Search Results (14)

Fusarium sacchari is one of the primary causal agents of Pokkah boeng disease (PBD), an important disease of sugarcane worldwide. The acyl-CoA dehydrogenases (ACADs) constitute a family of flavoenzymes involved in the β-oxidation of fatty acids and amino acid catabolism in mitochondria. However, the role of ACADs in the pathogenesis of F. sacchari is unclear. Here, 14 ACAD-encoding genes (FsACAD-1–FsACAD-14) were identified by screening the entire genome sequence of F. sacchari. The FsACAD genes are distributed across seven chromosomes and were classified into seven clades based on phylogenetic analysis of the protein sequences. In vivo mRNA quantification revealed that the FsACAD genes are differentially expressed during sugarcane infection, and their expression patterns differ significantly in response to the in vitro induction of fatty acids of different classes. Fatty acid utilization assays of the FsACAD-deletion mutants revealed that the FsACADs varied in their preference and ability to break down different fatty acids and amino acids. There was variation in the adverse impact of FsACAD-deletion mutants on fungal traits, including growth, conidiation, stress tolerance, and virulence. These findings provide insights into the roles of FsACADs in F. sacchari, and the identification of FsACADs offers potential new targets for the improved control of PBD. Full article

The pathogen Fusarium sacchari is responsible for the devastating pokkah boeng disease, which causes significant economic losses in sugarcane production. However, the mechanisms by which it affects plant immunity remain largely unknown. Common in Fungal Extracellular Membrane (CFEM) domain proteins have been implicated in fungal growth, infection processes, and pathogenicity. In this study, we identified three FsCFEM proteins (Fs08184, Fs10706, and Fs13617) that mediate the broad-spectrum suppression of the immune responses induced by typical effectors. A further analysis demonstrated that Fs08184, Fs10706, and Fs13617 suppressed host immunity through two potential iron-binding sites conserved in CFEM family members, characterized by Asp and Phe residues in Fs08184, Fs10706, and Fs13617. Additionally, the Asp and Phe residues within the iron-chelating site were necessary for the iron acquisition of F. sacchari and contributed to creating low-free-iron conditions at the interface of plant and pathogen interactions. It appeared that F. sacchari might employ Asp-Phe-type CFEM members to influence host iron homeostasis to suppress host immunity and to facilitate its successful colonization. Full article

Pokkah Boeng disease has been observed in nearly all countries where sugarcane is commercially cultivated. The disease was considered a minor concern in earlier times, but due to climate change, it has now become a major issue. It is caused by fungi, specifically the Fusarium fungal complex. Fusarium fujikuroi, F. sacchari, F. oxysporum, F. verticillioides, F. proliferatum, and F. subglutinans are the major species causing the disease in sugarcane. The disease spreads rapidly, and unpredictable environmental conditions, along with the overlap of crop stages with biotic factors, contributed to its increased severity and varied symptom patterns. This disease is primarily airborne, spreading through air currents. Secondary transmission occurs via infected setts, irrigation water, splashed rain, and soil. It typically emerges during hot and humid conditions, particularly when the sugarcane is experiencing rapid growth. The most effective way to control Pokkah Boeng is by cultivating resistant varieties and removing canes exhibiting ‘top rot’ or ‘knife cut’ symptoms. Apply 0.1% carbendazim, 0.2% copper oxychloride, or 0.3% mancozeb for two to three sprayings at 15-day intervals. Using biological methods to control plant pathogens presents a promising alternative to the heavy reliance on chemical fungicides in modern agriculture, which can lead to environmental pollution and the development of resistant strains. Full article

Fusarium sacchari is a significant pathogenic fungus that causes sugarcane Pokkah Boeng. Proteins secreted by pathogenic fungi can be delivered into hosts to suppress plant immunity and establish infection. However, there is still much to be discovered regarding F. sacchari’s secreted effectors in overcoming plant immunity. In this paper, we characterize a novel effector called FsMEP1, which is essential for the virulence of F. sacchari. FsMEP1 contains a conserved zinc-binding motif sequence, HEXXH, and is highly expressed during host infection. Using the Agrobacterium tumefaciens-mediated transient expression system, it was confirmed that FsMEP1 could suppress Bcl-2-associated X protein (BAX)-triggered cell death, callose deposition, and ROS explosion in Nicotiana benthamiana. Furthermore, the deletion of FsMEP1 demonstrated its requirement for contributing to the pathogenicity of F. sacchari in sugarcane. Further analysis revealed that FsMEP1 could interact with the sugarcane thiamine thiazole synthase ScTHI2 and disrupt its normal localization, thereby inhibiting the synthesis of thiamine and the defense responses mediated by ScTHI2. Based on these findings, we propose that ScTHI2 represents a potential molecular target for improving sugarcane resistance to Pokkah Boeng disease. Full article

