Virulence characterization of Puccinia graminis f. sp. avenae in Argentina

Virulence characterization of Puccinia graminis f. sp. avenae in Argentina | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Virulence characterization of Puccinia graminis f. sp. avenae in Argentina Juan Dietz, Laura Da Silva, María Rosa Simón, Pablo Campos This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4172543/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Jan, 2025 Read the published version in European Journal of Plant Pathology → Version 1 posted 6 You are reading this latest preprint version Abstract Oat stem rust in oats, caused by Puccinia graminis f. sp. avenae Erikss and Henning (Pg) , is a disease of great relevance on a global scale, recognized for its destructive capacity under favourable environmental conditions. The characterization of the Pg population provides valuable insights into population size, diversity, and complexity, and allows the identification of race specific genes potentially useful for breeding. This study documents for the first time the structure and complexity of Pg populations in Argentina and their evolution over a period of 17 years, based on 70 isolates collected in different sites during 2005, 2021, 2022 and 2023. We identified 22 different races among the 70 single-uredinial isolates collected during the period, showing a greater diversity in population. Moreover, most of the races identified in 2021, and all the races identified in 2022 and 2023, were different from those found in 2005. We found that current populations are more virulent and complex, and the predominant race demonstrated virulence against all 11 reference oat lines utilized in this study, emphasizing its potential threat to oat cultivation in the region. The change in population dynamics detected here suggests that the use of a few genes as a basis for resistance to stem rust in the Argentinian germplasm has resulted in the continuous selection of Pg phenotypes with virulence to these resistance genes. Additionally, our results demonstrated that the frequency of virulence of Pg isolates increase on most of the resistance genes compared to the 2005 population, and there are not genes potentially useful for breeding under Argentinian conditions. These findings underscore the pressing need to expand our search for new resistance genes and deepen our understanding of the genetic mechanisms governing resistance to stem rust in oats. Moreover, our research highlights the dynamic nature of plant-pathogen interactions, emphasizing the continual evolution of Pg populations and their interaction with oat Pg genes. Oat stem rust Pg genes seedling resistance Avena sativa Physiologic specialization Figures Figure 1 Introduction Oats ( Avena sativa L.) are a cereal of great importance worldwide due to their use as a dual-purpose crop (forage and grain). It is the sixth most important cereal in grain production, with approximately 23 million t occupying an area of around 10 million hectares (FAO, 2024). In Argentina, the crop covers an area of around 1.5 million hectares, the vast majority for forage use (MAGyP, 2024). Its cultivation has been a technically and economically viable alternative, mainly in animal production systems, due to its multiple uses: grain, green forage, preserved forage (hay and silage), dual purpose (forage-grain) and use of stubble (Dietz, 2018 ). Stem rust in oats, caused by Puccinia graminis f. sp. avenae Erikss and Henning (Pg) , is a disease of great relevance on a global scale, recognized for its destructive capacity under favourable environmental conditions (Roelfs & Long, 1980 ; Martens, 1985 ). Van Niekerk et al. ( 2001 ) have reported yield losses of up to 85%, and a 45% decrease in test weight in susceptible materials after a stem rust epidemic, while Leyva et al. ( 2004 ) document drops of up to 70% in grain yield. Previous works have provided valuable insights regarding the variability and complexity of Puccinia coronata (Pc) populations in regions of South America (Leonard & Martinelli, 2005 ; Vieira et al., 2007 ; Campos et al., 2008 ; Dietz et al., 2023 ). However, research on Pg populations has been relatively limited, with only a few studies conducted (Campos & Gimenez, 2011 ; Gnocato, 2017 ), which document significant variability in the Pg populations of our region. Although there is no evidence that Pg has sexual reproduction in this area (Martinelli, 2004 ), the genetic diversity in the populations is very high (Campos & Gimenez, 2011 ; Gnocato 2017 ), indicating that other factors may be the driving force for cause changes in the population structure of the stem rust pathogen. Moreover, it has been reported that the oat growing regions of Argentina, Brazil, and Uruguay share a common epidemiological system (Leonard & Martinelli, 2005 ; Campos et al., 2008 ; Dietz et al., 2023 ). Therefore, it might be expected that some races within the Pg population in Argentina exhibit similarities in their virulence pattern to races found in Brazil and Uruguay or that new biotypes may emerge because of migration. In Argentina, research on oat management for crown rust has been conducted (Campos et al., 2008 ; Dietz et al., 2016 ; Dietz et al., 2019 ; Dietz et al., 2023 ), but less effort has been dedicated to stem rust. Historically, it has been considered a disease of less relevance, which appears sporadically towards the end of the crop cycle, mainly affecting oats destined for grain production. In this sense, Campos & Gimenez ( 2011 ) and Wehrhahne & Storm ( 2014 ) have reported its presence during some campaigns, although showing a low level of the disease among the diseased genotypes. However, recent data (2021, 2022 and 2023) taken in trials and farmer´s field in different locations (Reconquista, La Plata, Barrow and Bordenave) show a greater intensity of the disease (Dietz, personal communication ). For example, in Reconquista during the 2023 campaign, most Argentinian materials reached 100% severity, showing stem breaking and panicle retention. This increase in the level of disease may be explained by the appearance of new biotypes with a greater spectrum of virulence. Genetic improvement is the most effective control method for managing the disease (Fetch & Jim, 2007; Villaseñor et al ., 2021; Li et al., 2022 ). However, the fact that only 16 genes have been described (Fetch & Jim, 2007) that are the basis of resistance to stem rust worldwide, suggests a limited availability of genetic resources for the development of oat varieties resistant to this disease. The characterization of the Pg population provides valuable insights into population size, diversity, and complexity, and allows the identification of race specific genes potentially useful for breeding, which is essential to guide regional breeding programs and/or establish management guidelines that tend to minimize the losses caused by this disease. In this study, we collected 70 Pg isolates from a vast area of Argentina in 2005 and during the 2021–2023 period with the objectives (i) to analyze the evolution of the pathogen population over time and (ii) to assess the efficacy of Pg resistance genes and their suitability for practical breeding applications in our region. Materials and methods Experimental material Samples of oat stems infected with Pg were collected during the 2005, 2021, 2022, and 2023 growing seasons (November) from experimental and farmer´s fields in different locations of Argentina [supplementary material; table S1 )]. Each year after collection in November, samples were natural dried at room temperature, and stored in a fridge at 4–6°C until virulence tests were conducted. The collection included 70 isolates, depicting 24 in 2005, 15 in 2021, 16 in 2022, and 15 in 2023. Virulence tests were conducted at the Rust laboratory belonging to the National Institute for Agricultural Technology (INTA) in Bordenave, Argentina (37º 52’ LS; 63º 01’ LW). Urediniospores from each sample of rusted oat stem were isolated and multiplied on seedlings of the oat cultivar “Boyera”, which is susceptible to all known races of Pg at the seedling stage, via the detached method described by Dietz et al. ( 2023 ). Virulence assessment Each single-spore isolate was tested for virulence on a set of 11 Pg reference lines ( Pg1 , Pg2 , Pg3 , Pg4 , Pg8, Pg9, Pg10, Pg13, Pg15, Pg16 and Pga ), each with a different single Pg gene for race specific stem rust resistance (Harder, 1994 ). The collection has been used in Argentina to characterize the Pg population and postulate genes in genotypes of interest (Campos, personal communication ). The previously described method for sowing and inoculation (Dietz et al., 2023 ) was followed. Briefly, at 10–12 days after planting (when the seedlings had two expanded leaves; GS12, Zadoks et al., 1974 ), the differential set seedlings were inoculated with freshly collected urediniospores of a single-uredinial isolate. Inoculated plants were placed in a 100% humidity dark chamber for 20 h at 20 +/-1ºC for spore germination and penetration. After incubation, seedlings were placed on benches in the greenhouse at 20 +/-1°C. Disease reactions were scored 15 days after inoculation according to the scale of Stakman (Stakman et. al., 1962 ). Seedlings showing infection types of 0;, 1, and 2 and their modifications (;1+, 11+, T... etc.) were classified as resistant, while those with ITs of 3 or 4 were considered susceptible. Data analysis Races/isolates of Pg were determined considering the virulence/avirulence patterns on the 11 Pg reference oat lines used in this study. Each isolate with a comparable virulence or avirulence pattern, irrespective of the year it was collected, was assigned the same number. Table 1 provides a summary of the identified isolates and the frequency of their occurrence each year. The virulence parameters were described using the Kosman approach (Kosman 1996 , 2003 ). The virulence within the pathogen population (virulence frequency) was calculated based on the average of the proportion of all Pg genes overcome by each isolate on the Pg set differential (Supplementary Table S1 ). Results were subjected to the Kruskal-Wallis one way analysis of variance appropriate for data with distributions far from normal with the mean ranks post hoc comparison, using Infogen Software (Balzarini & Di Rienzo, 2016 ), to determine if there were significant differences in the virulence through the years. The virulence complexity was calculated as the mean number of virulence genes per isolate detected over the 11 differential lines. In addition, frequency of virulence to each Pg differential was calculated as Frequency