling stage to measure the usefulness of their resistance in a breeding program. Among the 79 accessions tested, 35 were resistant to all races used in the tests. Two sample sources, CIMMYT (18/35) pre-breeding germplasm and Ethiopian landraces (17/35), showed seedling resistance to all races tested except for seven landraces from Ethiopia, which became susceptible to the Cirno race identified in 2017.

Wheat leaves infected with Puccinia triticina, the causal agent of wheat leaf rust, were collected annually throughout Canada from 2015 to 2019. There were 47, 75, 44, 38 and 54 different virulence...

Wheat leaf rust, caused by Puccinia triticina Eriks., is a common and destructive disease of wheat worldwide. The durable leaf rust-resistance gene Lr34 is typically described as an adult plant res...

Collections of Puccinia triticina were made from farmers’ fields of five different agro-ecological locations (Sakrand, Tandojam, Larkana, Sanghar and Badin) of Sindh province, Pakistan from 2015 and 2016, to identify the virulence variation. Single uredinial isolates were investigated for virulence phenotyping on 24 near isogenic (Thatcher wheat) lines which differ for single Lr resistance genes. Spores from two locations (Sakrand and Tandojam) were not viable and could not be revived and only urediniospores of three locations (Larkana, Sanghar and Badin) were revived. None of the pathotypes had virulence to Thatcher wheat lines with leaf rust resistance genes Lr23 and Lr42 . However, Lr24, LrB, Lr10, Lr14b and Lr20 genes exhibited susceptibility response i.e. (HITs 3 & 4) with all tested pathotypes. Based on virulence, ten virulence phenotypes (MSCTNS, RTSTNS, RKTRGS, PNDQDS, JDBQGJ, MDPSDS, RTPTPS, MNPSDS, MJLTGS and MSPTDS) were identified among the ten isolates, designated with six-letter code. Two phenotypes RTSTNS & RTPTPS exhibited broad spectrum, both were virulent to nineteen resistance genes of leaf rust while pathotype JDBQGJ had narrow spectrum as compared to all other tested, with virulence to just eight resistance genes of leaf rust. Among the locations virulence variability of leaf rust was also recorded. Most of identified races were virulent to more than one of leaf rust resistance genes. Resistance genes ( Lr42 and Lr23 ) identified as effective can be exploited to achieve leaf rust resistance in wheat. Further, the study provides virulence profile of the area may help to manage the leaf rust pathogen .

Wheat is the second most cultivated cereal crop in the world and is an important crop in India. Leaf (brown) rust, caused by Puccinia triticina, was the most prevalent among the three rusts found in all the wheat-growing areas of India, Bhutan, and Nepal during 2016 to 2019. Leaf rust samples from wheat crops in these countries were pathotyped using the wheat differential genotypes and binomial Indian system of nomenclature. To facilitate international communication, each pathotype identified was also tested using the North American differentials. A total of 33 pathotypes were identified from 1,086 samples, including three new pathotypes: 61R47 (162-5 = KHTPM) and 93R49 (49 = NHKTN) from India and 93R57 (20-1 = NHKTN) from Nepal. Two pathotypes, 121R60-1 (77-9/52 = MHTKL) and 121R63-1 (77-5 = THTTM), accounted for 79.46% of the population. Virulence on Lr19 was identified in 0.27% of the samples from Nepal only. The proportion of pathotype 121R60-1 (77-9 = MHTKL) increased to 57.55% during these years. Virulence was not observed on Lr9, Lr24, Lr25, Lr28, Lr32, Lr39, Lr45, and Lr47 in the population of the Indian subcontinent. Eighteen polymorphic simple sequence repeat (SSR) primer pairs tested on the isolates amplified 48 alleles with an average of 2.66 alleles per primer pair. Based on SSR genotyping, these pathotypes could be grouped into two clades with another two subclades each. Many of the Lr genes present in Indian wheat germplasm (Lr1, Lr3a, Lr10, Lr11, Lr14a, Lr15, Lr16, Lr17, Lr20, Lr23, and Lr26) were ineffective for a majority of pathotypes. Most of these varieties possessed a high degree of leaf rust resistance. The field resistance of wheat varieties could be attributed to the interaction of genes, unknown resistance, or adult plant resistance.

Triticum monococcum L. and T. boeoticum L., diploid wild relatives of bread wheat (T. aestivum L.), possess resistance to leaf rust (also known as brown rust) caused by Puccinia triticina Eriks. Haustorium formation-based resistance mechanisms (i.e. pre-haustorial and post-haustorial resistance) to leaf rust have been studied and reported in various T. monococcum accessions. In the present study, the mechanism of leaf rust resistance in T. monococcum and T. boeoticum accessions was studied using confocal laser scanning microscopy. Components of resistance studied at a histological level against leaf rust pathotypes, a Mexican pathotype (TCB/TD) and a Swiss pathotype (97512-19), indicated different types of resistance mechanism operative in the two accessions. The resistance in T. monococcum ranged from pre-haustorial resistance against 97512-19 to post-haustorial resistance against TCB/TD. The response in T. boeoticum was post-haustorial with necrosis against the two pathotypes. Pre-haustorial resistance observed in T. monococcum could serve as a potential source of durable rust resistance in wheat breeding.

Wheat leaf rust, triggered by Puccinia triticina Eriks (Pt), is among the most important diseases of wheat worldwide. Deploying resistant varieties against leaf rust is the most effective, environmentally-friendly and economic way to control the disease. In the present study, 66 wheat varieties form China and foreign countries were tested with 17 Pt races for gene postulation during the seedling stage in the greenhouse. All the varieties were also planted to identify slow rusting responses to leaf rust at the adult plant stage in Baoding and Zhoukou field trials during the 2016/2017 to 2017/2018 cropping seasons. Moreover, 12 closely linked molecular markers to known leaf rust resistance (Lr) genes were used for assessing all the varieties. The results of both gene postulation and molecular marker identification showed that a total of eight Lr genes, Lr1, Lr10, Lr17, Lr20, Lr26, Lr34, Lr37 and Lr46, either singly or in combination were detected in 32 varieties. Known Lr genes were not identified in the remaining 34 varieties. Seventeen varieties were found to have slow rusting resistance. The resistance sources identified in this study can be used as resources for resistance against leaf rust in wheat breeding programs in China and the respective foreign countries.

