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Wheat leaf rust caused by Puccinia triticina (Pt) is an important disease of bread wheat in Zimbabwe. This study was carried out to determine the distribution, avirulence/virulence profile(s) and genotypic variation among isolates of the pathogen. In total, 104 single-pustule isolates were established from infected wheat samples that were collected from the main wheat production regions in Zimbabwe in surveys conducted from 2019 to 2021. Phenotyping of the isolates on a set of 46 differential and additional wheat lines revealed a single Pt race, MCDS. For genotypic assessment, 48 Pt isolates, including eight South African races, were genotyped with 19 microsatellite markers. Using the Bayesian model, isolates were subdivided into three clusters in both a DARwin neighbour-joining tree and STRUCTURE analysis. The results confirmed a high genetic similarity between the Zimbabwean Pt isolates and the South African races MCDS, MCPS and MFPS. Furthermore, Pt isolates from Zimbabwe were clonal, which was in accordance with all 104 isolates that typed to race MCDS. [ABSTRACT FROM AUTHOR]

The first step in trait introgression is to identify and assess novel sources of variation. For shrub willow (Salix) breeders, there is an abundance of understudied species within a genus that readily hybridizes. Breeding targets in shrub willow center on traits contributing to biomass yield for bioenergy. These include stem biomass, insect and pathogen resistance, and leaf architecture traits. More specifically, breeding for durable resistance to willow leaf rust (Melampsora spp.) is of particular importance as the pathogen can significantly reduce biomass yields in commercial production. The Salix F1 hybrid common parent population (Salix F1 HCP) was created to characterize the variation among eight species‐hybrid families and map QTL for targeted traits. A female and male S. purpurea were used as common parents in crosses made to male S. suchowensis, S. viminalis, S. koriyanagi, and S. udensis and female S. viminalis, S. integra, S. suchowensis to produce eight families that were planted in field trials at Cornell AgriTech in Geneva, NY and phenotyped. Using 16 previously described parental backcross linkage maps and two newly generated S. purpurea consensus maps, we identified 215 QTL across all eight families and in every parent. These included 15 leaf rust severity, 61 herbivory, 65 leaf architecture, and 74 yield component QTL, resulting in 50 unique overlapping regions within the population. These genetic loci serve as an important foundation for future shrub willow breeding, and each interspecific family was identified as a novel source of useful alleles for trait introgression into high yielding cultivars. [ABSTRACT FROM AUTHOR]

Wheat leaf rust, caused by Puccinia triticina, poses a growing threat to global wheat production, necessitating alternative strategies for effective disease management. This study investigated the potential of gamma-aminobutyric acid (GABA) to enhance resistance to leaf rust in two wheat cultivars: the susceptible Morocco and moderately resistant Sakha 94 cultivar. Our findings revealed that GABA significantly improved resistance in both cultivars to P. triticina, particularly in Morocco, by mitigating disease severity and reducing pustule density and size while extending both incubation and latent periods. This study assessed the effectiveness of two GABA application methods: plants received 1 mM GABA treatment, as a foliar spray, twenty-four hours prior to infection (pre-GABA), and plants received 1 mM GABA treatment both 24 h before and after infection (pre-/post-GABA), with the latter yielding significantly better results in reducing infection severity and improving plant resilience. Additionally, GABA application influenced stomatal behavior, promoting closure that may enhance resilience against leaf rust. GABA application on plants also modulated the production of reactive oxygen species (ROS). This led to a stronger oxidative burst in both susceptible and moderately resistant cultivars. GABA increased O2●− levels in guard cells and surrounding stomata, enhancing stomatal closure and the hypersensitive response. GABA enhanced the accumulation of soluble phenols and increased the activity of key antioxidant enzymes, catalase (CAT) and peroxidase (POX), which are vital for managing oxidative stress. To the best of our knowledge, this investigation represents the first report into the impact of GABA on wheat leaf rust disease. [ABSTRACT FROM AUTHOR]

The leaf rust (Puccinia triticina f. sp. tritici), stripe rust (Puccinia striiformis f. sp. tritici), and stem rust (Puccinia graminis f. sp. tritici) are major fungal constraints affecting wheat production worldwide. Identifying and deploying wheat varieties with diverse resistance are the best ways to manage all the rusts. Therefore, a continuous search goes on to identify diverse germplasm with effective rust resistance that expresses at different stages of plant growth (seedling and adult plant). A set of 22 rust resistant wheat genotypes and 4 checks (controls), viz., Avocet‐Yr10, Avocet ‐Yr15, Agra Local, and respective positive checks were studied for characterising rust resistance genes using host–pathogen interactions complemented by molecular markers. Among 22 elite genotypes, 05 genotypes amplified 191 bp fragment with marker PSY1E1, confirmed the presence of gene Lr19/Sr25. These genotypes also expressed resistance to most virulent leaf rust pathotypes, 77‐5 and 77‐9 in host–pathogen interaction test (HPI). Seven genotypes showed the presence of Lr34/Yr18/Sr57/Pm38/Ltn1 in homozygous state, whereas G4 showed its presence in heterozygous condition. Among 22 genotypes, 16 genotypes possessed Yr10. Five genotypes (22.7%) exhibited two gene combinations, Lr19/Sr25, and Yr10 as revealed through the detection of 191 bp fragment with marker PSY1E1 and 260 bp fragment with co‐dominantly inherited microsatellite marker Xpsp3000, respectively. All five genotypes (G2, G3, G8, G9, and G18) also expressed brown glumes controlled by the gene Rg1 tightly linked to Yr10 on the 1BS chromosome. Broad spectrum rust resistance present in these lines in good agronomic backgrounds could be used as potent genetic donors for diverse and durable rust resistance breeding programmes in wheat. [ABSTRACT FROM AUTHOR]

The present study demonstrated the differences in the seed metabolome and mycobiome of two Aegilops tauschii Coss accessions with different resistance to brown rust and powdery mildew. We hypothesized that the seeds of resistant accession k-1958 Ae. tauschii ssp. strangulata can contain a larger number of metabolites with antifungal activity compared with the seeds of susceptible Ae. tauschii ssp meyeri k-340, which will determine differences in the seed fungal community. Our study emphasizes the differences in the seed metabolome of the studied Ae. tauschii accessions. The resistant accession k-1958 had a higher content of glucose and organic acids, including pyruvic, salicylic and azelaic acid, as well as pipecolic acids, galactinol, glycerol and sitosterol. The seeds of Ae. tauschii-resistant accession k-1958 were found to contain more active substances with antifungal activity. The genera Cladosporium and Alternaria were dominant in the seed mycobiome of the resistant accession. The genera Alternaria, Blumeria and Cladosporium dominated in seed mycobiome of susceptible accession k-340. In the seed mycobiome of the resistant k-1958, a higher occurrence of saprotrophic micromycetes was found, and many of the micromycetes were biocontrol agents. It was concluded that differences in the seed metabolome of Ae. tauschii contributed to the determination of the differences in mycobiomes. [ABSTRACT FROM AUTHOR]

The purpose of the current work was to search for sources of winter wheat varieties’ resistance to the most common pathogens of the area under artificial infectious backgrounds and recommend them for inclusion in the breeding process. The study was carried out on the experimental plots of the laboratory for plant immunity and protection of the FSBSI Agricultural Research Center “Donskoy” in 2021–2023. In order to expand the genetic diversity in immunity of newly developed varieties, it is necessary to use new sources of resistance. The objects of study were 78 winter wheat varieties from interstation variety testing, representing various breeding institutions in Russia and some foreign varieties. The study material was presented by the North Caucasian populations of pathogens of such wheat leaf diseases as powdery mildew, brown and yellow rust, and leaf spot (Septoria). Infectious backgrounds were formed according to generally accepted methods, using spore material of pathogens both stored and collected from crops in the previous year (types of rust) and collected from overwintered plants in the spring (powdery mildew, leaf spot). Weather conditions varied across the years of study (mainly in the autumn), but the damage to susceptible test varieties in the experiments was maximum. As a result of the study of the varieties on their resistance to one pathogen, there have been identified 23 varieties resistant to powdery mildew, 56 ones to leaf rust, 47 ones to yellow rust, 8 varieties to leaf spot. There has been given a characteristic of varieties according to various degree of resistance or susceptibility to each pathogen. On the resistance to two pathogens, there have been identified 17 varieties resistant to brown and yellow rust, 2 varieties resistant to brown rust and powdery mildew, 2 varieties resistant to yellow rust and powdery mildew, 1 variety resistant to brown rust and leaf spot. Ten varieties have shown resistance to no one pathogen, but they have had moderate resistance or moderate susceptibility to several other pathogens. 20 varieties were resistant to three diseases in various combinations, and 16 of them were resistant to brown, yellow rust, and powdery mildew. One variety ‘MV Nador’ from Hungary showed resistance to all 4 pathogens. All resistant varieties identified in the study can replenish the supply of winter wheat sources to the complex of leaf diseases for breeding purposes or be used in integrated crop protection against leaf diseases.