of virulence= (NVI/NTC) *100; where NVI is the number of times that a virulent reaction type was detected, and NTC is the number of all tested isolates collected each year. Results The origin, and virulence/avirulence patterns of isolates collected in Argentina in 2005, 2021, 2022, and 2023 are presented as supplementary material (Supplementary Table S1 ). In total, 22 different races were found among the 70 single-uredinial isolates collected during the period (Table 1 ), although 16 races were found only twice or one. In 2005, a total of 10 races were identified from 24 isolates (Supplementary Table S1 ). The race labeled as "race 1" ( Pg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16//Pg8-Pg10-Pga ) was the most prevalent, whereas races 2 through 10 were each found twice (Table 1 ). In 2021, 8 races were identified among 15 isolates. The most prevalent race was "race 11" (virulent on the 11 Pg reference genes), which was collected 3 times. Other races were found twice or only once. Moreover, most of the races identified in 2021 were different from those found in 2005, except for “race 1”, which was encountered twice. In 2022, a total of 7 races were identified from 16 isolates, while in 2023, 6 races were found among 15 isolates. During these years, “race 11” was also the most frequent, occurring 8 times per year. None of the races identified in 2005 were encountered during the years 2022 and 2023. Overall, races 1 and 11 were the most common phenotypes during the evaluated period, occurring 8 and 17 times respectively (Table 1 ). “Race 1” was the most frequent in 2005 and was not identified in 2022 and 2023, whereas race 11 was first identified 2021 and has been the most prevalent every year since then. Table 1 Virulence/avirulence pattern of the races identified and number of times found per year. Races Virulence Avirulence Year Total races 2005 2021 2022 2023 1 Pg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16 Pg8-Pg10-Pga 6 2 - - 8 2 Pg2-Pg3-Pg4-Pg8-Pg9-Pg13-Pg15-Pg16-Pga Pg1-Pg10 2 - - - 2 3 Pg1-Pg2-Pg3-Pg4-Pg9-Pg10-Pg13-Pg15-Pg16 Pg8-Pga 2 - - - 2 4 Pg3-Pg8-Pg9-Pg10-Pg16 Pg1-Pg2-Pg4 Pg13-Pg15-Pga 2 - - - 2 5 Pg10-Pg15 Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg13-Pg16-Pga 2 - - - 2 6 Pg3-Pg4-Pg9-Pg10-Pg13-Pg15-Pg16 Pg1-Pg2-Pg8-Pga 2 - - - 2 7 Pg1-Pg8-Pg10-Pg15-Pg16-Pga Pg2-Pg3-Pg4-Pg9-Pg13 2 - - - 2 8 Pg3-Pg4-Pg9-Pg10-Pg15-Pg16-Pga Pg1-Pg2-Pg8-Pg13 2 - - - 2 9 Pg10-Pg15-Pg16-Pga Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg13 2 - - - 2 10 Pg1-Pg3-Pg10-Pg16-Pga Pg2-Pg4-Pg8-Pg9-Pg13-Pg15 2 - - - 2 11 Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga - 3 8 8 19 12 Pg1-Pg2-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16 Pg3-Pga - 2 1 - 3 13 Pg1-Pg2-Pg3-Pg9-Pg13-Pg15-Pg16-Pga Pg4-Pg8-Pg10 - 1 - - 1 14 Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga Pg10 - 2 1 1 4 15 Pg1-Pg2-Pg3-Pg4-Pg8-Pg13-Pg15-Pg16 Pg9-Pg10-Pga - 1 - - 1 16 Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg16-Pga Pg15 - 2 1 - 3 17 Pg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16 Pga - 2 1 2 5 18 Pg1-Pg3-Pg4-Pg8-Pg10-Pg13-Pg15-Pg16-Pga Pg2-Pg9 - - 2 - 2 19 Pg2-Pg3-Pg4-Pg8-Pg10-Pg13-Pg15-Pga Pg1-Pg9-Pg16 - - 2 - 2 20 Pg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16-Pga Pg8-Pg10 - - - 1 1 21 Pg1-Pg2-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga Pg3 - - - 1 1 22 Pg1-Pg2-Pg3-Pg4-Pg8-Pg10-Pg16 Pg9-Pg13-Pg15-Pga - - - 2 2 Total isolates per year 24 15 16 15 70 The Kruskal–Wallis one-way variance analysis revealed statistically significant differences in the virulence of Pg populations collected in these years (p < 0.001). Post hoc comparisons of mean ranks indicated that isolates from 2005 exhibited the ability to overcome an average of 59% of oat differential resistance lines (ranging between 18% and 82%), which differed significantly from the other years. Virulence frequency within the populations has shown an increase over the past three years. By 2021, the average rose to 87%, marking a significant rise from 2005 (28%), though no difference was observed compared to 2022 (91%) and 2023 (92%). The level showed a range between 64 and 100% in these three years (Fig. 1 ). The Table 2 illustrates variations in virulence levels against reference genes. Pg isolates from 2005 demonstrated the capability to overcome between 2 and 9 reference genes, whereas for the following years, this range extended from 7 to 11 Pg genes. In 2005, many isolates (25%) exhibited virulence against 8 Pg reference genes, while only 8% were virulent against 2 and 4 Pg genes. In contrast, by 2021, 40% of isolates could overcome 10 Pg , while in 2022 and 2023, most isolates (50 and 53% respectively) could overcome the 11 Pg references genes of oat used in these assays (Table 2 ). Table 2 Percentage of isolates virulent on differential lines carrying Pg genes in Puccinia graminis populations collected in Argentina during 2005, 2021, 2022, and 2023. Number of Pg Genes Virulence complexity per year (%) 2005 2021 2022 2023 1 Pg gen 0 0 0 0 2 Pg genes 8 0 0 0 3 Pg genes 0 0 0 0 4 Pg genes 8 0 0 0 5 Pg genes 17 0 0 0 6 Pg genes 8 0 0 0 7 Pg genes 17 0 0 13 8 Pg genes 25 27 13 0 9 Pg genes 17 13 19 7 10 Pg genes 0 40 19 27 11 Pg genes 0 20 50 53 Total 100 100 100 100 Exploring the virulence of the 2005 population, we observed values ranging from 92 to 25%, with differences between genes. In the case of Pg15 and Pg16 , the frequencies were very high (above 80%), high for Pg3 , Pg9 , and Pg10 (between 65 and 80%), intermediate for Pg1 , Pg2 , Pg4 , Pg13 , and Pga (between 30 and 65%), and low for Pg8 (25%). In the current populations (2021, 2022, and 2023), most genes showed high frequencies, ranging from 100 to 53% for 2021, 100 to 75% for 2022, and 100 to 73% for 2023. Additionally, there was less variation between genes for each year. Pga was the least virulent gene in 2021 and 2023 (53% and 73%, respectively), while Pg9 was the least virulent in 2022 (75%). When analyzing the frequency of each gene overcome over the years, we observed that most genes showed an increase in their values compared to the 2005 population, although some exhibited certain fluctuations between years. Genes such as Pg1 , Pg2 , Pg4 , Pg8 , and Pg13 showed significant increases, while others like Pg9 and Pg13 showed smaller ones. Meanwhile, Pg15 and Pg16 already had high values in 2005, like the current ones. In the case of Pga and Pg10 , there were fluctuations, although Pga values were high in 2022 and 2023. Table 3 Frequency of virulence (%) of Puccinia graminis isolates collected in 2005, 2021, 2022, and 2023 in Argentina on 11 Pg reference lines of oat. Pg Line Frequency of virulence (%) 2005 2021 2022 2023 Pg 1 50 100 88 100 Pg 2 42 100 88 100 Pg 3 75 87 94 93 Pg 4 58 93 100 100 Pg 8 25 80 100 93 Pg 9 67 93 75 87 Pg 10 67 60 94 87 Pg 13 50 100 100 87 Pg 15 83 87 94 87 Pg 16 92 100 88 100 Pg a 42 53 88 73 Discussion Oat stem rust occurs worldwide and understanding the dynamics of the pathogen’s diversity is crucial to developing methods for its control. The diversity of Pg populations in oats has been documented for many authors (Harder, 1994 ; Mariscal et al ., 2011; Gnocato, 2017 ; Fetch et al., 2020;). Recently, Sowa et al. ( 2021 ) reported 57 Pg races among 157 isolates collected from 2017 to 2020 in Poland, showing a great diversity in the population; while Li et al. ( 2022 ) conducting a virulence survey in China found 8 races among 159 isolates collected during 2018 and 2019, indicating limited diversity. This study documents for the first time the structure and complexity of Pg populations and their evolution over a period of 17 years, based on 70 isolates collected in different sites in Argentina during 2005, 2021, 2022 and 2023. We identified 22 different races among the 70 single-uredinial isolates collected during the period, showing a greater diversity than in the China population but lower than in the Poland population. Although, there is limited information available on Pg in South America, Campos & Giménez (2011) characterizing 83 isolates collected between 2007 and 2009 in Argentina, reported high variability in the Pg population. Likewise, Gnocato ( 2017 ) found 9 Pg races among 16 isolates collected during two epidemic years in southern Brazil and suggests that the high virulence variation identified can be explained by a high genetic diversity on the host with respect to the resistance genes (samples collected on different Brazilian cultivars). It is unclear what causes the high level of virulence polymorphism observed in Argentinian Pg as there is no evidence of sexual reproduction in the region for Pg . Different authors studying the South American Pc populations (Martinelli, 2000 ; Leonard & Martinelli, 2005 ; Dietz et al., 2023 ) suggest that the high mutation rate would be the main factor for variation in these populations. Additionally, the existence of a large region established in southern Brazil, Argentina and Uruguay, where oats are cultivated most of the year and during the interval between successive oat crops; and the presence of volunteer oat plants contribute to the maintenance of these polymorphisms (Leonard & Martinelli, 2005 ; Vieira et al., 2007 ). It is important to mention that while in the present study we used 11 differential lines carrying individual genes (Harder, 1994 ), the inclusion of Pg6 and Pg12 , would allow for the utilization of the letter code nomenclature system presented by Fetch et al. (2007). This system will be beneficial in enabling us to uniformly characterize Pg isolates, facilitating discussions on virulence dynamics and population studies. We reported that most of the races identified in 2021, and all the races identified in 2022 and 2023, were different from those found in 2005. This allows us to affirm that the populations from 2005 and the current ones are markedly distinct. "Race 1", virulent on Pg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16 , was the most frequent in 2005 and was not identified in 2022 and 2023. Meanwhile, "race 11", virulent on all 11 Pg genes, was first identified in 2021 and has been the most prevalent every year since then. The change in population dynamics detected here suggests that the use of a few genes as a basis for resistance to stem rust in the Argentinian germplasm has resulted in the continuous selection of Pg phenotypes with virulence to these resistance genes, similar to what Dietz et al. ( 2023 ) mentioned for the Pc population. The introduction of certain genotypes carrying Pg genotypes (materials from the Quaker International Oat Nursery, either as cultivars or parentals in Argentinian germplasm), and their