Puccinia Triticina Research Articles

Global benefits and domestic costs of a cooperative surveillance strategy to control transboundary crop pathogens

Societal Impact StatementSurveillance of plant pathogens is usually designed according to country boundaries. Benefits of a global surveillance system to tackle long‐distance dispersed crop pathogens are unquantified. Here, a ‘non‐cooperative’ and a ‘cooperative’ strategy are compared in terms of minimizing the surveillance effort to achieve given domestic and global targets. Although a ‘cooperative’ strategy is always more suitable, impacts of its adoption are not equally distributed among countries. Medium‐sized countries in central Europe and Asia would benefit the most from reducing the domestic effort, whereas others would need to deploy more sentinels than they would place in their own interests.Summary Transboundary diseases are extremely complex to control and can cause global socio‐economic damage. In the context of crop protection, surveillance strategies are usually designed according to country boundaries, regardless of the spatial scale of the spread of the disease. In this study, we investigate the suitability of this scale for surveilling long‐distance dispersed pathogens. We use an epidemic network describing worldwide potential transport of Puccinia graminis, the causal agent of stem rust of wheat, modelled in a previous work. Based on network properties, we conceive two strategies for prioritizing areas to be monitored for the presence of the disease, either cooperative or each country alone, and we compare their performances in terms of minimizing the effort deployed in achieving given surveillance targets at global and domestic level. We find that a cooperative strategy is more efficient at the global scale. However, its adoption implies a heterogeneous geographic distribution of surveillance effort‐related costs and benefits. Medium‐sized countries in central Europe and Asia would benefit the most; on the other hand, countries placed in important spreading pathways should deploy more surveillance effort than they would place without cooperation. Among the major wheat producers, China is the only country that may have a cost from a cooperative strategy, whereas India, Russia, the United States, France and Ukraine would have the most benefits. The acknowledgement of how costs and benefits of a global governance would be shared among countries is needed to gain unanimous support for an international cooperative surveillance system.

Forewarning of stripe rust (Puccinia striiformis) of wheat in Jammu plains

Forewarning of stripe rust (Puccinia striiformis) of wheat in Jammu plains

Biochemical responses in wheat due to Puccinia triticina infection

Biochemical responses in wheat due to Puccinia triticina infection

Mapping of leaf rust resistance genes in common wheat ‘Guinong08-6’

Wheat leaf rust (Puccinia triticina Eriks.), a devastating disease of wheat in the world, causes severe yield losses and therefore the development of resistant cultivars is very important. Here, a Chinese wheat line (Guinong08-6) showed adult-plant resistance against mixed fungal isolates of leaf rust, which is common in Guiyang region. It was crossed with a susceptible wheat line (Guinong19) to develop F1, F2, and F3 hybrids. Combined SSR and STS markers were used to map leaf rust resistance genes in Guinong08-6, and the resistance phenotype of Guinong08-6 was co-regulated by two complementary dominant genes, named LrGn08-6A and LrGn08-6B. LrGn08-6A was mapped to chromosome 2AS with markers URIC-LN2 and Xgpw2204, which flanked the gene at distances of 1.8 centimorgan (cM) and 14.83 cM, respectively. LrGn08-6B was mapped to chromosome 4DL with markers Xgpw342 and Xbarc93, which both flanked the gene at a distance of 26.57 cM. Genetic and molecular marker analyses demonstrated that LrGn08-6A, which was inherited from Aegilops ventricosa may be the resistance gene Lr37, while LrGn08-6B may be a newly discovered leaf rust resistance gene.

Comparative Analysis of Metabolites of CAD-im Genotypes of Spring Bread Wheat under Brown Rust Infection

Determination of the role of specific genes and their products in plant resistance to stress factors, including those of a biotic nature, is an urgent task of phytopathology and provides additional information for practical use. For spring bread wheat Triticum aestivum, CAD-im genotypes (Cinnamyl alcohol dehydrogenase, cinnamyl alcohol dehydrogenase; EC 1.1.1.195) affecting leaf rust (Puccinia triticina) resistance were studied. Resistant and susceptible genotypes were grown on an infectious background and in its absence. Plant tissues were studied for a number of indicators, including the content of phenylpropanoid metabolites, as well as sterols and saponins. Phenylpropanoids show an increase in a number of metabolites due to infection, especially coniferyl acetate and synapic aldehyde. A decrease in the content of some sterols under the influence of infection in the resistant CADim+ ge-notype was found. It is assumed that the acetate-mevalonate pathway of metabolism in the resistant genotype CADim+ changes under the influence of infection from the synthesis of sterols to the synthesis of protective substances, phytoalexins.

