Quantitative Analysis of Fungal Contamination of Different Herbal Medicines in China

Herbal medicines are widely used for clinical purposes worldwide. These herbs are susceptible to phytopathogenic fungal invasion during the culturing, harvesting, storage, and processing stages. The threat of fungal and mycotoxin contamination requires the evaluation of the health risks associated with these herbal medicines. In this study, we collected 138 samples of 23 commonly used herbs from 20 regions in China, from which we isolated a total of 200 phytopathogenic fungi. Through morphological observation and ITS sequencing, 173 fungal isolates were identified and classified into 24 genera, of which the predominant genera were Fusarium (27.74%) and Alternaria (20.81%), followed by Epicoccum (11.56%), Nigrospora (7.51%), and Trichocladium (6.84%). Quantitative analysis of the abundance of both Fusarium and Alternaria in herbal medicines via RT-qPCR revealed that the most abundant fungi were found on the herb Taraxacum mongolicum, reaching 300,000 copies/μL for Fusarium and 700 copies/μL for Alternaria. The in vitro mycotoxin productivities of the isolated Fusarium and Alternaria strains were evaluated by using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and it was found that the Fusarium species mainly produced the acetyl forms of deoxynivalenol, while Alternaria species mainly produced altertoxins. These findings revealed widely distributed fungal contamination in herbal medicines and thus raise concerns for the sake of the quality and safety of herbal medicines.

Con7 is a key transcription regulator for conidiogenesis in the plant pathogenic fungus Fusarium graminearum

The mycelium of the plant pathogenic fungus Fusarium graminearum exhibits distinct structures for vegetative growth, asexual sporulation, sexual development, virulence, and chlamydospore formation. These structures are vital for the survival and pathogenicity of the fungus, necessitating precise regulation based on environmental cues. Initially identified in Magnaporthe oryzae, the transcription factor Con7p regulates conidiation and infection-related morphogenesis, but not vegetative growth. We characterized the Con7p ortholog FgCon7, and deletion of FgCON7 resulted in severe defects in conidium production, virulence, sexual development, and vegetative growth. The mycelia of the deletion mutant transformed into chlamydospore-like structures with high chitin level accumulation. Notably, boosting FgABAA expression partially alleviated developmental issues in the FgCON7 deletion mutant. Chromatin immunoprecipitation (ChIP)-quantitative PCR (qPCR) analysis confirmed a direct genetic link between FgABAA and FgCON7. Furthermore, the chitin synthase gene Fg6550 (FGSG_06550) showed significant upregulation in the FgCON7 deletion mutant, and altering FgCON7 expression affected cell wall integrity. Further research will focus on understanding the behavior of the chitin synthase gene and its regulation by FgCon7 in F. graminearum. This study contributes significantly to our understanding of the genetic pathways that regulate hyphal differentiation and conidiation in this plant pathogenic fungus.

IMPORTANCE

The ascomycete fungus Fusarium graminearum is the primary cause of head blight disease in wheat and barley, as well as ear and stalk rot in maize. Given the importance of conidia and ascospores in the disease cycle of F. graminearum, precise spatiotemporal regulation of these biological processes is crucial. In this study, we characterized the Magnaporthe oryzae Con7p ortholog and discovered that FgCon7 significantly influences various crucial aspects of fungal development and pathogenicity. Notably, overexpression of FgABAA partially restored developmental defects in the FgCON7 deletion mutant. ChIP-qPCR analysis confirmed a direct genetic link between FgABAA and FgCON7. Furthermore, our research revealed a clear correlation between FgCon7 and chitin accumulation and the expression of chitin synthase genes. These findings offer valuable insights into the genetic mechanisms regulating conidiation and the significance of mycelial differentiation in this plant pathogenic fungus.

Comparison of clinical outcomes of patients with serial negative surveillance cultures according to a subsequent polymerase chain reaction test for carbapenemase-producing Enterobacterales

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) are of serious concern worldwide due to high morbidity and mortality.

AIM

To evaluate the impact of the result of a subsequent polymerase chain reaction (PCR) test for carbapenemase after serial negative surveillance cultures on positive culture conversion in patients with three consecutive negative surveillance cultures for CPE, and to identify risk factors for conversion.