In a survey of mycoviruses in Fusarium species that cause sugarcane Pokkah boeng disease, twelve Fusarium strains from three Fusarium species (F. sacchari, F. andiyazi, and F. solani) were found to contain Fusarium sacchari hypovirus 1 (FsHV1), which we reported previously. The genomes of these variants range from 13,966 to 13,983 nucleotides, with 98.6% to 99.9% nucleotide sequence identity and 98.70% to 99.9% protein sequence similarity. Phylogenetic analysis placed these FsHV1 variants within the Alphahypovirus cluster of Hypoviridae. Intriguingly, no clear correlation was found between the geographic origin and host specificity of these viral variants. Additionally, six out of the twelve variants displayed segmental deletions of 1.5 to 1.8 kilobases, suggesting the existence of defective viral dsRNA. The presence of defective viral dsRNA led to a two-thirds reduction in the dsRNA of the wild-type viral genome, yet a tenfold increase in the total viral dsRNA content. To standardize virulence across natural strains, all FsHV1 strains were transferred into a single, virus-free Fusarium recipient strain, FZ06-VF, via mycelial fusion. Strains of Fusarium carrying FsHV1 exhibited suppressed pigment synthesis, diminished microspore production, and a marked decrease in virulence. Inoculation tests revealed varying capacities among different FsHV1 variants to modulate fungal virulence, with the strain harboring the FsHV1-FSA1 showing the lowest virulence, with a disease severity index (DSI) of 3.33, and the FsHV1-FS1 the highest (DSI = 17.66). The identification of highly virulent FsHV1 variants holds promise for the development of biocontrol agents for Pokkah boeng management. Full article

Fusarium sacchari, a key pathogen of sugarcane, is responsible for the Pokkah boeng disease (PBD) in China. The 14-3-3 proteins have been implicated in critical developmental processes, including dimorphic transition, signal transduction, and carbon metabolism in various phytopathogenic fungi. However, their roles are poorly understood in F. sacchari. This study focused on the characterization of two 14-3-3 protein-encoding genes, FsBmh1 and FsBmh2, within F. sacchari. Both genes were found to be expressed during the vegetative growth stage, yet FsBmh1 was repressed at the sporulation stage in vitro. To elucidate the functions of these genes, the deletion mutants ΔFsBmh1 and ΔFsBmh2 were generated. The ΔFsBmh2 exhibited more pronounced phenotypic defects, such as impaired hyphal branching, septation, conidiation, spore germination, and colony growth, compared to the ΔFsBmh1. Notably, both knockout mutants showed a reduction in virulence, with transcriptome analysis revealing changes associated with the observed phenotypes. To further investigate the functional interplay between FsBmh1 and FsBmh2, we constructed and analyzed mutants with combined deletion and silencing (ΔFsBmh/siFsBmh) as well as overexpression (O-FsBmh). The combinations of ΔFsBmh1/siFsBmh2 or ΔFsBmh2/siFsBmh1 displayed more severe phenotypes than those with single allele deletions, suggesting a functional redundancy between the two 14-3-3 proteins. Yeast two-hybrid (Y2H) assays identified 20 proteins with pivotal roles in primary metabolism or diverse biological functions, 12 of which interacted with both FsBmh1 and FsBmh2. Three proteins were specifically associated with FsBmh1, while five interacted exclusively with FsBmh2. In summary, this research provides novel insights into the roles of FsBmh1 and FsBmh2 in F. sacchari and highlights potential targets for PBD management through the modulation of FsBmh functions. Full article

Fusarium sacchari is a causal agent of sugarcane Pokkah boeng, an important fungal disease that causes a considerable reduction in yield and sugar content in susceptible varieties of sugarcane worldwide. Despite its importance, the fungal factors that regulate the virulence of this pathogen remain largely unknown. In our previous study, mapping of an insertional mutant defect in virulence resulted in the identification of a cutinase G-box binding protein gene, designated FsCGBP, that encodes a C2H2-type transcription factor (TF). FsCGBP was shown to localize in the nuclei, and the transcript level of FsCGBP was significantly upregulated during the infection process or in response to abiotic stresses. Deletion or silencing of FsCGBP resulted in a reduction in mycelial growth, conidial production, and virulence and a delay in conidial germination in the F. sacchari. Cutinase genes FsCUT2, FsCUT3, and FsCUT4 and the mitogen-activated protein kinase (MAPK) genes FsHOG1, FsMGV1, and FsGPMK1, which were significantly downregulated in ΔFsCGBP. Except for FsHOG1, all of these genes were found to be transcriptionally activated by FsCGBP using the yeast one-hybrid system in vitro. The deletion of individual cutinase genes did not result in any of the phenotypes exhibited in the ΔFsCGBP mutant, except for cutinase activity. However, disruption of the MAPK pathway upon deletion of FsMGV1 or FsGPMK1 resulted in phenotypes similar to those of the ΔFsCGBP mutant. The above results suggest that FsCGBP functions by regulating the MAPK pathway and cutinase genes, providing new insights into the mechanism of virulence regulation in F. sacchari. Full article