Classification of Image-Based Wheat Leaf Diseases using Deep Learning Approach: A Survey

This paper focuses on detecting leaf diseases in wheat plants from the beginning to the end of the plant's life cycle. It highlights the best techniques for detecting various types of wheat leaf diseases and emphasizes the use of computer vision, image processing, and machine learning. The main focus is on classifying these diseases through deep convolutional neural networks, a popular image recognition and classification approach. The paper reviews various techniques for classifying image-based wheat leaf diseases, including spot blotch, stripe rust, brown rust, and powdery mildew. The paper aims to summarize the state-of-the-art techniques for detecting wheat leaf diseases.

Winds of Change: Plant Pathology, Transnational Wheat Rust, and the Environmental Origins of the Green Revolution, 1904–1953

Abstract Created in 1943, the Mexican Agricultural Program (MAP) was a collaborative program between the Rockefeller Foundation and the Mexican government aimed at improving yields of corn and wheat varieties in Mexico. The MAP's wheat program was more influential than its corn breeding program, and wheat became the centerpiece of the Green Revolution beginning in the 1960s. This article reveals that the environmental origins of the MAP's wheat program lay in combating a plant disease fungus commonly known as wheat rust, which harmed farmers in both northern Mexico and the US hard red spring wheat region. Rust outbreaks originated in US barberry bushes, so one might think that Mexican scientists would have entered the United States to solve this problem with transnational wheat rust. Instead, the reverse occurred. Nevertheless, the MAP successfully produced new rust-resistant wheat during the formative years of the MAP's wheat program. Between 1943 and 1953, rust-resistant wheat helped increase Mexican wheat production 84 percent and yields 59 percent. Rust-resistant wheat offered an alternative model for a sustainable, resource-neutral green revolution. Rather than remain in their field of expertise, plant pathologists pivoted to semidwarf wheat and fertilizer use after 1953, a shift that defined the course of the Green Revolution.

Systematic Characterization of Multi-Rust Resistance Genes from a 'Parula × Thatcher' Population with a High-Density Genetic Map.

Pyramiding multiple resistant genes has been proposed as the most effective way to control wheat rust diseases globally. Identifying the most effective pyramids is challenged by the large pool of rust resistance genes and limited information about their mechanisms of resistance and interactions. Here, using a high-density genetic map, a double haploid population, and multi-rust field testing, we aimed to systematically characterize the most effective gene pyramids for rust resistance from the durable multi-rust resistant CIMMYT cultivar Parula. We revealed that the Parula resistance gene pyramid contains Lr34/Yr18/Sr57 (Lr34), Lr46/Yr29/Sr58 (Lr46), Lr27/Yr30/Sr2 (Sr2), and Lr68. The efficacy, magnitude of effect, and interactions varied for the three rust diseases. A subpopulation mapping approach was applied to characterize the complex interactions of the resistance genes by controlling for the effect of Lr34. Using this approach, we found that Lr34 and Lr68 have a strong additive effect for leaf rust, whereas no additive effects were observed for any rusts between Lr34 and Lr46. Lr34 combined synergistically with Sr12 from Thatcher for stem rust, whereas the additive effect of Lr34 and Sr2 was dependent on the type of rust and environment. Two novel leaf rust quantitative trait loci (QTLs) from Parula were identified in this study, a stable QTL QLr-7BS and QLr-5AS, which showed Lr34 dependent expression. With these findings, we propose combining two to three high-value genes from Canadian wheat (e.g., Sr12 from Thatcher) with a foundational multi-adult plant resistance cassette for desirable and durable resistance to all three rusts in Canadian wheat.

