Search Results (26)

Net blotch, caused by Pyrenophora teres, is a major barley disease that occurs in two forms, spot form net blotch (SFNB) and net form net blotch (NFNB), reducing grain yield and quality worldwide. Accurate detection is critical for disease management and breeding resistant cultivars; however, traditional disease scoring is labour-intensive and error-prone. This study evaluates the use of UAV-based red–green–blue (RGB) and multispectral imagery, combined with machine learning, for determining net blotch infection levels at the plot scale across multiple sites and seasons in Australia. Various colour features, vegetation indices, and algorithms were tested, including a cross-domain testing for model generalisation. We propose a robust UAV-driven pipeline enabling precise disease monitoring and phenotyping in barley breeding programs. Full article

Background/Objectives: Barley (Hordeum vulgare L.) is a major cereal crop in Kazakhstan; however, its productivity is frequently constrained by foliar diseases, particularly barley scald (BS) and net blotch (NB). Understanding the genetic diversity of barley germplasm and identifying resistance-associated alleles are essential for improving disease resistance in breeding programs. The objective of this study was to assess the genetic diversity and population structure in a collection of two-rowed spring barley accessions and to identify SSR alleles associated with resistance to BS and NB. Methods: A total of 86 two-rowed spring barley accessions were genotyped using 14 SSR markers. Phenotypic evaluation for BS and NB resistance was conducted under natural infection conditions across two environments in southeastern and southern Kazakhstan. Genetic diversity and population structure were analyzed using Neighbor-Joining (NJ) clustering, Principal Coordinate Analysis (PCoA), and STRUCTURE. Marker–trait associations were evaluated using MLM method. Results: Phenotypic assessments revealed significant environment-dependent variation in disease severity for both BS and NB. Population structure analyses consistently identified distinct genetic clusters within the collection. Seven significant (p < 0.05) allele–trait associations were detected. The Bmac209 176 bp allele exhibited the strongest association with NB severity at KRIAPG. Among the identified markers, Bmag206 246 bp was uniquely associated with reduced NB infection, whereas Bmag206 252 bp, Bmag613 176 bp, and HvLEU 186 bp were linked with higher susceptibility to NB and BS. Conclusions: The identified resistance- and susceptibility-associated SSR alleles provide useful diagnostic markers for marker-assisted selection and support the potential of allele pyramiding for developing barley cultivars with combined resistance to BS and NB. This study establishes a genetic framework to enhance barley disease resistance in Central Asian breeding programs. Full article

There is an urgent demand for sustainable agricultural practices that minimize environmental impacts and reduce the reliance on synthetic pesticides and fertilizers. Endophytes represent a largely untapped resource of beneficial microorganisms with multiple potential applications as natural biocontrol agents and promoters of plant growth and development. This paper aimed at identifying new fungal strains and performing a series of preliminary in vitro screenings to evaluate their potential use for plant-growth promotion and antifungal activity. A total of 102 fungal endophytes were isolated from different plant tissues of seven wild relatives of barley (Brachypodium sylvaticum, Bromus hordeaceus, Bromus sterilis, Elymus farctus, Elymus repens, Leymus arenarius and Lolium perenne) that were sourced from 22 contrasting wild habitats. Fungal endophytes were isolated using standard culture-based methods and identified via DNA barcoding of the nrITS marker. Based on a literature search, a sub-group of endophytes were selected and evaluated for indole-3-acetic acid (IAA) synthesis, ammonia production and phosphorous (P) solubilization. From these, 15 endophytes were also tested for antifungal activity against Ramularia collo-cygni, Pyrenophora teres, and Gaeumannomyces tritici. All the endophytes were positive for ammonia production at variable rates, but no P solubilization nor IAA synthesis without L-tryptophan were observed. On the contrary, five promising isolates (2 Daldinia concentrica, Metapochonia suchlasporia, Chaetomium sp., and Ophiocordyceps sinensis) had mean pathogen growth inhibition rates above 80%, compared to the untreated negative controls. To the best of our knowledge, this study is the first published report that investigates natural antagonism against Ramularia collo-cygni and expands the list of endophytic strains with natural antagonism on the tested cereal pathogens. Results are discussed in the context of endophytes application to barley cultivation within the European regulatory framework. Full article