METHODS

A retrospective study of patients with positive CPE cultures on CHROMagar KPC medium was performed in a Korean tertiary hospital from October 2018 to December 2022. PCR for blaKPC, blaNDM, blaIMP, blaVIM, blaGES, and blaOXA-48 was performed after three consecutive negative rectal swab cultures. Clinical characteristics and outcomes of patients were compared according to whether follow-up PCR was positive (CNPP) or negative (CNPN).

FINDINGS

Of 1075 patients with positive CPE cultures, 150 (14.0%) yielded three consecutive negative rectal swab cultures. Of these, 50 (33.3%) were CNPP, and 100 (66.7%) were CNPN. Risk factors associated with a positive PCR result on multivariate analysis were: age, central venous catheter, and Escherichia coli infection. CNPP patients were more likely to have positive culture conversion for CPE than CNPN patients (39/44 (88.6%) vs 21/50 (42.0%), P<0.001). In multivariate analysis, independent risk factors for culture conversion were: a positive PCR result after surveillance cultures, diabetes mellitus, central venous catheter, and Klebsiella pneumoniae.

CONCLUSION

CNPP patients have higher rates of culture conversion than CNPN patients, and a follow-up PCR test after serial negative surveillance cultures is useful in deciding whether or not to discontinue contact precautions.

Sulfur metabolism-mediated fungal glutathione biosynthesis is essential for oxidative stress resistance and pathogenicity in the plant pathogenic fungus Fusarium graminearum

IMPORTANCE

Fusarium graminearum is a destructive fungal pathogen that causes Fusarium head blight (FHB) on a wide range of cereal crops. To control fungal diseases, it is essential to comprehend the pathogenic mechanisms that enable fungi to overcome host defenses during infection. Pathogens require an oxidative stress response to overcome host-derived oxidative stress. Here, we identify the underlying mechanisms of the Fgbzip007-mediated oxidative stress response in F. graminearum. ChIP-seq and subsequent genetic analyses revealed that the role of glutathione in pathogenesis is not dependent on antioxidant functions in F. graminearum. Altogether, this study establishes a comprehensive framework for the Fgbzip007 regulon on pathogenicity and oxidative stress responses, offering a new perspective on the role of glutathione in pathogenicity.

A Hydrolase Produced by Rhodococcus erythropolis HQ Is Responsible for the Detoxification of Zearalenone

Zearalenone (ZEN), an estrogenic mycotoxin, is one of the prevalent contaminants found in food and feed, posing risks to human and animal health. In this study, we isolated a ZEN-degrading strain from soil and identified it as Rhodococcus erythropolis HQ. Analysis of degradation products clarified the mechanism by which R. erythropolis HQ degrades ZEN. The gene zenR responsible for degrading ZEN was identified from strain HQ, in which zenR is the key gene for R. erythropolis HQ to degrade ZEN, and its expression product is a hydrolase named ZenR. ZenR shared 58% sequence identity with the hydrolase ZenH from Aeromicrobium sp. HA, but their enzymatic properties were significantly different. ZenR exhibited maximal enzymatic activity at pH 8.0-9.0 and 55 °C, with a Michaelis constant of 21.14 μM, and its enzymatic activity is 2.8 times that of ZenH. The catalytic triad was identified as S132-D157-H307 via molecular docking and site-directed mutagenesis. Furthermore, the fermentation broth of recombinant Bacillus containing ZenR can be effectively applied to liquefied corn samples, with the residual amount of ZEN decreased to 0.21 μg/g, resulting in a remarkable ZEN removal rate of 93%. Thus, ZenR may serve as a new template for the modification of ZEN hydrolases and a new resource for the industrial application of biological detoxification. Consequently, ZenR could potentially be regarded as a novel blueprint for modifying ZEN hydrolases and as a fresh resource for the industrial implementation of biological detoxification.