Abstract Background Powdery mildew (caused by Blumeria graminis f. sp. tritici (Bgt)) and leaf rust (caused by Puccinia triticina (Pt)) are prevalent diseases in wheat (Triticum aestivum L.) production. Thinopyrum ponticum (2n = 10x = 70, EeEeEbEbExExStStStSt) contains genes that confer high levels of resistance to these diseases. Results An elite wheat-Th. ponticum disomic substitution line, DS5Ag(5D), was developed in the Bainong Aikang 58 (AK58) background. The line was assessed using genomic in situ hybridization (GISH), oligo-nucleotide probe multiplex (ONPM) fluorescence in situ hybridization (FISH), and molecular markers. Twenty eight chromosome-specific molecular markers were identified for the alien chromosome, and 22 of them were co-dominant. Additionally, SNP markers from the wheat 660 K SNP chip were utilized to confirm chromosome identification and they provide molecular tools for tagging the chromosome in concern. The substitution line demonstrated high levels of resistance to powdery mildew throughout its growth period and to leaf rust at the adult stage. Based on the resistance evaluation of five F5 populations between the substitution lines and wheat genotypes with different levels of sensitivity to the two diseases. Results showed that the resistance genes located on 5Ag confered stable resistance against both diseases across different backgrounds. Resistance spectrum analysis combined with diagnostic marker detection of known resistance genes of Th. ponticum revealed that 5Ag contained two novel genes, Pm5Ag and Lr5Ag, which conferred resistance to powdery mildew and leaf rust, respectively. Conclusions In this study, a novel wheat-Th. ponticum disomic substitution line DS5Ag(5D) was successfully developed. The Th. ponticum chromosome 5Ag contain new resistance genes for powdery mildew and leaf rust. Chromosomic—specific molecular markers were generated and they can be used to track the 5Ag chromosome fragments. Consequently, this study provides new elite germplasm resources and molecular markers to facilitate the breeding of wheat varieties that is resistant to powdery mildew and leaf rust.

Abstract Wheat is an essential food commodity cultivated throughout the world. However, this crop faces continuous threats from fungal pathogens, leaf rust (LR) and stripe rust (YR). To continue feeding the growing population, these major destructors of wheat must be effectively countered by enhancing the genetic diversity of cultivated germplasm. In this study, an introgression line with hexaploid background (IL sp3603 ) carrying resistance against Pt pathotypes 77−5 (121R63-1), 77−9 (121R60-1) and Pst pathotypes 46S119 (46E159), 110S119 (110E159), 238S119 (238E159) was developed from donor wheat wild progenitor, Aegilops speltoides acc pau 3603. To understand the genetic basis of resistance and map these genes (named Lr sp3603 and Yr sp3603 ), inheritance studies were carried out in F6 and F7 mapping population, developed by crossing IL sp3603 with LR and YR susceptible cultivar WL711, which revealed a monogenic (single gene) inheritance pattern for each of these traits. Bulk segregant analysis combined with 35 K Axiom SNP array genotyping mapped both genes as separate entities on the short arm of chromosome 6B. A genetic linkage map, comprising five markers, 1 SNP, 1 PLUG and three gene based SSRs, covered a genetic distance of 12.65 cM. Lr sp3603 was flanked by markers Tag-SSR14 (located proximally at 2.42 cM) and SNP AX-94542331 (at 3.28 cM) while Yr sp3603 was mapped at one end closest to AX-94542331 at 6.62 cM distance. Functional annotation of Lr sp3603 target region (∼ 1 Mbp) revealed 10 gene IDs associated with disease resistance mechanisms including three encoding typical R gene domains.

Leaf rust (caused by Puccinia triticina Erikss., Pt) is a severe foliar disease of cultivated wheat worldwide. Severe development of the disease results in significant losses in seed yield and quality. Growing immune varieties is the most rational method for Pt control in terms of effectiveness and ecological safety. However, the gene pool of cultivated wheat is very narrow for seedling Pt effective resistance genes, which hampers breeding for this trait. One of the well-known methods to broaden genetic diversity for resistance is the introgression of highly effective genes from wild relatives into the genomes of cultivated wheat. The Aegilops L. species have been proven to be perfectly suited for this purpose. No gene for Pt resistance has been transferred to wheat from Aegilops biuncialis Vis. (Lorent's goatgrass) up to now. Previously, we selected eight accessions of the species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) genebank that showed a perfect level of resistance to leaf rust. In this research, we studied the genetic control of resistance using hybridological, phytopathological, and molecular analyses. According to the F1–F3 hybrid evaluation results, each accession possesses one dominant gene for Pt resistance, and genes in different accessions are allelic or very tightly linked. Phytopathological test clone analysis showed that this gene is not identical to Lr9, Lr19, Lr24, Lr39, and Lr47, which are effective against Pt populations in some areas of Russia. This conclusion was partially supported by the results of the identification of DNA markers specific to these genes in bread wheat. Thus, we identified one dominant gene (temporarily symbolized as LrBi1) for effective seedling Pt resistance; it is recommended for introgression to cultivated wheat via interspecific hybridization. [ABSTRACT FROM AUTHOR]

The Research was conducted at KARC during June to November, 2023 to phenotypic screening of bread wheat genotypes for yellow and leaf rust resistance. Both rusts were recorded based on the modified Cobb scale. Severity of yellow rust showed from immune to 70%. 826 genotypes showed slow rusting resistance ranging from 0-30%), 575 genotypes observed as slow rusting plant resistance ranging from 31-50%) and 96 genotypes observed as low adult plant resistance (>50% of yellow rust severity). Tested genotypes showed diverse reactions for yellow rust ranging from immune to susceptible responses. 57 genotypes were observed immune, 161 genotypes were showed moderately resistant reaction type. 317 genotypes were observed moderately susceptible reaction and 962 genotypes were observed susceptible reactions for yellow rust response. The leaf rust severity of the studied genotypes showed from immune to 90. 607 genotypes (showed slow rusting resistance ranging from 0-20% of severity), 563 genotypes observed as slow rusting plant resistance ranging from 21-50% of severity) and 326 genotypes observed as low adult plant resistance (>50% of leaf rust severity. Tested genotypes showed diverse reactions for leaf rust ranging from immune to susceptible responses. 58 genotypes were observed immune, 30 genotypes were observed moderately resistant, 80 genotypes were observed moderately resistant to moderately susceptible, 464 genotypes were showed moderately susceptible reaction, 864 genotypes were showed susceptible reactions for leaf rust disease response. Based on yellow rust, leaf rust and agronomic performance 76 genotypes were selected for the next breeding step. [ABSTRACT FROM AUTHOR]

One of the biggest obstacles to increasing wheat production and yield is diseases. Diseases not only reduce the amount of product but also negatively affect product quality. Rust diseases in wheat are among the most important biotic stress factors limiting wheat production in our country. In epidemic years, early infections on cereals susceptible varieties can cause yield losses of up to 80-90% and can cause varieties to be completely removed from production. In our country, yield losses caused by different types of rust on wheat plants have been recorded between 12-80%. Product losses vary depending on the sensitivity of varieties, environmental conditions, and the races of the factors, as well as from year to year and from region to region. Leaf rust (Lr) (Puccinia triticina Eriks.) is seen almost everywhere wheat is grown, but the damage it causes is not as noticeable as the damage caused by black and yellow rust. However, these two rust agents are not effective every year and cause serious epidemics every 7-8 years. Leaf rust, on the other hand, occurs almost every year and causes a certain amount of yield loss. The most important method for creating broad-spectrum disease resistance in cereals is the combined use of biotechnology and traditional breeding methods. [ABSTRACT FROM AUTHOR]