Net form net blotch disease, caused by Pyrenophora teres f. teres (Ptt), is one of the most destructive barley diseases, resulting in severe yield and grain quality losses worldwide. The increasing prevalence of fungicide-resistant Ptt strains, driven by the pathogen’s high genetic variability, highlights the urgent need for sustainable and eco-friendly disease management strategies. The present study provides novel insights into the use of native seed-borne endophytic bacteria naturally associated with barley as biological control agents against Ptt. Two endophytic bacterial strains isolated from healthy barley seeds were identified based on 16S rRNA gene sequencing as Bacillus subtilis PX491551 and Stenotrophomonas rhizophila PX494419. Their biocontrol potential against Ptt was evaluated through in vitro, greenhouse, and field experiments. In the dual-culture assay, B. subtilis and S. rhizophila inhibited the mycelial growth of Pyrenophora teres f. teres by 64.34% and 50.14%, respectively. Under greenhouse conditions, B. subtilis and S. rhizophila significantly reduced disease severity at the seedling stage, with scores of 2.00 and 4.00, respectively, compared to 9.33 in the untreated control. Beyond disease suppression, both endophytic bacteria markedly enhanced the host’s defense system. S. rhizophila induced the highest accumulation of total soluble phenolics, while B. subtilis significantly increased flavonoid content and boosted higher activities of superoxide dismutase and phenylalanine ammonia-lyase. In contrast, S. rhizophila showed the strongest induction of ascorbate peroxidase activity. Notably, field application of both bacteria consistently reduced net blotch severity over two consecutive growing seasons (2023–2024 and 2024–2025) and considerably improved chlorophyll content, 1000-grain weight, and grain yield. Overall, this study demonstrates that native seed-derived endophytic bacteria not only suppress barley net blotch but also enhance host antioxidant and defense responses, highlighting their potential as effective and sustainable biological control agents for barley disease management. Full article

Barley (Hordeum vulgare L.) is a major fodder crop whose productivity is often reduced by phytopathogens, especially during early growth. Understanding how soil fertility management and microbial communities influence disease outcomes is critical for developing sustainable strategies that reduce fungicide dependence and enhance crop resilience. This study evaluated the resistance of the winter barley cultivar “Zemela” to powdery mildew (Blumeria graminis f. sp. hordei), brown rust (Puccinia hordei), and net blotch (Pyrenophora teres f. maculata). The crop was cultivated under two soil management systems—green manure and conventional—and five fertilisation regimes: mineral, vermicompost, combined, biochar, and control. Phytopathological assessment was integrated with functional predictions of soil microbial communities. Field trials showed high resistance to powdery mildew (RI = 95%) and brown rust (RI = 82.5%), and moderate resistance to net blotch (RI = 60%). While ANOVA indicated no significant treatment effects (p > 0.05), PCA explained 82.3% of the variance, revealing clear clustering of microbial community functions by soil management system and highlighting the strong influence of fertilisation practices on disease-related microbial dynamics. FAPROTAX analysis suggested that organic amendments enhanced antifungal functions, whereas conventional systems were dominated by nitrogen cycling. FUNGuild identified higher saprotrophic and mycorrhizal activity under organic and combined treatments, contrasting with greater pathogen abundance in conventional plots. Overall, results demonstrate that soil fertilisation practices, together with microbial functional diversity, play a central role in disease suppression and crop resilience, supporting sustainable barley production with reduced reliance on chemical inputs. Full article

Phytopathogenic fungi represent a significant biotic stress affecting global agriculture, often causing severe diseases and, in some cases, leading to plant death. They have been isolated from economically important crops, including cereals, legumes, and fruits. Among the compounds produced by fungi, phytotoxins play a key role in disease development by interfering with host physiological processes. In this study, organic extracts from Cercospora kikuchii, Cercospora nicotianae, Cercospora sojina, Diaporthe longicolla, Septoria glycines, Pyrenophora teres, and Pyrenophora tritici-repentis, isolated from three major Argentine crops, were first screened for the in vitro production of phytotoxic metabolites. Subsequently, selected metabolites were dereplicated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) spectroscopy. The phytotoxins identified varied according to the fungal species and extraction conditions. Cercosporin, putaminoxin, scytalone, and isosclerone were identified. These findings underscore the need for further chemical investigation to comprehensively characterize the metabolome of these phytopathogens and clarify their roles in plant–pathogen interactions. Full article

