Functional Analysis of Autophagy-Related Gene ATG12 in Potato Dry Rot Fungus Fusarium oxysporum.

Autophagy is an intracellular process in all eukaryotes which is responsible for the degradation of cytoplasmic constituents, recycling of organelles, and recycling of proteins. It is an important cellular process responsible for the effective virulence of several pathogenic plant fungal strains, having critical impacts on important crop plants including potatoes. However, the detailed physiological mechanisms of autophagy involved in the infection biology of soil-borne pathogens in the potato crop needs to be investigated further. In this study, the autophagy-related gene, FoATG12, in potato dry rot fungus Fusarium oxysporum was investigated by means of target gene replacement and overexpression. The deletion mutant ∆FoATG12 showed reduction in conidial formation and exhibited impaired aerial hyphae. The FoATG12 affected the expression of genes involved in pathogenicity and vegetative growth, as well as on morphology features of the colony under stressors. It was found that the disease symptoms were delayed upon being inoculated by the deletion mutant of FoATG12 compared to the wild-type (WT) and overexpression (OE), while the deletion mutant showed the disease symptoms on tomato plants. The results confirmed the significant role of the autophagy-related ATG12 gene in the production of aerial hyphae and the effective virulence of F. oxysporum in the potato crop. The current findings provid an enhanced gene-level understanding of the autophagy-related virulence of F. oxysporum, which could be helpful in pathogen control research and could have vital impacts on the potato crop.

Oxidative functionalization of a halimane diterpenoid achieved by fungal transformation.

Regio and stereoselective activation of sp3 CH bonds remain one of the major advantages of biocatalysis over traditional chemocatalytic methods. Herein, we describe the oxy-functionalization of halimane diterpenoid 1 by whole cells of three filamentous fungi, aiming to obtain derivatives with desirable biological properties. After incubating 1 with Fusarium oxysporum, Myrothecium verrucaria, and Rhinocladiella similis at different concentrations and incubation times, four known (3, 5, 6, and 7) and three new (2, 4, and 8) halimane derivatives were obtained and characterized. F. oxysporum catalyzed the hydroxylation of positions C-2 (2) and C-7 (4), while R. similis simultaneously mediated the 2-oxo-functionalization and the hydration of 13,14-(CC)double bond belonging to an α,ß-unsaturated carbonyl system (8). Compounds 1-7 were non-cytotoxic against HCT-116 and MCF-7 cancer cell lines at tested concentrations. However, substrate 1 displayed moderate reduction ability against biofilm produced by Staphylococcus epidermidis ATCC35984 (84% at 1.6 mM), and this effect was retained to some extent by derivatives 4 and 7. These results emphasize the prominent potential of filamentous fungi associated with the microbiota of medicinal plants as versatile catalysts for singularly useful reactions through their complex enzymatic machinery, as well as the high susceptibility of halimane-diterpenoid substrates.

Identification and Characterization of Fusarium proliferatum, a New Species of Fungi that Cause Fungal Keratitis.

Fusarium proliferatum (F. proliferatum) is known as a pathogen of corn and other crops, but its role in fungal keratitis has not been well investigated. Among 877 Fusarium isolates, we identified 155 (17.7%) stains as F. proliferatum according to their morphological features and partial DNA sequencing of translation elongation factor-[Formula: see text] (EF-[Formula: see text]) in this study. In vitro antifungal susceptibility tests showed that the F. proliferatum strains were sensitive to natamycin and vorionazole but resistant to amphotericin B, fluconazol, ketoconazole and itaconazole. Most of the F. proliferatum-positive keratitis patients (44/155,28.4%) were aged 51-60 years old. The main cause of infection was injury by a plant (51/155, 32.9%). A combination of 1% amphotericin B and 3% ketoconazole cured 45.2% (14/31) and a combination of 0.5% natamycin and 0.5% voriconazole cured 59.1% (13/22) of F. proliferatum-positive patients. The date suggests that F. proliferatum identified through EF-1ɑ DNA sequencing is an important new species that causes fungal keratitis. Based on antifungal susceptibility, treatment with a combination of 0.5% natamycin and 0.5% voriconazole improves the therapeutic efficacy in F. prolifertum-positive patients.

Epitypification of Fusisporium (Fusarium) solani and its assignment to a common phylogenetic species in the Fusarium solani species complex.

Fusisporium solani was described as the causal agent of a dry rot of potato in Germany in the mid 19th century. As Fusarium solani, the species became known as a plurivorous plant pathogen, endophyte, decomposer, and opportunistic pathogen of humans and nutritional symbiont of insects. In parallel, it became evident that the morphologically defined species F. solani represents a phylogenetically and biologically complex group of often morphologically cryptic species that has come to be known in part as the F. solani species complex (FSSC), accommodating several formae speciales and mating populations/biological species. The FSSC currently includes more than 60 phylogenetic species. Several of these have been named, but the majority remains unnamed and the identity of F. solani sensu stricto is unclear. To promote further taxonomic developments in the FSSC, lectoand epitypification is proposed for Fusisporium solani Although no type material for F. solani is known to exist, the species was abundantly illustrated in the protologue. Thus, a relevant illustration provided by von Martius is selected as the lectotype. The epitype selected here originates from a rotting potato collected in a field in Slovenia. This strain causes a dry rot of artificially inoculated potatoes. It groups in the heretofore unnamed phylogenetic species 5, which is nested within clade 3 of the FSSC (FSSC 5). Members of this phylogenetic species have a wide geographic distribution and include soil saprotrophs and plant and opportunistic human pathogens. This typification is consistent with the original description of Fusisporium solani and the concept of F. solani as a widely distributed soil inhabitant and pathogen.