Leaf rust is an important wheat disease that is a significant hindrance for wheat production in most areas of the world. Breeding resistant cultivars can effectively and economically control the disease. In the present study, a wheat collection consisting of 100 cultivars from China and 18 improved germplasms from global landrace donors together with 36 known single Lr gene lines were tested with 20 strains of Puccinia triticina Eriks. in the seedling stage to postulate the Lr gene in the cultivars and germplasms. In addition, 12 diagnostic molecular markers specific to 10 Lr genes were used to detect the presence of the Lr genes in the wheat collection. Resistance to leaf rust of these cultivars at the adult plant stage was tested in fields under natural infection during the 2016 to 2018 cropping seasons in Baoding, Hebei Province. The gene postulation combined with molecular marker detection showed that six Lr genes (Lr1, Lr26, Lr33, Lr34, Lr45, and Lr46) were identified in 44 wheat accessions, including 37 cultivars and seven improved germplasms. Among the 44 wheat accessions postulated with Lr genes, Lr1 was present in four accessions, Lr26 in 12 accessions, Lr33 in two accessions, Lr34 in 14 accessions, Lr45 in three accessions, and Lr46 in 16 accessions. In the collection of 118 cultivars/germplasms, 34 wheat lines displayed adult-plant resistance carrying Lr34, Lr46, and/or underdetermined genes. Therefore, a high level of leaf rust resistance can be achieved through the combination of all-stage resistance and adult-plant resistance genes together in wheat cultivars.

Gene postulation is one of the fastest and most cost-effective methods for identifying seedling leaf rust resistance genes in wheat cultivars. Many researchers use this approach to identify Lr genes in wheat cultivars. The purpose of our research was to identify seedling leaf rust resistance genes in 20 wheat cultivars from different breeding centers of Russia, Ukraine and Germany. Forty-two near isogenic Thatcher lines and 10 Puccinia triticina isolates were used for gene postulation. When assessing the infection types to cultivars and lines, a scale was used, according to Oelke and Kolmer. In 20 wheat cultivars 19 Lr genes were postulated: 2c, 3, 10, 3bg, 3ka, 14a, 17, 18, 23, 25, 26, 30, 33, 40, 44, 50, B, Exch, Kanred. The most common for cultivars was the Lr10 gene. In five cultivars, showing high field resistance, most postulated seedling genes (Lr2c, Lr3, Lr10, Lr14а, Lr26, Lr33) were not effective in the adult stage. It is possible that resistance of such cultivars is associated with APR genes, the postulation of which requires an expansion in the number and spectrum of P. triticina isolate virulence. Most of the studied cultivars (60%) have recently been entered into the register (2015–2019) and in the field show a stable or moderately susceptible response to P. triticina infection, despite the fact that the Lr genes postulated in them were not effective in the adult stage. The data obtained indicated a variety of genotypes of the studied cultivars, as well as the tendency of breeders to use the effect of pyramiding ineffective genes, which can prolong the resistance of the cultivar. Annual monitoring of varieties is necessary in each region, especially when reacting with a medium susceptible type (MS), which may indicate the initial stage of resistance loss.

Wheat leaf rust, caused by Puccinia triticina, is a common fungal disease of wheat in China. In order to identify races and determine the individual virulence of isolates in different wheat-growing regions in China, leaf rust samples collected from 18 provinces in 2011 to 2013 were tested on 37 Thatcher near-isogenic lines each carrying a different single leaf rust resistance gene. A total of 158 races were identified. Races THTT (19.5%), THTS (16.9%), PHTT (7.7%), THJS (5.0%), THJT (4.2%), and PHTS (4.0%) were the most predominant races in 2011 to 2013. All of these races were avirulent to resistance genes Lr9 and Lr24. The two most frequent races, THTT and THTS, were widely distributed. The frequencies of the isolates with virulence to Lr1, Lr2c, Lr3, Lr16, Lr26, Lr17, LrB, Lr10, Lr14a, Lr3bg, Lr14b, Lr33, Lr37, and Lr50 exceeded 90%. Frequencies of virulence to Lr2a, Lr3ka, Lr11, Lr30, Lr2b, and Lr32 exceeded 70% but were less than 90%. Frequencies of virulence to Lr18, Lr21, Lr15, Lr23, Lr33+34, Lr36, Lr39, and Lr44 were below 70%, whereas the frequency of virulence to Lr25 was less than 1%. All isolates were avirulent to Lr9, Lr19, Lr24, Lr28, Lr42, Lr29, Lr38, and Lr47. The identified races and individual virulence frequencies provide a basis for selection of effective leaf rust resistance genes for use in breeding programs and can also provide information for the study of race evolution of P. triticina.

Six commercial bread wheat (Triticum aestivum L.) cultivars were evaluated against leaf rust (Puccinia triticina) at two different locations in Egypt during three successive growing seasons, i.e., 2016/2017, 2017/2018 and 2018/2019. Correlation between eight weekly environmental factors: solar radiation, total precipitation, average wind speed, maximum wind speed, minimum air temperature, maximum air temperature, minimum relative humidity and maximum relative humidity to leaf rust severity (%) and yield losses (%), was determined using stepwise regression analysis. Predictive models for each tested cultivar for final leaf rust severity (%) and yield losses using environmental data were determined. Generally, maximum relative humidity was positively correlated with final leaf rust severity (%). Significant correlation between yield losses (%) and the two factors, i.e., final leaf rust severity (%) and maximum relative humidity, was also found in this study. Meanwhile, negative correlation was found between final leaf rust severity (%) and yield losses (%) and the two environmental factors, i.e., solar radiation and minimum relative humidity. The effectiveness of tested models was estimated by using R2 values for all models, and these models were validated to predict leaf rust severity (%) and yield loss.

