Search Results (30)

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

Rice bakanae disease (RBD), a major threat in rice-cropping nations, can reduce rice yield and quality. As it is a seed-borne disease, effective seed detection is crucial. Loop-mediated isothermal amplification (LAMP) can rapidly and specifically amplify DNA at a constant temperature with high sensitivity. This research uses LAMP to develop rapid RBD pathogen detection systems. Primers were designed targeting the NRPS31 gene of Fusarium fujikuroi and conserved TEF1α sequences of Fusarium asiaticum, Fusarium proliferatum, and Fusarium andiyazi. These reactions at 60 °C for 60 min had a detection limit of 100 pg·μL⁻¹, and LAMP proved applicable in field trials. Full article

Rice spikelet rot disease (RSRD) affects the production and market price of rice, and can be harmful to humans and livestock. In this study, 51 strains of Fusarium spp. were isolated from rice spikelets in the Lin’an, Yuhang, and Fuyang regions. The isolates comprised four composite species: Fusarium incarnatum-equiseti species complex (FIESC), Fusarium asiaticum species complex (FSAMSC), Fusarium fujikuroi species complex (FFSC), Fusarium commune species complex (FNSC), and five species of Fusarium spp. (F. luffae, F. sulawesiense, F. asiaticum, F. fujikuroi, and F. commune). The separation rate of F. sulawesiense was the highest (41.2%), followed by F. asiaticum at 37.3%. The results of this study, compared with those of other studies, found that the newly discovered species of Fusarium spp. associated with RSRD were FSAMSC (F. asiaticum) and FNSC (F. commune). Temperature is one of the important factors causing RSRD; the optimal growth temperature for F. sulawesiense and F. commune was 30 °C, and the optimal growth temperature for other species was 25 °C. A high temperature of 35 °C did not inhibit the growth of Fusarium, as F. commune and F. fujikuroi could grow at this temperature. At 20–30 °C, the growth rate of F. asiaticum was higher than those of other strains. To determine whether the occurrence of RSRD is related to the correlation between Fusarium and other fungi in rice spikelets under different health conditions, the genetic diversity of fungi in rice spikelets was analyzed by amplicon Internal Transcribed Spacer (ITS) sequencing, and the correlations between strains of Fusarium spp. were measured. The results showed that the fungal diversity of diseased rice spikelets (RD) was higher than that of relatively healthy rice spikelets (RH). Curvularia spp., which was affected by the condition of the spikelets, was negatively correlated with Fusarium spp. in RH and positively correlated with Fusarium spp. in RD. Therefore, Fusarium spp. and Curvularia spp. can jointly cause the occurrence of RSRD. The results of the study are significant for understanding the occurrence of RSRD and formulating prevention and control measures. Full article

Fusarium head blight (FHB) is one of the major wheat diseases caused by Fusarium species (mainly Fusarium graminearum and Fusarium asiaticum), resulting in significant global wheat yield losses and risks to food security. Breeding wheat varieties with resistance genes is the most environmentally friendly and economical strategy for controlling FHB. Psathyrostachys huashanica Keng ex P. C. Kuo (2n = 2x = 14, NsNs), which showed abiotic tolerance and biotic resistance, has significant research value and potential as an important genetic resource for wheat improvement. In previous studies, we crossed Psathyrostachys huashanica with common wheat and developed wheat lines containing different N_S chromosomes. In this study, we identified a 4N_S additional line, DA26, from the progenies of wheat-P. huashanica-derived lines using genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) analyses. Line DA26 showed high resistance to Fusarium head blight (FHB) in the greenhouse and field conditions. However, the parental common wheat lines Chinese Spring (CS) and CSph2b mutant showed high susceptibility to FHB. A field evaluation of the agronomic traits showed that the plant height of DA26 was significantly lower than CS, while there were no significant differences in the other agronomic traits. In addition, we also developed eight 4Ns-specific primers to identify the 4Ns chromosome, which can facilitate wheat breeding and FHB resistance gene mapping in the future. Full article