HapX-mediated H2B deub1 and SreA-mediated H2A.Z deposition coordinate in fungal iron resistance

Plant pathogens are challenged by host-derived iron starvation or excess during infection, but the mechanism through which pathogens counteract iron stress is unclear. Here, we found that Fusarium graminearum encounters iron excess during the colonization of wheat heads. Deletion of heme activator protein X (FgHapX), siderophore transcription factor A (FgSreA) or both attenuated virulence. Further, we found that FgHapX activates iron storage under iron excess by promoting histone H2B deubiquitination (H2B deub1) at the promoter of the responsible gene. Meanwhile, FgSreA is shown to inhibit genes mediating iron acquisition during iron excess by facilitating the deposition of histone variant H2A.Z and histone 3 lysine 27 trimethylation (H3K27 me3) at the first nucleosome after the transcription start site. In addition, the monothiol glutaredoxin FgGrx4 is responsible for iron sensing and control of the transcriptional activity of FgHapX and FgSreA via modulation of their enrichment at target genes and recruitment of epigenetic regulators, respectively. Taken together, our findings elucidated the molecular mechanisms for adaptation to iron excess mediated by FgHapX and FgSreA during infection in F. graminearum and provide novel insights into regulation of iron homeostasis at the chromatin level in eukaryotes.

A combined transcriptomic and physiological approach to understanding the adaptive mechanisms to cope with oxidative stress in Fusarium graminearum

In plant-pathogen interactions, oxidative bursts are crucial for plants to defend themselves against pathogen infections. Rapid production and accumulation of reactive oxygen species kill pathogens directly and cause local cell death, preventing pathogens from spreading to adjacent cells. Meanwhile, the pathogens have developed several mechanisms to tolerate oxidative stress and successfully colonize plant tissues. In this study, we investigated the mechanisms responsible for resistance to oxidative stress by analyzing the transcriptomes of six oxidative stress-sensitive strains of the plant pathogenic fungus Fusarium graminearum. Weighted gene co-expression network analysis identified several pathways related to oxidative stress responses, including the DNA repair system, autophagy, and ubiquitin-mediated proteolysis. We also identified hub genes with high intramodular connectivity in key modules and generated deletion or conditional suppression mutants. Phenotypic characterization of those mutants showed that the deletion of FgHGG4, FgHGG10, and FgHGG13 caused sensitivity to oxidative stress, and further investigation on those genes revealed that transcriptional elongation and DNA damage responses play roles in oxidative stress response and pathogenicity. The suppression of FgHGL7 also led to hypersensitivity to oxidative stress, and we demonstrated that FgHGL7 plays a crucial role in heme biosynthesis and is essential for peroxidase activity. This study increases the understanding of the adaptive mechanisms to cope with oxidative stress in plant pathogenic fungi. IMPORTANCE Fungal pathogens have evolved various mechanisms to overcome host-derived stresses for successful infection. Oxidative stress is a representative defense system induced by the host plant, and fungi have complex response systems to cope with it. Fusarium graminearum is one of the devastating plant pathogenic fungi, and understanding its pathosystem is crucial for disease control. In this study, we investigated adaptive mechanisms for coping with oxidative stress at the transcriptome level using oxidative stress-sensitive strains. In addition, by introducing genetic modification technique such as CRISPR-Cas9 and the conditional gene expression system, we identified pathways/genes required for resistance to oxidative stress and also for virulence. Overall, this study advances the understanding of the oxidative stress response and related mechanisms in plant pathogenic fungi.

Genetic and Transcriptional Regulatory Mechanisms of Lipase Activity in the Plant Pathogenic Fungus Fusarium graminearum

