Fulminant keratomycosis caused by Cylindrocarpon lichenicola- A case report.

PURPOSE: To report the clinical features, phylogenetic characteristics, microbiological characteristics, and the management of the rare emerging fungal species Cylindrocarpon lichenicola. METHODS: A 55-year-old male farmer presented with a history of pain, redness, and defective vision. The corneal scrapings revealed septate hyphae macroconidia and multi-celled chlamydospores with lactophenol cotton blue mount. In addition, the culture revealed velvety to floccose, white growth with a pinkish-brown rim on the Sabouraud's dextrose agar. The growth was suggestive of the rare fungus Cylindrocarpon lichenicola. RESULTS: The course of the infection was rapidly progressive, involving the entire cornea with descemetocele and impending perforation. Reinfection with the rapid spread of disease to the sclera was noted; finally, evisceration with scleral frill excision was done. CONCLUSION: To our knowledge, this is the first case report of Fulminant Sclero Keratomycosis caused by Cylindrocarpon lichenicola.

Molecular Identification and Analysis on Differential Pathogenicity of Cylindrocarpon Species Associated With Ginseng Root Rust Rot in Northeastern China.

Panax ginseng C. A. Meyer is one of the most important medicinal herbs in China. It is known for its high medicinal value and economic value. The ginseng root rust rot (RRR) has always been one of the important diseases troubling the ginseng industry. The yield reduction rate of RRR is ~30%. To understand why the Cylindrocarpon species bring about the ginseng RRR in Northeastern China, this study isolates 45 strains from samples collected in Liaoning, Jilin, and Heilongjiang provinces. The rDNA-internal transcribed spacer (ITS) sequence was analyzed to identify the pathogenic species. The morphological characteristics of colonies and conidia of each strain on potato dextrose agar (PDA) medium were observed, and the pathogenicity difference between different pathogenic species was analyzed by pricking method and determining the cell wall degrading enzyme activity. The BLAST alignment analysis shows that the homology of rDNA-ITS between 45 strains and Cylindrocarpon is more than 99%, among which 28 are identified as Cylindrocarpon destructans, three are identified as C. destructans var. destructans, and 14 are identified as Ilyonectria robusta. The colony diameters of all 45 isolated range from 4.21 ± 0.16a to 7.78 ± 0.25c cm after several days of incubation. Among all the species, I. robusta has the fastest growth rate, and C. destructans var. destructans has the slowest growth rate. Pathogenicity test results show that the pathogenicity of C. destructans var. destructans is the strongest, followed by C. destructans. I. robusta has relatively weak pathogenicity.

Evaluation of Fungicide Soil Drench Treatments to Manage Black Root Rot Disease of Avocado.

Four common fungicidal products were evaluated for their effect on symptoms caused by two nectriaceous black root rot fungi, Calonectria ilicicola and Dactylonectria macrodidyma, when applied as pot drenches to avocado (Persea americana) seedlings in the greenhouse. Applications of fludioxonil, thiophanate-methyl + etridiazole, prochloraz, and prochloraz MnCl at 2 and 4 weeks after inoculation with C. ilicicola significantly reduced root necrosis and improved root and aboveground plant biomass compared with water-treated controls. Fludioxonil reduced necrosis by 60% and had a significantly lower frequency of reisolation of C. ilicicola than the other three fungicide treatments. D. macrodidyma inoculation caused less severe symptoms in seedlings than C. ilicicola despite the longer duration of the trial. Pot drenches with fludioxonil, thiophanate-methyl + etridiazole, and prochloraz MnCl, but not prochloraz alone, significantly reduced root necrosis caused by D. macrodidyma. Prochloraz MnCl was the only fungicide treatment to increase root and plant biomass compared with water-treated controls. Both fludioxonil and prochloraz MnCl reduced the frequency of reisolation of D. macrodidyma from necrotic roots by about 50% compared with the other fungicides or water controls. The results indicated that drenches with these fungicides may suppress existing low to moderate black root rot infection, allowing new root growth and improved establishment in the orchard. Fungicide drenching must not replace best-practice disease management strategies in nurseries but may be a useful tool in crisis situations.

Fungal Keratitis Due to Fusarium lichenicola: A Case Report and Global Review of Fusarium lichenicola Keratitis.

