Search Results (47)

(1) Background: Oat (Avena sativa L.) is a crop that is widely used in human nutrition, while it also plays an important role in animal husbandry as a high-quality forage crop. However, this crop is particularly susceptible to combined biotic stressors, including insect pests (Agriotes lineatus) and fungal infections (Fusarium spp.). These stresses act synergistically: root damage caused by wireworms increases the plant’s susceptibility to fungal infection, while pathogens further limit nutrient uptake and root system development. In recent years, the reduced efficacy of chemical pesticides against both insect pests and fungal pathogens has highlighted the need for alternative strategies in oat protection, leading to an increased focus on developing bacterial bio-inoculants as sustainable and effective biocontrol agents. (2) Methods: This study aimed to identify bacterial strains capable of suppressing wireworms (Agriotes lineatus) and Fusarium spp. in oats, while simultaneously promoting plant growth. Bacterial isolates were screened for key Plant Growth Promoting (PGP) and biocontrol traits, including IAA and siderophore production, phosphate solubilization, and the presence of toxin- and antibiotic-coding genes. (3) Results: The highest insecticidal effect against wireworms was recorded for Bacillus velezensis BHC 3.1 (63.33%), while this isolate also suppressed the growth of F. proliferatum for 59%, F. oxysporum for 65%, F. poae for 71%, and F. graminearum for 15%. The most effective Bacillus strains (with insecticidal and antifungal activity) were identified and tested in two pot experiments, where their ability to enhance plant growth in the presence of insects and fungi was evaluated under semi-controlled conditions. An increase in plant biomass, grain yield, and nitrogen content was observed in oat inoculated with B. velezensis BHC 3.1 and B. thuringiensis BHC 2.4. (4) Conclusions: These results demonstrate the strong potential of both strains as multifunctional bio-inoculants for enhancing oat growth and mitigating the adverse effects of wireworm damage and Fusarium infection. Full article

Kentucky bluegrass powdery mildew, caused by the fungus Blumeria graminis f. sp. poae, is a destructive disease affecting Poa pratensis L. In this study, endophytic bacteria were isolated from the resistant Kentucky bluegrass cultivar ‘Taihang’. Employing a combination of conidia germination inhibition assays and control efficacy tests, the biocontrol endophytic bacterial strains were screened. The impact of inoculation with the powdery mildew pathogen and biocontrol endophytic bacteria on the difference in endophytic bacterial community in the leaves of Kentucky bluegrass were studied via Illumina Miseq high-throughput 16S ribosomal RNA gene sequencing technology. A total of 18 endophytic bacterial isolates were obtained from ‘Taihang’, belonging to 3 phyla: Proteobacteria (3 isolates), Actinobacteria (6 isolates), and Firmicutes (9 isolates). The conidia germination assay revealed that isolates 6213 (Bacillus sp.) and 718 (Neobacillus sp.) exhibited the strongest inhibitory against Blumeria graminis f. sp. poae, with inhibition rate exceeding 80%. Isolate 718 exhibited superior control efficacy over strain 6213. A concentration of 10⁹ colony-forming units per milliliter (CFU/mL) was the most effective in suppressing powdery mildew on Kentucky bluegrass. The abundance of Proteobacteria on Kentucky bluegrass after the application of isolate 718 may enhance the resistance of Kentucky bluegrass to powdery mildew, and the dominant endophytic bacterial communities were Burkholderiales, Burkholderiaceae and Cupriavidus, indicating that the application of isolate 718 modulated the plant’s response to powdery mildew infection. These results demonstrate that isolate 718 enhanced the resistance of Kentucky bluegrass against powdery mildew by reshaping the endophytic bacterial community within the leaves. These findings provide molecular insights into plant−pathogen−endophytic bacteria interactions and support the development of sustainable strategies, eco-friendly strategies for plant diseases management. Full article

Fusarium head blight (FHB) is a major threat to cereal crops, causing yield losses and mycotoxin contamination. This study investigated Fusarium species associated with spikes and grains of cereals in the Volga region, focusing on species diversity, virulence, and mycotoxin production. F. sporotrichioides, F. avenaceum, and F. poae were the most prevalent species isolated from wheat, rye, barley, triticale, and stored grains in the Volga region. Individual strains of F. culmorum and F. graminearum were also identified. High intraspecific variability in virulence was observed for the first time within F. sporotrichioides and F. poae species, and highly virulent strains were identified for the first time within these species. Not only symptomatic but also asymptomatic (weakly expressed) infections caused by F. sporotrichioides were shown to be associated with the accumulation of high levels of T-2 toxin in the grains of infected plants. F. sporotrichioides strains were first demonstrated to exhibit intraspecific variability in zearalenone-producing potential. A F. graminearum strain possessing the nivalenol chemotype was first identified in Russia. The study highlights the diversity of the regional FHB pathocomplex and the risks it poses to grain safety. Full article