Lipases, which catalyze the hydrolysis of long-chain triglycerides, diglycerides, and monoglycerides into free fatty acids and glycerol, participate in various biological pathways in fungi. In this study, we examined the biological functions and regulatory mechanisms of fungal lipases via two approaches. First, we performed a systemic functional characterization of 86 putative lipase-encoding genes in the plant-pathogenic fungus Fusarium graminearum. The phenotypes were assayed for vegetative growth, asexual and sexual reproduction, stress responses, pathogenicity, mycotoxin production, and lipase activity. Most mutants were normal in the assessed phenotypes, implying overlapping roles for lipases in F. graminearum. In particular, FgLip1 and Fgl1 were revealed as core extracellular lipases in F. graminearum. Second, we examined the lipase activity of previously constructed transcription factor (TF) mutants of F. graminearum and identified three TFs and one histone acetyltransferase that significantly affect lipase activity. The relative transcript levels of FgLIP1 and FGL1 were markedly reduced or enhanced in these TF mutants. Among them, Gzzc258 was identified as a key lipase regulator that is also involved in the induction of lipase activity during sexual reproduction. To our knowledge, this study is the first comprehensive functional analysis of fungal lipases and provides significant insights into the genetic and regulatory mechanisms underlying lipases in fungi. IMPORTANCE Fusarium graminearum is an economically important plant-pathogenic fungus that causes Fusarium head blight (FHB) on wheat and barley. Here, we constructed a gene knockout mutant library of 86 putative lipase-encoding genes and established a comprehensive phenotypic database of the mutants. Among them, we found that FgLip1 and Fgl1 act as core extracellular lipases in this pathogen. Moreover, several putative transcription factors (TFs) that regulate the lipase activities in F. graminearum were identified. The disruption mutants of F. graminearum-lipase regulatory TFs all showed defects in sexual reproduction, which implies a strong relationship between sexual development and lipase activity in this fungus. These findings provide valuable insights into the genetic mechanisms regulating lipase activity as well as its importance to the developmental stages of this plant-pathogenic fungus.

Antifungal activities of a novel triazole fungicide, mefentrifluconazole, against the major maize pathogen Fusarium verticillioides

Fusarium ear rot (FER) is a serious fungal disease occurring the late growth stage of maize. FER not only reduces the yield of maize but also causes mycotoxin contamination, which affects the quality of maize and threatens human and animal health. Fusarium verticillioides is the predominant causative pathogen of FER worldwide. At present, there is no registered fungicide for use against maize FER in China. The novel isopropyl alcohol-triazole fungicide mefentrifluconazole (MFZ) has been shown to be effective against several Fusarium spp., but little is known about its specific activity against F. verticillioides. MFZ exhibited strong antifungal activities against 50 strains of F. verticillioides collected from the major maize-growing areas in China. MFZ inhibited mycelial growth, conidium production, germination and germ tube elongation of F. verticillioides. MFZ treatment significantly reduced fumonisin production and the expression levels of fumonisin biosynthetic genes. Genome-wide transcriptional profiling of F. verticillioides in response to MFZ indicated that the expression of genes involved in ergosterol biosynthesis, including fungicide target genes (cyp51 genes), was significantly downregulated by MFZ. MFZ treatment resulted in reduced ergosterol production and increased glycerol and malonaldehyde production as well as relative conductivity in F. verticillioides. A 2-year field experiment showed a significant reduction in FER severity in maize after spraying with MFZ at the tasseling stage. This study evaluated the potential of MFZ to control FER in maize and provides insights into its antifungal activities and mechanism of action against F. verticillioides.

Paralogous FgIDO genes with differential roles in tryptophan catabolism, fungal development and virulence in Fusarium graminearum

Indoleamine 2,3-dioxygenase (Ido) is a tryptophan-degrading enzyme that is widely distributed across species. Ido catalyzes the first step of tryptophan (TRP) degradation and drives the de novo synthesis of nicotinamide adenine dinucleotide (NAD⁺) coenzymes via the kynurenine (KYN) pathway. The budding yeast Saccharomyces cerevisiae possesses a single IDO gene (BNA2) that is responsible for NAD⁺ synthesis, whereas a number of fungal species contain multiple IDO genes. However, the biological roles of IDO paralogs in plant pathogens remain unclear. In the current study, we identified three FgIDOs from the wheat head blight fungus Fusarium graminearum. FgIDOA/B/C expression was significantly induced upon TRP treatment. Targeted disruption of FgIDOA and/or FgIDOB caused different levels of NAD⁺ auxotrophy, thus resulting in pleotropic phenotypic defects. Loss of FgIDOA resulted in abnormal conidial morphology, reduced mycelial growth, decreased virulence in wheat heads and reduced deoxynivalenol accumulation. Exogenous addition of KYN or various intermediates involved in the KYN pathway rescued auxotrophy of the mutants. Metabolomics analysis revealed shifts toward alternative TRP degradation pathways to melatonin and indole derivatives in mutants lacking FgIDOB. Upregulation of partner genes in auxotrophic mutants and the capacity to rescue the auxotroph by overexpressing a partner gene indicated functional complementation among FgIDOA/B/C. Taken together, the results of this study provide insights into differential roles in paralogous FgIDOs and how fungal TRP catabolism modulates fungal development and virulence.