Fusarium species are among the most commonly isolated causes of fungal keratitis. Most species of the genus Fusarium belong to Fusarium solani species complex (FSSC). Fusarium lichenicola, a member of the FSSC complex, is a well-established plant and human pathogen. However, reports of fungal keratitis due to Fusarium lichenicola have not been frequently reported. To the best of our knowledge, only twelve cases of Fusarium lichenicola keratitis have been reported in the past fifty years. Clinical cases of Fusarium lichenicola may have most likely been misidentified because of the lack of clinical and microbiological suspicion, as well as inadequate diagnostic facilities in many tropical countries where the burden of the disease may be the highest. We report a case of fungal keratitis caused by Fusarium lichenicola and present a global review of the literature of all cases of fungal keratitis caused by this potentially blinding fungus.

Mycotic keratitis due to Cylindrocarpon lichenicola: Successful salvage of the eye.

We hereby report a successfully salvaged eye due to mycotic keratitis by Cylindrocarpon lichenicola in a 60-year-old female from Kasaragod (Kerala). The patient came with a history of pain, photophobia and decreased vision of the right eye. The microbiological investigations of the corneal scraping revealed C. lichenicola. C. lichenicola is a soil saprophyte. Since the ulcer worsened paracentesis followed by therapeutic keratoplasty and adjunct therapy with natamycin drops, voriconazole drops and oral ketoconazole was given. We stress that evidence-based timely medical and surgical intervention helped in the restoration of the vision in an infected eye.

Inhibitory mechanism of 6-Pentyl-2H-pyran-2-one secreted by Trichoderma atroviride T2 against Cylindrocarpon destructans.

Root rot caused by Cylindrocarpon destructans is one of the most devastating diseases of Panax notoginseng, and Trichoderma species are potential agents for the biocontrol of fungal diseases. Thus, we screened a total of 10 Trichoderma isolates against C. destructans and selected Trichoderma atroviride T2 as an antagonistic strain for further research. 6-Pentyl-2H-pyran-2-one (6PP) was identified as an important active metabolite in the fermentation broth of the strain and exhibited antifungal activity against C. destructans. Transcriptome and metabolome analyses showed that 6PP significantly disturbed the metabolic homeostasis of C. destructans, particularly the metabolism of amino acids. By constructing a gene coexpression network, ECHS1 was identified as the hub gene correlated with 6PP stress. 6PP significantly downregulated the expression of ECHS1 at the transcriptional level and combined with the ECHS1 protein. Autophagy occurred in C. destructans cells under 6PP stress. In conclusion, 6PP may induce autophagy in C. destructans by downregulating ECHS1 at the transcriptional level and inhibiting ECHS1 protein activity. 6PP is a potential candidate for the development of new fungicides against C. destructans.

Taxonomy of fungal complex causing red-skin root of Panax ginseng in China.

BACKGROUND: Red-skin root of Asian ginseng (Panax ginseng) significantly reduces the quality and limits the production of ginseng in China. The disease has long been thought to be a noninfectious physiological disease, except one report that proved it was an infectious disease. However, the causal agents have not been successfully determined. In the present study, we were to reveal the pathogens that cause red-skin disease. METHODS: Ginseng roots with red-skin root symptoms were collected from commercial fields in Northeast China. Fungi were isolated from the lesion and identified based on morphological characters along with multilocus sequence analyses on internal transcription spacer, ß-tubulin (tub2), histone H3 (his3), and translation elongation factor 1α (tef-1α). Pathogens were confirmed by inoculating the isolates in ginseng roots. RESULTS: A total of 230 isolates were obtained from 209 disease samples. These isolates were classified into 12 species, including Dactylonectria sp., D. hordeicola, Fusarium acuminatum, F. avenaceum, F. solani, F. torulosum, Ilyonectria mors-panacis, I. robusta, Rhexocercosporidium panacis, and three novel species I. changbaiensis, I. communis, and I. qitaiheensis. Among them, I. communis, I. robusta, and F. solani had the highest isolation frequencies, being 36.1%, 20.9%, and 23.9%, respectively. All these species isolated were pathogenic to ginseng roots and caused red-skin root disease under appropriate condition. CONCLUSION: Fungal complex is the causal agent of red-skin root in P. ginseng.

Transcriptome analyses of the ginseng root rot pathogens Cylindrocarpon destructans and Fusarium solani to identify radicicol resistance mechanisms.