This study investigates the connection between meteorological variables and the presence of Fusarium species across 26 grain sampling sites over five years. We analyzed average temperatures for May, June, and July, which showed substantial year-to-year fluctuations, with the most significant deviations in 2019 and the smallest in 2014. Precipitation also varied greatly each year, with notable differences between 2014 and 2019. The measurement of Fusarium DNA revealed its presence in most samples, with peak levels observed in southeastern and northwest Poland. Five Fusarium species were identified, with F. graminearum s.s. and F. poae being the most prevalent, depending on the year. The geographic distribution of Fusarium DNA demonstrated significant regional differences, with the highest levels found in specific provinces each year. Statistical analysis indicated significant correlations between DNA levels of F. avenaceum, F. culmorum, and F. graminearum s.s. Principal Component Analysis (PCA) uncovered strong relationships among these species, especially in samples from 2016 and 2017. Additionally, we observed a positive correlation between Fusarium DNA levels and precipitation during flowering and ripening stages, and a negative correlation with temperature during stem elongation and milk-dough phases. These findings highlight the complex interactions between climate factors and Fusarium presence in winter wheat grain, providing insight into environmental influences on fungal ecology in agricultural systems. Full article

Fusarium head blight in barley (Hordeum vulgare) reduces grain yield and can lead to the accumulation of deoxynivalenol (DON) and nivalenol (NIV) in grains. We surveyed Fusarium species and evaluated DON and NIV concentrations in barley grains in four regions of Rio Grande do Sul, the southernmost state in subtropical Brazil. Seven Fusarium species were identified: F. asiaticum, F. avenaceum, F. cortaderiae, F. graminearum, F. gerlachii, F. meridionale and F. poae. DON (0 to 10,200 µg/kg) and NIV (0 to 1630 µg/kg) were detected in 74% and 70% of the samples, respectively, with higher concentrations found in experimental fields. However, in commercial barley fields, most samples fell below 2000 µg/kg of DON, which is the maximum limit allowed by Brazilian legislation for grains intended for processing. The seasonality of temperature and precipitation influenced mycotoxin concentrations. Therefore, the variability of Fusarium species in Rio Grande do Sul and a high incidence of DON and NIV in barley grains highlight the complexity of this pathosystem. This variability of Fusarium species may also influence the effectiveness of measures to control the disease, particularly in relation to genetic resistance and fungicide application. Full article

High-throughput sequencing (HTS) has revolutionized phytopathology by overcoming many limitations of traditional diagnostic methods, as it permits precise pathogen monitoring, identification, and control, with ribosomal DNA (rDNA) regions serving as reliable markers for fungal classification. In this study, next-generation sequencing (NGS) was used, targeting the ITS1 and ITS2 regions to explore fungal diversity and pathogen presence in winter wheat grain samples and identifying 183 OTU sequences across 115 taxa. The ITS1 analysis yielded 249,743 reads, with Fusarium sp. (61%) as the dominant pathogenic taxon, followed by Sporobolomyces sp. (14%), Cladosporium sp. (3%), and other yeast-like or saprotrophic fungi, such as Cryptoccocus spp., F. wieringae, and B. alba. Sequencing of ITS1 also permitted the detection of F. acuminatum and the quarantine-regulated pathogens T. caries and T. triticoides. The ITS2 analysis produced 179,675 reads, with F. culmorum (47%) as the most abundant taxon, confirming significant grain contamination with this pathogen. Other frequently detected taxa included yeast-like fungi such as C. tephrensis (21%) and V. victoriae (13%), along with saprotrophic species like S. roseus and Davidella sp. ITS2 provided better resolution for the identification of Fusarium species by the detection of more pathogenic taxa associated with cereal diseases, including F. culmorum, as well as F. cerealis, F. poae, and F. tricinctum. The analysis revealed a diverse fungal community, including other pathogens such as A. porri, B. cinerea, and C. herbarum, as well as various non-pathogenic and saprotrophic fungal taxa. These findings underscore the complementary utility of ITS1 and ITS2 in profiling fungal diversity and detecting critical pathogens using HTS, highlighting the potential of these DNA regions for monitoring and managing cereal crop health. Full article