Efficient early pathogen detection, before symptom apparition, is crucial for optimizing disease management. In barley, the fungal pathogen Pyrenophora teres is the causative agent of net blotch disease, which exists in two forms: P. teres f. sp. teres (Ptt), causing net-form of net blotch (NTNB), and P. teres f. sp. maculata (Ptm), responsible for spot-form of net blotch (STNB). In this study, we developed primers and a TaqMan probe to detect both Ptt and Ptm. A comprehensive k-mer based analysis was performed across a collection of P. teres genomes to identify the conserved regions that had potential as universal genetic markers. These regions were then analyzed for their prevalence and copy number across diverse Moroccan P. teres strains, using both a k-mer analysis for sequence identification and a phylogenetic assessment to establish genetic relatedness. The designed primer-probe set was successfully validated through qPCR, and early disease detection, prior to symptom development, was achieved using ddPCR. The k-mer analysis performed across the available P. teres genomes suggests the potential for these sequences to serve as universal markers for P. teres, transcending environmental variations. Full article

Pyrenophora teres f. teres (Ptt) is a severe pathogen to spring barley in Northern Europe. Ptt with relevant mutations in fungicide target proteins, sterol 14α-demethylase (CYP51A), cytochrome b (Cyt b), and succinate dehydrogenase (SDH) would put efficient disease control at risk. In the growing seasons of 2021 and 2022, 193 Ptt isolates from Estonia were analysed. In this study, mutation detection and in vitro fungicide sensitivity assays of single-spore isolates were carried out. Reduced sensitivity phenotype to mefentrifluconazole was evident in Ptt isolates with a F489L mutation in CYP51A or with 129 bp insert in the Cyp51A gene-promoter region. However, sensitivity to a prothioconazole-desthio remained high regardless of these molecular changes. The Ptt population was mostly sensitive to bixafen, fluxapyroxad, pyraclostrobin, and azoxystrobin. The sensitivity of fluxapyroxad and bixafen has been affected by two mutations, C-S135R and D-H134R, found in SDH subunits. The F129L mutation in Cyt b influenced azoxystrobin but not pyraclostrobin sensitivity. In total, 30 isolates from five fields had relevant mutations in three target protein genes simultaneously. Most of these isolates had a reduced sensitivity phenotype to mefentrifluconazole, fluxapyroxad, and azoxystrobin, while sensitivity to other tested fungicides remained high. Furthermore, possible sexual reproduction may enhance the pathogen’s fitness and help it adapt to fungicides. Full article

Pyrenophora teres f. teres (Ptt), the causal agent of net form net blotch (NFNB) disease, is an important and widespread pathogen of barley. This study aimed to quantify and characterize the virulence of Ptt isolates collected from experimental fields of barley in Hungary. Infection responses across 20 barley differentials were obtained from seedling assays of 34 Ptt isolates collected from three Hungarian breeding stations between 2008 and 2018. Twenty-eight Ptt pathotypes were identified. Correspondence analysis followed by hierarchical clustering on the principal components and host-by-pathogen GGE biplots suggested a continuous range of virulence and an absence of specific isolate × barley differential interactions. The isolates were classified into four isolate groups (IG) using agglomerative hierarchical clustering. One IG could be distinguished from other IGs based on avirulence/virulence on one to five barley differentials. Several barley differentials expressed strong resistance against multiple Ptt isolates and may be useful in the development of NFNB-resistant barley cultivars in Hungary. Our results emphasize that the previously developed international barley differential set needs to be improved and adapted to the Hungarian Ptt population. This is the first report on the pathogenic variations of Ptt in Hungary. Full article