China is the largest strawberry producer in the world. Strawberry black root rot is a novel disease that occurs in Hohhot, Inner Mongolia. In the present study, the inhibitory effects of Bacillus subtilis S-16 and its fermented form on strawberry black root rot caused by Fusarium asiaticum were tested. The inhibition rates were 56.31% and 65.95%, respectively. Furthermore, the metabolic substances were analysed using LC-MS/MS. A total of 68 substances were identified, including 18 amino acids, 7 of which have been reported to have pro-growth and antibacterial functions. Among these seven amino acids, N-acetyl-D-alloisoleucine (NAD) had the strongest inhibitory effect on F. asiaticum. In addition, NAD caused the mycelia of F. asiaticum to appear shrivelled and deformed under electron microscopy. Furthermore, the effect of NAD on F. asiaticum was tested. The results indicate that NAD had a better prevention effect when used with hymexazol. Finally, the fungal biomass of F. asiaticum in strawberry roots was measured at different times using two treatment methods: treating plant roots with NAD and a spore suspension of F. asiaticum concurrently and with F. asiaticum alone. The colonisation response of F. asiaticum in terms of the target gene EF-1α when treated with F. asiaticum alone at 72 hpi was significantly higher than that when treated with NAD and a spore suspension of F. asiaticum. The relative expression levels of defence-related genes in strawberry roots treated with NAD at 72 hpi were determined. The genes NPR1 and PDF1 were markedly upregulated compared with other genes, suggesting that the expression of genes related to disease resistance was activated by NAD, resulting in disease resistance in strawberries. Our results provide theoretical support for the biological control of strawberry black root rot. Full article

Soybean root rot, a soil-borne fungal disease, is caused by multiple pathogens that seriously affect soybean production. During spring 2021, 92 pathogenic fungal strains were isolated from soybean plants with root rot in Hailun City, Heilongjiang Province, China. Through morphological and molecular identification, these strains were identified as Fusarium oxysporum (39.1%), F. asiaticum (30.4%), F. graminearum (13.0%), Pythium macrosporum (8.7%), and Rhizoctonia solani (8.7%). Among them, F. oxysporum was the dominant species, and F. asiaticum, not previously reported as a soybean root rot pathogen in Northeast China. Approximately 50% of the F. asiaticum isolates were moderately pathogenic. In addition, F. asiaticum had a wide host range, infecting black soybean, French bean, white hyacinth bean, mung bean, and adzuki bean but not corn, peanut, rice, and oat roots. Regarding field management, fludioxonil and pyraclostrobin had the best control effects of 73.8% and 69.4%, with EC₅₀ values of 0.0029–0.0071 μg·mL⁻¹ and 0.0045–0.0076 μg·mL⁻¹, respectively. The study reported that F. asiaticum is a pathogen causing soybean root rot in northeast China. The application of chemical fungicides and non-host crop rotation can effectively control the disease caused by F. asiaticum. Full article

Fusarium head blight (FHB), a disease inflicted by Fusarium graminearum and F. asiaticum, poses a growing threat to wheat in China, particularly in the face of climate change and evolving agricultural practices. This study unveiled the discovery of the victorivirus FgVV2 from the F. asiaticum strain F16176 and comprehensively characterized the function of the two victoriviruses FaVV1 and FaVV2 in virulence. Through comparative analysis with a virus-free strain, we established that these mycoviruses markedly repress the sexual reproduction and pathogenicity of their fungal hosts. Furthermore, we synthesized the coat protein (CP) genes CP1 from FaVV1 and CP2 from FaVV2, which were fused with the green fluorescent protein (GFP) gene and successfully expressed in Fusarium strains in wild-type isolates of F. asiaticum and F. graminearum. Similar to virus-infected strains, the transformed strains expressing CPs showed a significant decrease in perithecia formation and pathogenicity. Notably, CP2 exhibited a stronger inhibitory effect than CP1, yet the suppression of sexual reproduction in F. graminearum was less pronounced than that in F. asiaticum. Additionally, the pathogenicity of the F. asiaticum and F. graminearum strains expressing CP1 or CP2 was substantially diminished against wheat heads. The GFP-tagged CP1 and CP2 revealed distinct cellular localization patterns, suggesting various mechanisms of interaction with the host. The findings of this study provide a significant research foundation for the study of the interaction mechanisms between FaVV1 and FaVV2 with their hosts, as well as for the exploration and utilization of fungal viral resources. Full article

The Fusarium graminearum species complex (FGSC) is a worldwide phytopathogenic fungus of small grain cereals. Genetics and bioinformatics tools have been providing an efficient strategy for identifying FGSC. However, the potential reliability of tef1−α sequencing in FGSC members has not been well investigated. In this study, the tef1−α sequencing data of 246 FGSC members, one F. culmorum, and one F. solani isolate were subjected to distance-, character-, and PCA-based phylogenetic analysis. Linux terminals and the R programming language were used in phylogenetic analysis. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) and maximum likelihood methods produced relatively more homogenous F. graminearum sensu stricto (Fgss) and F. asiaticum isolates. Fgss and F. asiaticum isolates co-clustered in two separate sub-divisions in the ML and UPGMA methods, with significant differences in the Chi2 test (p < 0.05). PCA profiling revealed a low level of variation in FGSC members, with 99–99.5% percentages in axis 1. An increased number of taxa and isolates would be tested for tef1−α in future studies. To our knowledge, this is also the first study to combine phylogenetic methods with PCA tests for comprehensive characterization of FGSC members. Full article