Barley (Hordeum vulgare L.) is the second winter crop in Argentina. In the national market, grains are mainly destined to produce malt for beer manufacture. Fusarium species are common, causing Fusarium Head Blight (FHB) in barley, which generates yield and quality losses, as well as mycotoxin occurrence. The aims of this study were to determine (a) the incidence of the main species causing FHB in different locations of the barley-growing region of Argentina, (b) their ability to produce mycotoxins, and (c) the levels of deoxynivalenol (DON) and nivalenol (NIV) natural occurrence in grains at the harvest stage. Additionally, a strain of Bacillus velezensis was studied as a biocontrol agent in order to control F. graminearum sensu stricto and mycotoxin accumulation during the malting process, with the final objective being to reduce DON contamination in the beer manufacture chain. Fusarium graminearum ss was the most prevalent species causing FHB, with Fusarium poae being less distributed. Both species produced several mycotoxins, including NX-2 and NX-3, which is the first report of their production by strains isolated from barley in Argentina. Deoxynivalenol contamination was found in 95% of barley grains during the 2016 harvest season (mean: 0.4 mg/kg), while NIV contamination was present in 29% of samples (mean: 0.49 mg/kg). In the 2017 harvest season, 53.6% of grains were contaminated with DON (mean: 0.42 mg/kg), and 21% with NIV (mean: 0.8 mg/kg). Quantification of F. graminearum ss by real-time PCR during the micro-malting process showed that application of the biocontrol agent before the germination stage was the most effective treatment, with a 45% reduction in fungal DNA levels. Reduction in DON contamination (69.3–100%) in artificially infected grains with F. graminearum ss, was also observed. The present work contributes to the knowledge of FHB in Argentina and to the development of a strategy to control this disease and mycotoxin contamination in barley, promoting at the same time food security. Full article

Cereal crops are affected by one of the most devastating diseases worldwide, known as Fusarium head blight (FHB), with Fusarium graminearum being the most isolated causal pathogen. Another species associated with this disease is Fusarium poae. This species has been considered a relatively weak pathogen compared to F. graminearum, but its importance has increased due to its occurrence in cereal grains worldwide. Considering the advantages of using B. distachyon as a plant model and the importance of F. poae in crops, our study aimed to evaluate the potential use of Brachypodium as a plant model to evaluate the compatible interaction with F. poae. Twelve Brachypodium spp. accessions from different countries were inoculated with a selected F. poae set of isolates. Disease severity, conidial quantification, fungal DNA biomass, and nivalenol quantification were assessed. The results showed a compatible interaction between Brachypodium accessions and Fusarium poae, which allowed the use of the model plant for future plant–pathogen interaction studies. Full article

The increasing contamination of cereals by micromycetes and mycotoxins during malting still poses an unresolved food safety problem. This study characterises the potential of the novel, rapidly developing food production technology of Pulsed Electric Field (PEF) to reduce the viability of Fusarium fungi and the production of mycotoxins during malting. Barley, artificially inoculated with four Fusarium species, was treated by PEF with two different intensities and then malted using a standard Pilsner-type technology. Concentrations of fungi were quantified by RT-PCR, expression of fungal growth-related genes was assessed using mRNA sequencing, and mycotoxin levels were analysed by U-HPLC-HRMS/MS. Despite the different trends for micromycetes and mycotoxins after application of variously intense PEF conditions, significant reductions were generally observed. The greatest decrease was for F. sporotrichioides and F. poae, where up to six fold lower levels were achieved for malts produced from the PEF-treated barley when compared to the control. For F. culmorum and F. graminearum, up to a two-fold reduction in the PEF-generated malts was observed. These reductions mostly correlated with a decrease in relevant mycotoxins, specifically type A trichothecenes. Full article

Fusarium poae is a pathogen that is widespread in the temperate zone and poses a serious threat to crops due to its wide range of host plants (including cereals). Electronic nose measurements were performed on wheat grains infected with F. poae to evaluate the application of early detection of fungal infections. Wheat seeds were artificially inoculated to test the devices. Three same-weight but different infection level experiment variants were prepared: 3 g infected seeds with 12 g healthy seeds, 5 g infected seeds with 10 g healthy seeds, and 10 g infected seeds with only 5 g healthy seeds. The seeds were infected with fresh fragments of F. poae mycelium. Measurements were carried out for five constructive days, recording the changes in volatile odor compounds released each day. A custom-built, low-cost device based on Figaro Inc. TGS metal-oxide semiconductor gas sensors and a commercially available PEN3 electronic nose device from Airsense Analytics GmbH were used for the experiment. A non-linear sensor response for the measured sample odor was observed with both devices. Spoiled grain in a proportion of 1/15 of the sample could be detected by measuring the volatile components. However, the patterns of the sensor responses were different for the various concentrations of spoiled grain in the measured samples. Full article