Wheat leaf rust, caused by Puccinia triticina, is an important fungal disease of wheat in China. To study races of the pathogen in China, leaf rust samples were collected from 14 provinces in 2014 and 15 provinces in 2015. From the samples, 494 single-uredinial isolates were derived from the 2014 collection and 649 from the 2015 collection. These isolates were tested on 40 near-isogenic lines of Thatcher carrying single leaf rust resistance genes. From the isolates, 84 races were identified in 2014 and 65 races in 2015. Races THTT (22.1%), THTS (19.6%), THJT (8.7%), PHTT (4.9%), and PHJT (3.6%) were the most common races in 2014, and THTT (28.4%), THTS (12.8%), THJT (11.6%), THJS (9.9%), and PHTT (9.7%) were the most frequent in 2015. All of these races were avirulent to resistance genes Lr9 and Lr24. THTT and THTS, the most frequent races in both years, were widely distributed throughout the country. The frequencies of isolates with virulence to Lr1, Lr2a, Lr2c, Lr3, Lr16, Lr26, Lr11, Lr17, LrB, Lr10, Lr14a, Lr2b, Lr3bg, Lr14b, Lr32, Lr33, and Lr50 were over 80%, whereas the frequencies of virulence to Lr9, Lr19, Lr25, Lr28, Lr29, and Lr47 were less than 3.5%. In the present study, all isolates were avirulent to Lr24 and Lr38. The race analysis and individual virulence frequencies provide guidance to breeders in choosing leaf rust resistance genes for use in breeding programs.

Stripe rust (Puccinia striiformis f. sp. tritici) and leaf rust (Puccinia triticina) can cause significant yield reductions to hard red spring wheat (HRSW) in North Dakota (ND). The use of host resistance and fungicides can successfully manage this disease. However, the combination of them may not be appropriate every year. From 2016 to 2018, fungicide timing by cultivar experiments were conducted to update recommendations for rust management. Experiments were designed in a randomized complete block with a split-plot arrangement. Main plots included three HRSW cultivars that were moderately resistant, moderately susceptible, and susceptible. Subplots included the fungicide timings of Feekes 9, Feekes 10.5.1, a sequential application, and a nontreated control. Field experiments were categorized into three environments depending on rust onset and disease progress. When rust was detected at early heading, the susceptible cultivar benefited from all fungicide application timings. The detection of rust at tillering leaf stages suggested that fungicide treatments statistically lowered disease and in most cases had statistically higher yield, regardless of host resistance. These results suggest that the benefit from a fungicide application to manage leaf rust and stripe rust is highly influenced by the timing of disease onset and level of host resistance. Results will improve fungicide suggestions for HRSW producers in ND.

Puccinia triticina is a highly damaging wheat pathogen. The efficacy of leaf rust control by genetic resistance is mitigated by the adaptive capacity of the pathogen, expressed as changes in its virulence combinations (pathotypes). An extensive P. triticina population survey has been carried out in France over the last 30 years, describing the evolution dynamics of this pathogen in response to cultivar deployment. We analyzed the dataset for the 2006-2016 period to determine the relationship between the Lr genes in the cultivars and virulence in the pathotypes. Rust populations were dominated by a small number of pathotypes, with variations in most of the virulence frequencies related to the corresponding Lr gene frequencies in the cultivated landscape. Furthermore, the emergence and spread of a new virulence matched the introduction and use of the corresponding Lr gene (Lr28), confirming that the deployment of qualitative resistance genes is an essential driver of evolution in P. triticina populations. However, PCA revealed that certain pathotype-cultivar associations cannot be explained solely by the distribution of Lr genes in the landscape. This conclusion is supported by the predominance of a few pathotypes on some cultivars, with the persistence of several other compatible pathotypes at low frequencies. Specific interactions are not, therefore, sufficient to explain the distribution of virulence in rust populations. Our findings suggest that aggressiveness is a driver of changes in pathotype frequencies. Accordingly, the hypothesis of “dual selection”, based on both qualitative and quantitative interactions between P. triticina populations and bread wheat cultivars, is favored.

Wheat leaf rust is one of the world’s most widespread rusts. The progress of the disease was monitored using two treatments: chitosan nanoparticles and salicylic acid (SA), as well as three application methods; spraying before or after the inoculation by 24 h, and spraying both before and after the inoculation by 24 h. Urediniospore germination was significantly different between the two treatments. Wheat plants tested for latent and incubation periods, pustule size and receptivity and infection type showed significantly reduced leaf rust when compared to untreated plants. Pucciniatriticina urediniospores showed abnormalities, collapse, lysis, and shrinkage as a result of chitosan nanoparticles treatment. The enzymes, peroxidase and catalase, were increased in the activities. In both treatments, superoxide (O2−) and hydrogen peroxide (H2O2), were apparent as purple and brown discolorations. Chitosan nanoparticles and SA treatments resulted in much more discoloration and quantitative measurements than untreated plants. In anatomical examinations, chitosan nanoparticles enhanced thickness of blade (µ), thickness of mesophyll tissue, thickness of the lower and upper epidermis and bundle length and width in the midrib compared to the control. In the control treatment’s top epidermis, several sori and a large number of urediniospores were found. Most anatomical characters of flag leaves in control plants were reduced by biotic stress with P. triticina. Transcription levels of PR1-PR5 and PR10 genes were activated in chitosan nanoparticles treated plants at 0, 1 and 2 days after inoculation. In light of the data, we suggest that the prospective use of chitosan nanoparticles might be an eco-friendly strategy to improve growth and control of leaf rust disease.