Wheat plants are impacted by Fusarium head blight (FHB) infection, which poses a huge threat to wheat growth, development, storage and food safety. In this study, a fungal strain was isolated from diseased wheat plants and identified as Fusarium asiaticum F1, known to be a member of the Fusarium graminearum species complex, agents causally responsible for FHB. In order to control this disease, new alternatives need to be developed for the use of antagonistic bacteria. Bacillus velezensis E2 (B. velezensis E2), isolated from a previous investigation in our laboratory, showed a notable inhibitory effect on F. asiaticum F1 growth and deoxynivalenol (DON) synthesis in grains. The spore germination of F. asiaticum F1 was significantly reduced and the spores showed vesicular structures when treated with B. velezensis E2. Observations using scanning electron microscopy (SEM) showed that the hyphae of F. asiaticum F1 were shrunken and broken when treated with B. velezensis E2. The RNA-seq results of F1 hyphae treated with B. velezensis E2 showed that differentially expressed genes (DEGs), which were involved in multiple metabolic pathways such as toxin synthesis, autophagy process and glycan synthesis, especially the genes associated with DON synthesis, were significantly downregulated. In summary, those results showed that B. velezensis E2 could inhibit F. asiaticum F1 growth and reduce the gene expression of DON synthesis caused by F1. This study provides new insights and antagonistic mechanisms for the biological control of FHB during wheat growth, development and storage. Full article

Fusarium head blight (FHB) is a global cereal disease caused by a complex of Fusarium species. Both Fusarium graminearum and F. asiaticum are the causal agents of FHB in China. F. asiaticum is the predominant species in the Middle–Lower Reaches of the Yangtze River (MLRYR) and southwest China. Therefore, detecting F. asiaticum in a timely manner is crucial for controlling the disease and preventing mycotoxins from entering the food chain. Here, we combined rapid genomic DNA extraction, recombinase polymerase amplification, Cas12a cleavage, and lateral flow detection techniques to develop a method for the rapid detection of F. asiaticum. The reaction conditions were optimized to provide a rapid, sensitive, and cost-effective method for F. asiaticum detection. The optimized method demonstrated exceptional specificity in detecting F. asiaticum while not detecting any of the 14 other Fusarium strains and 3 non-Fusarium species. Additionally, it could detect F. asiaticum DNA at concentrations as low as 20 ag/μL, allowing for the diagnosis of F. asiaticum infection in maize and wheat kernels even after 3 days of inoculation. The developed assay will provide an efficient and robust detection platform to accelerate plant pathogen detection. Full article

Smi1 is a protein required for cell cycle progression, morphogenesis, stress response and life span of Saccharomyces cerevisiae. FaSmi1 was identified as a Smi1 homolog in a wheat scab pathogenic fungus Fusarium asiaticum strain 2021. The deletion of FaSmi1 leads to defects in mycelial growth, asexual reproduction, and virulence. The FaSmi1 deletion mutant also exhibited increased sensitivity to osmotic stresses generated by NaCl and KCl, but increased tolerance to oxidative stresses and cell wall integrity inhibitors. All of these defects were restored by genetic complementation of the mutant with the whole parental FaSmi1 gene. Interestingly, the antioxidant system-associated genes exhibit a lower expression level and the mycotoxins’ DON content was decreased in the FaSmi1 deletion mutant compared with the parental strain 2021. These results indicate that FaSmi1 plays a critical role in the vegetative development, asexual reproduction, DON production and virulence of F. asiaticum. Full article

Fusarium spp. are among the most important plant pathogens in the world. A survey on maize leaf blight was carried out in Heilongjiang province from 2019 to 2021. Based on morphological characteristics and a phylogenetic analysis on translation elongation factor (tef1) and second-largest subunit of RNA polymerase II (rpb2) genes, 146 Fusarium isolates were obtained and grouped into 14 Fusarium species, including F. ipomoeae (20.5%), F. compactum (17.1%), F. sporotrichioides (9.59%), F. graminearum (9.59%), F. citri (8.9%), F. asiaticum (6.85%), F. verticillioides (6.85%), F. acuminatum (5.48%), F. glycines (5.48%), F. temperatum (2.74%), F. armeniacum (2.74%), Fusarium sp. (2.05%), F. flagelliforme (1.4%), and F. annulatum (0.68%). The Fusarium incarnatum-equiseti species complex (FIESC, including F. ipomoeae, F. compactum, F. citri, and F. flagelliforme) was the most prevalent, indicating an evolving occurrence of the Fusarium species causing maize leaf blight. The typical symptoms observed on the maize leaves were oval to long strip lesions, with a gray to dark gray or brownish red coloration in the center and a chlorotic area at the edges. Based on the tef1 gene, seven haplotypes of FIESC were identified in Heilongjiang province, suggesting a population expansion. This is the first report of F. ipomoeae, F. compactum, F. flagelliforme, F. citri, F. sporotrichioides, F. graminearum, F. asiaticum, F. acuminatum, F. glycines, F. temperatum, F. armeniacum, Fusarium sp., and F. annulatum causing maize leaf blight in Heilongjiang province, China. The current research is informative for managing disease, exploring the phylogenetic relationship among Fusarium species, and clarifying the diversity of Fusarium species associated with maize leaf blight. Full article