Kentucky bluegrass (Poa pratensis L.) is a valuable cool-season turfgrass widely utilized for forage, turf, and ecological purposes; however, its productivity and ornamental value are significantly compromised by powdery mildew, caused by Blumeria graminis f. sp. Poae, which negatively affects turf quality. In the present study, we examined the interactions between P. pratensis varieties and B. graminis, focusing on primary haustorium formation at 24 h post-inoculation and the formation of germ tubes at 48 h post-inoculation. We explored the molecular mechanisms underlying the response of different P. pratensis varieties at 48 h post-inoculation via transcriptomic techniques. Our results revealed that the primary haustorium formation rate in ‘Taihang’ at 24 h after B. graminis inoculation was significantly lower than that in ‘Explorer’ and ‘Black Jack’. The conidia of B. graminis could form two to five germ tubes, and the proportion of conidia that formed five germ tubes in ‘Taihang‘ at 48 h post-inoculation was significantly lower than that in the other two varieties. Transcriptome analysis revealed 680,765 transcripts as unigenes. A total of 9983 unigenes were identified as differentially expressed genes in one or more varieties of P. pratensis after inoculation with powdery mildew compared with the control. In total, 6284 differentially expressed genes were upregulated in ‘Taihang’, which was substantially greater than those in ‘Black Jack’ (4530) and ‘Explorer’ (4666). Moreover, 2843 differentially expressed genes were specific to ‘Taihang’, whereas 1644 and 1590 unique differentially expressed genes were specific to ‘Explorer’ and ‘Black Jack’, respectively. The specifically expressed genes play crucial roles in determining the disease resistance of powdery mildew. Notably, the expression of genes encoding chitinase, gamma-glutamyltranspeptidase 1, UDP-arabinopyranose mutase 1, oxalate oxidase 2, mitogen-activated protein kinase kinase 1-like, tryptophan decarboxylase, and aromatic L-amino acid decarboxylase was closely related to powdery mildew resistance in ‘Taihang’, making them promising candidate genes for studying resistance to powdery mildew in P. pratensis. This study identified critical genes involved in powdery mildew resistance in P. pratensis, providing a basis for future gene mining and molecular breeding to increase disease resistance in P. pratensis. Full article

This study investigated the effects of delayed harvesting, varying meteorological conditions, and barley variety on Fusarium spp. infection rates, nutritional composition, and mycotoxin contamination in barley grains. Field experiments were conducted from 2020 to 2022 and involved two barley varieties: ‘Laureate’ for malting and ‘Luokė’ for feed. The results indicated that the dominant Fusarium species isolated were F. avenaceum, F. culmorum, F. poae, F. sporotrichioides, F. tricinctum, and F. equiseti. These tended to increase in number with delayed harvest times and were more prevalent during harvest periods of higher precipitation (p < 0.05). Malting barley had higher starch and lower protein content compared to feed barley (p < 0.05). Delayed harvesting generally increased dry matter, crude fat, and crude ash contents while decreasing crude protein, zinc, and iron contents (p < 0.05). Mycotoxin analysis revealed significant differences under specific weather conditions. HT-2 toxin levels were higher under slightly warmer and wetter conditions during flowering, with harvest conditions similar to the long-term average. Zearalenone levels increased with dry, warm growing seasons followed by rainy harvests. Nivalenol and enniatin levels increased with rainy growing seasons and dry, warm harvests. Deoxynivalenol concentrations did not reach the limit of quantification throughout the study. No consistent trend was observed for higher contamination in any specific barley variety (p > 0.05). The strongest correlations between mycotoxins and nutritional value indicators were observed with less-studied mycotoxins, such as nivalenol and enniatins, which exhibited negative correlations with crude protein (p < 0.01), crude fat (p < 0.05), and zinc (p < 0.01), and positive correlations with crude ash (p < 0.05) and phosphorus (p < 0.01). Full article