Puccinia triticina Erikss. is a causative agent of wheat leaf rust spread worldwide. Wheat rust is a major disease on wheat in southern regions of Russia, which are leaders in grain production and have favorable conditions for pathogen development. In this paper we studied the effectiveness of 52 NILs of cv. Thatcher with Lr genes in field trials and 41 NILs—in the juvenile phase in a greenhouse during 2011–2020. We conclude that the lines with Lr9, Lr42 and Lr43+24 genes remained immune in the adult phase during ten years of research. Lines with Lr genes: 19, 24, 29, 36, 37, 38, 43, 45, 47, 50 showed efficiency in field tests (1–5 R on the CIMMYT scale). No immune lines to Puccinia triticina were registered in the juvenile phase during 2011–2020. The line with the Lr9 gene remained immune up to 2020; Lr19 and Lr41—up to 2015; Lr42—up to 2018, and Lr50—up to 2019. In 2020, there was an increase of P. triticina isolates with virulence to Thatcher lines with Lr: 9, 14a, 16, 19, 21, 28, 30, 33, 40, 45, W, 50. Additionally, we registered a change in infection types towards more susceptible in isogenic Lr gene lines: 1, 2a, 12, 14b, 15, 18, 20, 23, 25, 28, 29, 32, 35, 36, 37, 38, 40, 44, 45 in the field. A sharp increase in the frequencies of virulent isolates was recorded in 2018–2020 due to unfavorable weather in the growing seasons. This indicates the ability of a dangerous pathogen to rapidly evolve in response to biotic and abiotic stresses. Therefore, annual monitoring of the reaction of isogenic lines, selected released varieties and the study of the virulence of the phytopathogen are important measures necessary to prevent and control leaf rust in grain-producing regions of the world.

Twenty-three wheat genotypes were evaluated for stripe and leaf rusts, caused by Puccinia striiformis f. sp. tritici and Puccinia triticina f. sp. tritici, respectively, at seedling and adult stages under greenhouses and field conditions during the 2019/2020 and 2020/2021 growing seasons. The race analysis revealed that 250E254 and TTTST races for stripe and leaf rusts, respectively were the most aggressive. Eight wheat genotypes (Misr-3, Misr-4, Giza-171, Gemmeiza-12, Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46) were resistant to stripe and leaf rusts at seedling and adult stages. This result was confirmed by identifying the resistance genes: Lr34/Yr18, Lr37/Yr17, Lr46/Yr29, and Lr67/Yr46 in these genotypes showing their role in the resistance. Sids-14 and Shandweel-1 genotypes were susceptible to stripe and leaf rusts. Twelve crosses between the two new susceptible wheat genotypes and the three slow rusting genes (Lr34/Yr18, Lr37/Yr17, and Lr67/Yr46) were conducted. The frequency distribution of disease severity (%) in F2 plants of the twelve crosses was ranged from 0 to 80%. Resistant F2 plants were selected and the resistance genes were detected. This study is important for introducing new active resistance genes into the breeding programs and preserving diversity among recently released wheat genotypes.

The southern Ural is consistently among the 10 best regions in Russia for agricultural production, including wheat. Breeding in the Chelyabinsk Research Institute of Agriculture aims to develop wheat cultivars genetically protected from the main diseases (leaf and stem rust, septoria leaf blotch and tan spot). The genes for resistance to leaf rust, Lr1, Lr9, Lr10 and Lr26/Sr31, alone or in combination, are widespread in cultivars grown in the southern Ural. In 2012, a new wheat cultivar, Chelyaba 75, was proposed for commercial production in the southern Ural, being highly resistant to leaf rust with the highly effective genes LrSp and SrSp transferred from the cuckoo line with the genetic material Aegilops speltoides. Isolates virulent to cv. Chelyaba 75 were not found in Russian populations of Puccinia triticina. Additionally, for a long period, genes Lr29, Lr 41, Lr42, Lr45, Lr47, Lr50, Lr51, Lr53 and Lr57 were characterized by high efficiency. Virulence frequencies to other Lr genes vary annually, but no races with new virulence have been identified. The resistance of lines with the Sr31 and Sr24 genes indicates that the Puccinia graminis population does not contain genotypes with the potentially damaging race Ug99. Mixed septoria and tan spot infections occurred in the southern Ural, with the latter dominating. Races producing the exotoxin ToxA are widely distributed in Pyrenophora tritici-repentis populations. Two causal agents of septoria leaf blotch (Parastagonospora nodorum and P. avenae f. sp. tritici) occur in the region, with the first dominating. Aggressiveness of P. nodorum isolates to wheat cultivars was higher than that of P. avenae f. sp. tritici. All Parastagonospora isolates showed the presence of the SnTox3 marker. SnToxA and SnTox1 markers were found in P. nodorum isolates, usually separately, but in one isolate, these genes were found together. The analysis of the genetic diversity of wheat cultivars grown in the southern Ural, and the pathogenic complex present, indicate that pathogens continuously evolve under the influence of the host plant.

Brown (leaf) rust of wheat (Puccinia triticina) was widely prevalent in all the wheat growing areas of India and neighbouring countries during 2013–16. To have an effective rust management strategy, monitoring of virulence patterns of P. triticina on wheat were undertaken. Brown rust samples were analyzed from the wheat growing areas in India, Bangladesh, Bhutan and Nepal using standard differential Indian System and named as per the binomial system of nomenclature. A new pathotype 77-12 was also identified during this period. Thirty seven pathotypes of P. triticina were identified in 1427 samples. Five predominant pathotypes 121R63-1(77-5 = THTTM), 121R60-1(77-9 = MHTKL), 21R55 (104-2 = PHTTL), 21R63 (104-3 = PHTTL) and 77-11(125R28 = MGTTL) accounted for 75.1% of the population. All of the prevalent pathotypes are virulent to Lr1, Lr3, Lr10, Lr11,Lr12 Lr13, Lr14a, Lr16, Lr17, Lr23, Lr26. Virulences for Lr9 and Lr19 though recorded from India long back, however, were not observed during present surveys whereas virulence on Lr28 was identified in 0.4% samples only. The proportion of pathotype 121R60-1 (77-9 = MHTKL) has increased during these years and was recorded in 23.7% samples against 12% in the previous report. Brown rust of wheat was not observed on Lr9, Lr24, Lr25, Lr32, Lr39 and Lr45 in the field population of Indian subcontinent during 2013–16. Diversity of pathotypes detected during this period could, to some extent, be related to cultivation of different varieties but was also appeared to be affected by different weather patterns in different agro-ecological areas.