Background: Powdery mildew (caused by Blumeria graminis f. sp. tritici (Bgt)) and leaf rust (caused by Puccinia triticina (Pt)) are prevalent diseases in wheat (Triticum aestivum L.) production. Thinopyrum ponticum (2n = 10x = 70, EeEeEbEbExExStStStSt) contains genes that confer high levels of resistance to these diseases. Results: An elite wheat-Th. ponticum disomic substitution line, DS5Ag(5D), was developed in the Bainong Aikang 58 (AK58) background. The line was assessed using genomic in situ hybridization (GISH), oligo-nucleotide probe multiplex (ONPM) fluorescence in situ hybridization (FISH), and molecular markers. Twenty eight chromosome-specific molecular markers were identified for the alien chromosome, and 22 of them were co-dominant. Additionally, SNP markers from the wheat 660 K SNP chip were utilized to confirm chromosome identification and they provide molecular tools for tagging the chromosome in concern. The substitution line demonstrated high levels of resistance to powdery mildew throughout its growth period and to leaf rust at the adult stage. Based on the resistance evaluation of five F5 populations between the substitution lines and wheat genotypes with different levels of sensitivity to the two diseases. Results showed that the resistance genes located on 5Ag confered stable resistance against both diseases across different backgrounds. Resistance spectrum analysis combined with diagnostic marker detection of known resistance genes of Th. ponticum revealed that 5Ag contained two novel genes, Pm5Ag and Lr5Ag, which conferred resistance to powdery mildew and leaf rust, respectively. Conclusions: In this study, a novel wheat-Th. ponticum disomic substitution line DS5Ag(5D) was successfully developed. The Th. ponticum chromosome 5Ag contain new resistance genes for powdery mildew and leaf rust. Chromosomic—specific molecular markers were generated and they can be used to track the 5Ag chromosome fragments. Consequently, this study provides new elite germplasm resources and molecular markers to facilitate the breeding of wheat varieties that is resistant to powdery mildew and leaf rust. [ABSTRACT FROM AUTHOR]

Background: JUB1, a NAC domain containing hydrogen peroxide-induced transcription factor, plays a critical role in plant immunity. Little is known about how JUB1 responds to leaf rust disease in wheat. Recent discoveries in genomics have also unveiled a multitude of sORFs often assumed to be non-functional, to argue for the necessity of including them as potential regulatory players of translation. However, whether methylation on sORFs spanning the 3'UTR of regulatory genes like JUB1 modulate gene expression, remains unclear. Methods and results: In this study, we identified the methylation states of two sORFs in 3'UTR of a homologous gene of JUB1 in wheat, TaJUB1-L, at cytosine residues in CpG, CHH and CHG sites at different time points of disease progression in two near-isogenic lines of wheat (HD2329), with and without Lr24 gene during leaf rust pathogenesis. Here, we report a significant demethylation of the CpG dinucleotides occurring in the sORFs of the 3'UTR in the resistant isolines after 24 h post-infection. Also, the up-regulated gene expression observed through RT-qPCR was directly proportional to the demethylation of the CpG sites in the sORFs. Conclusions: Our findings indicate that TaJUB1-L might be a positive regulator in providing tolerance during leaf rust pathogenesis and cytosine methylation at 3'UTR might act as a switch for its expression control. These results enrich the potential benefit of conventional methylation assay techniques for unraveling the unexplored enigma in epigenetics during plant-pathogen interaction in a cost-effective and confidentially conclusive manner. [ABSTRACT FROM AUTHOR]

Wheat is one of the most significant food security crops in Ethiopia. However, the production and productivity of wheat is far below its potential due to many challenges. Wheat disease epidemics, typified by wheat rusts, are among the most important challenges, causing large‐scale production losses that put farmers' income and food security at risk. We analysed and presented the long‐term and comprehensive wheat rust surveillance results to better understand the past rust disease occurrences, ultimately contributing to future wheat production and rust control strategies. A total of 1140 wheat fields have been surveyed from 2009 to 2021 throughout four administrative zones of the North Western Amhara region. We identified spatial and temporal trends in the distribution and status of wheat stem rust (Sr), yellow rust (Yr) and leaf rust (Lr) using a combination of different statistical tools and data‐analysis methods. The results of the study indicated that 52.5%, 11.3% and 3.4% of the wheat fields were infected with yellow, stem and leaf rust, respectively. Even so, the distribution and intensity of wheat rust disease vary across locations, elevations and cultivated varieties. The associations between altitude and disease prevalence show a linear correlation. We also identified hotspots of yellow and stem rust, which will be used by the country's wheat rust disease early warning system. In order to reverse low varietal diversification in the farmer's field, it is necessary to work with all stakeholders involved in the wheat production sector in a better synergy. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between yield, thousand kernel weight (TKW), and crude protein of soft white winter wheat–club variety (Barbee) and soft white winter wheat common variety (Zvezdana) susceptible to leaf rust and powdery mildew under different cultivation practices. Results revealed divergence in associations between yield, TKW, and crude protein loss of winter wheat varieties susceptible to obligate pathogens. Under the same level of leaf rust infection, N-input limited yield loss of the two varieties but not to the same extent. TKW loss was affected only by variety×cultivation practice and was significantly correlated with yield loss (r = −0.727, p = 0.011) and crude protein loss (r = −0.600, p = 0.05) only in club winter wheat. We suspected that Ninput affects the difference in the relationship between yield and TKW loss among varieties. Crude protein and yield loss had a low association (R2 = 18%, p = 0.05). Finally, this study indicated that more attention should be paid to the determination of pathogen pressure that triggers yield loss. It also pointed out that yield, TKW, and crude protein response to fungicides could differ in susceptible varieties. The contribution of fungicide to yield enhancement was highly associated with the specific reaction of the variety to pathogen infection rather than solely the disease level itself. [ABSTRACT FROM AUTHOR]

Leaf rust, caused by Puccinia triticina, is a major cause of wheat yield losses globally, and novel leaf rust resistance genes are needed to enhance wheat leaf rust resistance. Teremai Bugdai is a landrace from Uzebekistan that is highly resistant to many races of P. triticina in the United States. To unravel leaf rust resistance loci in Teremai Bugdai, a recombinant inbred line (RIL) population of Teremai Bugdai × TAM 110 was evaluated for response to P. triticina race Pt54-1 (TNBGJ) and genotyped using single nucleotide polymorphism (SNP) markers generated by genotyping-by-sequencing (GBS). Quantitative trait loci (QTL) analysis using 5,130 high-quality GBS-SNPs revealed three QTLs, QLr-Stars-2DS, QLr-Stars-6BL, and QLr. Stars-7BL, for leaf rust resistance in two experiments. QLr-Stars-2DS, which is either a new Lr2 allele or a new resistance locus, was delimited to an ~19.47-Mb interval between 46.4 and 65.9 Mb on 2DS and explained 31.3 and 33.2% of the phenotypic variance in the two experiments. QLr-Stars-6BL was mapped in an ~84.0-kb interval between 719.48 and 719.56 Mb on 6BL, accounting for 33 to 36.8% of the phenotypic variance in two experiments. QLr. Stars-7BL was placed in a 350-kb interval between 762.41 and 762.76 Mb on 7BL and explained 4.4 to 5.3% of the phenotypic variance. Nine GBS-SNPs flanking these QTLs were converted to kompetitive allele specific PCR (KASP) markers, and these markers can be used to facilitate their introgression into locally adapted wheat lines. [ABSTRACT FROM AUTHOR]

The near-isogenic lines (66) and wheat cultivars/germplasm (20) carrying known leaf rust resistance genes along with susceptible checks (BWL 4444, HD 3086 and Agra local) were evaluated against leaf rust of wheat at four different locations across Punjab, India [Ludhiana (West), Gurdaspur, Abohar, Langroya (SBS Nagar)]. The genes namely Lr9, Lr19, Lr24, Lr28, Lr42, Lr45, Lr47, Lr52, Lr57, Lr58, Lr76 were found effective in Punjab (India) against the most prevalent pathotypes of leaf rust pathogen [77-9 (121R60-1), 121R60-1,7 and 77-5 (121R63-1)]. These genes can be deployed singly or in combination for successful management of leaf rust. The disease severity was comparatively less at Abohar. So, the correlation of disease severity with environmental factors (maximum temperature, minimum temperature, relative humidity and total rainfall) were worked out and found highly significant. Strong positive correlation of disease severity with minimum temperature (0.86) followed by moderate positive correlation with rainfall (0.54) was observed. Disease severity level was higher when 25.4–28.3 °C maximum temperature; 13.8–15.7 °C minimum temperature coupled with relative humidity of 67–71% and rainfall in the range of 9–21 mm prevails during the months of February–March. [ABSTRACT FROM AUTHOR]

Cereal rust diseases, including leaf, stem, and stripe rust, are some of the most devastating and economically important diseases of barley. However, host–pathogen genetic interaction research for each pathosystem is typically conducted independently and in isolation. Examples of host resistance/susceptibility genes functioning sympathetically to multiple pathogens or antagonistically to additional pathogens have been reported. Therefore, consolidation of loci that have been reported in multiple studies and across pathosystems is useful for variety development to maximize resistance to multiple pathogens and avoid inadvertent incorporation of susceptibility loci that act antagonistically to other pathogens. This review summarizes loci reported in three key biotrophic pathosystems of barley, including leaf, stem, and stripe rust. In conjunction with previously consolidated net blotch loci, this review lays the foundation for a wider barley rust resistance/susceptibility atlas. This review aims to inform breeders and researchers in rapidly identifying accessions and loci that need further characterization and which loci would be most useful to introgress into elite varieties.