Barley is the third most important cereal crop in terms of production in Canada, and Fusarium head blight (FHB) is one of the main fungal diseases of barley. FHB is caused by a species complex of Fusaria, of which Fusarium graminearum Schwabe is the main causal species of FHB epidemics in Canada. Field surveys show that two or more Fusarium species often co-exist within the same field or grain sample, and F. poae is reported as another important species in barley. This study aimed to determine the pathogenicity of F. graminearum, F. poae, and a co-inoculation of both species causing FHB in barley. Two susceptible barley cultivars were spray-inoculated at 10 to 14 days after heading. Phenotypic disease severity was rated on a scale of 0–9 at 4, 7, 14, 21, and 28 days after inoculation. There was a significant difference in FHB severity between F. graminearum and F. poae, where infection with F. graminearum produced more severe disease ratings. F. poae generated lower disease ratings and was not statistically different from the control. When heads were co-inoculated with both Fusarium species, the resulting FHB severity was unchanged relative to heads inoculated with F. graminearum only. The ratio of F. graminearum to F. poae genomic DNA was also no different than when heads were inoculated with F. graminearum alone, as quantified with ddPCR using markers specific to each species. The metabolomic analysis of sample extracts showed that F. graminearum-associated metabolites dominated the mycotoxin profile of co-inoculated samples, which corroborated our other findings where F. graminearum appeared to outcompete F. poae in barley. No significant effect on visual FHB disease ratings or fungal DNA detection was observed between the cultivars tested. However, there were some metabolome differences between cultivars in response to the challenge by both F. graminearum and F. poae. Full article

Fusarium Head Blight (FHB), predominantly caused by Fusarium species, is a devastating cereal disease worldwide. While considerable research has focused on Fusarium communities in grains, less attention has been given to residues and soil, the primary inoculum sources. Knowledge of Fusarium spp. diversity, dynamics, and mycotoxin accumulation in these substrates is crucial for assessing their contribution to wheat head infection and the complex interactions among Fusarium communities throughout the wheat cycle. We monitored six minimum-tillage wheat fields, with maize as the preceding crop, over two years. Soils, maize residues, and wheat grains were sampled at four stages. Fusarium composition was analyzed using a culture-dependent method, species-specific qPCR, and EF1α region metabarcoding sequencing, enabling species-level resolution. The Fusarium communities were primarily influenced by substrate type, accounting for 35.8% of variance, followed by sampling location (8.1%) and sampling stage (3.2%). Among the 32 identified species, F. poae and F. graminearum dominated grains, with mean relative abundances of 47% and 29%, respectively. Conversely, residues were mainly contaminated by F. graminearum, with a low presence of F. poae, as confirmed by species-specific qPCR. Notably, during periods of high FHB pressure, such as in 2021, F. graminearum was the dominant species in grains. However, in the following year, F. poae outcompeted F. graminearum, resulting in reduced disease pressure, consistent with the lower pathogenicity of F. poae. Source Tracker analysis indicated that residues were a more significant source of Fusarium contamination on wheat in 2021 compared to 2022, suggesting that F. graminearum in 2021 primarily originated from residues, whereas F. poae’s sources of infection need further investigation. Additionally, multiple mycotoxins were detected and quantified in maize residues during the wheat cycle, raising the question of their ecological role and impact on the soil microbiota. Full article

An electronic device based on the detection of volatile substances was developed in response to the need to distinguish between fungal infestations in food and was applied to wheat grains. The most common pathogens belong to the fungi of the genus Fusarium: F. avenaceum, F. langsethiae, F. poae, and F. sporotrichioides. The electronic nose prototype is a low-cost device based on commercially available TGS series sensors from Figaro Corp. Two types of gas sensors that respond to the perturbation are used to collect signals useful for discriminating between the samples under study. First, an electronic nose detects the transient response of the sensors to a change in operating conditions from clean air to the presence of the gas being measured. A simple gas chamber was used to create a sudden change in gas composition near the sensors. An inexpensive pneumatic system consisting of a pump and a carbon filter was used to supply the system with clean air. It was also used to clean the sensors between measurement cycles. The second function of the electronic nose is to detect the response of the sensor to temperature disturbances of the sensor heater in the presence of the gas to be measured. It has been shown that features extracted from the transient response of the sensor to perturbations by modulating the temperature of the sensor heater resulted in better classification performance than when the machine learning model was built from features extracted from the response of the sensor in the gas adsorption phase. By combining features from both phases of the sensor response, a further improvement in classification performance was achieved. The E-nose enabled the differentiation of F. poae from the other fungal species tested with excellent performance. The overall classification rate using the Support Vector Machine model reached 70 per cent between the four fungal categories tested. Full article