Juchi F2000, Náhuatl F2000 y Tlaxcala F2000 son variedades de trigo harinero recientemente liberadas para siembras de temporal o secano en México. La roya de la hoja del trigo causada por Puccinia triticina E. afecta la producción de este cereal en forma continua, por lo que; el mejoramiento genético para resistencia a esta enfermedad ha sido el método más eficiente para su control. Con el fin de determinar la genética de la resistencia a la roya de la hoja en Juchi F2000, Náhuatl F2000 y Tlaxcala F2000, éstas se cruzaron con la variedad susceptible Avocet-YrA (AOC-YrA). Ciento cuarenta y ocho familias F3 por cruza y sus progenitores fueron evaluadas en el Valle del Yaqui, Sonora, por su respuesta a la roya de la hoja, durante el ciclo de cultivo otoño-invierno 2001-2002. Se creó una epifitia artificial mediante la inoculación con urediniosporas de roya de la hoja de la raza MCJ/SP. Las familias se clasificaron en resistentes, susceptibles y segregantes. Con base en el número de familias homocigóticas resistentes y susceptibles, se determinó que Juchi F2000 y Tlaxcala F2000 poseen cuatro genes de efecto aditivo que condicionan el desarrollo lento de la roya. También se determinó que Náhuatl F2000 posee tres genes de efecto aditivo, que incluye el posible efecto del gene Lr16. Un gene en común en las tres variedades fue Lr34, que confiere resistencia de desarrollo lento de la roya de la hoja. El número de genes se discute de acuerdo con el tamaño de la población y a las frecuencias esperadas.

Leaf rust, caused by the fungus Puccinia triticina Erikss (Pt), is a destructive disease affecting wheat (Triticum aestivum L.) and a threat to food security. Developing resistant cultivars represents a useful method of disease control, and thus, understanding the genetic basis for leaf rust resistance is required. To this end, a comprehensive bibliographic search for leaf rust resistance quantitative trait loci (QTL) was performed, and 393 QTL were collected from 50 QTL mapping studies. Afterward, a consensus map with a total length of 4,567 cM consisting of different types of markers (simple sequence repeat [SSR], diversity arrays technology [DArT], chip-based single-nucleotide polymorphism [SNP] markers, and SNP markers from genotyping-by-sequencing) was used for QTL projection, and meta-QTL (MQTL) analysis was performed on 320 QTL. A total of 75 MQTL were discovered and refined to 15 high-confidence MQTL (hcmQTL). The candidate genes discovered within the hcmQTL interval were then checked for differential expression using data from three transcriptome studies, resulting in 92 differentially expressed genes (DEGs). The expression of these genes in various leaf tissues during wheat development was explored. This study provides insight into leaf rust resistance in wheat and thereby provides an avenue for developing resistant cultivars by incorporating the most important hcmQTL. info:eu-repo/semantics/publishedVersion

The main growing regions for winter wheat in the Russian Federation are the North Caucasian, Central Black Earth, and Central agroecological regions. Spring wheat crops dominate in the Urals, Volga region, and Western Siberia. Wheat leaf rust, caused by Puccinia triticina, is an important disease, impacting greatly on wheat production. In Russia, the disease was an annual problem until 2010 but has since been more effectively controlled. However, changes in virulence in pathogen populations may arise from climate change, evolving cropping practices, intense use of chemical protectants, and an increase in the release of resistant cultivars. In the 2000s, the State Register of the Russian Federation included an increase in the number of winter and spring wheat cultivars resistant to leaf rust. However, successful genetic protection requires a diversity of cultivars with different resistance genes (Lr genes). Studies by the All Russian Institute of Plant Protection identified Lr genes in Russian cultivars’ phenotypes and molecular markers. In addition, the prevalence of virulence in pathogen populations was studied and the influence of the cultivar used in wheat production on the changes in these populations was evaluated. This paper reviews research on the genetic diversity of winter and spring wheat cultivars included in the State Register of Russia from 2000 to 2020 and analyzes their impact on the prevalence of virulence in pathogen populations. These data demonstrate the continuous evolution of P. triticina in response to wheat breeding efforts. Populations of the pathogen showed higher variability in regions where pathotype-specific resistance cultivars were commonly grown.

The characterization of leaf rust (caused by Puccinia triticina) and stripe rust (caused by Puccinia striiformis f. sp. tritici) resistance genes is the basis for breeding resistant wheat varieties and managing epidemics of these diseases in wheat. A cross between the susceptible wheat variety ‘Apav#1’ and resistant variety ‘Neimai 836’ was used to develop a mapping population containing 148 F5 recombinant inbred lines (RILs). Leaf rust phenotyping was done in field trials at Ciudad Obregón, Mexico, in 2017 and 2018, and stripe rust data were generated at Toluca, Mexico, in 2017 and in Mianyang, Ezhou, and Gansu, China, in 2019. Inclusive complete interval mapping (ICIM) was used to create a genetic map and identify significant resistance quantitative trait loci (QTL) with 2,350 polymorphic markers from a 15K wheat single-nucleotide polymorphism (SNP) array and simple-sequence repeats (SSRs). The pleiotropic multipathogen resistance gene Lr46/Yr29 and four QTL were identified, including two new loci, QLr.hzau-3BL and QYr.hzau-5AL, which explained 3 to 16% of the phenotypic variation in resistance to leaf rust and 7 to 14% of that to stripe rust. The flanking SNP markers for the two loci were converted to Kompetitive Allele-Specific PCR (KASP) markers and used to genotype a collection of 153 wheat lines, indicating the Chinese origin of the loci. Our results suggest that Neimai 836, which has been used as a parent for many wheat varieties in China, could be a useful source of high-level resistance to both leaf rust and stripe rust.

Spain has a great landrace diversity of the subspecies of the tetraploid species Triticum turgidum L., namely, durum (or durum wheat), turgidum (or rivet wheat) and dicoccon (or domesticated emmer wheat). These wheats have to confront several foliar diseases such as the leaf rust. In this work, a core collection of 94 landraces of tetraploid wheats were inoculated with three leaf rust isolates. Besides, a larger collection (of 192 accessions) was evaluated in the field. Although the majority of landraces were susceptible, approximately 20% were resistant, especially domesticated emmer wheat landraces. Several variables, such as late heading and red coat seeds were associated to resistant accessions. Regarding ecogeographic variables, a higher rainfall from October to February and more uniform temperature were found in the area of origin of resistant landraces. Based on these results, several resistant landraces were identified that potentially may be used in durum wheat breeding programs. In addition, a predictive model was elaborated to develop smaller subsets for future screening with a higher hit rate for rust resistance.