ABSTRACT The first step in trait introgression is to identify and assess novel sources of variation. For shrub willow (Salix) breeders, there is an abundance of understudied species within a genus that readily hybridizes. Breeding targets in shrub willow center on traits contributing to biomass yield for bioenergy. These include stem biomass, insect and pathogen resistance, and leaf architecture traits. More specifically, breeding for durable resistance to willow leaf rust (Melampsora spp.) is of particular importance as the pathogen can significantly reduce biomass yields in commercial production. The Salix F1 hybrid common parent population (Salix F1 HCP) was created to characterize the variation among eight species‐hybrid families and map QTL for targeted traits. A female and male S. purpurea were used as common parents in crosses made to male S. suchowensis, S. viminalis, S. koriyanagi, and S. udensis and female S. viminalis, S. integra, S. suchowensis to produce eight families that were planted in field trials at Cornell AgriTech in Geneva, NY and phenotyped. Using 16 previously described parental backcross linkage maps and two newly generated S. purpurea consensus maps, we identified 215 QTL across all eight families and in every parent. These included 15 leaf rust severity, 61 herbivory, 65 leaf architecture, and 74 yield component QTL, resulting in 50 unique overlapping regions within the population. These genetic loci serve as an important foundation for future shrub willow breeding, and each interspecific family was identified as a novel source of useful alleles for trait introgression into high yielding cultivars.

Leaf rust caused by Puccinia triticina (Pt) is one of the most dangerous diseases causing significant losses in common wheat crops. In adult plants resistant to rust, a horizontal adult plant resistance (APR) type is observed, which protects the plant against multiple pathogen races and is distinguished by greater persistence under production conditions. Crucial pleiotropic slow-rust genes such as Lr34, Lr46, Lr67, and Lr68, in combination with other genes of lesser influence, continue to increase durable resistance to rust diseases. Based on our previous results, we selected four candidate genes for Lr46 out of ten candidates and analysed them for expression before and after inoculation by P. triticina. As part of our study, we also investigated the expression patterns of miRNA molecules complementary to Lr34 and the candidate genes. The aim of the study was to analyse the expression profiles of candidate genes for the Lr46 gene and the Lr34 and Lr67 genes responsible for the differential leaf-rust resistance of hybrid forms of the F1 generation resulting from crosses between the Glenlea cultivar and cultivars from Polish breeding companies. In addition, the expression of five miRNAs (tae-miR9653b, tae-miR5384-3p, tae-miR9780, tae-miR9775 and tae-miR164), complementary to Lr34, and selected candidate genes were analysed using stem-loop RT-PCR and ddPCR. Biotic stress was induced in adult plants by inoculation with Pt fungal spores, under controlled conditions. Plant material was collected before and 6, 12, 24, and 48 h after inoculation (hpi). Differences in expression patterns of Lr34, Lr67, and candidate genes (for Lr46) were analysed by qRT-PCR and showed that gene expression changed at the analysed time points. Identification of molecular markers coupled to the Lr genes studied was also carried out to confirm the presence of these genes in wheat hybrids. qRT-PCR was used to examine the expression levels of the resistance genes. The highest expression of Lr46/Yr29 genes (Lr46-Glu2, Lr46-RLK1, Lr46-RLK2, and Lr46-RLK3) occurred at 12 and 24 hpi, and such expression profiles were obtained for only one candidate gene among the four genes analysed (Lr46-Glu2), indicating that it may be involved in resistance mechanisms of response to Pt infection.

Abstract Triticum militinae (2n = 4X = 28, AtAtGG), belonging to the secondary gene pool of wheat, is known to carry resistance to many diseases. Though some disease resistance genes were reported from T. timopheevii, the closest wild relative of T. militinae, there are no reports from T. militinae. Twenty-one T. militinae Derivatives (TMD lines) developed at the Division of Genetics, IARI, New Delhi, were evaluated for leaf and stripe rusts at seedling and adult plant stages. Eight TMD lines (6–4, 6–5, 11–6, 12–4, 12–8, 12–12, 13–7 and 13–9) showed seedling resistance to both leaf and stripe rusts while six TMD lines (7–5, 7–6, 11–5, 13–1, 13–3 and 13–4) showed seedling resistance to leaf rust but adult plant resistance to stripe rust and three TMD lines (9–1, 9–2 and 15) showed seedling resistance to leaf rust but susceptibility to stripe rust. Three TMD lines (2–7, 2–8 and 6–1) with adult plant resistance to leaf and stripe rusts were found to carry the known gene Lr34/Yr18. Ten TMD lines (7–5, 7–6, 9–1, 9–2, 11–5, 11–6, 12–12, 12–4, 12–8, and 15) with seedling resistance to leaf rust, showing absence of known genes Lr18 and Lr50 with linked markers requires further confirmation by the test of allelism studies. As not a single stripe rust resistance gene has been reported from T. militinae or its close relative T. timpopheevii, all the 8 TMD lines (6–4, 6–5, 11–6,12–4, 12–8, 12–12, 13–7 and 13–9) identified of carrying seedling resistance to stripe rust and 3 TMD lines (13–1, 13–3 and 13–4) identified of carrying adult plant resistance to stripe rust are expected to carry unknown genes. Also, all the TMD lines were found to be cytologically stable and thus can be used in inheritance and mapping studies.

Abstract Background Foliar diseases namely late leaf spot (LLS) and leaf rust (LR) reduce yield and deteriorate fodder quality in groundnut. Also the high oleic acid content has emerged as one of the most important traits for industries and consumers due to its increased shelf life and health benefits. Results Genetic mapping combined with pooled sequencing approaches identified candidate resistance genes (LLSR1 and LLSR2 for LLS and LR1 for LR) for both foliar fungal diseases. The LLS-A02 locus housed LLSR1 gene for LLS resistance, while, LLS-A03 housed LLSR2 and LR1 genes for LLS and LR resistance, respectively. A total of 49 KASPs markers were developed from the genomic regions of important disease resistance genes, such as NBS-LRR, purple acid phosphatase, pentatricopeptide repeat-containing protein, and serine/threonine-protein phosphatase. Among the 49 KASP markers, 41 KASPs were validated successfully on a validation panel of contrasting germplasm and breeding lines. Of the 41 validated KASPs, 39 KASPs were designed for rust and LLS resistance, while two KASPs were developed using fatty acid desaturase (FAD) genes to control high oleic acid levels. These validated KASP markers have been extensively used by various groundnut breeding programs across the world which led to development of thousands of advanced breeding lines and few of them also released for commercial cultivation. Conclusion In this study, high-throughput and cost-effective KASP assays were developed, validated and successfully deployed to improve the resistance against foliar fungal diseases and oleic acid in groundnut. So far deployment of allele-specific and KASP diagnostic markers facilitated development and release of two rust- and LLS-resistant varieties and five high-oleic acid groundnut varieties in India. These validated markers provide opportunities for routine deployment in groundnut breeding programs.

Abstract. Leaf rust on wheat caused by P. triticina is the most widespread fungal disease worldwide and in Bulgaria. The development of wheat genotypes resistant to leaf rust is related to the different types of resistance and ways of gene inheritance. The different varieties have different susceptibility during the different stages of their ontogenetic development. The study of the initial material is an important step in the breeding for resistance and it is an ongoing process. Two hundred and forty-six breeding lines were tested against the local population of P. triticina during 2015-2017, under conditions of infection field and in a greenhouse at Dobrudzha Agricultural Institute – General Toshevo, Bulgaria. Twenty lines were selected, which demonstrated different degrees of resistance under infection field conditions and which showed resistance to some of the seven pathotypes used in the study. The identification of the pathotypes was based on the type of reaction of 20 monogenic lines. The reaction of isogenic lines was compared with the reaction of the selection lines and the results showed that the reaction of line 165/05-46 corresponded to isogenic lines carrying genes Lr 9, Lr 19 and Lr 25. The response of the other 3 lines (245/03-72, 13/04-97, 14/06-110) partially coincided with the response of the above mentioned genes. The reaction of the other 3 lines (169/05-69, 14/06-81, 8/08-25) partially coincided with the reaction of isogenic lines carrying genes Lr 2a, Lr 28 and Lr 29. It was determined that seven of the lines were carriers of a race-specific gene and that it was necessary to subject these lines to further breeding and genetic studies to determine presence of race-specific resistance. Five of the lines (72/05-53, 61/03-75, 106/04-189, 268/03-151, 79/04-131) combined incomplete resistance at young stage with resistance at adult stage. Four of the tested lines (68/06-78, 29/02-133-38, 79/04-125-28, 197/05-33) exhibited typical race non-specific resistance or APR. Four lines (13/04-165, 14/05-119, 19/06-79 and 61/03-81) demonstrated “slow rusting” type of resistance. Twenty of the studied lines were carriers of effective resistance and can be included in the breeding programs as donors of resistance to P. triticina.

