Genomic footprints related with adaptation and fumonisins production in Fusarium proliferatum

First Report of Fusarium proliferatum Infection in Pods of Four-Seeded Vetch and Its Relationships with Plants

Vicia species are of great value in ecological restoration, soil improvement, and the development of a forage resource. In 2024, a novel pod disease affecting four-seeded vetches (Vicia tetrasperma) emerged in Rongchang District, China, leading to severe yield loss. After obtaining the main pathogenic strain, FVS1, through the tissue isolation method, which was verified according to Koch's postulates, and by combining morphological characteristics with multigene phylogenetic analysis, FVS1 was identified as Fusarium proliferatum. The biological properties indicated that the most suitable culture medium of the fungus was oatmeal agar (OA), with the optimum growth temperature 25 °C and the lethal temperature being 35 °C. FVS1 exhibited insensitivity within a pH range of 7 to 9, as well as high adaptability to variations in light duration. To elucidate the physiological and biochemical changes in four-seeded vetches in response to FVS1 infection, non-targeted metabolomics analysis identified 379 differential metabolites, mainly comprising organic acids and derivatives, lipids and lipid-like molecules, and phenylpropanoids and polyketides. The results demonstrated that F. proliferatum primarily induced the disease by influencing alterations in the secondary metabolites associated with amino acid metabolism, lipid metabolism, and flavonoid biosynthesis. Four-seeded vetches improved tolerance to the fungus by accumulating histidine, aspartic acid, arginosuccinate, ethanolamine, glycerophosphocholine, naringenin, and catechin. Trichoderma harzianum (M3) had the best control effectiveness, and the inhibition rate was 60.68%. This study, for the first time, revealed that F. proliferatum caused a pod disease in four-seeded vetches. We analyzed the mechanism of plant-pathogen interaction and screened potential biocontrol strains, providing a theoretical basis for regional disease management.

The Role of FpfetC from Fusarium proliferatum in Iron Acquisition, Fumonisin B1 Production, and Virulence

Iron is an essential micronutrient required for the fungal growth and propagation. Fusarium proliferatum is the causal agent of rice spikelet rot disease. In this study, we characterized the role of F. proliferatum multicopper ferroxidase (FpfetC), which mediated the oxidization of ferrous to ferric iron in the reductive system of iron assimilation. Deletion of FpfetC led to impaired growth under iron-deprived conditions, and the growth defect could be restored by exogenous iron. Compared to wild-type Fp9 strain, ΔFpfetC showed increased conidiation, resistance to copper stress, and sensitivity to zinc stress. FpfetC deficiency rendered a transcription remodeling of genes involved in high-affinity iron assimilation, iron homeostasis and iron storage. Moreover, production of fumonisin B1 (FB1) and transcript levels of fumonisin biosynthesis (Fpfums) genes were elevated in ΔFpfetC. ΔFpfetC exhibited hypervirulence to rice, accompanied with aggravation of invasive hyphae and activation of siderophore synthesis at the sites of inoculation. Additionally, disruption of FpfetC attenuated penetration ability to cellophane membrane under iron starvation. Taken together, these results demonstrated that FpfetC played important roles in iron uptake, conidiation, response to metal stress, fumonisin biosynthesis, and virulence in F. proliferatum.

The Toxin-Producing Ability of Fusarium Proliferatum Strains Isolated from Grain

The widespread fungus Fusarium proliferatum can infect numerous plant species and produce a range of mycotoxins, the amount of which can vary significantly. Twelve F. proliferatum sensu lato strains isolated from six wheat, four oat, and two maize grain samples were analyzed. The strains were identified through a phylogenetic analysis of nucleotide sequences derived from gene fragments of the translation elongation factor EF-1α, β-tubulin, and RNA polymerase II second subunit. The mating types of the strain were determined by allele-specific PCR. Secondary toxic metabolite production by the strains was quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). All twelve Fusarium strains formed a distinct clade alongside the F. proliferatum reference strains, thereby confirming the taxonomic identification. Only one idiomorph at the MAT locus in each F. proliferatum strain was found, indicative of heterothallic mating. The frequency of the MAT1-1 idiomorph was double that of the MAT1-2 idiomorph. The active biosynthesis of fumonisins B1 (71-6175 mg/kg), B2 (12-2661 mg/kg), and B3 (6-588 mg/kg), significant beauvericin (64-455 mg/kg), and trace amounts of moniliformin (12-6565 μg/kg) were identified across all examined F. proliferatum strains.

Antagonistic activity of Trichoderma asperellum against Fusarium species, chemical profile and their efficacy for management of Fusarium-root rot disease in dry bean

BACKGROUND

Diseases caused by Fusarium pathogens lead to significant yield losses on many economically important crops. The purpose of this study was to evaluate the antagonistic capability and chemical profile of the bioagent Trichoderma asperellum against several Fusarium strains. The efficacy of this strain in reducing Fusarium-root rot disease in dry bean was also examined.

RESULTS

The T. asperellum strain was identified based on sequencing the internal transcribed spacer (ITS) and tef1 gen regions of ribosomal DNA. Dual cultural assay demonstrated their antagonistic activity against the studied Fusarium strains due to the probable combination of competition, mycoparasitism and antibiosis. This strain was positive for cellulase, chitinase and protease activity. The crude extracts of T. asperellum significantly suppressed the growth of the tested Fusarium strains with inhibition zone values ranging from 7.3 to 19.7 mm and minimum inhibitory concentration (MIC) values ranging from 0.15 to 1.42 mg mL-1 . The gas chromatography-mass spectrometry (GC-MS) analysis of cell free supernatant and mycelial biomass of T. asperellum showed the presence of 27 and 21 compounds, respectively. The main compounds responsible for the bioactivity were butylated hydroxytoluene, hexadecanoic acid, 9-octadecenoic acid, ergosterol and hexadecanoic acid, ethyl ester. Trichoderma asperellum significantly increased plant emergence and reduced root rot caused by Fusarium solani in dry bean grown under glasshouse and field trials. Further, plant biomass and dry bean yield were higher in T. asperellum-treated plants than in control plants.

CONCLUSION

Trichoderma asperellum was highly effective, through various mechanisms, against Fusarium strains especially F. solani which causes root rot in dry bean. © 2023 Society of Chemical Industry.