BACKGROUND: The ascomycete fungi Cylindrocarpon destructans (Cd) and Fusarium solani (Fs) cause ginseng root rot and significantly reduce the quality and yield of ginseng. Cd produces the secondary metabolite radicicol, which targets the molecular chaperone Hsp90. Fs is resistant to radicicol, whereas other fungal genera associated with ginseng disease are sensitive to it. Radicicol resistance mechanisms have not yet been elucidated. METHODS: Transcriptome analyses of Fs and Cd mycelia treated with or without radicicol were conducted using RNA-seq. All of the differentially expressed genes (DEGs) were functionally annotated using the Fusarium graminearum transcript database. In addition, deletions of two transporter genes identified by RNA-seq were created to confirm their contributions to radicicol resistance. RESULTS: Treatment with radicicol resulted in upregulation of chitin synthase and cell wall integrity genes in Fs and upregulation of nicotinamide adenine dinucleotide dehydrogenase and sugar transporter genes in Cd. Genes encoding an ATP-binding cassette transporter, an aflatoxin efflux pump, ammonium permease 1 (mep1), and nitrilase were differentially expressed in both Fs and Cd. Among these four genes, only the ABC transporter was upregulated in both Fs and Cd. The aflatoxin efflux pump and mep1 were upregulated in Cd, but downregulated in Fs, whereas nitrilase was downregulated in both Fs and Cd. CONCLUSION: The transcriptome analyses suggested radicicol resistance pathways, and deletions of the transporter genes indicated that they contribute to radicicol resistance.

Occurrence and Diversity of Black-Foot Disease Fungi in Symptomless Grapevine Nursery Stock in Spain.

In this study, 3,426 grafted grapevines ready to be planted from 15 grapevine nursery fields in Northern Spain were inspected from 2016 to 2018 for black-foot causing pathogens. In all, 1,427 isolates of black-foot pathogens were collected from the asymptomatic inner tissues of surface sterilized secondary roots and characterized based on morphological features and DNA sequence data of the nuclear ribosomal DNA-internal transcribed spacer region, histone H3, translation elongation factor 1-alpha and ß-tubulin genes. Eleven species belonging to the genera Dactylonectria, Ilyonectria, Neonectria, and Thelonectria were identified, including Dactylonectria alcacerensis, D. macrodidyma, D. novozelandica, D. pauciseptata, D. torresensis, Ilyonectria liriodendri, I. pseudodestructans, I. robusta, Neonectria quercicola, Neonectria sp. 1, and Thelonectria olida. In addition, two species are newly described, namely D. riojana and I. vivaria. Twenty-four isolates representing 13 black-foot species were inoculated onto grapevine seedlings cultivar 'Tempranillo'. The pathogenicity tests detected diversity in virulence among fungal species and between isolates within each species. The most virulent species was D. novozelandica isolate BV-0760, followed by D. alcacerensis isolate BV-1240 and I. vivaria sp. nov. isolate BV-2305. This study improves our knowledge on the etiology and virulence of black-foot disease pathogens, and opens up new perspectives in the study of the endophytic phase of these pathogens in grapevines.

Diversity of bacterial endophytes in Panax ginseng and their protective effects against pathogens.

Although endophytic bacteria are known to colonize Panax ginseng, little is known about their diversity and roles. We addressed in the present study by comparing endophytic bacterial populations in P. ginseng plants of different ages (2-6 years) and in various tissue types (root, stem, leaf, and flower stalk). A total of 116 strains assigned to 42 species were identified by 16S rDNA sequencing. The predominant phylum was Firmicutes. Two-year-old ginseng plants and root tissues showed the greatest diversity of endophytic bacteria, with Bacillales being the predominant order. The antifungal activity of isolates against two pathogens, Cylindrocarpon destructans and/or Botrytis cinerea, was evaluated in dual-culture assays. In total, 28 strains showed antifungal activity with PgBE14 (Bacillus amyloliquefaciens), PgBE40 (B. megaterium), PgBE39, PgBE45 (Pseudomonas frederiksbergensis), and PgBE42 (Staphylococcus saprophyticus) inhibiting both pathogens. These results improve our understanding of the structure and diversity of endophytic bacterial communities of P. ginseng and identify strains with antifungal activity that have potential applications as biocontrol agents.