The F-box proteins in fungi perform diverse functions including regulation of cell cycle, circadian clock, development, signal transduction and nutrient sensing. Genome-wide analysis revealed 10 F-box genes in Puccinia triticina, the causal organism for the leaf rust disease in wheat and were characterized using in silico approaches for revealing phylogenetic relationships, gene structures, gene ontology, protein properties, sequence analysis and gene expression studies. Domain analysis predicted functional domains like WD40 and LRR at C-terminus along with the obvious presence of F-box motif in N-terminus. MSA showed amino acid replacements, which might be due to nucleotide substitution during replication. Phylogenetic analysis revealed the F-box proteins with similar domains to be clustered together while some sequences were spread out in different clades, which might be due to functional diversity. The clustering of Puccinia triticina GG705409 with Triticum aestivum TaAFB4/TaAFB5 in a single clade suggested the possibilities of horizontal gene transfer during the coevolution of P. triticina and wheat. Gene ontological annotation categorized them into three classes and were functionally involved in protein degradation through the protein ubiquitination pathway. Protein–protein interaction network revealed F-box proteins to interact with other components of the SCF complex involved in protein ubiquitination. Relative expression analysis of five F-box genes in a time course experiment denoted their involvement in leaf rust susceptible wheat plants. This study provides information on structure elucidation of F-box proteins of a basidiomycetes plant pathogenic fungi and their role during pathogenesis. [ABSTRACT FROM AUTHOR]

Leaf rust, caused by Puccinia triticina (Pt), is a major disease of wheat and a significant problem for wheat production in Brazil. The Brazilian variety Toropi, released in 1965, has maintained high levels of field, adult plant resistance (APR) to leaf rust across global locations, while microscopic studies have indicated prehaustorial resistance mechanisms. Analyses of gene expression in flag leaves of Toropi, during the early stages of Pt infection, were undertaken to explore the mechanisms behind the APR in Toropi. Differential expression of wheat genes was undertaken, comparing Pt‐ to mock‐inoculated and Pt‐ to Pt‐inoculated time points. Analysis of gene expression indicated a strong response to Pt, which was fully active by 6 h after inoculation (hai). More genes were downregulated than upregulated, particularly at 6 and 12 hai. Gene Ontology enrichment analysis indicated a shutting down of RNA and protein synthesis and an early effect on photosynthesis, with disruption of the electron transfer chain. Analyses of upregulated genes identified genes involved in ATP‐binding and protein kinase activity at 6 hai, supporting a rapid metabolic response to Pt infection. A general upregulation of genes involved in transport and metabolism indicated the need to relocate protein and organic‐based resources. Alignment of differentially expressed genes with the genomic regions defining four leaf rust APR quantitative trait loci (QTLs) in Toropi identified candidate resistance genes, including a sugar transporter, a receptor kinase and a seven‐transmembrane MLO family protein. In addition, 60 Pt genes were identified, 11 being annotated as potential effector proteins. [ABSTRACT FROM AUTHOR]

Leaf rust caused by the pathogen Puccinia triticina (Pt) is a destructive fungal disease of wheat that occurs in almost all wheat-growing areas across the globe. Genetic resistance has proven to be the best solution to mitigate the disease. Wheat breeders are continuously seeking new diversified and durable sources of resistance to use in developing new varieties. We developed recombinant inbred line (RIL) populations from two leaf rust-resistant genotypes (Kenya Kudu and AUS12568) introduced from Kenya to identify and characterize resistance to Pt and to develop markers linked closely to the resistance that was found. Our studies detected four QTL conferring adult plant resistance (APR) to leaf rust. Two of these loci are associated with known genes, Lr46 and Lr68, residing on chromosomes 1B and 7B, respectively. The remaining two, QLrKK_2B and QLrAus12568_5A, contributed by Kenya Kudu and AUS12568 respectively, are putatively new loci for Pt resistance. Both QLrKK_2B and QLrAus12568_5A were found to interact additively with Lr46 in significantly reducing the disease severity at adult plant growth stages in the field. We further developed a suite of six closely linked markers within the QLrAus12568_5A locus and four within the QLrKK_2B region. Among these, markers sunKASP_522 and sunKASP_524, flanking QLrAus12568_5A, and sunKASP_536, distal to QLrKK_2B, were identified as the most closely linked and reliable for marker-assisted selection. The markers were validated on a selection of 64 Australian wheat varieties and found to be polymorphic and robust, allowing for clear allelic discrimination. The identified new loci and linked molecular markers will enable rapid adoption by breeders in developing wheat varieties carrying diversified and durable resistance to leaf rust. [ABSTRACT FROM AUTHOR]

Leaf rust and net blotch are two important fungal diseases of barley. Leaf rust is the most important rust disease of barley, whereas net blotch can result in significant yield losses and cause the deterioration of crop quality. The best and the most environmentally friendly method to control diseases is to cultivate resistant varieties. The aim of the current study was to identify barley varieties with an improved resistance to leaf rust and net blotch in Polish organic post-registration trials conducted in the years 2020–2022. For this purpose, the cumulative link mixed model with several variance components was applied to model resistance to leaf rust and net blotch. It was found that the reference variety Radek was the most resistant to leaf rust, whereas variety Avatar outperformed the reference variety in terms of resistance to net blotch, although the difference between the two varieties was non-significant. In the present study, the use of the cumulative link mixed model framework made it possible to calculate cumulative probabilities or the probability of a given score for each variety and disease, which might be useful for plant breeders and crop experts. Both, the method of analysis and resistant varieties may be used in the breeding process to derive new resistant varieties suitable for the organic farming system. [ABSTRACT FROM AUTHOR]

Background: Foliar diseases namely late leaf spot (LLS) and leaf rust (LR) reduce yield and deteriorate fodder quality in groundnut. Also the high oleic acid content has emerged as one of the most important traits for industries and consumers due to its increased shelf life and health benefits. Results: Genetic mapping combined with pooled sequencing approaches identified candidate resistance genes (LLSR1 and LLSR2 for LLS and LR1 for LR) for both foliar fungal diseases. The LLS-A02 locus housed LLSR1 gene for LLS resistance, while, LLS-A03 housed LLSR2 and LR1 genes for LLS and LR resistance, respectively. A total of 49 KASPs markers were developed from the genomic regions of important disease resistance genes, such as NBS-LRR, purple acid phosphatase, pentatricopeptide repeat-containing protein, and serine/threonine-protein phosphatase. Among the 49 KASP markers, 41 KASPs were validated successfully on a validation panel of contrasting germplasm and breeding lines. Of the 41 validated KASPs, 39 KASPs were designed for rust and LLS resistance, while two KASPs were developed using fatty acid desaturase (FAD) genes to control high oleic acid levels. These validated KASP markers have been extensively used by various groundnut breeding programs across the world which led to development of thousands of advanced breeding lines and few of them also released for commercial cultivation. Conclusion: In this study, high-throughput and cost-effective KASP assays were developed, validated and successfully deployed to improve the resistance against foliar fungal diseases and oleic acid in groundnut. So far deployment of allele-specific and KASP diagnostic markers facilitated development and release of two rust- and LLS-resistant varieties and five high-oleic acid groundnut varieties in India. These validated markers provide opportunities for routine deployment in groundnut breeding programs. [ABSTRACT FROM AUTHOR]

Triticum militinae (2n = 4X = 28, AtAtGG), belonging to the secondary gene pool of wheat, is known to carry resistance to many diseases. Though some disease resistance genes were reported from T. timopheevii, the closest wild relative of T. militinae, there are no reports from T. militinae. Twenty-one T. militinae Derivatives (TMD lines) developed at the Division of Genetics, IARI, New Delhi, were evaluated for leaf and stripe rusts at seedling and adult plant stages. Eight TMD lines (6–4, 6–5, 11–6, 12–4, 12–8, 12–12, 13–7 and 13–9) showed seedling resistance to both leaf and stripe rusts while six TMD lines (7–5, 7–6, 11–5, 13–1, 13–3 and 13–4) showed seedling resistance to leaf rust but adult plant resistance to stripe rust and three TMD lines (9–1, 9–2 and 15) showed seedling resistance to leaf rust but susceptibility to stripe rust. Three TMD lines (2–7, 2–8 and 6–1) with adult plant resistance to leaf and stripe rusts were found to carry the known gene Lr34/Yr18. Ten TMD lines (7–5, 7–6, 9–1, 9–2, 11–5, 11–6, 12–12, 12–4, 12–8, and 15) with seedling resistance to leaf rust, showing absence of known genes Lr18 and Lr50 with linked markers requires further confirmation by the test of allelism studies. As not a single stripe rust resistance gene has been reported from T. militinae or its close relative T. timpopheevii, all the 8 TMD lines (6–4, 6–5, 11–6,12–4, 12–8, 12–12, 13–7 and 13–9) identified of carrying seedling resistance to stripe rust and 3 TMD lines (13–1, 13–3 and 13–4) identified of carrying adult plant resistance to stripe rust are expected to carry unknown genes. Also, all the TMD lines were found to be cytologically stable and thus can be used in inheritance and mapping studies. [ABSTRACT FROM AUTHOR]