DILKASH-20: A NEWLY APPROVED WHEAT VARIETY RECOMMENDED FOR PUNJAB, PAKISTAN, WITH SUPREME YIELDING POTENTIAL AND DISEASE RESISTANCE

Wheat Research Institute (WRI), Faisalabad, Pakistan, a premier foundational birthplace of the Green revolution in Pakistan, has played a vital role in attaining food self-sufficiency. Latest grown varieties have succumbed to ever-changing pathogens, unable to stand in the fields. Hence, the initiative to develop an indigenous type to withstand high disease pressure producing better grain yield transpired during 2008–2009, with the hybridization of Dilkash-20 (WBLL*2/4/SNI/TRAP#1/3/KAUZ*2/TRAP//KAUZ/5/ PB.96//LU26/HD2179). It proceeded with segregating generations from F2 to F7 from 2009 to 2016. During 2016–2017 and 2017–2018, its testing followed at station yield trials, including Preliminary (A) and Regular (B), under code V-16005. It produced a significantly higher yield (10.86% and 10.40%) than the check varieties (Faisalabad-08 [FSD-08] and Punjab-11 [PB-11]). In provincial trials, it out-yielded a check variety by 4.06%. Testing in national yield trials, line V-16005 produced 17.40% and 12.03% higher grain yield than check cultivars during 2018–2019 and 2019–2020, respectively. It yielded better when planted on the first 10 days of November with a 100 kg ha-1 seed rate and 120:90:60 NPK (kg ha-1) fertilizer rate. The Dilkash-20 variety is a medium-height (105–115 cm), semi-erect producing 425 tillers per m2, with 119 days to heading and 145–150 days to maturity. It is of excellent quality, with protein (15.1%), starch (52.7%), gluten (28.7%), and test weight (72.1 kg hl-1), highly suitable for chapatti making. It has an effectual, durable resistance against brown and yellow rusts based on adult plant resistance genes. Therefore, the Punjab Seed Council approved Dilkash-20 for general cultivation throughout the irrigated areas of Punjab.

Omskaya 42 - a new middle-late variety of soft spring wheat for the southern forest-steppe and steppe

The results of research on the creation of the soft spring wheat variety of Omskaya 42 are described. The variety is characterized by high indices of drought tolerance (IR in vitro = 0.55). Assessments of resistance to leaf rust pathogens in 2017 and 2018 showed that the variety Omskaya 42 has a medium level of resistance to powdery mildew (IR = 0.47 and 0.59) and high resistance to brown rust (IR = 0.05 and 0.18) and stem rust (IR = 0.07 and 0.28). With a significant lack of moisture and mass development of diseases in 2019 and 2020 during tillering - earing (HTC = 0,20-0,45), the yield of the variety Omskaya 42 was higher than the susceptible standard Serebristaya, respectively, by 2.15 and 2.88 t / ha, and the variety Element 22 resistant to these diseases - by 0.16 and 0.5 t / ha. The ear length of the new variety is 0.5 cm longer than the standard Serebristaya. Significant excess compared to the standard was revealed by the weight of 1000 grains (by 5.6 g). The results of the study of the variety in the international ecological nursery KASIB (2015 and 2016) showed that on the experimental plots with a mass infestation of crops with brown and stem rust, the variety Omskaya 42 showed high and moderate resistance to these diseases, its yield was by 0.39-1.23 t/ha higher than susceptible varieties. Indicators of grain quality in the years of transferring the variety for state variety testing were as follows: crude gluten content of 31.8%, protein - 16.36%, the flour strength - 415 e. a., the overall baking score - 4.3 points. Since 2019, the variety is included in the State Register of Breeding Achievements of the Russian Federation for the West Siberian (10) region as a middle-late variety. In terms of grain quality, it belongs to the strong wheat. As part of the import substitution program, the introduction of the new variety Omskaya 42 will significantly increase and stabilize the gross yield of grain in the Omsk region and the West Siberian region of Russia.

Characterizing the Response of Puccinia striiformis f. sp. tritici to Periods of Heat Stress that Are Common in Kansas and the Great Plains Region of North America.