Barley is one of the economically important crop species and the net form of net blotch (NFNB) caused by Pyrenophora teres f. teres has a significant impact on the quantity and quality of grain yield. Selection and inbreeding have resulted in a lack of genetic diversity in elite barley accessions. Old varieties often possess unique genetic traits that may have been lost in modern crop breeding. Therefore, the aim of the current study was to identify sources of resistance to barley NFNB in the collection of European old varieties. In this study, 431 European barley accessions were evaluated phenotypically under field conditions scoring APR to NFNB and genotypically using DArTseq. The range of adult plant resistance (APR) variability at the HA growth stage was sufficient to determine marker–trait associations (MTAs). The net form of net blotch at the HA stage was scored with a range of 1.0–4.0 according to a scale of 1–9, and GWAS identified 10 marker–trait associations (MTAs) for NFNB resistance. In the HA stage, two MTAs were identified on each chromosome 1H, 3H, 5H and 6H. Moreover, one was identified on the chromosome 7H and un. One of these MTA is localized on chromosome 6H, corresponding with findings from other studies, and could contribute to the exploration of genetic resistance of barley to NFNB. Additionally, the results of this study will be utilized to establish a Polish Gene Bank platform for precise breeding programs. Full article

Crop Wild Relatives (CWRs), as potential sources of new genetic variants, are being extensively studied to identify genotypes that will be able to confer resistance to biotic stresses. In this study, a collection of barley wild relatives was assessed in the field, and their phenotypic variability was evaluated using a Barley Description List, reflecting the identified ecosites. Overall, the CWRs showed significant field resistance to various fungal diseases. To further investigate their resistance, greenhouse tests were performed, revealing that several CWRs exhibited resistance against Fusarium culmorum, Pyrenophora teres, and Puccinia hordei G.H. Otth. Additionally, to characterize the genetic diversity within the collection, DNA polymorphisms at 21 loci were examined. We successfully employed barley-specific SSR markers, confirming their suitability for identifying H. spontaneum and even H. marinum, i.e., perennial species. The SSR markers efficiently clustered the investigated collection according to species and ecotypes, similarly to the phenotypic assessment. Moreover, SSR markers associated with disease resistance revealed different alleles in comparison to those found in resistant barley cultivars. Overall, our findings highlight that this evaluated collection of CWRs represents a valuable reservoir of genetic variability and resistance genes that can be effectively utilized in breeding programs. Full article

Necrotrophic fungi affect a wide range of plants and cause significant crop losses. For the activation of multi-layered innate immune defences, plants can be primed or pre-conditioned to rapidly and more efficiently counteract this pathogen. Untargeted and targeted metabolomics analyses were applied to elucidate the biochemical processes involved in the response of 3,5-dichloroanthranilic acid (3,5-DCAA) primed barley plants to Pyrenophora teres f. teres (Ptt). A susceptible barley cultivar (‘Hessekwa’) at the third leaf growth stage was treated with 3,5-DCAA 24 h prior to infection using a Ptt conidia suspension. The infection was monitored over 2, 4, and 6 days post-inoculation. For untargeted studies, ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC–MS) was used to analyse methanolic plant extracts. Acquired data were processed to generate the data matrices utilised in chemometric modelling and multi-dimensional data mining. For targeted studies, selected metabolites from the amino acids, phenolic acids, and alkaloids classes were quantified using multiple reaction monitoring (MRM) mass spectrometry. 3,5-DCAA was effective as a priming agent in delaying the onset and intensity of symptoms but could not prevent the progression of the disease. Unsupervised learning methods revealed clear differences between the sample extracts from the control plants and the infected plants. Both orthogonal projection to latent structure-discriminant analysis (OPLS-DA) and ‘shared and unique structures’ (SUS) plots allowed for the extraction of potential markers of the primed and naïve plant responses to Ptt. These include classes of organic acids, fatty acids, amino acids, phenolic acids, and derivatives and flavonoids. Among these, 5-oxo-proline and citric acid were notable as priming response-related metabolites. Metabolites from the tricarboxylic acid pathway were only discriminant in the primed plant infected with Ptt. Furthermore, the quantification of targeted metabolites revealed that hydroxycinnamic acids were significantly more prominent in the primed infected plants, especially at 2 d.p.i. Our research advances efforts to better understand regulated and reprogrammed metabolic responses that constitute defence priming in barley against Ptt. Full article