Background and Objectives Brown rust, or leaf rust, of wheat, caused by Puccinia triticina Eriks., is one of the most damaging diseases affecting wheat worldwide, including in Iran. Under epidemic conditions, brown rust can reduce wheat yields by 20 to 50%. This disease's impact is exacerbated by the fungus's sexual cycle and the resulting new genetic recombinations, which occur in regions where intermediate hosts are present. Additionally, the fungus's asexual cycle thrives under favorable weather conditions. The high genetic diversity and flexibility of Puccinia triticina, driven by mutation, migration, and selection pressure from host resistance genes, enable the production of new physiological races that can overcome existing genetic resistance. These new races can rapidly spread between regions via wind, increasing racial diversity in other areas' disease populations. The most reliable and fundamental method for controlling and managing brown rust is through genetic resistance. Accurate knowledge of the pathogenic population's genetic structure in each region is essential for developing effective and stable genetic resistance in wheat. This can be achieved by monitoring harmful pathogenic factors using differential genotypes of brown rust in trap nurseries. Materials and Methods The effectiveness of resistance genes in international differential cultivars of brown rust was investigated in the Moghan region of Ardabil Province, a major wheat production area in Iran, over two consecutive crop years (2022-2023). To identify resistance sources against the local races of brown rust, the responses of 40 commercial wheat varieties and 40 promising wheat lines were evaluated. Resistance was assessed at the full plant stage under natural infection conditions. Parameters measured included the coefficient of infection (CI), final disease severity (FDS), and the relative value of the area under the disease progress curve (rAUDPC). These evaluations were conducted at the research station of the Research and Training Center for Agriculture and Natural Resources of Ardabil Province (Moghan). Results The populations of brown rust races in the Moghan region varied between the two years studied. The results indicated that the pathogenic fungus population in both years was resistant to differential cultivars carrying the resistance genes Lr18, Lr19, Lr20, Lr22a, and Lr29. Thus, these genes were effective in providing resistance against brown rust pathogenic races in the Moghan region. Additionally, differential cultivars with resistance genes Lr2a, Lr2b, Lr9, Lr17, Lr21, Lr23, Lr10/Lr27/Lr31, Lr33, and Lr34 demonstrated relatively acceptable resistance to the brown rust pathogenic strains in the Ardabil region. The resistance reactions of these genotypes were race- specific, showing resistance in one year and semi-resistant to semi-sensitive reactions with 5-20% infection intensity in another year. Commercial cultivars and promising wheat lines that exhibited effective resistance and the lowest values for the measured traits were identified as sources of effective genetic resistance to the brown rust pathogenic population in the Moghan region and similar hot and humid climates in the country. These include the cultivars Sahar, Rakhshan, Shush, Farin, Sirvan, Araz, Meraj, Danesh, Talai, Sana, Aran, Tirgan, Taban, Hana, Mehrgan, Avan, Arman, Fallah, and Tektaz, as well as the lines N-95-6, N-98-8, S-95-3, S-96-15, S-96-16, S-97- 10, S-98-11, S-98-22, M-97-12, M-97-18, M-98-18, CD-91-12, C-97-4, CD-97-19, C-98-7, C-98- 8, CD-98-17, MS-92-5, MS-94-5, D-97-15, and D-97-16. Discussion Correct and conscious use of the effective resistance genes identified in this research can foster more stable resistance to brown rust. The resistance genes present in the identified resistant genotypes can be utilized in multi-breeding programs to pyramid resistance genes in desirable wheat genotypes. This approach aims to combine agricultural traits, yield, and other physiological characteristics to produce cultivars with stable resistance, which would be better equipped to combat brown rust. [ABSTRACT FROM AUTHOR]

Leaf rust on wheat caused by P. triticina is the most widespread fungal disease worldwide and in Bulgaria. The development of wheat genotypes resistant to leaf rust is related to the different types of resistance and ways of gene inheritance. The different varieties have different susceptibility during the different stages of their ontogenetic development. The study of the initial material is an important step in the breeding for resistance and it is an ongoing process. Two hundred and forty-six breeding lines were tested against the local population of P. triticina during 2015-2017, under conditions of infection field and in a greenhouse at Dobrudzha Agricultural Institute -- General Toshevo, Bulgaria. Twenty lines were selected, which demonstrated different degrees of resistance under infection field conditions and which showed resistance to some of the seven pathotypes used in the study. The identification of the pathotypes was based on the type of reaction of 20 monogenic lines. The reaction of isogenic lines was compared with the reaction of the selection lines and the results showed that the reaction of line 165/05-46 corresponded to isogenic lines carrying genes Lr 9, Lr 19 and Lr 25. The response of the other 3 lines (245/03-72, 13/04-97, 14/06-110) partially coincided with the response of the above mentioned genes. The reaction of the other 3 lines (169/05-69, 14/06-81, 8/08-25) partially coincided with the reaction of isogenic lines carrying genes Lr 2a, Lr 28 and Lr 29. It was determined that seven of the lines were carriers of a race-specific gene and that it was necessary to subject these lines to further breeding and genetic studies to determine presence of race-specific resistance. Five of the lines (72/05-53, 61/03-75, 106/04-189, 268/03-151, 79/04-131) combined incomplete resistance at young stage with resistance at adult stage. Four of the tested lines (68/06-78, 29/02-133-38, 79/04-125-28, 197/05-33) exhibited typical race non-specific resistance or APR. Four lines (13/04-165, 14/05-119, 19/06-79 and 61/03-81) demonstrated "slow rusting" type of resistance. Twenty of the studied lines were carriers of effective resistance and can be included in the breeding programs as donors of resistance to P. triticina. [ABSTRACT FROM AUTHOR]

The prevalence of wheat leaf rust has increased in recent years due to global climate change conditions. The disease spreads in warm and humid areas in the north and south regions of Iran, causing damage to the susceptible cultivars. Plant germplasms in each country hold rich reserves of resistance genes that influence biotic and abiotic stress. In this study, 100 germplasms of Iranian bread wheat which had previously shown resistance to stem rust, 10 cultivars commonly grown in Iran and two susceptible cultivars, Bolani and Morocco, were selected for greenhouse and field experiments. Greenhouse experiments were conducted to evaluate the performance of a pure isolate from the northern region of the country. The greenhouse experiment followed a completely randomized design, while the field experiment was conducted on the IraqiMahalleh farm in Golestan province using an augmented experimental design. The Bolani and Morocco cultivars showed over 90% infection in the field and 4 scales in the greenhouse. The results indicate that 24.7% of the accessions and cultivars were resistant in both the greenhouse and the field. In addition, 38.1% of the accessions and cultivars were susceptible in the greenhouse but resistant in the field. Conversely, 2.9% were resistant in the greenhouse but, susceptible in the field. Finally, 34.3% exhibited susceptibility in both the greenhouse and the field. The wheat germplasms that were resistant in both conditions and those showing susceptibility in the greenhouse but, resistance in the field were selected for further investigations in developing resistant cultivars. [ABSTRACT FROM AUTHOR]

The present study was carried out at the Plant Pathology Hafizabad Research Station, the University of Layyah, during the crop seasons 2021–2022 and 2022–2023 to evaluate the response of various wheat genotypes against leaf rust severity (%), environmental conditions favourable for disease development and grain yield. Except for minimum temperature and minimum relative humidity, which had a negative association with disease development, there was a significant correlation between leaf rust severity (%) and all environmental conditions such as maximum temperature, maximum relative humidity, rainfall, and wind speed. All epidemiological variables such as maximum temperature, minimum temperature, minimum relative humidity, rainfall and wind speed significantly affect the disease progression. The disease predictive model accounted for 48–69 % variability in leaf rust severity. The model performance was evaluated using the coefficient of determination (R2 = 0.69) and RMSE, both demonstrated acceptable predictive results for leaf rust severity (%) management. Leaf rust severity (%) increased with an increase in maximum temperature (17.8–30 °C), maximum relative humidity (76.3–85 %), rainfall (2.2–10.85 mm) and wind speed 1.1–2.7 km/h and decreased with the increase of minimum temperature (7.91–16.71 °C) minimum relative humidity (47.15–56.45 %) during both rating seasons 2021–2022 and 2022–2023. The single and two applications of fungicides at the Zadok's scale 3, ZS 4.3, and ZS 5.4 stages led to a significant reduction in grain yield losses caused by leaf rust severity (%) in both the 2021–2022 and 2022–2023 crop seasons. Single and two sprays of prothioconazole, were found to be the first choice among all treatments to reduce the disease severity and increase grain production and maximum gross revenue (513.1–777.8$/ha), as compared to followed by single and two sprays of propiconazole (Progress), tebuconazole + trifloxystrobin, tebuconazole, bixafen + tebuconazole, and propiconazole (Tilt), respectively. These findings recommend the involvement of genotype resistance and weather predictors in wheat leaf rust development, along with fungicide application studies, to improve the predictability of host resistance to disease, future models, and the sustainability of disease control methods.