NAC transcription factors are one of the largest transcription factor families having functions in a variety of stress responses. Few NACs have been reported for interactions between wheat and the wheat rust fungus Puccinia triticina (Pt). In this study, based on analysis of RNA-seq data from wheat line TcLr19 inoculated by Pt, the NAC transcription factor TaNAC069 was cloned from wheat, and its transcriptional activity and homologous dimer formation were verified. Quantitative real-time PCR analysis showed that the expression of TaNAC069 was induced by Pt and associated signaling molecules. To further characterize the function of the TaNAC069 gene in wheat resistance to Pt, virus-induced gene silencing (VIGS) was utilized, and it revealed that Pt resistance in TaNAC069-silenced plants was significantly reduced. Potential interaction targets of TaNAC069 from wheat and Pt were screened and identified by yeast two-hybrid technology. Eukaryotic elongation factor eEF1A, CBSX3 protein, and cold acclimation protein WCOR410c were screened by yeast one-hybrid technology. The results indicate that the TaNAC069 gene plays a positive regulatory role in wheat resistance to Pt, laying a good foundation to analyze the molecular mechanisms of TaNAC069 and its functional role in wheat resistance to Pt.

We present a summary of Puccinia triticina virulence surveys in former Czechoslovakia and Czech Republic from the 1960s to 2019. Cultivars Malakoff, Carina, Brevit, Webster, Loros, Mediterranean, Hussar, Democrat and, later Salzmünder Bartweizen, were used as differentials until 2002. Thereafter tests were carried out on Thatcher near-isogenic lines (NILs) possessing resistance genes Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr10, Lr11, Lr13, Lr15, Lr17a, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. In tests with differential cultivars, races 14, 77, 61, 53 and 2 progressively prevailed, first avirulent to cultivar Salzmünder Bartweizen and later virulent. In tests with NILs the average virulence frequency to most Lr lines was above 50%. Virulences below 50% included Lr2a, Lr2b, Lr2c, Lr24 and Lr28, and below 1% Lr9 and Lr19. During the 1960s and 1970s Lr3a and Lr26 were commonly used resistance genes. In the first decades of the 21st century genes Lr37 and Lr10 prevailed. We used molecular markers to postulate the presence of Lr1, Lr3a, Lr10, Lr24, Lr26, Lr28, Lr34 and Lr37 in winter wheat cultivars registered in the Czech Republic.

NAC transcription factors are one of the largest transcription factor families having functions in a variety of stress responses. Few NACs have been reported for interactions between wheat and the wheat rust fungus Puccinia triticina (Pt). In this study, based on analysis of RNA-seq data from wheat line TcLr19 inoculated by Pt, the NAC transcription factor TaNAC069 was cloned from wheat, and its transcriptional activity and homologous dimer formation were verified. Quantitative real-time PCR analysis showed that the expression of TaNAC069 was induced by Pt and associated signaling molecules. To further characterize the function of the TaNAC069 gene in wheat resistance to Pt, virus-induced gene silencing (VIGS) was utilized, and it revealed that Pt resistance in TaNAC069-silenced plants was significantly reduced. Potential interaction targets of TaNAC069 from wheat and Pt were screened and identified by yeast two-hybrid technology. Eukaryotic elongation factor eEF1A, CBSX3 protein, and cold acclimation protein WCOR410c were screened by yeast one-hybrid technology. The results indicate that the TaNAC069 gene plays a positive regulatory role in wheat resistance to Pt, laying a good foundation to analyze the molecular mechanisms of TaNAC069 and its functional role in wheat resistance to Pt.

Leaf or brown rust of wheat caused by Puccinia triticina (Pt) is one of the most damaging diseases globally. Considerable progress has been made to control leaf rust through crop protection chemicals and host plant resistance breeding in southern Africa. However, frequent changes in the pathogen population still present a major challenge to achieve durable resistance. Disease surveillance and monitoring of the pathogen have revealed the occurrence of similar pathotypes across the region, justifying the need for concerted efforts by countries in southern Africa to develop and deploy more efficient and sustainable strategies to manage the disease. Understanding the genetic variability and composition of Pt is a pre-requisite for cultivar release with appropriate resistance gene combinations for sustainable disease management. This review highlights the variability and distribution of the Pt population, and the current control strategies, challenges and future prospects of breeding wheat varieties with durable leaf rust resistance in southern Africa. The importance of regular, collaborative and efficient surveillance of the pathogen and germplasm development across southern Africa is discussed, coupled with the potential of using modern breeding technologies to produce wheat cultivars with durable resistance.

This research aims to assess genotype × environment interactions (G × E) of the leaf rust (Puccinia triticina) reactions of 29 Turkish landrace-derived pure lines over seven environments. Field experiments were conducted in Çanakkale, Edirne and Samsun (Turkey) in three consecutive growing seasons from 2011-2012 to 2013–2014 under natural conditions. Leaf rust reactions of genotypes were recorded in accordance with the Modified Cobb scale. Genotype stabilities assessed by non-parametric stability statistics. Furthermore, a Principal Component Analysis (PCA) biplot of non- parametric stability statistics were used to compare their capability for capturing both stability and leaf rust reactions of genotypes in the given dataset. PCA Biplot results showed that non-parametric parameters of Thennarasu and Percentage Availability (PA) showed a positive association with mean disease severity while Rank Means (RM) were negatively associated. Non-parametric stability analyses revealed that Genotypes 29, 25 and 15 were the most stable pure lines when only 25 and 15 could be considered as resistant-stable. In order to determine both stability and leaf rust resistance in bread wheat, PA and RM are recommended. © 2020, Springer Nature B.V.