Effect of Crop Rotation on Fusarium Mycotoxins and Fusarium Species in Cereals in Sichuan Province (China)

The present study was performed to evaluate the effect of crop rotation on Fusarium mycotoxins and species in cereals in Sichuan Province. A total of 311 cereal samples were randomly collected and analyzed from 2018 to 2019 in Sichuan Province. The results of mycotoxin analysis showed that the major trichothecene mycotoxins in Sichuan Province were nivalenol (NIV) and deoxynivalenol (DON), and the mean concentration of total trichothecenes (including NIV, fusarenone X [4ANIV], DON, 3-acetyldeoxynivalenol [3ADON], and 15-acetyldeoxynivalenol [15ADON]) in wheat was significantly higher than that in maize and rice. The concentration of total trichothecenes in the succeeding crops was significantly higher than that in the previous crops. In addition, wheat grown after maize had reduced incidence and concentration of trichothecene mycotoxins compared with that grown after rice, and ratooning rice grown after rice had increased incidence and concentration of trichothecene mycotoxins. Our data indicated that Fusarium asiaticum with the NIV chemotype was predominant in wheat and rice samples, while the number of the NIV chemotypes of F. asiaticum and Fusarium meridionale and the 15ADON chemotype of Fusarium graminearum in maize were almost the same. Although the composition of Fusarium species was affected by crop rotations, there were no differences when comparing the same crop rotation except for the maize-wheat rotation. Moreover, the same species and chemotype of Fusarium strains originated from different crops in various rotations, but there were no significant differences in pathogenicity in wheat and rice. These results contribute to the knowledge of the effect of crop rotation on Fusarium mycotoxins and species affecting cereals in Sichuan Province, which may lead to improved strategies for control of Fusarium mycotoxins and fungal disease in China.

New Hydrolase from Aeromicrobium sp. HA for the Biodegradation of Zearalenone: Identification, Mechanism, and Application

Zearalenone (ZEN) is an estrogenic mycotoxin most frequently found in cereals that can cause reproductive disorders in livestock and pose a severe threat to animal husbandry. In this study, we isolated a ZEN-degrading Aeromicrobium strain from soil and found that ZenH, a hydrolase, is responsible for the hydrolysis of ZEN through comparative proteomics and biochemical studies. ZenH exhibited the highest similarity with lactone hydrolase ZHD607 from Phialophora americana at 21.52%. ZenH displayed maximal enzymatic activity at pH 7.0 and 55 °C with a Michaelis constant of 12.64 μM. The catalytic triad of ZenH was identified as S117-D142-H292 by molecular docking and site-directed mutagenesis. ZenH catalyzed the hydrolysis of ZEN to a novel metabolite, (S,E)-4-hydroxy-2-(10-hydroxy-6-oxoundec-1-en-1-yl)-7-oxabicyclo[4.2.0]octa-1,3,5-trien-8-one, which exhibited significantly lower estrogenic toxicity than ZEN. This study illustrates a novel ZEN-degrading enzyme and reveals a new degradation product. Furthermore, the enzyme showed good potential for detoxifying ZEN during food processing.

The autophagy-related proteins FvAtg4 and FvAtg8 are involved in virulence and fumonisin biosynthesis in Fusarium verticillioides

Autophagy is the main intracellular degradation system by which cytoplasmic materials are transported to and degraded in the vacuole/lysosome of eukaryotic cells, and it also controls cellular differentiation and virulence in a variety of filamentous fungi. However, the contribution of the autophagic pathway to fungal development and pathogenicity in the important maize pathogen and mycotoxigenic fungus Fusarium verticillioides is still unknown. In this study, we characterized two autophagy-related proteins, FvAtg4 and FvAtg8. The F. verticillioides deletion mutants ΔFvAtg4 and ΔFvAtg8 were impaired in autophagosome formation, aerial hyphal formation, sexual growth, lipid turnover, pigmentation and fungal virulence. Interestingly, ΔFvAtg4 and ΔFvAtg8 were defective in fumonisin B1 (FB1) synthesis, which may have resulted from decreased intracellular levels of alanine in the mutants. Our results indicate that FvAtg4 and FvAtg8 contribute to F. verticillioides pathogenicity by regulating the autophagic pathway to control lipid turnover, fumonisin biosynthesis, and pigmentation during its infectious cycle.