Nitrogen availability might play an essential role in plant diseases by enhancing fungal cell growth and influencing the expression of genes required for successful pathogenesis. Nitrogen availability could modulate secondary metabolic pathways as evidenced by the significant differential expression of several core genes involved in mycotoxin biosynthesis and genes encoding polyketide synthase/nonribosomal peptide synthetases, cytochrome P450 and carbohydrate-active enzymes in Fusarium sacchari, grown on different nitrogen sources. A combined analysis was carried out on the transcript and metabolite profiles of regulatory metabolic processes and the virulence of Fusarium sacchari grown on various nitrogen sources. The nitrogen regulation of the gibberellin gene cluster included the metabolic flux and multiple steps of gibberellin synthesis. UHPLC-MS/MS-based metabolome analysis revealed the coordination of these related transcripts and the accumulation of gibberellin metabolites. This integrated analysis allowed us to uncover additional information for a more comprehensive understanding of biological events relevant to fungal secondary metabolic regulation in response to nitrogen availability. Full article

In this study, seven different silver nanoparticles (AgNPs) were obtained using the fungi species from the phylum Ascomycota, Aspergillus tubingensis, Aspergillus spp., Cladosporium pini-ponderosae, Fusarium proliferatum, Epicoccum nigrum, Exserohilum rostratum, and Bionectria ochroleuca, isolated from the Brazilian biodiversity, particularly from the mangrove and Caatinga biomes. The nanoparticles were coded as AgNP-AT, AgNP-Asp, AgNP-CPP, AgNP-FP, AgNP-EN, AgNP-ER, and AgNP-BO and characterized using spectrophotometry (UV-Vis), dynamic light scattering (DLS), zeta potential, transmission electron microcopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. All the AgNPs presented homogeneous size in the range from 43.4 to 120.6 nm (DLS) and from 21.8 to 35.8 nm (TEM), pH from 4.5 to 7.5, negative charge, and presence of protein coating on their surface. The antifungal activity of the AgNPs was evaluated on clinical strains of Candida albicans, and on the non-albicans species, Candida krusei, Candida glabrata, Candida parapsilosis, Candida tropicalis, and Candida guilliermondii, common in hospital infections, and against the phytopathogens Fusarium oxysporum, Fusarium phaseoli, Fusarium sacchari, Fusarium subglutinans, Fusarium verticillioides, and Curvularia lunata, which are species responsible for serious damage to agriculture production. The AgNPs were effective against the yeasts with MICs ranging from 1.25 to 40 µM and on the phytopathogens with MICs from 4 to 250 µM, indicating the promising possibility of application of these AgNPs as antifungal agents. The results indicated that the physicochemical parameters of the AgNPs, including the functional groups present on their surface, interfered with their antifungal activity. Overall, the results indicate that there is no specificity of the AgNPs for the yeasts or for the phytopathogens, which can be an advantage, increasing the possibility of application in different areas. Full article

Endophytic fungi inhabiting plant tissues show extensive functional diversity, ranging from mutualism to pathogenicity. The present study evaluated the histological responses of corn plants to colonization by three species of endophytic fungi isolated from corn. Corn seedlings were inoculated with 1 × 10⁶ conidia per mL spore suspensions of endophytic Fusarium verticillioides, Fusarium sacchari, and Penicillium citrinum and observed for 14 days for the emergence of disease symptoms. Histological examination of diseased root, stem, and leaf tissues was conducted using light and transmission electron microscopy. The results indicated that the mean diameters of root phloem, stem vascular bundles, and leaf vascular bundles, of corn plants infected with endophytic P. citrinum (18.91 µm, 146.96 µm, and 107.86 µm, respectively), F. verticillioides (18.75 µm, 85.45 µm, and 118.24 µm, respectively), and F. sacchari (24.15 µm root phloem, and 98.90 µm stem vascular bundle diameters), were significantly lower than the root phloem (33.68 µm), stem vascular bundle (186.77 µm), and leaf vascular bundle (155.88 µm) of the uninfected corn plants (p ≤ 0.05). Endophytic F. verticillioides was the most virulent, resulting in severe degradation and the eventual collapse of infected plant tissues. The study showed that endophytic fungi recovered from corn plants are capable of initiating significant disease responses in infected corn tissues. Full article