Metabolites from the endophytic fungus Cylindrocarpon sp. isolated from tropical plant Sapium ellipticum.

Three new polyketides, cylindrocarpones A-C (1-3), two new pyridone alkaloids, cylindrocarpyridones A-B (5-6), a new pyrone cylindropyrone (7), together with seven know compounds were isolated from the endophytic fungus, Cylindrocarpon sp., obtained from the tropical plant Sapium ellipticum. The structures of the new compounds were elucidated by extensive analysis of their spectroscopic data (1D and 2D NMR, HRESIMS). The absolute configuration of 19-O-methyl-pyrrocidine B (13) was confirmed by X-ray analysis. All isolated compounds were screened for their cytotoxic and antibacterial activities. Pyrrocidine A (12) exhibited potent cytotoxicity against the human ovarian cancer cell line A2780 with an IC50 value of 1.7 µM. 19-O-Methyl-pyrrocidine B (13) showed moderate antibacterial activity against S. aureus ATCC25923 and ATCC700699 with MIC values of 50 and 25 µM, respectively.

Cylindrocarpon destructans/Ilyonectria radicicola-species complex: Causative agent of ginseng root-rot disease and rusty symptoms.

Cylindrocarpon destructans/Ilyonectria radicicola is thought to cause both rusty symptom and root-rot disease of American and Korean ginseng. Root-rot disease poses a more serious threat to ginseng roots than rusty symptoms, which we argue result from the plant defense response to pathogen attack. Therefore, strains causing rotten root are characterized as more aggressive than strains causing rusty symptoms. In this review, we state 1- the molecular evidence indicating that the root-rot causing strains are genetically distinct considering them as a separate species of Ilyonectria, namely I. mors-panacis and 2- the physiological and biochemical differences between the weakly and highly aggressive species as well as those between rusty and rotten ginseng plants. Eventually, we postulated that rusty symptom occurs on ginseng roots due to incompatible interactions with the weakly aggressive species of Ilyonectria, by the established iron-phenolic compound complexes while root-rot is developed by I. mors-panacis infection due to the production of high quantities of hydrolytic and oxidative fungal enzymes which destroy the plant defensive barriers, in parallel with the pathogen growth stimulation by utilizing the available iron. Furthermore, we highlight future areas for study that will help elucidate the complete mechanism of root-rot disease development.

Ginsenosides and ginsenosidases in the pathobiology of ginseng-Cylindrocarpon destructans (Zinss) Scholten.

To investigate the role that ginsenosides (and some of their metabolites) play in interactions between plants and phytopathogenic fungi (e.g. Cylindrocarpon destructans (Zinss) Scholten), we systematically determined the anti-fungal activities of six major ginsenosides (Rb1, Rb2, Rc, Rd, Re and Rg1), along with the metabolites of ginsenoside Rb1 (Gypenoside XVII (G-XVII) and F2), against the ginseng root pathogen C. destructans (Zinss) Scholten and non-ginseng pathogens Fusarium graminearum Schw., Exserohilum turcicum (Pass.) Leonard et Suggs, Phytophthora megasperma Drech. and Pyricularia oryzae Cav. Our results showed that the growth of both ginseng pathogens and non-pathogens could be inhibited by using the proto-panaxatriol (PPT) ginsenosides Re and Rg1. In addition, the growth of the non-pathogens could also be inhibited by using proto-panaxadiol (PPD) ginsenosides Rb1, Rb2, Rc and Rd, whereas the growth of ginseng pathogen C. destructans (Zinss) Scholten was enhanced by ginsenosides Rb1 and Rb2. In contrast, ginsenoside G-XVII and F2 strongly inhibited the hyphal growth of both C. destructans (Zinss) Scholten and the non-pathogens tested. Furthermore, addition of sucrose to the media increased the growth of C. destructans (Zinss) Scholten, whereas glucose did not affect the growth. Moreover, C. destructans (Zinss) Scholten and all four non-pathogens were able to deglycosylate PPD ginsenosides using a similar transformation pathway, albeit with different sensitivities. We also discussed the anti-fungal structure-activity relationships of the ginsenosides. Our results suggest that the pathogenicity of C. destructans (Zinss) Scholten against ginseng root is independent of its ability to deglycosylate ginsenosides.