Fusarium species can cause head blight of cereals worldwide. This is accompanied by impacts on yield and contamination of grains with mycotoxins. Regulations, with maximum limits, exist for the relevant Fusarium mycotoxins (e.g., type A and B trichothecenes, zearalenone and fumonisins). There is interest in a better understanding of the effect of key interacting abiotic factors which determine colonization and mycotoxin production in small grain cereals. Thus, this study examined the ecophysiological relationship between temperature and water availability (10–35 °C; water activity, a_w, 0.87–0.98) on growth and production of Fusarium mycotoxins (zearelenone, ZEA; deoxynivalenol, DON; 3-acetyl deoxynivalenol, 3-Ac-DON and nivalenol, NIV) by three strains of F. asiaticum, a head blight pathogen isolated from China and becoming important in other global regions. These were carried out on simulated wheat-based matrices that identified the optimum (25 °C/0.98 a_w) and marginal boundary conditions for growth (35 °C/0.90 a_w) for all three strains. Contrarily, different mycotoxigenic profiles were observed between strains (p < 0.05). Four mycotoxins assessed were produced at 30 °C while cold temperature inhibited the production of NIV and ZEA, which were never detected at <20 and <15 °C, respectively. Optimal mycotoxin production conditions varied for each toxin with ZEA production which was best at 30 °C/0.93–0.95 a_w, DON, 3-Ac-DON and NIV which was 0.98 a_w/20–30 °C. Probabilistic models were used to predict growth and regulated mycotoxin production by the strains of F. asiaticum. This study will be beneficial in the development mitigation strategies for control of pre- and post-harvest colonization of cereals and mycotoxin contamination by this Fusarium species in cereals. Full article

Fusarium poae virus 1 (FpV1, a betapartitivirus) is one of the mycoviruses which is discovered earlier. Due to the vegetative incompatibility barrier that often exists between different species or strains of filamentous fungi, FpV1 has been thought to be limited to its host, F. poae, as a non-hypovirulence mycovirus in the past 20 years in the field. Here, a novel strain of FpV1 (FpV1-Fa) with two dsRNA segments (2157-and 2080-nt) was consistently identified in F. asiaticum isolates in the field. FpV1-Fa induced abnormal morphology and hypovirulence of F. asiaticum, along with a high viral load. FpV1-Fa was detected only from the F. asiaticum and F. tricinctum strains at a FpV1-Fa sampling site (119.014289, 33.8261), while the other strains from other sites were not identified FpV1-Fa. A horizontal transmission experiment showed that FpV1-Fa can transfer from F. asiaticum to F. poae and F. tricinctum, but not to F. graminearum. The selection analysis of FpV1-Fa revealed RdRP and CP were under strong purifying selection, and the C-terminal side of RdRP was under positive selection. In these regions, 9 amino acid mutations in RdRP and 21 mutations in CP appeared to cause the variation of host range and virulence in FpV1-Fa. Full article

Members of the Fusarium graminearum species complex (Fg complex) are the primary pathogens that cause Fusarium head blight in wheat and barley. Fg complex members grow poorly on Fusarium oxysporum-selective media, such as Komada and Fo-G2, that have also been used for the isolation of other Fusarium species. Therefore, Komada medium was modified as FG medium for the isolation of Fg complex members. However, the production of pentachloronitrobenzene that is the most effective component of FG medium is discontinued and new media is required for the selective isolation of Fg complex members. In addition, the rapid diagnosis of isolated fungi is useful for the disease control. Novel tools have been developed for isolating and characterizing Fg complex members. FG21, a semi-selective medium for isolating Fg complex members, was developed using potato dextrose agar. Furthermore, a dipstick DNA chromatography assay was developed both to identify Fusarium graminearum sensu stricto and Fusarium asiaticum in the Fg complex and their trichothecene mycotoxin types. The easier isolation and characterization of Fg complex members in Japan was attained by the combined use of FG21 medium and the dipstick DNA chromatography assay. Full article