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici, is considered a disease of cool environments, and it has been observed that high temperatures can suppress disease development. However, recent field observations in Kansas suggest that the pathogen may be recovering from heat stress more quickly than expected. Previous research indicates that some strains of this pathogen were adapted to warm temperature regimes but did not consider how the pathogen responds to periods of heat stress that are common in the Great Plains region of North America. Therefore, the objectives of this study were to characterize the response of contemporary isolates of P. striiformis f. sp. tritici to periods of heat stress and to look for evidence of temperature adaptations within the pathogen population. These experiments evaluated nine isolates of the pathogen: eight isolates collected in Kansas between 2010 and 2021 and a historical reference isolate. Treatments compared the latent period and colonization rate of isolates given a cool temperature regime (12 to 20°C) and as they recovered from 7 days of heat stress (22 to 35°C). Results documented that contemporary isolates of the pathogen had similar latent periods and colonization rates as the historical reference under the cool temperature regime. Following exposure to 7 days of heat stress, the contemporary isolates had shorter latent periods and higher colonization rates than the historical isolate. There was also variability in how the contemporary isolates recovered from heat stress, with some isolates collected during 2019 to 2021 recovering sooner than those collected just 5 to 10 years ago.

Evolution within a given virulence phenotype (pathotype) is driven by changes in aggressiveness: a case study of French wheat leaf rust populations

Plant pathogens are constantly evolving and adapting to their environment, including their host. Virulence alleles emerge, and then increase, and sometimes decrease in frequency within pathogen populations in response to the fluctuating selection pressures imposed by the deployment of resistance genes. In some cases, these strong selection pressures cannot fully explain the evolution observed in pathogen populations. A previous study on the French population of Puccinia triticina, the causal agent of wheat leaf rust, showed that two major pathotypes — groups of isolates with a particular combination of virulences — predominated but then declined over the 2005-2016 period. The relative dynamics and the domination of these two pathotypes — 166 317 0 and 106 314 0 —, relative to the other pathotypes present in the population at a low frequency although compatible, i.e. virulent on several varieties deployed, could not be explained solely by the frequency of Lr genes in the landscape. Within these two pathotypes, we identified two main genotypes that emerged in succession. We assessed three components of aggressiveness — infection efficiency, latency period and sporulation capacity — for 44 isolates representative of the four P. triticina pathotype-genotype combinations. We showed, for both pathotypes, that the more recent genotypes were more aggressive than the older ones. Our findings were highly consistent for the various components of aggressiveness for pathotype 166 317 0 grown on Michigan Amber — a ‘naive’ cultivar never grown in the landscape — or on Apache — a ‘neutral’ cultivar, which does not affect the pathotype frequency in the landscape and therefore was postulated to have no or minor selection effect on the population composition. For pathotype 106 314 0, the most recent genotype had a shorter latency period on several of the cultivars most frequently grown in the landscape, but not on ‘neutral’ and ‘naive’ cultivars. We conclude that the quantitative components of aggressiveness can be significant drivers of evolution in pathogen populations. A gain in aggressiveness stopped the decline in frequency of a pathotype, and subsequently allowed an increase in frequency of this pathotype in the pathogen population, providing evidence that adaptation to a changing varietal landscape not only affects virulence but can also lead to changes in aggressiveness.

Mapping a leaf rust resistance gene LrOft in durum wheat Ofanto and its suppressor SuLrOft in common wheat.

Epidemics of leaf rust (caused by the fungal pathogen Puccinia triticina Erikss., Pt) raise concerns regarding sustainability of wheat production. Deployment of resistant cultivars is the most effective and economic strategy for combating this disease. Ofanto is a durum wheat cultivar that exhibits high resistance to Pt race PHT throughout its entire growing period. In the present study, we identified a leaf rust resistance gene in Ofanto and temporarily designated it as LrOft. LrOft was mapped to a 2.5 cM genetic interval in chromosome arm 6BL between Indel markers 6B6941 and 6B50L24. During introgression of LrOft from Ofanto to common wheat it was observed that F1 plants of Ofanto crossed with Shi4185 exhibited leaf rust resistance whereas the F1 of Ofanto crossed with ND4503 was susceptible. In order to map the presumed suppressor locus, a Shi4185/ND4503//Ofanto three-way pentaploid population was generated and SuLrOft was mapped on chromosome arm 2AS. SuLrOft was mapped within a 2.6 cM genetic interval flanked by 2AS50L14 and 2AS50L6. Fine mapping using 2,268 plants of the three-way cross narrowed the suppressor locus to a 68.2-kbp physical interval according to IWGSC RefSeq v1.1. Sequence analysis of genes in the physical interval revealed that TraesCS2A02G110800 encoding an RPP-13-like protein with an NB-ARC domain was a potential candidate for SuLrOft.