Aim. To study resistance to leaf, yellow and stem rusts of winter and spring wheat and winter triticale samples from the collection of the N. I. Vavilov All‐Russian Institute of Plant Genetic Resources (VIR) and breeding centres of southern Russia in different phases of ontogenesis and to identify new sources with group resistance. Material and Methods. The resistance of 158 wheat and triticale samples from the VIR collection and southern breeding centres to populations of leaf, stem and yellow rusts in different plant growth stages was analysed. In the juvenile phase the samples studied were inoculated with populations of rust fungi in climate chambers of the Federal Research Centre of Biological Plant Protection and the type of plant reaction to lesions was noted. In field conditions the samples were evaluated according to the CIMMYT scale on an artificial infectious background. Results. In the adult plant stage under field conditions 79 wheat and triticale samples with group resistance to leaf, yellow and stem rusts were identified, and in the juvenile stage 26 samples. 22 samples showed resistance to three rusts in both phases of ontogenesis. Of these, 5 samples belong to the VIR collection, 3 winter triticale varieties (Dozor, Knyaz, Svat) and the Kavalerka wheat variety selection of the P.P. Lukyanenko National Grain Centre, 9 lines from the Donskoy Agrarian Research Centre and the Federal Rostov Agrarian Research Centre, and 4 winter triticale varieties (Ataman Platov, Zimogor, Kapral, Legion) of selections of the Federal Rostov Agrarian Research Centre. Conclusion. The samples of wheat and winter triticale with group resistance which have been identified are promising for use in breeding for immunity to rust diseases.

In Indonesia, coffee is one of the plantation products with a relatively high level of productivity and is a source of foreign exchange income for the country. However, unfortunately, certain factors can threaten productivity and quality in cultivating coffee plants, one of which is rust leaf disease. This disease causes disturbances in photosynthesis, thereby reducing plant yields. Therefore, to maintain and control productivity in coffee cultivation, this research carried out the process of observing coffee leaf images through segmentation using the Otsu Thresholding and Mean Denoising methods. The entire series of processes in this research was carried out using the Python programming language and succeeded in providing output in the form of image comparisons showing areas affected by Rust Leaf disease using the Otsu thresholding method alone and the Otsu thresholding method combined with a non-local means denoising algorithm. The test results prove that the Otsu thresholding method with the non-local means denoising algorithm has a smaller MSE value. It is the most optimal method for handling coffee leaf disease image segmentation with an accuracy level of 88%. It is hoped that this research can support farmers in providing insight into early detection of coffee plant diseases and increasing productivity through visual analysis.

The relationship between a variety’s genotype, environmental conditions and phytopathogenic load are the key factors contributing to high yields that should be taken into account in selecting donors for resistance and high manifestation of valuable traits. The study of leaf rust resistance in 49 common wheat varieties was carried out in the field against the natural pathogen background and under laboratory conditions using single-pustule isolates with virulence to Lr9 and Lr24. It has been shown that the varieties carrying alien genes Lr6Agi2 (Tulaikovskaya 10) and Lr6Agi1 (Voevoda) were resistant to leaf rust infection both in the field and in the laboratory. Varieties KWS Buran, KWS Akvilon, KW 240-3-13, and Etyud producing crop yields from 417 to 514 g/m2 comparable to the best standard variety Sibirskaya 17 can be reasonably used as Lr24 resistance gene donors under West Siberian conditions. Oms kaya 44 variety showing crop yield of 440g/m2 can be used as a donor for Lr19 and partially effective Lr26. Varieties Tuleevskaya and Altayskaya 110 with Lr9 in their genomes are recommended for the development of resistance gene-pyramided genotypes. The highest protein and gluten contents were observed in the CS2A/2M sample, while KWS Buran, Altayskaya 110, Volgouralskaya, and KWS Akvilon showed the lowest values. Varieties CS2A/2M, Tulaikovskaya 10, Pavon, and Tuleevskaya were ranked the highest in micro- (Cu, Mn, Zn, Fe) and macronutrient (Ca, Mg, K) contents among the common wheat samples from the collection, while the lowest values for most elements were observed in KWS Buran, Novosibirskaya 15, and Volgouralskaya. Winter varieties demonstrating leaf rust resistance against the infectious background typically carry adult plant resistance genes (Lr34, Lr12, and Lr13), particularly combined with the juvenile Lr26 gene. The presence of Lr41 in a winter type line (KS 93 U 62) allowed it to maintain resistance against a leaf rust pathogen clone kLr24, despite the presence of Lr24 in the genotype. Varieties Doka and Cheshskaya 17 may act as donors of resistance genes Lr26 + Lr34 and Lr9 + Lr12 + Lr13 + Lr34, as well as sources of dwarfing without losses in winter hardiness and yield under West Siberian conditions.

Wheat leaf rust, caused by Puccinia triticina, poses a growing threat to global wheat production, necessitating alternative strategies for effective disease management. This study investigated the potential of gamma-aminobutyric acid (GABA) to enhance resistance to leaf rust in two wheat cultivars: the susceptible Morocco and moderately resistant Sakha 94 cultivar. Our findings revealed that GABA significantly improved resistance in both cultivars to P. triticina, particularly in Morocco, by mitigating disease severity and reducing pustule density and size while extending both incubation and latent periods. This study assessed the effectiveness of two GABA application methods: plants received 1 mM GABA treatment, as a foliar spray, twenty-four hours prior to infection (pre-GABA), and plants received 1 mM GABA treatment both 24 h before and after infection (pre-/post-GABA), with the latter yielding significantly better results in reducing infection severity and improving plant resilience. Additionally, GABA application influenced stomatal behavior, promoting closure that may enhance resilience against leaf rust. GABA application on plants also modulated the production of reactive oxygen species (ROS). This led to a stronger oxidative burst in both susceptible and moderately resistant cultivars. GABA increased O2●− levels in guard cells and surrounding stomata, enhancing stomatal closure and the hypersensitive response. GABA enhanced the accumulation of soluble phenols and increased the activity of key antioxidant enzymes, catalase (CAT) and peroxidase (POX), which are vital for managing oxidative stress. To the best of our knowledge, this investigation represents the first report into the impact of GABA on wheat leaf rust disease.

Wheat leaf rust, caused by Puccinia triticina, is reported annually in southern Russia, the main wheat production region in Russia. The effect of biotic (types of cultivar resistance) and abiotic (northern, central and southern agro‐ecological zones) factors on virulence variability of the pathogen was analysed with 43 Lr differentials. Virulence frequencies to Lr genes 1, 2c, 3, 3bg, 11, 14a, 14b, 16, 17, 18, 23, 25, 26, 33, 34, 40 and Kanr exceeded 50% in all populations. A total of 81 virulence phenotypes (based on the standard set of 20 differentials) were identified among 108 isolates. The most common phenotypes were PHSTQ, THTTR, PHTTR and TKTTR. The minimum genetic distance (the highest similarity) was established between the P. triticina populations from susceptible cv. Krasnodarskaya 99 and cv. Brigada with race‐specific resistance. P. triticina populations from the susceptible cultivar in the three agro‐ecological zones were less variable and more similar than the cultivar‐specific and natural pathogen populations. Resistance types of host cultivars seem to have a greater effect on the pathogen population than abiotic factors. Nevertheless, abiotic factors need to be considered when making decisions about deployment of wheat varieties. Our results support the paradigm of a shift in the population of an obligate parasite towards increased virulence in response to the selection pressure of cultivars with race‐specific resistance. [ABSTRACT FROM AUTHOR]