widespread adoption for larger areas, has led to cycles of selection and displacement of specific virulences like Person's conceptual model (Person, 1966 ). This phenomenon, known as directional selection, occurs when advantageous isolates increase due to variations in survival and reproduction among different phenotypes. This pressure results in an increase in the proportion of races virulent on these genes and/or the emergence of new virulent races (Carson, 2011 ; Chong et al., 2011 ; Dietz et al., 2023 ). Descriptive parameters, such as virulence frequency and virulence complexity (Kosman,1996; 2003), were calculated for all isolate populations, providing us with a deeper comprehension of the population's dynamics. These parameters enable us to gain insight into how virulence manifests within the population and how it evolves over time. Our findings indicate that the current population (2021, 2022, and 2023) exhibits greater virulence compared to that of 2005; in other words, it possesses the ability to overcome a larger number of genes than in the past. The virulence complexity reached its highest level in 2022 and 2023; where most of the isolates (50 and 53%, respectively) were able to overcome the 11 Pg reference oat lines used in this work. Moreover, the Kruskal–Wallis one-way variance analysis revealed that Pg isolates from 2005 were less virulent than those collected in 2021, 2022, and 2023, indicating an increase in virulence frequency within the populations over the past three years. By 2021, there was a substantial rise in the average virulence level to 87%, compared to 59% in 2005. However, no significant difference was observed compared to 2022 (91%) and 2023 (92%). Therefore, current populations are more virulent and complex, and the predominant race is virulent over all the reference genes used in this study. This suggests that the widespread use of genotypes containing only a few resistance genes in large areas of Argentina creates strong selection pressure (Harder & Haber, 1992 ; Dietz et al., 2023 ), which is the driving force behind the increase in virulence in the Argentinean Pg population. There are no studies in South America that describe the complexity of the virulence of Pg populations, although studies carried out on crown rust mention the presence of super-races (Leonard & Martinelli, 2005 ; Vieira et al., 2007 ), high complexity in populations (Leonard & Martinelli, 2005 ; Dietz et al., 2023 ), and an increase in the virulence of current populations as a result of the use of a few genes as the basis of resistance in oat cultivars. An additional goal of the study was a preliminary evaluation of Pg genes and their potential for use in practical breeding in Argentinian growing conditions. In 2021–2023, Pg1, Pg2, Pg3, Pg4, Pg8, Pg13 , and Pg16 presented low levels of effectiveness. Likewise, Pga was the most effective gene in 2021 and 2023 (53% and 73%, respectively), while Pg9 was the most effective in 2022 (75%). The Pga gene has shown its utility in some areas of Canada (Fetch et al ., 2020), as well as in the south of Brazil (Gnocato, 2017 ). However, the high values reported here indicate its limited effectiveness in Argentinian conditions, even when both genes are used in combination. Our results demonstrated that the frequency of virulence of Pg isolates increase on most of the resistance genes compared to the 2005 population. Genes such as Pg1 , Pg2 , Pg4 , Pg8 , and Pg13 showed significant increases, while others like Pg3, Pg9 and Pg15 showed smaller ones. These findings confirmed changes in the race dynamics of the population as a consequence of the use of a few resistance genes, an increment in the virulence frequency and the existence of complex Pg races in Argentina. This emphasizes the dynamic nature of plant (genes)-pathogen interactions and underscores the importance of ongoing surveys and surveillance efforts to monitor these changes. Moreover, our findings highlight the necessity to broaden the search for new resistance genes and deepen our understanding of the genetic mechanisms underlying resistance to stem rust in oats. Abbreviations Puccinia graminis ( Pg ); Puccinia coronata (Pc) Declarations Acknowledgements We wish to thank the staff from the rust laboratory belonging to the National Institute for Agricultural Technology (INTA) in Bordenave, Argentina. The authors declare that they do not have any actual or potential conflict of interest. Funding This study was funded by projects from ANPCyT (PICT-2021-I-A-00770), UNLP (A352-19), and CICPBA (RESO 2022-517-GDEBA-CIC). References Balzarini M.G. & Di Rienzo J.A. 2016. InfoGen versión 2016. FCA, Universidad Nacional de Córdoba, Argentina. https://www.info-gen.com.ar/ Campos P., Gimenes F., Tomaso J. & Brach A. 2008. Caracterización de la población patógena de Puccinia coronata (Roya de la hoja de la avena), en las campañas 2004-05-06 y comportamiento de cultivares frente al patógeno. VII Congreso Nacional de Trigo. V Simposio Nacional de Cereales de Siembra Otoño-Invernal. I Encuentro del MERCOSUR. Santa Rosa, La Pampa. 2,3 y 4 de Julio. pp. SO4. In: https://www.researchgate.net/publication/371632340_Caracterizacion_de_la_poblacion_patogena_de_Puccinia _coronata_roya_de_la_hoja_de_la_avena_en_las_campanas_2004-05-06_y_comportamiento_de_cultivares_frente_al_patogeno Campos P & Gimenez F. 2011. Caracterización de la población patógena de Puccinia graminis f.sp . avenae , agente causal de roya del tallo de avena en argentina en los años 2007-2008 y 2009. Actas del 2 º Congreso Argentino de Fitopatología. Pp 198. In: https://aafitopatologos.com.ar/wp/wp-content/uploads/2014/11/Libro-de-res%C3%BAmenes-2%C2%B0-CAF.pdf Carson M.L. 2011. Virulence in oat crown rust (Puccinia coronata f. sp . avenae ) in the United States from 2006 through 2009. Plant Disease ., 95, 1528–1534. https://doi.org/10.1094/PDIS-09-10-0639 Chong J., Gruenke J., Dueck R., Mayert W., Fetch J.M. & Mccartney C. 2011. Virulence of Puccinia coronata f sp. avenae in the Eastern Prairie Region of Canada during 2007–2009 . Canadian Journal of Plant Pathology , 33:77-87. In: https:// /doi/epdf/10.1080/07060661.2010.546957?src=getftr Dietz J.I., Schierenbeck M., Martinez N. & Simon M.R. 2016. Aplicación de fungicidas y fertilización nitrogenada en avena: efectos sobre la generación de biomasa aérea y rendimiento. Revista FAVE Sección Agrarias. In: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1666-77192016000200002 Dietz J.I. 2018. Características de sanidad, rendimiento y calidad en genotipos de avena en filiales avanzadas de un programa de mejoramiento. Trabajo final de Maestría en Protección vegetal, Universidad Nacional de La Plata. 153pp. In: https://doi.org/10.35537/10915/68021 Dietz J.I., Schierenbeck M. & Simón M.R. 2019. Impact of foliar diseases and its interaction with nitrogen fertilization and fungicides mixtures on green leaf area dynamics and yield in oat genotypes with different resistance. Crop Protection , 121 , 80-88. https://doi.org/10.1016/j.cropro.2019.03.017 Dietz J.I., Da Silva L.V., Simón M.R. & Campos P. 2023. Evolution of the Puccinia coronata population in Argentina and identification of resistance genes useful in oat breeding programs. European Journal of Plant Pathology . https://doi.org/10.1007/s10658-023-02775-z FAO (Food and Agriculture Organization of the United Nations) 2024. Food and agriculture data. Disponible en: http://www.fao.org/ Fetch T.G. & Jin Y. 2007. Letter code system of nomenclature for Puccinia graminis f.sp. avenae . Plant Disease . 91:763-766. https://doi.org/10.1094/PDIS-91-6-0763 Fetch T.J., Fetch M, Zegeye T & A. Xue A. 2021. Races of Puccinia graminis on barley, oat, and wheat in Canada from 2015 to 2019. Canadian Journal of Plant Pathology , 43:463-471. https://doi.org/10.1080/07060661.2020.1829066 Gnocato F.S. 2017. Ferrugem do colmo da aveia: fatores genéticos da virulência do patógeno e da resistência do hospedeiro. Tesis de Doctorado en Fitotecnia, Universidade Federal Do Rio Grande Do Sul, Brasil. 113pp. Disponible en: http://hdl.handle.net/10183/163923 Harder D. 1994. Identification of new races of Puccinia graminis f.sp. avenae. Plant Disease , 78:367–368. Harder D. & Haber S. 1992. Oat diseases and pathologic techniques. En: H.G. Marshall & M.E. Sorrells (Eds). Oat Science and Technology. American Society of Agronomy Inc. and Crop Science Society of America Inc., Madison, WI. pp. 307- 425 Kosman, E. 1996. Difference and diversity of plant pathogen populations: A new approach for measuring. Phytopathology , 86:1152–1155. Kosman, E. 2003. Measure of multilocus correlation as a new parameter for study of plant pathogen populations. Phytopathology, 93:1464–1470. https://doi.org/10.1094/PHYTO.2003.93.12.1464 Leonard K.J. & Martinelli J.A. 2005. Virulence of oat crown rust in Brasil and Uruguay. Plant Disease , 89:802-808. In:https://doi.org/10.1094/PD-89-0802 Leyva M.S., Espitia R.E., Villaseñor M.H.E y Huerta E.J. 2004. Pérdidas ocasionadas por Puccinia graminis f. sp. Avenae Ericks. y Henn., causante de la roya del tallo en seis cultivares de avena ( Avena sativa L.) en Valles Altos de México. Revista Mexicana de Fitopatología, 22:166-171. https://www.redalyc.org/pdf/612/61222202.pd Li T., Xu Y., Zhang X., Wu X., Zhang Y., Xuan Y. & Wang S. 2022. Virulence Characterization of Puccinia graminis f. sp. avenae and Resistance of Oat Cultivars in China. Plant Disease , 106:901-905. https://doi.org/10.1094/PDIS-06-21-1239-RESECTIONSABSTRACTPDFSUPPLEMENTAL Martens J. 1985. Oat stem rust. In: The cereal rusts. Roelfs A & Bushnell W (eds). Elsevier, Orlando, pp 103–129 Martinelli J. 2000. Major diseases on oats in South America. In: Proc.VI International Oat Conference, Canterburry, New Zealand, 2000. pp. 277-283. Martinelli J. 2004. Fooder oats: Oat diseases and their control. In: SUTTIE, J. M.; REYNOLDS, S. G. (Ed.). Fodder oats: a world overview. Rome: FAO (FAO Plant Production and Protection Series). MAGyP (Ministerio de agricultura, Ganadería y Pesca). 