Registration of ‘L 14‐267’ sugarcane

Abstract‘L 14‐267’ (Reg. no. CV‐213, PI 701487) sugarcane (Saccharum spp. hybrid) was released for commercial production in Louisiana because of its high yield potential and broad‐spectrum disease resistance. The final testing stage resulted in data from 62 trials at 12 representative sandy silt (light‐textured) and clayey (heavy‐textured) soil locations. Cane yield of L 14‐267 was comparable to that of ‘L 01‐299’, the most widely grown cultivar in the Louisiana sugar industry, in the plant and first ratoon crops but significantly lower in the second ratoon crop. Sucrose content was significantly higher in L 14‐267 than in L 01‐299 in the plant and first ratoon crops and was comparable to that of L 01‐299 in the second ratoon crop. Sugar yield was significantly higher in L 14‐267 than in L 01‐299 in the plant crop, comparable in the first ratoon crop but significantly lower in the second ratoon crop. The performance of L 14‐267 did not differ significantly between the two soil types for any of the traits. L 14‐267 is a mid‐ to late‐season maturing cultivar that appears to respond well to plant growth regulators but poorly to sub‐freezing temperatures. L 14‐267 displayed broad‐spectrum disease resistance, being resistant to mosaic, yellow leaf, smut, and ratoon stunt and moderately resistant to brown rust and leaf scald. L 14‐267 is moderately susceptible to the sugarcane borer and the Mexican rice borer.

Accumulation of complex oligosaccharides and CAZymes activity under acid conditions constitute the Thatcher+Lr9 defence responses to Puccinia triticina

Puccinia triticina (Pt) is an important pathogen of wheat. While breeding programmes develop resistant wheat cultivars to mitigate the effects of such rust-causing pathogens, the emergence of new rust races with wider virulence mandates the implementation of other control strategies. Our study investigated whether acidic pH conditions affected selected Carbohydrate-Active Enzymes (CAZymes) in Pt-inoculated Thatcher + Lr9 (IR) wheat compared to those found in the Thatcher (IS) wheat. The β-glucosidase and amyloglucosidase activity levels significantly increased in IR compared to the control from 1 to 14 days post-inoculation (dpi). In contrast, activity levels of invertase did not change in the IR wheat relative to the control at 1 and 7 dpi, but were significantly reduced in the IR plants at 14 dpi. The IS had higher activity of all three hexose-producing enzymes under acidic conditions. These enzyme activities could be increased in the IS to produce hexose sugars required by Pt to develop and advance infection. The phenotypic analysis supported this view because leaf rust disease symptoms were only visible in the IS plants. For cell wall loosening-related enzymes, the IR displayed higher activity of exoglucanase, xylanase and peroxidase enzymes compared to IS. The liquid chromatography–mass spectrometry analysis showed IR had higher concentrations of complex oligosaccharides compared to the IS. Thus, we concluded that the higher exoglucanase, xylanase and peroxidase activity could be involved in cell wall loosening under acidic conditions, while oligosaccharides could be building-blocks for synthesizing cell wall barriers that apprehend Pt growth in inoculated Thatcher + Lr9.