Twenty-four fungal endophytes, isolated from a wild relative of barley, Elymus repens, were screened in barley against an isolate of Fusarium culmorum and an isolate of Pyrenophora teres under controlled conditions. In all experiments, the endophytes were applied individually as seed dressings. Five endophytes could significantly reduce symptoms of Fusarium culmorum (Periconia macrospinosa E1 and E2, Epicoccum nigrum E4, Leptodontidium sp. E7 and Slopeiomyces cylindrosporus E18). In particular, treatment with Periconia macrospinosa E1 significantly reduced Fusarium symptoms on roots by 29–63% in two out of four experiments. Using, a gfp transformed isolate of P. macrospinosa E1, it was possible to show that the fungus was present on roots 14 days after sowing, coinciding with the disease scoring. To test for a potential systemic effect of the seed treatment, eight endophyte isolates were tested against the leaf pathogen Pyrenophora teres. Three isolates could significantly reduce symptoms of P. teres (Lasiosphaeriaceae sp. E10, Lindgomycetaceae sp. E13 and Leptodontidium sp. E16). Seed treatment with Lasiosphaeriaceae sp. E10 reduced net blotch leaf lesion coverage by 89%, in one out of three experiments. In conclusion, specific endophyte isolates exerted varying degrees of protection in the different experiments. Nevertheless, data suggest that endophytic strains from E. repens in a few cases are antagonistic against F. culmorum and P. teres, but otherwise remain neutral when introduced to a barley host in a controlled environment. Full article

The genus Pyrenophora includes two important cereal crop foliar pathogens and a large number of less well-known species, many of which are also grass pathogens. Only a few of these have been examined in terms of secondary metabolite production, yet even these few species have yielded a remarkable array of bioactive metabolites that include compounds produced through each of the major biosynthetic pathways. There is little overlap among species in the compounds identified. Pyrenophora tritici-repentis produces protein toxin effectors that mediate host-specific responses as well as spirocyclic lactams and at least one anthraquinone. Pyrenophora teres produces marasmine amino acid and isoquinoline derivatives involved in pathogenesis on barley as well as nonenolides with antifungal activity, while P. semeniperda produces cytochalasans and sesquiterpenoids implicated in pathogenesis on seeds as well as spirocyclic lactams with phytotoxic and antibacterial activity. Less well-known species have produced some unusual macrocyclic compounds in addition to a diverse array of anthraquinones. For the three best-studied species, in silico genome mining has predicted the existence of biosynthetic pathways for a much larger array of potentially toxic secondary metabolites than has yet been produced in culture. Most compounds identified to date have potentially useful biological activity. Full article

Wheat and barley are the main cereal crops cultivated worldwide and serve as staple food for a third of the world’s population. However, due to enormous biotic stresses, the annual production has significantly reduced by 30–70%. Recently, the accelerated use of beneficial bacteria in the control of wheat and barley pathogens has gained prominence. In this review, we synthesized information about beneficial bacteria with demonstrated protection capacity against major barley and wheat pathogens including Fusarium graminearum, Zymoseptoria tritici and Pyrenophora teres. By summarizing the general insights into molecular factors involved in plant-pathogen interactions, we show to an extent, the means by which beneficial bacteria are implicated in plant defense against wheat and barley diseases. On wheat, many Bacillus strains predominantly reduced the disease incidence of F. graminearum and Z. tritici. In contrast, on barley, the efficacy of a few Pseudomonas, Bacillus and Paraburkholderia spp. has been established against P. teres. Although several modes of action were described for these strains, we have highlighted the role of Bacillus and Pseudomonas secondary metabolites in mediating direct antagonism and induced resistance against these pathogens. Furthermore, we advance a need to ascertain the mode of action of beneficial bacteria/molecules to enhance a solution-based crop protection strategy. Moreover, an apparent disjoint exists between numerous experiments that have demonstrated disease-suppressive effects and the translation of these successes to commercial products and applications. Clearly, the field of cereal disease protection leaves a lot to be explored and uncovered. Full article