One of the causative agents of pokkah boeng disease (PBD), which affects sugarcane crops globally, is the fungus Fusarium sacchari. These fungal infections reduce sugar quality and yield, resulting in severe economic losses. Effector proteins play important roles in the interactions between pathogenic fungi and plants. Here, we used bioinformatic prediction approaches to identify 316 candidate secreted effector proteins (CSEPs) in the complete genome of F. sacchari. In total, 95 CSEPs contained known conserved structures, representing 40 superfamilies and 18 domains, while an additional 91 CSEPs contained seven known motifs. Of the 130 CSEPs containing no known domains or motifs, 14 contained one of four novel motifs. A heterogeneous expression system in Nicotiana benthamiana was used to investigate the functions of 163 CSEPs. Seven CSEPs suppressed BAX-triggered programmed cell death in N. benthamiana, while four caused cell death in N. benthamiana. The expression profiles of these eleven CSEPs during F. sacchari infection suggested that they may be involved in sugarcane-F. sacchari interaction. Our results establish a basis for further studies of the role of effector molecules in pathogen–sugarcane interactions, and provide a framework for future predictions of pathogen effector molecules. Full article

The re-emergence of the Fusarium wilt caused by Fusarium odoratissimum (F. odoratissimum) causes global banana production loss. Thirty-eight isolates of Fusarium species (Fusarium spp.) were examined for morphological characteristics on different media, showing the typical Fusarium spp. The phylogenetic trees of Fusarium isolates were generated using the sequences of histone gene (H3) and translation elongation factor gene (TEF-1α). Specific primers were used to confirm the presence of F. odoratissimum. The phylogenetic trees showed the rich diversity of the genus Fusarium related to Fusarium wilt, which consists of F. odoratissimum, Fusarium grosmichelii, Fusarium sacchari, and an unknown species of the Fusarium oxysporum species complex. By using Foc-TR4 specific primers, 27 isolates were confirmed as F. odoratissimum. A pathogenicity test was conducted for 30 days on five different local cultivars including, Musa acuminata (AAA, AA) and Musa paradisiaca (AAB, ABB). Although foliar symptoms showed different severity of those disease progression, vascular symptoms of the inoculated plantlet showed that infection was uniformly severe. Therefore, it can be concluded that the Fusarium oxysporum species complex related to Fusarium wilt of banana in Malaysia is rich in diversity, and F. odoratissimum has pathogenicity to local banana cultivars in Malaysia regardless of the genotype of the banana plants. Full article

In this study, twenty of the most common Fusarium species were molecularly characterized and inoculated on potato dextrose agar (PDA), rice and maize medium, where thirty three targeted mycotoxins, which might be the secondary metabolites of the identified fungal species, were detected by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Statistical analysis was performed with principal component analysis (PCA) to characterize the mycotoxin profiles for the twenty fungi, suggesting that these fungi species could be discriminated and divided into three groups as follows. Group I, the fusaric acid producers, were defined into two subgroups, namely subgroup I as producers of fusaric acid and fumonisins, comprising of F. proliferatum, F. verticillioides, F. fujikuroi and F. solani, and subgroup II considered to only produce fusaric acid, including F. temperatum, F. subglutinans, F. musae, F. tricinctum, F. oxysporum, F. equiseti, F. sacchari, F. concentricum, F. andiyazi. Group II, as type A trichothecenes producers, included F. langsethiae, F. sporotrichioides, F. polyphialidicum, while Group III were found to mainly produce type B trichothecenes, comprising of F. culmorum, F. poae, F. meridionale and F. graminearum. A comprehensive picture, which presents the mycotoxin-producing patterns by the selected fungal species in various matrices, is obtained for the first time, and thus from an application point of view, provides key information to explore mycotoxigenic potentials of Fusarium species and forecast the Fusarium infestation/mycotoxins contamination. Full article

The objective of this study was to identify Fusarium species in the Gibberella fujikuroi species complex from rice, sugarcane and maize as most of the Fusarium species in the species complex are found on the three crops. Isolates used were collected from the field and obtained from culture collection. The Fusarium isolates were initially sorted based on morphology and identifications confirmed based on the DNA sequence of the translation elongation factor 1-α (TEF-1α) gene. Based on the closest match of BLAST analysis, five species were recovered, namely, F. sacchari, F. fujikuroi, F. proliferatum, F. andiyazi and F. verticillioides. This is the first report regarding F. andiyazi from rice in Malaysia and Southeast Asia. The phylogenetic tree generated by using the neighbor joining method showed that isolates from the same species were grouped in the same clade. The present study indicated that Fusarium species in the G. fujikuroi species complex are widespread in rice, sugarcane and maize in Peninsular Malaysia. The findings also suggest that the use of morphological characters for identification of Fusarium species in the G. fujikuroi species complex from the three crops will lead to incorrect species designation. Full article