Assessment of Resistance of Different Varieties of Winter Wheat to Leaf Fungal Diseases in Organic Farming

A change in agricultural policy in the European Union aims, among other things, to halve the use of pesticides and increase the share of organic farming to 25% by 2030. One of the challenges associated with this target will be the control of plant fungal diseases. The key methods in organic farming include the selection of less susceptible crop varieties. In order to test this method, a long-term trial of organic farming in Eastern Poland was established. In total, 41 different winter wheat varieties were grown from 2018 to 2022 and their resistance to fungal leaf diseases was monitored. Brown rust was found to be the disease causing the highest infestation towards the end of vegetation, often exceeding 80% of the flag leaf area. However, yield reductions were mainly related to the severe occurrence of leaf Septoria. Other leaf diseases such as tan spot, yellow rust, powdery mildew, and fusariosis were of little importance and only occurred at low infestations of Septoria and brown rust. The course of the weather was found to have a significant effect on disease incidence. Drought occurring in May and June significantly increased the incidence of brown rust and Septoria, while prolonged rains increased tan spot and Fusarium infestation. Greater overall infestation occurred in years with high average temperatures. Ten varieties with high resistance to foliar fungal diseases were selected and can be recommended for organic farming.

Changes in aggressiveness in pathotypes of wheat leaf rust

A recommendation of: Cécilia FONTYN, Kevin JG MEYER, Anne-Lise BOIXEL, Ghislain DELESTRE, Emma PIAGET, Corentin PICARD, Frédéric SUFFERT, Thierry C MARCEL, Henriette GOYEAU Evolution within a given virulence phenotype (pathotype) is driven by changes in aggressiveness: a case study of French wheat leaf rust populations https://doi.org/10.1101/2022.08.29.505401

Virulence of Puccinia triticina and Puccinia tritici-duri on durum wheat in southern Spain, from 2020 to 2022

Leaf rust is a major wheat disease in southern Spain, where durum wheat is an important crop. Until the 2019/2020 season, this disease was effectively managed, as the most widely planted cultivars in southern Spain had effective resistance genes. A problem arose in the spring of 2020, when every farm field and durum wheat trial examined displayed leaf rust symptoms. Leaves had few but large uredinial pustules, different from those of the normal leaf rust caused by Puccinia triticina, and telia developed rapidly after only a few days. The symptoms clearly fitted with P. tritici-duri, another wheat leaf rust species already reported in the western Mediterranean Basin. This species is not new in southern Spain but has never been observed at such high severity on almost every durum wheat cultivar grown in that region. Leaf rust severity was assessed in durum wheat field trials in the 2020, 2021 and 2022 growing seasons in four provinces of southern Spain. During 2020 and 2021, 13 single pustule isolates of leaf rust were also collected from different cultivars of durum wheat. Inoculation of the isolates on a differential host set showed that four different races were present, two being of P. tritici-duri. Only cultivar Calero showed consistent resistance to the races of P. tritici-duri employed in this study.

Resistance to Brown and Stem Rust in Spring Soft Wheat Varieties in the Arid Climate of Northern Kazakhstan

Resistance to Brown and Stem Rust in Spring Soft Wheat Varieties in the Arid Climate of Northern Kazakhstan

The Keys to Controlling Wheat Rusts: Identification and Deployment of Genetic Resistance.

Rust diseases are among the major constraints for wheat production worldwide due to the emergence and spread of highly destructive races of Puccinia. The most common approach to minimise yield losses due to rust is to use cultivars that are genetically resistant. Modern wheat cultivars, landraces, and wild relatives can contain undiscovered resistance genes, which typically encode kinase or nucleotide-binding site leucine rich repeat domain containing receptor proteins. Recent research has shown these genes can provide either resistance in all growth stages (all-stage resistance; ASR) or specially in later growth stages (adult-plant resistance; APR). ASR genes are pathogen and race-specific, meaning they can function against selected races of the rust fungus due to the necessity to recognise specific avirulence molecules in the pathogen. APR genes are either pathogen specific or multipathogen resistant but often race-nonspecific. Prediction of resistance genes through rust infection screening alone remains complex when more than one resistance gene is present. However, breakthroughs during the past half century such as single nucleotide polymorphism (SNP) based genotyping techniques and resistance gene isolation strategies such as MutRenSeq (Mutagenesis, Resistance gene enrichment and Sequencing), MutChromSeq (Mutagenesis and Chromosome Sequencing), and AgRenSeq (Association genetics combined with RenSeq) enable rapid transfer of resistance from source to modern cultivars. There is a strong need for combining multiple genes for better efficacy and longer-lasting resistance. Hence techniques such gene cassette creation speed up the gene combination process, but their widespread adoption and commercial use is limited due to their transgenic nature.