2024. Estimaciones agrícolas. Disponible en: http://datosestimaciones.magyp.gob.ar/reportes.php?reporte=Estimaciones Person C. 1966. Genetic polymorphism in parasitic systems. Nature , 212:266-267. Roelfs A.P. & Long D.L. 1980. Analysis of recent oat stem rust epidemics . Phytopathology , 70: 436-440. Stakman E.C, Stewart D.M & Loegering W.Q. 1962. Identification of physiologic races of Puccinia graminis var. tritici. Agricultural Research Service Technical Bulletin. No. E-617. Washington, DC. US Dept. Agriculture. Sowa S., Toporowska J., Koroluk A. & Paczos-Grzęda E. 2021. First detailed report on Puccinia graminis f. sp. avenae virulence structure and Pg resistance genes effective in Poland. European Journal of Plant Pathology , 161:371-381. https://doi.org/10.1007/s10658-021-02329-1 Van Niekerk B.D., Pretorius Z.A. & Boshoff W.H.P. 2001. Potential yield losses caused by barley leaf rust and oat leaf and stem rust to South African barley and oat cultivars. South African Journal of Plant and Soil , 18:108-113. Vieira E., Carvalho F., Chaves M., Oliveira A., Benin G., Hartwig I. & Martins, L. 2007. Virulence variability of Puccinia coronata f. sp. avenae isolates collected in three counties from Rio Grande do Sul State, Brazil. Plant Disease , 91: 66-70. https://doi.org/10.1094/PD-91-0066 Wehrhahne L. & Storm A. 2014. Evaluación de avena para producción de grano. Disponible en: http://inta.gob.ar/sites/default/files/script-tmp-inta_barrow_-_evaluacin_de_avena Zadoks J.C., Chang T. & Konzak C. 1974. A decimal code for the growth stages of cereals. Weed Research , 14:415-421. Supplementary Files SupplementaryTables.docx Cite Share Download PDF Status: Published Journal Publication published 27 Jan, 2025 Read the published version in European Journal of Plant Pathology → Version 1 posted Editorial decision: Revision 26 Aug, 2024 Reviewers agreed at journal 06 Jun, 2024 Reviewers invited by journal 05 Apr, 2024 Editor invited by journal 28 Mar, 2024 Editor assigned by journal 27 Mar, 2024 First submitted to journal 26 Mar, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4172543","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":287846688,"identity":"f5072019-3479-409f-a610-a6002cff5f57","order_by":0,"name":"Juan Dietz","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAUlEQVRIiWNgGAWjYDCCw2CSDYiZDxyACPEQ1MLYANHClnCAIYEYLQfAWsAqDRiI0sJ3nPn4wx8MfIn9s3s+Hi78Yccg7957gOHnHtxaJA+zJTZIMLAlzrhzdsPhGQnJDIZnziUw9jzDrcXgMI9hgwFQS8ON3A2HeRKYGQxn5Bgw8BzAp4X/Y0MCUMv8GzkPgFrqwVoY/+DVwsPYcACoZcONHAaglsMM8hI5Bsz4bAH6xXBmgwGb8cYbaUDtacd5DHjOJRyWwaOF7/zhBx9/VByTnXcj+fFnHptqOfn23oMP3+DRAnXeMTiTx+AAKLIIgxoEU76BCPWjYBSMglEwogAACvJV7zIEvU4AAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-8658-6791","institution":"CONICET: Consejo Nacional de Investigaciones Cientificas y Tecnicas","correspondingAuthor":true,"prefix":"","firstName":"Juan","middleName":"","lastName":"Dietz","suffix":""},{"id":287846689,"identity":"1edfe2fa-83e5-4b4b-a4c9-42c35fd59970","order_by":1,"name":"Laura Da Silva","email":"","orcid":"","institution":"CONICET: Consejo Nacional de Investigaciones Cientificas y Tecnicas","correspondingAuthor":false,"prefix":"","firstName":"Laura","middleName":"Da","lastName":"Silva","suffix":""},{"id":287846690,"identity":"b5f1575d-580f-42e1-814e-78b0e12b1064","order_by":2,"name":"María Rosa Simón","email":"","orcid":"","institution":"CONICET: Consejo Nacional de Investigaciones Cientificas y Tecnicas","correspondingAuthor":false,"prefix":"","firstName":"María","middleName":"Rosa","lastName":"Simón","suffix":""},{"id":287846691,"identity":"38f8f3fd-9928-4637-be72-a1866d8f2df7","order_by":3,"name":"Pablo Campos","email":"","orcid":"","institution":"INTA: Instituto Nacional de Tecnologia Agropecuaria","correspondingAuthor":false,"prefix":"","firstName":"Pablo","middleName":"","lastName":"Campos","suffix":""}],"badges":[],"createdAt":"2024-03-26 23:53:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4172543/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4172543/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10658-025-03004-5","type":"published","date":"2025-01-27T15:57:53+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54422901,"identity":"79b08733-a528-4455-8201-1d5e68dacf4f","added_by":"auto","created_at":"2024-04-10 08:36:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":8633,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot of virulence frequency of the \u003cem\u003ePuccinia graminis \u003c/em\u003eisolates collected in Argentina during 2005, 2021, 2022 and 2023 on different \u003cem\u003ePg \u003c/em\u003eresistance genes.\u003c/p\u003e\n\u003cp\u003e[Symbols in the figure represent; ( ) Median; ( ) 25–75%, ( )]. Different letters show significant differences in the mean between years. LSD p \u0026lt; 0.05 (Kruskal Wallis, post hoc comparison).\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4172543/v1/d2b90f95859b0d2e981d2b8c.png"},{"id":75351473,"identity":"2c3e5bd0-0067-4c73-90fd-aa3038d69556","added_by":"auto","created_at":"2025-02-03 16:11:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":808818,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4172543/v1/42c408cc-bc3a-4461-b436-c2eeb88d99ac.pdf"},{"id":54422902,"identity":"97d01a74-8800-4091-90bb-07293f6293ae","added_by":"auto","created_at":"2024-04-10 08:36:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":27107,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTables.docx","url":"https://assets-eu.researchsquare.com/files/rs-4172543/v1/76ec8f343abf7d87ba16f5d5.docx"}],"financialInterests":"","formattedTitle":"\u003cp\u003eVirulence characterization of Puccinia graminis f. sp. avenae in Argentina\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOats (\u003cem\u003eAvena sativa\u003c/em\u003e L.) are a cereal of great importance worldwide due to their use as a dual-purpose crop (forage and grain). It is the sixth most important cereal in grain production, with approximately 23\u0026nbsp;million t occupying an area of around 10\u0026nbsp;million hectares (FAO, 2024). In Argentina, the crop covers an area of around 1.5\u0026nbsp;million hectares, the vast majority for forage use (MAGyP, 2024). Its cultivation has been a technically and economically viable alternative, mainly in animal production systems, due to its multiple uses: grain, green forage, preserved forage (hay and silage), dual purpose (forage-grain) and use of stubble (Dietz, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Stem rust in oats, caused by \u003cem\u003ePuccinia graminis\u003c/em\u003e f. sp. \u003cem\u003eavenae\u003c/em\u003e Erikss and Henning \u003cem\u003e(Pg)\u003c/em\u003e, is a disease of great relevance on a global scale, recognized for its destructive capacity under favourable environmental conditions (Roelfs \u0026amp; Long, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e1980\u003c/span\u003e; Martens, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1985\u003c/span\u003e). Van Niekerk et al. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) have reported yield losses of up to 85%, and a 45% decrease in test weight in susceptible materials after a stem rust epidemic, while Leyva et al. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2004\u003c/span\u003e) document drops of up to 70% in grain yield.\u003c/p\u003e \u003cp\u003ePrevious works have provided valuable insights regarding the variability and complexity of \u003cem\u003ePuccinia coronata (Pc)\u003c/em\u003e populations in regions of South America (Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Vieira et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Campos et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, research on \u003cem\u003ePg\u003c/em\u003e populations has been relatively limited, with only a few studies conducted (Campos \u0026amp; Gimenez, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Gnocato, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), which document significant variability in the \u003cem\u003ePg\u003c/em\u003e populations of our region. Although there is no evidence that \u003cem\u003ePg\u003c/em\u003e has sexual reproduction in this area (Martinelli, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2004\u003c/span\u003e), the genetic diversity in the populations is very high (Campos \u0026amp; Gimenez, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Gnocato \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), indicating that other factors may be the driving force for cause changes in the population structure of the stem rust pathogen. Moreover, it has been reported that the oat growing regions of Argentina, Brazil, and Uruguay share a common epidemiological system (Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Campos et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Therefore, it might be expected that some races within the \u003cem\u003ePg\u003c/em\u003e population in Argentina exhibit similarities in their virulence pattern to races found in Brazil and Uruguay or that new biotypes may emerge because of migration.\u003c/p\u003e \u003cp\u003eIn Argentina, research on oat management for crown rust has been conducted (Campos et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), but less effort has been dedicated to stem rust. Historically, it has been considered a disease of less relevance, which appears sporadically towards the end of the crop cycle, mainly affecting oats destined for grain production. In this sense, Campos \u0026amp; Gimenez (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) and Wehrhahne \u0026amp; Storm (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) have reported its presence during some campaigns, although showing a low level of the disease among the diseased genotypes. However, recent data (2021, 2022 and 2023) taken in trials and farmer\u0026acute;s field in different locations (Reconquista, La Plata, Barrow and Bordenave) show a greater intensity of the disease (Dietz, \u003cem\u003epersonal communication\u003c/em\u003e). For example, in Reconquista during the 2023 campaign, most Argentinian materials reached 100% severity, showing stem breaking and panicle retention. This increase in the level of disease may be explained by the appearance of new biotypes with a greater spectrum of virulence.\u003c/p\u003e \u003cp\u003eGenetic improvement is the most effective control method for managing the disease (Fetch \u0026amp; Jim, 2007; Villase\u0026ntilde;or \u003cem\u003eet al\u003c/em\u003e., 2021; Li et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, the fact that only 16 genes have been described (Fetch \u0026amp; Jim, 2007) that are the basis of resistance to stem rust worldwide, suggests a limited availability of genetic resources for the development of oat varieties resistant to this disease.\u003c/p\u003e \u003cp\u003eThe characterization of the \u003cem\u003ePg\u003c/em\u003e population provides valuable insights into population size, diversity, and complexity, and allows the identification of race specific genes potentially useful for breeding, which is essential to guide regional breeding programs and/or establish management guidelines that tend to minimize the losses caused by this disease. In this study, we collected 70 \u003cem\u003ePg\u003c/em\u003e isolates from a vast area of Argentina in 2005 and during the 2021\u0026ndash;2023 period with the objectives (i) to analyze the evolution of the pathogen population over time and (ii) to assess the efficacy of \u003cem\u003ePg\u003c/em\u003e resistance genes and their suitability for practical breeding applications in our region.