Leaf rust caused by Puccinia triticina Eriks. is a serious threat to wheat production worldwide. Exploiting wild relatives can effectively help to improve the genetic resistance of wheat against rust. This study aimed to evaluate the responses of 34 Aegilops triuncialis accessions to seven Pt pathotypes and to analyse expression of genes associated with resistance at the seedling stage. Following multipathotype testing, two accessions with contrasting resistance were analysed at 0, 6, 12 and 24 h post‐inoculation for the expression profile of genes related to PR1, PR2, PR4, PR9, phenylalanine ammonia‐lyase and ATP‐binding cassette transporter. Of the accessions tested, eight showed high infection types of "3" to at least one Pt pathotype, while the remaining accessions had low ITs ("0;=" to "2+") against all pathotypes. The relative expressions of all candidate genes increased at all‐time points, but the expression level in the incompatible interaction was significantly higher than that of the compatible. The close relationship between PR proteins, PAL, salicylic acid‐ and jasmonic acid‐responsive proteins, as well as the proteins involved in the production of reactive oxygen species and lignin, could point to the specific recognition of the pathogen followed by the timely and intense induction of the expression of PR genes as the main reasons for resistance in incompatible interaction. In conclusion, the present study identified potentially new sources of resistance in this Ae. triuncialis population, which can be exploited in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Rust fungi are devastating plant pathogens, and several Puccinia species have exerting substantial financial impacts on global barley cultivation. Fungicides are used on a large scale as an effective method for combating phytopathogenic fungi. The negative environmental impacts of fungicides are steadily escalating on a daily basis. Consequently, researchers are currently exploring alternative approaches to mitigate the use of fungicides, such as the utilization of plant extracts. This method has proven effective due to its incorporation of natural antifungal substances. Among the nine natural elicitors that were tested, the application of plant extracts on barley seedlings resulted in an increase in the incubation and latent periods of Puccinia hordei. These periods are integral components of partial and induced resistance, effectively mitigating the incidence of barley leaf rust disease by over 70% on mature plants. Similarly, the biochemical analyses demonstrated a notable augmentation in all the tested treatments' overall phenolics and oxidative enzyme activities (peroxidase and polyphenol oxidase). Random amplified polymorphic DNA (SCoT) test serves as a viable approach for assessing the impact of plant extracts and microorganisms on barley plants. The results obtained from this study indicate that the detection of DNA polymorphism through SCoT analysis holds a significant potential powerful tool to evaluate genetic changes compared with untreated plants although some of them tested displayed high similarities at the morphological reaction. [ABSTRACT FROM AUTHOR]

Cereal rust is one of the most damaging diseases of small-grain cereals. The fungus Puccinia hordei causes leaf rust in barley and other small grain crops. Puccinia hordei causes serious yield losses in the cultivating areas where susceptible and late-maturing barley varieties are cultivated. Therefore, rust-resistant barley cultivar is highly demandable for sustainable small-grain crop production. Improving barley yields and quality is one of the major objectives of barley breeding programs in our country. Exotic and indigenous germplasm is one of the best sources of resistance to biotic stresses in barley particularly leaf rust caused by Puccinia hordei. Hence, the present investigation was carried out to identify the resistance sources to P. hordei and incorporate them into the breeding programs for higher barley yields under changing climatic scenarios. The study aimed to identify new resistant cultivars in barley and other small grain crops. In this study, 100 barley genotypes (Hordeum vulgare L.) were considered for screening susceptibility to P. hordei causing rust disease. Several biochemical responses were analyzed in P. hordei infected barley genotypes. However, the variable response was observed among the 100 barley genotypes while those were screened against leaf rust disease under high altitude cold arid conditions of Ladakh, India. The efficiency of the 100 barley genotypes were categorized into different classes including high resistance (4 genotypes)>resistance (14 genotypes)> moderately resistance (20 genotypes)> moderately susceptible (33 genotypes)>moderately susceptible to susceptible (19 genotypes)> and susceptible (10 genotypes) based on plant response to P. hordei. Among the total genotypes, SHEIKH/KP-706, SHEIKH-B1, SHEIKH-636, and IC-062190 showed high resistance (8.07-8.63) as per the international leaf rust scale, while EC-667381, EC-667390, EC-667392, EC667396, EC-667417, Jyoti, EC-667434, EC-667442, EC-667445, and EC-667446 were found as susceptible (3.13-3.97) to P. hordei. The highly resistant genotypes accumulated a high level of phenols and flavonoids and cooperated with susceptible and other rest of the genotypes in response to P. hordei rust. The efficiency of plant immune response and or fitness to P. hordei was correlated to the disease susceptibility index of particular genotypes. This provides a new insight and the mechanistic basis of genotype-specific rust disease susceptibility against P. hordei. A large number of genotype-based studies at the field level could be useful to plant breeders and farmers for improving rust resistance in barley and other small-grain cereals. [ABSTRACT FROM AUTHOR]

Leaf rust (also called Brown rust) caused by Puccinia triticina Eriks severely reduces the grain yield of bread wheat and causes huge economic losses globally. Identification and development of wheat genotypes having resistance is only durable and ecofriendly solution to combat this devastating disease. Therefore, characterization of the 101 diverse panel of wheat genotypes was done to assess the resistance and diversity against leaf rust based on morphological parameters under natural field conditions. Field trials were conducted under Augmented Design during the two cropping seasons 2020-21 and 2021-22. Out of 101 genotypes, 09 genotypes (G10, G20, G28, G35, G55, G59, G69, G81 and G90) were found to be completely resistant, 63 genotypes were moderately resistant, 17 genotypes were moderately-susceptible to susceptible and 06 genotypes were susceptible to leaf rust. Ninety genotypes had Coefficient of Infection (CI) value between 0 and 20 exhibiting high resistance, 05 genotypes had CI value 21–40 and 06 genotypes had 41–100 CI value indicating moderate and low resistance respectively. Correlation analysis revealed that leaf rust significantly reduced the growth and yield of studied genotypes because the CI showed highly significant negative correlation with Spike Length (SL), Flag Leaf Area (FLA), Chlorophyll content index (CC), Spikelet per Spike (SS), Grain yield per Spike (GYS) and Thousand Grain Weight (TGW). The principal component analysis (PCA) showed that out of ten, three PCs had Eigenvalues greater than 01 which thus being significant contributed 53.84% of variations. Cluster analysis classified 101 genotypes into eight major clusters at Euclidean distance of 0.950. [ABSTRACT FROM AUTHOR]

The two recombinant inbred line (RIL) populations developed by crossing Almaly × Avocet S (206 RILs) and Almaly × Anza (162 RILs) were used to detect the novel genomic regions associated with adult plant resistance (APR) and seedling or allstage resistance (ASR) to yellow rust (YR) and leaf rust (LR). The quantitative trait loci (QTLs) were detected through multi-year phenotypic evaluations (2018–2020) and using high-throughput DArTseq genotyping technology. RILs exhibited significant genetic variation with p < 0.001, and the coefficient of variation ranged from 9.79% to 47.99% for both LR and YR in all Environments and stages of evaluations. The heritability is quite high and ranged between 0.47 and 0.98. We identified nine stable QTLs for YR APR on chromosomes 1B, 2A, 2B, 3D, and 4D and four stable QTLs for LR APR on chromosomes 2B, 3B, 4A, and 5A. Furthermore, in silico analysis revealed that the key putative candidate genes such as cytochrome P450, protein kinase-like domain superfamily, zincbinding ribosomal protein, SANT/Myb domain, WRKY transcription factor, nucleotide sugar transporter, and NAC domain superfamily were in the QTL regions and probably involved in the regulation of host response toward pathogen infection. The stable QTLs identified in this study are useful for developing rust-resistant varieties through marker-assisted selection (MAS). [ABSTRACT FROM AUTHOR]

The research was carried out to identify varieties of winter triticale that are resistant to North Caucasian populations of brown rust and yellow leaf spot in different phases of ontogenesis. The experiments were performed in 2020–2022 in the Krasnodar krai under conditions of an artificial infectious background. The material for the study was 12 varieties of winter triticale of domestic selection. Michigan Amber varieties were used as a control for leaf rust susceptibility, and the Tanya variety was used for yellow leaf spot. The degree of damage to the control variety by leaf rust during the years of research was 80%, by yellow leaf spot in 2021 it was 55%, and in 2022 it was 60%. On average, over two years, 8% of the studied varieties were highly resistant to the pathogen of yellow leaf spot, 67% were moderately resistant and 25% were moderately susceptible and susceptible. Fifty percent of varieties were absolutely resistant to leaf rust, 17% were highly resistant, and 33% were moderately susceptible and susceptible. The varieties Arioso, Iliya, Slon and Khleborob were of particular interest since they were absolutely resistant to leaf rust (plants without signs of damage) and moderately resistant to yellow leaf spot (degree of damage from 15 to 25%). The Stewart variety also proved to be highly resistant to both pathogens (degree of damage by leaf rust was 5%, yellow spot was 10%). Varieties with group resistance are promising for cultivation in the southern region of the Russian Federation, which has favorable climatic conditions for the development of leaf rust and yellow leaf spot. [ABSTRACT FROM AUTHOR]