La roya de la hoja, ocasionada por el hongo Puccinia triticina, es una enfermedad común en trigo (Triticum aestivum) que causa pérdidas económicas significativas. Actualmente se cuenta con variedades que presentan resistencia a razas específicas del hongo; sin embargo, el patógeno frecuentemente vence la resistencia en corto tiempo. Una estrategia alterna es la acumulación de genes de resistencia con efecto aditivo. Para lograrlo es necesario encontrar marcadores moleculares que faciliten la selección de nuevos genotipos con resistencia genética. Por lo anterior, el objetivo de esta investigación fue aislar e identificar nuevos genes para la resistencia a P. triticina a través de la generación de una biblioteca sustractiva supresiva de ADNc de la variedad resistente Monarca F2007. La respuesta general de Monarca ante la presencia del hongo fue la activación de genes que codifican principalmente proteínas relacionadas con patogénesis y con sequía moderada. La inducción de estos genes es crucial para mantener en buen estado el tejido foliar ante la infección por P. triticina. Por otra parte, se demostró que líneas de trigo resistentes a roya inducen la expresión de un mayor número de genes que las líneas susceptibles, lo que indica que pueden tener efectos aditivos. La expresión de transcritos diferenciales es un indicador de la respuesta del trigo contra la infección de la roya de la hoja y los perfiles de expresión de estos genes se pueden emplear como marcadores moleculares para la selección de genotipos con mayor resistencia.

A monitoring survey focused on the local leaf rust pathogen on spring bread wheat was conducted during 2008–2017 in the Western Siberian region of the Russian Federation. Resistance genetics in cultivars released in the region during the last twenty years has been limited to only a few Lr genes: Lr1, Lr9, L10, Lr26, and Lr34. The effectiveness of Lr genes was assessed in field tests of 38 «Thatcher» Near Isogenic Lines (NILs). Resistance genes were classified into four groups based on infection types (ITs) in response to the local population of Puccinia triticina. Lines carrying genes Lr17, Lr18, Lr24, Lr25, Lr29, Lr35, Lr37, Lr44, and LrW(52) remained almost free of infection for the whole duration of rating. Their disease scores did not exceed the level of medium resistant even in seasons favorable for the spread of leaf rust. ITs indicative of moderate resistance were revealed in lines carrying genes Lr12, Lr13, Lr28, Lr34, and Lr38, except under conditions favorable to infection when plants became susceptible. Genes Lr1, Lr2a, Lr2c, Lr9, Lr14a, Lr14b, Lr15, Lr16, Lr19, and Lr22 showed reduced effectiveness against leaf rust in the region during the monitoring dates. Virulence to lines carrying genes Lr2b, Lr3, Lr3bg, Lr3 ka, Lr10, Lr11, Lr20, Lr21, Lr26, Lr30, Lr32, Lr33, and LrB was recorded during the whole time of monitoring from 2008 to 2017. Since race-specific genes Lr24 and Lr29 are still effective in the Western Siberian region, they may be recommended for breeding purposes deployed in combination with slow rusting gene Lr34 and the race-specific adult plant resistance genes Lr12 and/or Lr13, to provide durable resistance.

Puccinia triticina, the causal agent of wheat leaf rust, is one of the most devastating rust fungi attacking wheat worldwide. Seventy-six isolates of the wheat leaf rust pathogen from Yunnan, Sichuan, Gansu and Henan provinces, China, were tested on wheat leaf rust differentials and the population structure was analyzed using four presumably neutral partial sequence markers such as elongation factor-1α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB) and the second largest RNA polymerase subunit (RPB2). The phenotypic diversity of Yunnan and Sichuan populations was higher than that of Gansu and Henan populations. The four populations were separated into two clusters based on the pathogenic data. A total of 12 single nucleotide polymorphisms (SNPs) and 32 haplotypes were identified among the four sequences. The 32 haplotypes were divided into two clusters in a neighbor-joining tree. Bayesian analyses also identified two clusters. Pairwise FST between populations in different regions were significantly different (P

Wheat leaf rust, caused by Puccinia triticina, is a commonly occurring disease in wheat growing areas of the world. Research on the virulence and genetic diversity of P. triticina will be helpful for a better understanding of the evolution tendencies and subsequently for controlling this disease. In this study, 59 isolates of P. triticina collected from Hebei Province of China in 2008 and 2010 were analyzed for virulence diversity based on 37 near-isogenic Thatcher wheat lines at seedling stage, and genetic diversity using 21 pairs of EST-SSR primers. The predominant virulence phenotypes were PHTT, THTT, and THJT in 2008, while THTS, THSS, THTT, and THST were most common in Hebei province in 2010. Clustering analysis based on the virulence and EST-SSR data revealed a high diversity of P. triticina, and differences between the populations of 2008 and 2010. There was no significant correlation between the molecular and virulence data. Genetic parameters analysis also showed high diversity of the P. triticina population in Hebei province. Nei’s gene diversity index (H) and Shannon’s information index (I) showed that the genetic diversity of population 2008 was higher than 2010. The AMOVA analysis suggested that genetic variation mainly from intra-population (61.11%).

Damage to wheat crop is associated with leaf rust (Puccinia triticina) and powdery mildew (Blumeria graminis f. sp. tritici). The present study aimed to evaluate the effect of potassium phosphite and acibenzolar-S-methyl alone or associated with the fungicide epoxiconazole + pyraclostrobin on powdery mildew and leaf rust control, as well as on grain yield. The experiments were designed as randomized blocks with four replicates consisting of plots with 17 planting rows spaced at 0.17 m, with dimensions of 2.89 x 5.0 m each. Severity of powdery mildew and leaf rust was assessed in ten flag leaves and ten whole plants all over the crop season; yield was also evaluated. Severity data were used to calculate the area under the disease progress curve. There was no effect of phosphite applied alone or associated with the fungicide epoxiconazole + pyraclostrobin at different times on mildew. Acibenzolar-S-methyl controlled, on average, 70% powdery mildew. Phosphites applied alone and/or associated with the fungicide had an effect on leaf rust, reducing the severity by 59 and 62%, compared to control. Applications of phosphites alone did not affect the yield components. RESUMO Danos na cultura do trigo estão associados a ferrugem da folha (Puccinia triticina) e ao oídio (Blumeria graminis f. sp. tritici). O presente trabalho objetivou avaliar o efeito de fosfito de potássio e acibenzolar-S-metil isolados e/ou associados ao fungicida epoxiconazole + piraclostrobina no controle do oídio e da ferrugem da folha e no rendimento de grãos. Os experimentos foram delineados em bloco ao acaso, com quatro repetições constituídas por parcelas com 17 linhas de semeadura espaçadas em 0,17 m, com dimensões de 2,89 x 5,0 m. A severidade do oídio e da ferrugem da folha foi avaliada em 10 folhas bandeira e em 10 plantas inteiras ao longo do ciclo de cultivo, avaliou-se também a produtividade. Com os dados de severidade calculou-se a área abaixo da curva de progresso das doenças. Não houve efeito das aplicações de fosfito isolado ou associado ao fungicida epoxiconazole + piraclostrobina em diferentes épocas sobre o oídio. O acibenzolar-S-metil controlou em média cerca de 70% do oídio. Os fosfitos isolados e/ou associados ao fungicida tiveram efeito sobre a ferrugem da folha reduzindo a severidade em 59 e 62% em relação à testemunha. Aplicações de fosfitos isolados não afetaram os componentes de rendimento.