New Metabolites Produced by Cylindrocarpon sp. SY-39 from a Driftwood.

Four novel compounds, cylindropyrone A (1), 10'-hydroxyilicicolinic acid D (3), cylindrolactones A (4) and B (5), together with known dihydroinfectopyrone (2) were isolated from the culture of Cylindrocarpon sp. SY-39 from a driftwood. Their structures were elucidated using 1D- and 2D-NMR spectroscopy. Compound 3 showed antimicrobial activity against Staphylococcus aureus with MIC value of 5.0 µg/mL.

Spectroscopic characterisation of two polyketide metabolites from Cylindrocarpon sp. from driftwood.

Two new polyketides, (5R,7R,9R)-7,9-dihydroxy-5-decanolide and (4E,6R,9R)- 6,9-dihydroxydec-4-enoic acid (2), were isolated from rice cultures of Cylindrocarpon sp. SY-39 discovered during screening of driftwood at a Shonai coast area in Yamagata, Japan. The structures of 1 and 2 were determined using a variety of spectroscopic methods. Compound 2 exhibited moderate antimicrobial activity against Staphylococcus aureus NBRC 13276 and Aspergillus clavatus F 318a at a concentration of 50 µg per disk.

The Effect of Fungicides on Mycelial Growth and Conidial Germination of the Ginseng Root Rot Fungus, Cylindrocarpon destructans.

Ginseng root rot caused by Cylindrocarpon destructans is the most destructive disease of ginseng. Six different fungicides (thiophanate-methyl, benomyl, prochloraz, mancozeb, azoxystrobin, and iprodione) were selected to evaluate the inhibitory effect on the mycelial growth and conidial germination of C. destructans isolates. Benomyl and prochloraz were found to be the most effective fungicides in inhibiting mycelial growth of all tested isolates, showing 64.7% to 100% inhibition at a concentration of 10 µg/mL, whereas thiophanate-methyl was the least effective fungicide, showing less than 50% inhibition even at a higher concentration of 100 µg/mL. The tested fungicides exhibited less than 20% inhibition of conidium germination at concentrations of 0.01, 0.1, and 1 µg/mL. However, the inhibition effect of mancozeb on condium germination of C. destructans was significantly increased to 92% to 99% at a higher concentration of 100 µg/mL, while the others still showed no higher than 30% inhibition.

Antagonistic Evaluation of Chromobacterium sp. JH7 for Biological Control of Ginseng Root Rot Caused by Cylindrocarpon destructans.

Cylindrocarpon destructans is an ascomycete soil-borne pathogen that causes ginseng root rot. To identify effective biocontrol agents, we isolated several bacteria from ginseng cultivation soil and evaluated their antifungal activity. Among the isolated bacteria, one isolate (named JH7) was selected for its high antibiotic activity and was further examined for antagonism against fungal pathogens. Strain JH7 was identified as a Chromobacterium sp. using phylogenetic analysis based on 16S rRNA gene sequences. This strain was shown to produce antimicrobial molecules, including chitinases and proteases, but not cellulases. Additionally, the ability of JH7 to produce siderophore and solubilize insoluble phosphate supports its antagonistic and beneficial traits for plant growth. The JH7 strain suppressed the conidiation, conidial germination, and chlamydospore formation of C. destructans. Furthermore, the JH7 strain inhibited other plant pathogenic fungi. Thus, it provides a basis for developing a biocontrol agent for ginseng cultivation.

Chlamydospore Induction from Conidia of Cylindrocarpon destructans Isolated from Ginseng in Korea.

Cylindrocarpon destructans causes root rot disease in ginseng and can survive for a long time, producing chlamydospores. We optimized conditions to induce chlamydospore production from the conidia of C. destructans, isolated from Korean ginseng. This will provide the basis for testing the efficacy of control agents targeting these chlamydospores.

Tinea pedis due to Cylindrocarpon lichenicola beginning onycholysis.

A 33 year old woman presented with both feet, humid and white Tinea pedis at the second, third and fourth inter-toes areas associated with a beginning onycholysis of the nails lasting for 18 months. KOH mount of the samples was positive for fungal hyphae. The fungus was isolated on Sabouraud-chlorampphenicol agar and identified as Cylindrocarpon lichenicola. The patient was treated with an association of terbinafine tablet and terbinafine cream and presented clinical cure after three months.