The F-box protein Fbp1 functions in the invasive growth and cell wall integrity mitogen-activated protein kinase (MAPK) pathways in Fusarium oxysporum.

F-box proteins determine substrate specificity of the ubiquitin-proteasome system. Previous work has demonstrated that the F-box protein Fbp1, a component of the SCF(Fbp1) E3 ligase complex, is essential for invasive growth and virulence of the fungal plant pathogen Fusarium oxysporum. Here, we show that, in addition to invasive growth, Fbp1 also contributes to vegetative hyphal fusion and fungal adhesion to tomato roots. All of these functions have been shown previously to require the mitogen-activated protein kinase (MAPK) Fmk1. We found that Fbp1 is required for full phosphorylation of Fmk1, indicating that Fbp1 regulates virulence and invasive growth via the Fmk1 pathway. Moreover, the Δfbp1 mutant is hypersensitive to sodium dodecylsulfate (SDS) and calcofluor white (CFW) and shows reduced phosphorylation levels of the cell wall integrity MAPK Mpk1 after SDS treatment. Collectively, these results suggest that Fbp1 contributes to both the invasive growth and cell wall integrity MAPK pathways of F. oxysporum.

Characterization of Fusarium secorum, a new species causing Fusarium yellowing decline of sugar beet in north central USA.

This study characterized a novel sugar beet (Beta vulgaris L.) pathogen from the Red River Valley in north central USA, which was formally named Fusarium secorum. Molecular phylogenetic analyses of three loci (translation elongation factor1α, calmodulin, mitochondrial small subunit) and phenotypic data strongly supported the inclusion of F. secorum in the Fusarium fujikuroi species complex (FFSC). Phylogenetic analyses identified F. secorum as a sister taxon of F. acutatum and a member of the African subclade of the FFSC. Fusarium secorum produced circinate hyphae sometimes bearing microconidia and abundant corkscrew-shaped hyphae in culture. To assess mycotoxin production potential, 45 typical secondary metabolites were tested in F. secorum rice cultures, but only beauvericin was produced in detectable amounts by each isolate. Results of pathogenicity experiments revealed that F. secorum isolates are able to induce half- and full-leaf yellowing foliar symptoms and vascular necrosis in roots and petioles of sugar beet. Inoculation with F. acutatum did not result in any disease symptoms. The sugar beet disease caused by F. secorum is named Fusarium yellowing decline. Since Fusarium yellowing decline incidence has been increasing in the Red River Valley, disease management options are discussed.

Combination antifungal therapy for disseminated fusariosis in immunocompromised patients : a case report and literature review.

Fusarium species are the second leading cause of disseminated mold infections in immunocompromised patients. The high mortality caused by such infections is attributed to the high resistance of Fusarium species to current antifungal agents. We report the first case of disseminated fusariosis after the use of alemtuzumab, an anti-CD52 monoclonal antibody, in a patient who presented with striking cutaneous and oral cavity lesions. Case reports of combination antifungal therapy for disseminated fusariosis in immunocompromised patients were reviewed. Among 19 published cases in the last 10 years plus this patient, the patients in 14 cases (70%) responded positively to combination antifungal therapy. A clinical response was achieved in seven cases before resolution of neutropenia.

Role of pyruvate and ascorbate production in regulation of antioxidant enzymes and membrane LPO levels in Fusarium acuminatum.

The role of pyruvate and ascorbate in the regulation of superoxide dismutase (SOD); catalase (CAT); glutathione peroxidase enzymes; and, therefore, membrane lipid peroxidation (LPO) levels in Fusarium acuminatum was investigated in media containing either glycerin or glucose as a carbon source, depending on the incubation period, in the range of 5-25 g/L. Increasing SOD activity between d 9 and 16 of the incubation period showed a positive correlation with a significant increase in pyruvate production up to 15 g/L of glycerin and glucose. In addition, maximum ascorbate production was observed at 15 g/L of glycerin as 82.5+/-2.1 and 20 g/L of glucose as 54+/-1.51, whereas CAT activity decreased with an increased concentration of both carbon sources. When compared with the LPO levels determined in media supplemented with glycerin and glucose, the minimum LPO level was 1.88+/-0.028 nmol of malondialdehyde/g wet wt at 15 g/L of glycerin on d 16, at which it was also observed to have a maximum pyruvate and ascorbate production and SOD, CAT, and GSH-Px activities of 75+/-1.42 microg/mL, 82.5+/-2.1 microg/mL, 32.5+/-0.634 microg/mL, 86.8+/-2.58 IU/mg, and 1.867 IU/mg, respectively. These results indicate that the biosynthesis of pyruvate and ascorbate may be involved in the regulation of antioxidant enzymes, depending on the glycerin and glucose concentrations, and also this defense network was effective in preventing membrane damage from oxidative stress.

Disseminated infection by Fusarium moniliforme during treatment for malignant lymphoma.

Disseminated infection caused by Fusarium moniliforme is described in a 32-year-old granulocytopenic man with malignant lymphoma being treated with cytotoxic drugs and corticosteroids. Infected skin denuded by antecedent severe varicella-zoster infection was the probable source of fungemia. F. moniliforme grows rapidly on common mycological media as a lavender- to violet-colored mold at 25 to 37 degrees C. Its aerial hyphae produce fusoid macroconidia and characteristic fusiform microconidia in chains. The morphology of hyphae in tissue closely resembles species of Aspergillus and is not diagnostically specific. Morphological characteristics which distinguish cultures of F. moniliforme from other medically important species of Fusarium are discussed.