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eExperimental material\u003c/h2\u003e \u003cp\u003eSamples of oat stems infected with \u003cem\u003ePg\u003c/em\u003e were collected during the 2005, 2021, 2022, and 2023 growing seasons (November) from experimental and farmer´s fields in different locations of Argentina [supplementary material; table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e)]. Each year after collection in November, samples were natural dried at room temperature, and stored in a fridge at 4–6°C until virulence tests were conducted. The collection included 70 isolates, depicting 24 in 2005, 15 in 2021, 16 in 2022, and 15 in 2023.\u003c/p\u003e \u003cp\u003eVirulence tests were conducted at the Rust laboratory belonging to the National Institute for Agricultural Technology (INTA) in Bordenave, Argentina (37º 52’ LS; 63º 01’ LW). Urediniospores from each sample of rusted oat stem were isolated and multiplied on seedlings of the oat cultivar “Boyera”, which is susceptible to all known races of \u003cem\u003ePg\u003c/em\u003e at the seedling stage, via the detached method described by Dietz et al. (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eVirulence assessment\u003c/h2\u003e \u003cp\u003eEach single-spore isolate was tested for virulence on a set of 11 \u003cem\u003ePg\u003c/em\u003e reference lines (\u003cem\u003ePg1\u003c/em\u003e, \u003cem\u003ePg2\u003c/em\u003e, \u003cem\u003ePg3\u003c/em\u003e, \u003cem\u003ePg4\u003c/em\u003e, \u003cem\u003ePg8, Pg9, Pg10, Pg13, Pg15, Pg16\u003c/em\u003e and \u003cem\u003ePga\u003c/em\u003e), each with a different single \u003cem\u003ePg\u003c/em\u003e gene for race specific stem rust resistance (Harder, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1994\u003c/span\u003e). The collection has been used in Argentina to characterize the \u003cem\u003ePg\u003c/em\u003e population and postulate genes in genotypes of interest (Campos, \u003cem\u003epersonal communication\u003c/em\u003e).\u003c/p\u003e \u003cp\u003eThe previously described method for sowing and inoculation (Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) was followed. Briefly, at 10–12 days after planting (when the seedlings had two expanded leaves; GS12, Zadoks et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1974\u003c/span\u003e), the differential set seedlings were inoculated with freshly collected urediniospores of a single-uredinial isolate. Inoculated plants were placed in a 100% humidity dark chamber for 20 h at 20 +/-1ºC for spore germination and penetration. After incubation, seedlings were placed on benches in the greenhouse at 20 +/-1°C.\u003c/p\u003e \u003cp\u003eDisease reactions were scored 15 days after inoculation according to the scale of Stakman (Stakman et. al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1962\u003c/span\u003e). Seedlings showing infection types of 0;, 1, and 2 and their modifications (;1+, 11+, T... etc.) were classified as resistant, while those with ITs of 3 or 4 were considered susceptible.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eRaces/isolates of \u003cem\u003ePg\u003c/em\u003e were determined considering the virulence/avirulence patterns on the 11 \u003cem\u003ePg\u003c/em\u003e reference oat lines used in this study. Each isolate with a comparable virulence or avirulence pattern, irrespective of the year it was collected, was assigned the same number. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e provides a summary of the identified isolates and the frequency of their occurrence each year. The virulence parameters were described using the Kosman approach (Kosman \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1996\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2003\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe virulence within the pathogen population (virulence frequency) was calculated based on the average of the proportion of all \u003cem\u003ePg\u003c/em\u003e genes overcome by each isolate on the \u003cem\u003ePg\u003c/em\u003e set differential (Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Results were subjected to the Kruskal-Wallis one way analysis of variance appropriate for data with distributions far from normal with the mean ranks post hoc comparison, using Infogen Software (Balzarini \u0026amp; Di Rienzo, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), to determine if there were significant differences in the virulence through the years. The virulence complexity was calculated as the mean number of virulence genes per isolate detected over the 11 differential lines. In addition, frequency of virulence to each \u003cem\u003ePg\u003c/em\u003e differential was calculated as Frequency of virulence= (NVI/NTC) *100; where NVI is the number of times that a virulent reaction type was detected, and NTC is the number of all tested isolates collected each year.\u003c/p\u003e \u003c/div\u003e "},{"header":"Results","content":"\u003cp\u003eThe origin, and virulence/avirulence patterns of isolates collected in Argentina in 2005, 2021, 2022, and 2023 are presented as supplementary material (Supplementary Table \u003cspan\u003eS1\u003c/span\u003e). In total, 22 different races were found among the 70 single-uredinial isolates collected during the period (Table \u003cspan\u003e1\u003c/span\u003e), although 16 races were found only twice or one. In 2005, a total of 10 races were identified from 24 isolates (Supplementary Table \u003cspan\u003eS1\u003c/span\u003e). The race labeled as \u0026quot;race 1\u0026quot; (\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16//Pg8-Pg10-Pga\u003c/em\u003e) was the most prevalent, whereas races 2 through 10 were each found twice (Table \u003cspan\u003e1\u003c/span\u003e). In 2021, 8 races were identified among 15 isolates. The most prevalent race was \u0026quot;race 11\u0026quot; (virulent on the 11 \u003cem\u003ePg\u003c/em\u003e reference genes), which was collected 3 times. Other races were found twice or only once. Moreover, most of the races identified in 2021 were different from those found in 2005, except for \u0026ldquo;race 1\u0026rdquo;, which was encountered twice. In 2022, a total of 7 races were identified from 16 isolates, while in 2023, 6 races were found among 15 isolates. During these years, \u0026ldquo;race 11\u0026rdquo; was also the most frequent, occurring 8 times per year. None of the races identified in 2005 were encountered during the years 2022 and 2023. Overall, races 1 and 11 were the most common phenotypes during the evaluated period, occurring 8 and 17 times respectively (Table \u003cspan\u003e1\u003c/span\u003e). \u0026ldquo;Race 1\u0026rdquo; was the most frequent in 2005 and was not identified in 2022 and 2023, whereas race 11 was first identified 2021 and has been the most prevalent every year since then.\u003c/p\u003e\n\u003cdiv align=\"char\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eVirulence/avirulence pattern of the races identified and number of times found per year.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eRaces\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eVirulence\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eAvirulence\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cem\u003eYear\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eTotal races\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e2005\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e2021\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e2022\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e2023\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg8-Pg10-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg2-Pg3-Pg4-Pg8-Pg9-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg10\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg9-Pg10-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg8-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg3-Pg8-Pg9-Pg10-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg4 Pg13-Pg15-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg10-Pg15\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg13-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg3-Pg4-Pg9-Pg10-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg8-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e7\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg8-Pg10-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg2-Pg3-Pg4-Pg9-Pg13\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg3-Pg4-Pg9-Pg10-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg8-Pg13\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg10-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg13\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg3-Pg10-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg2-Pg4-Pg8-Pg9-Pg13-Pg15\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e11\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e19\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e12\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg3-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e13\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg9-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg4-Pg8-Pg10\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e14\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg10\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e15\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg9-Pg10-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e16\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg15\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e17\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e18\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg3-Pg4-Pg8-Pg10-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg2-Pg9\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e19\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg2-Pg3-Pg4-Pg8-Pg10-Pg13-Pg15-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg9-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e20\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg8-Pg10\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e21\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg4-Pg8-Pg9-Pg10-Pg13-Pg15-Pg16-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg3\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e22\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg8-Pg10-Pg16\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg9-Pg13-Pg15-Pga\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal isolates per year\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e24\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e15\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e16\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e15\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e70\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003eThe Kruskal\u0026ndash;Wallis one-way variance analysis revealed statistically significant differences in the virulence of \u003cem\u003ePg\u003c/em\u003e populations collected in these years (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Post hoc comparisons of mean ranks indicated that isolates from 2005 exhibited the ability to overcome an average of 59% of oat differential resistance lines (ranging between 18% and 82%), which differed significantly from the other years. Virulence frequency within the populations has shown an increase over the past three years. By 2021, the average rose to 87%, marking a significant rise from 2005 (28%), though no difference was observed compared to 2022 (91%) and 2023 (92%). The level showed a range between 64 and 100% in these three years (Fig. \u003cspan\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eThe Table \u003cspan\u003e2\u003c/span\u003e illustrates variations in virulence levels against reference genes. \u003cem\u003ePg\u003c/em\u003e isolates from 2005 demonstrated the capability to overcome between 2 and 9 reference genes, whereas for the following years, this range extended from 7 to 11 \u003cem\u003ePg\u003c/em\u003e genes. In 2005, many isolates (25%) exhibited virulence against 8 \u003cem\u003ePg\u003c/em\u003e reference genes, while only 8% were virulent against 2 and 4 \u003cem\u003ePg\u003c/em\u003e genes. In contrast, by 2021, 40% of isolates could overcome 10 \u003cem\u003ePg\u003c/em\u003e, while in 2022 and 2023, most isolates (50 and 53% respectively) could overcome the 11 \u003cem\u003ePg\u003c/em\u003e references genes of oat used in these assays (Table \u003cspan\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv align=\"char\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003ePercentage of isolates virulent on differential lines carrying \u003cem\u003ePg\u003c/em\u003e genes in \u003cem\u003ePuccinia graminis\u003c/em\u003e populations collected in Argentina during 2005, 2021, 2022, and 2023.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eNumber of \u003cem\u003ePg\u003c/em\u003e Genes\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eVirulence complexity per year (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2005\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2021\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2022\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e2023\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e1 Pg gen\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e2 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e3 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e4 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e5 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e6 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e7 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e8 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e9 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e10 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003e11 Pg genes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003eExploring the virulence of the 2005 population, we observed values ranging from 92 to 25%, with differences between genes. In the case of \u003cem\u003ePg15\u003c/em\u003e and \u003cem\u003ePg16\u003c/em\u003e, the frequencies were very high (above 80%), high for \u003cem\u003ePg3\u003c/em\u003e, \u003cem\u003ePg9\u003c/em\u003e, and \u003cem\u003ePg10\u003c/em\u003e (between 65 and 80%), intermediate for \u003cem\u003ePg1\u003c/em\u003e, \u003cem\u003ePg2\u003c/em\u003e, \u003cem\u003ePg4\u003c/em\u003e, \u003cem\u003ePg13\u003c/em\u003e, and \u003cem\u003ePga\u003c/em\u003e (between 30 and 65%), and low for \u003cem\u003ePg8\u003c/em\u003e (25%). In the current populations (2021, 2022, and 2023), most genes showed high frequencies, ranging from 100 to 53% for 2021, 100 to 75% for 2022, and 100 to 73% for 2023. Additionally, there was less variation between genes for each year. \u003cem\u003ePga\u003c/em\u003e was the least virulent gene in 2021 and 2023 (53% and 73%, respectively), while \u003cem\u003ePg9\u003c/em\u003e was the least virulent in 2022 (75%).\u003c/p\u003e\n\u003cp\u003eWhen analyzing the frequency of each gene overcome over the years, we observed that most genes showed an increase in their values compared to the 2005 population, although some exhibited certain fluctuations between years. Genes such as \u003cem\u003ePg1\u003c/em\u003e, \u003cem\u003ePg2\u003c/em\u003e, \u003cem\u003ePg4\u003c/em\u003e, \u003cem\u003ePg8\u003c/em\u003e, and \u003cem\u003ePg13\u003c/em\u003e showed significant increases, while others like \u003cem\u003ePg9\u003c/em\u003e and \u003cem\u003ePg13\u003c/em\u003e showed smaller ones. Meanwhile, \u003cem\u003ePg15\u003c/em\u003e and \u003cem\u003ePg16\u003c/em\u003e already had high values in 2005, like the current ones. In the case of \u003cem\u003ePga\u003c/em\u003e and \u003cem\u003ePg10\u003c/em\u003e, there were fluctuations, although \u003cem\u003ePga\u003c/em\u003e values were high in 2022 and 2023.\u003c/p\u003e\n\u003cdiv\u003e\n \u003cdiv align=\"left\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eFrequency of virulence (%) of \u003cem\u003ePuccinia graminis\u003c/em\u003e isolates collected in 2005, 2021, 2022, and 2023 in Argentina on 11 \u003cem\u003ePg\u003c/em\u003e reference lines of oat.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ePg Line\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cem\u003eFrequency of virulence (%)\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2023\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 8\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 9\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 13\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 15\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg 16\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePg a\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOat stem rust occurs worldwide and understanding the dynamics of the pathogen\u0026rsquo;s diversity is crucial to developing methods for its control. The diversity of \u003cem\u003ePg\u003c/em\u003e populations in oats has been documented for many authors (Harder, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Mariscal \u003cem\u003eet al\u003c/em\u003e., 2011; Gnocato, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Fetch et al., 2020;). Recently, Sowa et al. (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) reported 57 \u003cem\u003ePg\u003c/em\u003e races among 157 isolates collected from 2017 to 2020 in Poland, showing a great diversity in the population; while Li et al. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) conducting a virulence survey in China found 8 races among 159 isolates collected during 2018 and 2019, indicating limited diversity.\u003c/p\u003e \u003cp\u003eThis study documents for the first time the structure and complexity of \u003cem\u003ePg\u003c/em\u003e populations and their evolution over a period of 17 years, based on 70 isolates collected in different sites in Argentina during 2005, 2021, 2022 and 2023. We identified 22 different races among the 70 single-uredinial isolates collected during the period, showing a greater diversity than in the China population but lower than in the Poland population. Although, there is limited information available on \u003cem\u003ePg\u003c/em\u003e in South America, Campos \u0026amp; Gim\u0026eacute;nez (2011) characterizing 83 isolates collected between 2007 and 2009 in Argentina, reported high variability in the \u003cem\u003ePg\u003c/em\u003e population. Likewise, Gnocato (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) found 9 \u003cem\u003ePg\u003c/em\u003e races among 16 isolates collected during two epidemic years in southern Brazil and suggests that the high virulence variation identified can be explained by a high genetic diversity on the host with respect to the resistance genes (samples collected on different Brazilian cultivars). It is unclear what causes the high level of virulence polymorphism observed in Argentinian \u003cem\u003ePg\u003c/em\u003e as there is no evidence of sexual reproduction in the region for \u003cem\u003ePg\u003c/em\u003e. Different authors studying the South American \u003cem\u003ePc\u003c/em\u003e populations (Martinelli, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) suggest that the high mutation rate would be the main factor for variation in these populations. Additionally, the existence of a large region established in southern Brazil, Argentina and Uruguay, where oats are cultivated most of the year and during the interval between successive oat crops; and the presence of volunteer oat plants contribute to the maintenance of these polymorphisms (Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Vieira et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt is important to mention that while in the present study we used 11 differential lines carrying individual genes (Harder, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1994\u003c/span\u003e), the inclusion of \u003cem\u003ePg6\u003c/em\u003e and \u003cem\u003ePg12\u003c/em\u003e, would allow for the utilization of the letter code nomenclature system presented by Fetch \u003cem\u003eet al.\u003c/em\u003e (2007). This system will be beneficial in enabling us to uniformly characterize \u003cem\u003ePg\u003c/em\u003e isolates, facilitating discussions on virulence dynamics and population studies.\u003c/p\u003e \u003cp\u003eWe reported that most of the races identified in 2021, and all the races identified in 2022 and 2023, were different from those found in 2005. This allows us to affirm that the populations from 2005 and the current ones are markedly distinct. \"Race 1\", virulent on \u003cem\u003ePg1-Pg2-Pg3-Pg4-Pg9-Pg13-Pg15-Pg16\u003c/em\u003e, was the most frequent in 2005 and was not identified in 2022 and 2023. Meanwhile, \"race 11\", virulent on all 11 \u003cem\u003ePg\u003c/em\u003e genes, was first identified in 2021 and has been the most prevalent every year since then.