Leaf rust (Puccinia triticina Eriks.) is one of the most widespread disease of wheat (Triticum aestivum L.) in Egypt and worldwide. The two leaf rust resistance genes i.e. Lr 9 and Lr 19 were previously highly effective against the predominant Puccinia triticina races in Egypt. In 2015/2016 growing season, susceptible field reaction was recorded on these two genes, where rust severity reached to 40% for Lr 9 and 5% for Lr 19 under Egyptian field conditions at the four locations i.e. El-Behira, El-Minufiya, El-Qalubiya and El-Fayom governorates. In this study, eight leaf rust field samples were collected from these governorates (four from each of Lr 9 and Lr 19). Forty single isolates were derived from the collected samples of Lr 9 and Lr 19 (each with 20 isolates). Eight pathotypes were identified from Lr 9, while only two pathotypes were identified from Lr 19. Also, 39 leaf rust monogenic lines (Lr,s) and 16 commercial wheat cultivars were tested for their seedling reaction against ten leaf rust pathotypes isolated from Lr 9 and Lr 19. While, 12 leaf rust monogenic lines and the same 16 wheat cultivars were evaluated at adult plant stage. The most frequent pathotype (virulent to Lr 9) was KTSPT (30% frequency), followed by TTTMS (25% frequency). The other pathotypes ranged from only 5%–10% frequency. Whereas, the most frequent pathotype (virulent to Lr 19) was CTTTT (85% frequency), but the lowest frequent one was PKTST (15% frequency). Pathotypes i.e. PRSTT, NTKTS and TTTMS (identified from Lr 9) were more aggressive pathotypes on most of the tested leaf rust monogenic lines than others. Also, the two pathotypes; PKTST and CTTTT (identified from Lr 19) were more aggressive pathotypes on most of the tested leaf rust monogenic lines. The leaf rust resistance gene Lr 2a was the most effective gene against almost all of the tested pathotypes at adult plant stage. On the other hand, the three wheat cultivars; Misr 1, Misr 2 and Nubariya 1 proved to be of highly resistance against all of the tested leaf rust pathotypes at adult plant stage.

Population behaviour of two sets of pathotypes (77-5, 77-9, 104-2, 104-2; 77-5, 77-9, 104-2) of Puccinia triticina was studied in relation to wheat cultivars DBW71, DBW90, HD3086, HPW349, K1006, Local Wheat Hango (LWH), MP3336, PBW343, WH1124 and Agra Local at two temperature regimes under controlled greenhouse conditions. These wheat cvs belonged to different areas and were susceptible to all the pathotypes used in the studies. Predominance of a pathotype was the outcome of temperature, wheat variety and competition among the pathotypes. Both pathotype 77-9 and 104-2 were equally dominant in a population of 77-5, 77-9, 104-2 and 104-3. Pathotype 77-5 was less frequent. In a set of three pathotypes 77-5 was more frequent followed by 104-2 whereas 77-9 was nearly eliminated. Among the pathotypes used in the studies, 104-2 was the simplest and it emerged dominant on Agra Local and some other wheat cultivars. In fitness studies, pathotype 77-9 was found to possess less incubation period, latent period, produced more uredinio-pustules and urediniospores/cm2 as compared to other pathotypes. It is indicative of the fact that the pathotype 77-9 followed by 104-2 is more competitive and fit in population and can overtake other pathotypes in the years to come.

Wheat is a major nutritional cereal crop that has economic and strategic value worldwide. The sustainability of this extraordinary crop is facing critical challenges globally, particularly leaf rust disease, which causes endless problems for wheat farmers and countries and negatively affects humanity’s food security. Developing effective marker-assisted selection programs for leaf rust resistance in wheat mainly depends on the availability of deep mining of resistance genes within the germplasm collections. This is the first study that evaluated the leaf rust resistance of 50 Egyptian wheat varieties at the adult plant stage for two successive seasons and identified the absence/presence of 28 leaf rust resistance (Lr) genes within the studied wheat collection. The field evaluation results indicated that most of these varieties demonstrated high to moderate leaf rust resistance levels except Gemmeiza 1, Gemmeiza 9, Giza162, Giza 163, Giza 164, Giza 165, Sids 1, Sids 2, Sids 3, Sakha 62, Sakha 69, Sohag 3 and Bany Swif 4, which showed fast rusting behavior. On the other hand, out of these 28 Lr genes tested against the wheat collection, 21 Lr genes were successfully identified. Out of 15 Lr genes reported conferring the adult plant resistant or slow rusting behavior in wheat, only five genes (Lr13, Lr22a, Lr34, Lr37, and Lr67) were detected within the Egyptian collection. Remarkedly, the genes Lr13, Lr19, Lr20, Lr22a, Lr28, Lr29, Lr32, Lr34, Lr36, Lr47, and Lr60, were found to be the most predominant Lr genes across the 50 Egyptian wheat varieties. The molecular phylogeny results also inferred the same classification of field evaluation, through grouping genotypes characterized by high to moderate leaf rust resistance in one cluster while being highly susceptible in a separate cluster, with few exceptions.