\u003c/p\u003e \u003cp\u003eThe change in population dynamics detected here suggests that the use of a few genes as a basis for resistance to stem rust in the Argentinian germplasm has resulted in the continuous selection of \u003cem\u003ePg\u003c/em\u003e phenotypes with virulence to these resistance genes, similar to what Dietz et al. (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) mentioned for the \u003cem\u003ePc\u003c/em\u003e population. The introduction of certain genotypes carrying \u003cem\u003ePg\u003c/em\u003e genotypes (materials from the Quaker International Oat Nursery, either as cultivars or parentals in Argentinian germplasm), and their widespread adoption for larger areas, has led to cycles of selection and displacement of specific virulences like Person's conceptual model (Person, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1966\u003c/span\u003e). This phenomenon, known as directional selection, occurs when advantageous isolates increase due to variations in survival and reproduction among different phenotypes. This pressure results in an increase in the proportion of races virulent on these genes and/or the emergence of new virulent races (Carson, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Chong et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDescriptive parameters, such as virulence frequency and virulence complexity (Kosman,1996; 2003), were calculated for all isolate populations, providing us with a deeper comprehension of the population's dynamics. These parameters enable us to gain insight into how virulence manifests within the population and how it evolves over time. Our findings indicate that the current population (2021, 2022, and 2023) exhibits greater virulence compared to that of 2005; in other words, it possesses the ability to overcome a larger number of genes than in the past. The virulence complexity reached its highest level in 2022 and 2023; where most of the isolates (50 and 53%, respectively) were able to overcome the 11 \u003cem\u003ePg\u003c/em\u003e reference oat lines used in this work.\u003c/p\u003e \u003cp\u003eMoreover, the Kruskal\u0026ndash;Wallis one-way variance analysis revealed that \u003cem\u003ePg\u003c/em\u003e isolates from 2005 were less virulent than those collected in 2021, 2022, and 2023, indicating an increase in virulence frequency within the populations over the past three years. By 2021, there was a substantial rise in the average virulence level to 87%, compared to 59% in 2005. However, no significant difference was observed compared to 2022 (91%) and 2023 (92%). Therefore, current populations are more virulent and complex, and the predominant race is virulent over all the reference genes used in this study. This suggests that the widespread use of genotypes containing only a few resistance genes in large areas of Argentina creates strong selection pressure (Harder \u0026amp; Haber, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), which is the driving force behind the increase in virulence in the Argentinean \u003cem\u003ePg\u003c/em\u003e population. There are no studies in South America that describe the complexity of the virulence of \u003cem\u003ePg\u003c/em\u003e populations, although studies carried out on crown rust mention the presence of super-races (Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Vieira et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), high complexity in populations (Leonard \u0026amp; Martinelli, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Dietz et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and an increase in the virulence of current populations as a result of the use of a few genes as the basis of resistance in oat cultivars.\u003c/p\u003e \u003cp\u003eAn additional goal of the study was a preliminary evaluation of Pg genes and their potential for use in practical breeding in Argentinian growing conditions. In 2021\u0026ndash;2023, \u003cem\u003ePg1, Pg2, Pg3, Pg4, Pg8, Pg13\u003c/em\u003e, and \u003cem\u003ePg16\u003c/em\u003e presented low levels of effectiveness. Likewise, \u003cem\u003ePga\u003c/em\u003e was the most effective gene in 2021 and 2023 (53% and 73%, respectively), while \u003cem\u003ePg9\u003c/em\u003e was the most effective in 2022 (75%). The \u003cem\u003ePga\u003c/em\u003e gene has shown its utility in some areas of Canada (Fetch \u003cem\u003eet al\u003c/em\u003e., 2020), as well as in the south of Brazil (Gnocato, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, the high values reported here indicate its limited effectiveness in Argentinian conditions, even when both genes are used in combination.\u003c/p\u003e \u003cp\u003eOur results demonstrated that the frequency of virulence of \u003cem\u003ePg\u003c/em\u003e isolates increase on most of the resistance genes compared to the 2005 population. Genes such as \u003cem\u003ePg1\u003c/em\u003e, \u003cem\u003ePg2\u003c/em\u003e, \u003cem\u003ePg4\u003c/em\u003e, \u003cem\u003ePg8\u003c/em\u003e, and \u003cem\u003ePg13\u003c/em\u003e showed significant increases, while others like \u003cem\u003ePg3, Pg9\u003c/em\u003e and \u003cem\u003ePg15\u003c/em\u003e showed smaller ones.\u003c/p\u003e \u003cp\u003eThese findings confirmed changes in the race dynamics of the population as a consequence of the use of a few resistance genes, an increment in the virulence frequency and the existence of complex \u003cem\u003ePg\u003c/em\u003e races in Argentina. This emphasizes the dynamic nature of plant (genes)-pathogen interactions and underscores the importance of ongoing surveys and surveillance efforts to monitor these changes. Moreover, our findings highlight the necessity to broaden the search for new resistance genes and deepen our understanding of the genetic mechanisms underlying resistance to stem rust in oats.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cem\u003ePuccinia graminis\u0026nbsp;\u003c/em\u003e(\u003cem\u003ePg\u003c/em\u003e); \u003cem\u003ePuccinia coronata (Pc)\u003c/em\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe wish to thank the staff from the rust laboratory belonging to the National Institute for Agricultural Technology (INTA) in Bordenave, Argentina.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare that they do not have any actual or potential conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by projects from ANPCyT (PICT-2021-I-A-00770), UNLP (A352-19), and CICPBA (RESO 2022-517-GDEBA-CIC).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBalzarini M.G. \u0026amp; Di Rienzo J.A. 2016. InfoGen versi\u0026oacute;n 2016. FCA, Universidad Nacional de C\u0026oacute;rdoba, Argentina. https://www.info-gen.com.ar/ \u003c/li\u003e\n\u003cli\u003eCampos P., Gimenes F., Tomaso J. \u0026amp; Brach A. 2008. Caracterizaci\u0026oacute;n de la poblaci\u0026oacute;n pat\u0026oacute;gena de \u003cem\u003ePuccinia coronata\u003c/em\u003e (Roya de la hoja de la avena), en las campa\u0026ntilde;as 2004-05-06 y comportamiento de cultivares frente al pat\u0026oacute;geno. VII Congreso Nacional de Trigo. V Simposio Nacional de Cereales de Siembra Oto\u0026ntilde;o-Invernal. I Encuentro del MERCOSUR. Santa Rosa, La Pampa. 2,3 y 4 de Julio. pp. SO4. In: https://www.researchgate.net/publication/371632340_Caracterizacion_de_la_poblacion_patogena_de_Puccinia\u003cbr\u003e_coronata_roya_de_la_hoja_de_la_avena_en_las_campanas_2004-05-06_y_comportamiento_de_cultivares_frente_al_patogeno \u003c/li\u003e\n\u003cli\u003eCampos P \u0026amp; Gimenez F. 2011. Caracterizaci\u0026oacute;n de la poblaci\u0026oacute;n pat\u0026oacute;gena de \u003cem\u003ePuccinia graminis\u003c/em\u003e f.sp\u003cem\u003e. avenae\u003c/em\u003e, agente causal de roya del tallo de avena en argentina en los a\u0026ntilde;os 2007-2008 y 2009. Actas del 2 \u0026ordm; Congreso Argentino de Fitopatolog\u0026iacute;a. Pp 198. In: https://aafitopatologos.com.ar/wp/wp-content/uploads/2014/11/Libro-de-res%C3%BAmenes-2%C2%B0-CAF.pdf \u003c/li\u003e\n\u003cli\u003eCarson M.L. 2011. Virulence in oat crown rust \u003cem\u003e(Puccinia coronata\u003c/em\u003e f. sp\u003cem\u003e. avenae\u003c/em\u003e) in the United States from 2006 through 2009. \u003cem\u003ePlant Disease\u003c/em\u003e., 95, 1528\u0026ndash;1534. https://doi.org/10.1094/PDIS-09-10-0639 \u003c/li\u003e\n\u003cli\u003eChong J., Gruenke J., Dueck R., Mayert W., Fetch J.M. \u0026amp; Mccartney C. 2011. Virulence of \u003cem\u003ePuccinia coronata\u003c/em\u003e f sp. \u003cem\u003eavenae\u003c/em\u003e in the Eastern Prairie Region of Canada during 2007\u0026ndash;2009\u003cem\u003e. Canadian Journal of Plant Pathology\u003c/em\u003e, 33:77-87. In: https:// /doi/epdf/10.1080/07060661.2010.546957?src=getftr \u003c/li\u003e\n\u003cli\u003eDietz J.I., Schierenbeck M., Martinez N. \u0026amp; Simon M.R. 2016. Aplicaci\u0026oacute;n de fungicidas y fertilizaci\u0026oacute;n nitrogenada en avena: efectos sobre la generaci\u0026oacute;n de biomasa a\u0026eacute;rea y rendimiento. Revista FAVE Secci\u0026oacute;n Agrarias. In: http://www.scielo.org.ar/scielo.php?script=sci_arttext\u0026amp;pid=S1666-77192016000200002\u003cu\u003e \u003c/u\u003e\u003c/li\u003e\n\u003cli\u003eDietz J.I. 2018. Caracter\u0026iacute;sticas de sanidad, rendimiento y calidad en genotipos de avena en filiales avanzadas de un programa de mejoramiento. Trabajo final de Maestr\u0026iacute;a en Protecci\u0026oacute;n vegetal, Universidad Nacional de La Plata. 153pp. In: https://doi.org/10.35537/10915/68021\u003c/li\u003e\n\u003cli\u003eDietz J.I., Schierenbeck M. \u0026amp; Sim\u0026oacute;n M.R. 2019. Impact of foliar diseases and its interaction with nitrogen fertilization and fungicides mixtures on green leaf area dynamics and yield in oat genotypes with different resistance. \u003cem\u003eCrop Protection\u003c/em\u003e, \u003cem\u003e121\u003c/em\u003e, 80-88. https://doi.org/10.1016/j.cropro.2019.03.017 \u003c/li\u003e\n\u003cli\u003eDietz J.I., Da Silva L.V., Sim\u0026oacute;n M.R. \u0026amp; Campos P. 2023. Evolution of the \u003cem\u003ePuccinia coronata\u003c/em\u003e population in Argentina and identification of resistance genes useful in oat breeding programs. \u003cem\u003eEuropean Journal of Plant Pathology\u003c/em\u003e. https://doi.org/10.1007/s10658-023-02775-z\u003cu\u003e \u003c/u\u003e\u003c/li\u003e\n\u003cli\u003eFAO (Food and Agriculture Organization of the United Nations) 2024. Food and agriculture data. Disponible en: http://www.fao.org/ \u003c/li\u003e\n\u003cli\u003eFetch T.G. \u0026amp; Jin Y. 2007. Letter code system of nomenclature for \u003cem\u003ePuccinia graminis\u003c/em\u003e f.sp. \u003cem\u003eavenae\u003c/em\u003e. \u003cem\u003ePlant Disease\u003c/em\u003e. 91:763-766. https://doi.org/10.1094/PDIS-91-6-0763 \u003c/li\u003e\n\u003cli\u003eFetch T.J., Fetch M, Zegeye T \u0026amp; A. Xue A. 2021. Races of \u003cem\u003ePuccinia graminis\u003c/em\u003e on barley, oat, and wheat in Canada from 2015 to 2019. \u003cem\u003eCanadian Journal of Plant Pathology\u003c/em\u003e, 43:463-471. https://doi.org/10.1080/07060661.2020.1829066 \u003c/li\u003e\n\u003cli\u003eGnocato F.S. 2017. Ferrugem do colmo da aveia: fatores gen\u0026eacute;ticos da virul\u0026ecirc;ncia do pat\u0026oacute;geno e da resist\u0026ecirc;ncia do hospedeiro. Tesis de Doctorado en Fitotecnia, Universidade Federal Do Rio Grande Do Sul, Brasil. 113pp. Disponible en: http://hdl.handle.net/10183/163923 \u003c/li\u003e\n\u003cli\u003eHarder D. 1994. Identification of new races of \u003cem\u003ePuccinia graminis\u003c/em\u003e f.sp. \u003cem\u003eavenae. Plant Disease\u003c/em\u003e, 78:367\u0026ndash;368.\u003c/li\u003e\n\u003cli\u003eHarder D. \u0026amp; Haber S. 1992. Oat diseases and pathologic techniques. En: H.G. Marshall \u0026amp; M.E. Sorrells (Eds). Oat Science and Technology. American Society of Agronomy Inc. and Crop Science Society of America Inc., Madison, WI. pp. 307- 425\u003c/li\u003e\n\u003cli\u003eKosman, E. 1996. Difference and diversity of plant pathogen populations: A new approach for measuring. \u003cem\u003ePhytopathology\u003c/em\u003e, 86:1152\u0026ndash;1155.\u003c/li\u003e\n\u003cli\u003eKosman, E. 2003. Measure of multilocus correlation as a new parameter for study of plant pathogen populations. \u003cem\u003ePhytopathology,\u003c/em\u003e 93:1464\u0026ndash;1470. https://doi.org/10.1094/PHYTO.2003.93.12.1464 \u003c/li\u003e\n\u003cli\u003eLeonard K.J. \u0026amp; Martinelli J.A. 2005. Virulence of oat crown rust in Brasil and Uruguay. \u003cem\u003ePlant Disease\u003c/em\u003e, 89:802-808. In:https://doi.org/10.1094/PD-89-0802 \u003c/li\u003e\n\u003cli\u003eLeyva M.S., Espitia R.E., Villase\u0026ntilde;or M.H.E y Huerta E.J. 2004. P\u0026eacute;rdidas ocasionadas por \u003cem\u003ePuccinia graminis\u003c/em\u003e f. sp. \u003cem\u003eAvenae \u003c/em\u003eEricks. y Henn., causante de la roya del tallo en seis cultivares de avena (\u003cem\u003eAvena sativa\u003c/em\u003e L.) en Valles Altos de M\u0026eacute;xico. \u003cem\u003eRevista Mexicana de Fitopatolog\u0026iacute;a,\u003c/em\u003e 22:166-171. https://www.redalyc.org/pdf/612/61222202.pd\u003cu\u003e \u003c/u\u003e \u003c/li\u003e\n\u003cli\u003eLi T., Xu Y., Zhang X., Wu X., Zhang Y., Xuan Y. \u0026amp; Wang S. 2022. Virulence Characterization of \u003cem\u003ePuccinia graminis\u003c/em\u003e f. sp. \u003cem\u003eavenae \u003c/em\u003eand Resistance of Oat Cultivars in China. \u003cem\u003ePlant Disease\u003c/em\u003e, 106:901-905. https://doi.org/10.1094/PDIS-06-21-1239-RESECTIONSABSTRACTPDFSUPPLEMENTAL \u003c/li\u003e\n\u003cli\u003eMartens J. 1985. Oat stem rust. In: The cereal rusts. Roelfs A \u0026amp; Bushnell W (eds). Elsevier, Orlando, pp 103\u0026ndash;129\u003c/li\u003e\n\u003cli\u003eMartinelli J. 2000. Major diseases on oats in South America. In: Proc.VI International Oat Conference, Canterburry, New Zealand, 2000. pp. 277-283.\u003c/li\u003e\n\u003cli\u003eMartinelli J. 2004. Fooder oats: Oat diseases and their control. In: SUTTIE, J. M.; REYNOLDS, S. G. (Ed.). Fodder oats: a world overview. Rome: FAO (FAO Plant Production and Protection Series).\u003c/li\u003e\n\u003cli\u003eMAGyP (Ministerio de agricultura, Ganader\u0026iacute;a y Pesca). 2024. Estimaciones agr\u0026iacute;colas. Disponible en: http://datosestimaciones.magyp.gob.ar/reportes.php?reporte=Estimaciones\u003cu\u003e \u003c/u\u003e\u003c/li\u003e\n\u003cli\u003ePerson C. 1966. Genetic polymorphism in parasitic systems. \u003cem\u003eNature\u003c/em\u003e, 212:266-267.\u003c/li\u003e\n\u003cli\u003eRoelfs A.P. \u0026amp; Long D.L. 1980. Analysis of recent oat stem rust epidemics\u003cem\u003e. \u003c/em\u003e\u003cem\u003ePhytopathology\u003c/em\u003e, 70: 436-440.\u003c/li\u003e\n\u003cli\u003eStakman E.C, Stewart D.M \u0026amp; Loegering W.Q. 1962. Identification of physiologic races of \u003cem\u003ePuccinia graminis\u003c/em\u003e var. \u003cem\u003etritici.\u003c/em\u003e Agricultural Research Service Technical Bulletin. No. E-617. Washington, DC. US Dept. Agriculture.\u003c/li\u003e\n\u003cli\u003eSowa S., Toporowska J., Koroluk A. \u0026amp; Paczos-Grzęda E. 2021. First detailed report on \u003cem\u003ePuccinia graminis\u003c/em\u003e f. sp. \u003cem\u003eavenae\u003c/em\u003e virulence structure and Pg resistance genes effective in Poland. \u003cem\u003eEuropean Journal of Plant Pathology\u003c/em\u003e, 161:371-381. https://doi.org/10.1007/s10658-021-02329-1 \u003c/li\u003e\n\u003cli\u003eVan Niekerk B.D., Pretorius Z.A. \u0026amp; Boshoff W.H.P. 2001. Potential yield losses caused by barley leaf rust and oat leaf and stem rust to South African barley and oat cultivars. \u003cem\u003eSouth African Journal of Plant and Soil\u003c/em\u003e, 18:108-113.\u003c/li\u003e\n\u003cli\u003eVieira E., Carvalho F., Chaves M., Oliveira A., Benin G., Hartwig I. \u0026amp; Martins, L. 2007. Virulence variability of \u003cem\u003ePuccinia coronata\u003c/em\u003e f. sp. \u003cem\u003eavenae\u003c/em\u003e isolates collected in three counties from Rio Grande do Sul State, Brazil. \u003cem\u003ePlant Disease\u003c/em\u003e, 91: 66-70. https://doi.org/10.1094/PD-91-0066 \u003c/li\u003e\n\u003cli\u003eWehrhahne L. \u0026amp; Storm A. 2014. Evaluaci\u0026oacute;n de avena para producci\u0026oacute;n de grano. Disponible en: http://inta.gob.ar/sites/default/files/script-tmp-inta_barrow_-_evaluacin_de_avena\u003cu\u003e \u003c/u\u003e\u003c/li\u003e\n\u003cli\u003eZadoks J.C., Chang T. \u0026amp; Konzak C. 1974. A decimal code for the growth stages of cereals. \u003cem\u003eWeed Research\u003c/em\u003e, 14:415-421.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plant-pathology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpp","sideBox":"Learn more about [European Journal of Plant Pathology](http://link.springer.com/journal/10658)","snPcode":"10658","submissionUrl":"https://www.editorialmanager.com/ejpp/default2.aspx","title":"European Journal of Plant Pathology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Oat stem rust, Pg genes, seedling resistance, Avena sativa, Physiologic specialization","lastPublishedDoi":"10.21203/rs.3.rs-4172543/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4172543/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOat stem rust in oats, caused by \u003cem\u003ePuccinia graminis\u003c/em\u003e f. sp. \u003cem\u003eavenae\u003c/em\u003e Erikss and Henning \u003cem\u003e(Pg)\u003c/em\u003e, is a disease of great relevance on a global scale, recognized for its destructive capacity under favourable environmental conditions. The characterization of the \u003cem\u003ePg\u003c/em\u003e population provides valuable insights into population size, diversity, and complexity, and allows the identification of race specific genes potentially useful for breeding. This study documents for the first time the structure and complexity of \u003cem\u003ePg\u003c/em\u003e populations in Argentina and their evolution over a period of 17 years, based on 70 isolates collected in different sites during 2005, 2021, 2022 and 2023. We identified 22 different races among the 70 single-uredinial isolates collected during the period, showing a greater diversity in population. Moreover, most of the races identified in 2021, and all the races identified in 2022 and 2023, were different from those found in 2005. We found that current populations are more virulent and complex, and the predominant race demonstrated virulence against all 11 reference oat lines utilized in this study, emphasizing its potential threat to oat cultivation in the region. The change in population dynamics detected here suggests that the use of a few genes as a basis for resistance to stem rust in the Argentinian germplasm has resulted in the continuous selection of \u003cem\u003ePg\u003c/em\u003e phenotypes with virulence to these resistance genes. Additionally, our results demonstrated that the frequency of virulence of \u003cem\u003ePg\u003c/em\u003e isolates increase on most of the resistance genes compared to the 2005 population, and there are not genes potentially useful for breeding under Argentinian conditions. These findings underscore the pressing need to expand our search for new resistance genes and deepen our understanding of the genetic mechanisms governing resistance to stem rust in oats. Moreover, our research highlights the dynamic nature of plant-pathogen interactions, emphasizing the continual evolution of Pg populations and their interaction with oat \u003cem\u003ePg\u003c/em\u003e genes.\u003c/p\u003e","manuscriptTitle":"Virulence characterization of Puccinia graminis f. sp. avenae in Argentina","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-10 08:36:01","doi":"10.21203/rs.3.rs-4172543/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision","date":"2024-08-26T12:03:15+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-06-06T11:42:55+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-05T09:17:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"European Journal of Plant Pathology","date":"2024-03-29T03:01:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-03-27T05:50:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Plant Pathology","date":"2024-03-26T19:53:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plant-pathology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpp","sideBox":"Learn more about [European Journal of Plant Pathology](http://link.springer.com/journal/10658)","snPcode":"10658","submissionUrl":"https://www.editorialmanager.com/ejpp/default2.aspx","title":"European Journal of Plant Pathology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c8f11c4a-6aff-4c20-9922-581144788551","owner":[],"postedDate":"April 10th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-02-03T16:06:30+00:00","versionOfRecord":{"articleIdentity":"rs-4172543","link":"https://doi.org/10.1007/s10658-025-03004-5","journal":{"identity":"european-journal-of-plant-pathology","isVorOnly":false,"title":"European Journal of Plant Pathology"},"publishedOn":"2025-01-27 15:57:53","publishedOnDateReadable":"January 27th, 2025"},"versionCreatedAt":"2024-04-10 08:36:01","video":"","vorDoi":"10.1007/s10658-025-03004-5","vorDoiUrl":"https://doi.org/10.1007/s10658-025-03004-5","workflowStages":[]},"version":"v1","identity":"rs-4172543","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4172543","identity":"rs-4172543","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}