Improved Whole-Genome Sequence of Fusarium meridionale, the Fungal Pathogen Causing Fusarium Head Blight in Rice

Members of the Fusarium graminearum species complex (FGSC) cause extensive yield losses in cereal production worldwide, and food safety concerns due to the accumulation of Fusarium toxins in infected grains. Among these pathogens, F. meridionale is responsible for Fusarium head blight of wheat and rice, ear and stalk rot of maize, and pod blight of soybean. Here, we present an improved genome assembly of F. meridionale strain SR5 isolated from rice in China based on PacBio long-read sequencing and Illumina short-read sequencing technology. The assembled genome of SR5 has a total size of 36.82 Mb, an N₅₀ scaffold length of 7.82 Mb, nine scaffolds, and encodes 12,409 predicted genes. These high-quality data expand FGSC genomic resources and provide a valuable resource for better understanding their genetic diversity and the molecular basis of pathogenesis, which will facilitate the development of an effective control strategy.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The FaFlbA mutant of Fusarium asiaticum is significantly increased in nivalenol production

AIMS

Cereals contaminated with type B trichothecene nivalenol (NIV) and its acetylated derivative 4-acetyl-nivalenol (4-AcNIV) are a global mycotoxicological problem threatening the health of humans and livestock. Toxicological studies, quantitative determinations and screening for biodegrading micro-organisms require massive amounts of pure toxins. However, the low yield from fungal cultures and high prices of NIV and 4-AcNIV limit research progress in these areas. This work aimed to select Fusarium asiaticum mutant strains with enhanced production of NIV and 4-AcNIV.

METHODS AND RESULTS

A total of 62 NIV-producing F. asiaticum strains were isolated and compared regarding their ability to produce NIV. Strain RR108 had the highest yield of NIV among 62 field isolates surveyed and was then genetically modified for higher production. Targeted deletion of the FaFlbA gene, encoding a regulator of G protein signalling protein, resulted in a significant increase in NIV and 4-AcNIV production in the FaFlbA deletion mutant ΔFaFlbA. The expression of three TRI genes involved in the trichothecene biosynthetic pathway was upregulated in ΔFaFlbA. ΔFaFlbA produced the highest amount of NIV and 4-AcNIV when cultured in brown long-grain rice for 21 days, and the yields were 2.07 and 2.84 g kg^-1 , respectively. The mutant showed reduced fitness, including reduced conidiation, loss of perithecial development and decreased virulence on wheat heads, which makes it biologically safe for large-scale preparation and purification of NIV and 4-AcNIV.

CONCLUSIONS

The F. asiaticum mutant strain ΔFaFlbA presented improved production of NIV and 4-AcNIV with reduced fitness and virulence in plants.

SIGNIFICANCE AND IMPACT OF THE STUDY

Targeted deletion of the FaFlbA gene resulted in increased NIV and 4-AcNIV production. Our results provide a practical approach using genetic modification for large-scale mycotoxin production.

Analysis of the Fusarium graminearum Species Complex from Gramineous Weeds Near Wheat Fields in Jiangsu Province, China

Several weed species are known as alternative hosts of the Fusarium graminearum species complex (FGSC), and their epidemiological significance in Fusarium head blight (FHB) has been investigated; however, scant information is available regarding FGSC occurrence in weeds near Chinese wheat fields. To evaluate the potential role of gramineous weeds surrounding wheat fields in FHB, 306 FGSC isolates were obtained from 210 gramineous weed samples in 2018 in Jiangsu Province. Among them, 289 were Fusarium asiaticum, and the remainder were F. graminearum. Trichothecene genotype and mycotoxin analyses revealed that 74.3% of the F. asiaticum isolates were the 3-acetyldeoxynivalenol (3ADON) chemotype, and the remainder were the nivalenol (NIV) chemotype. Additionally, 82.4% of F. graminearum isolates were the 15-acetyldeoxynivalenol (15ADON) chemotype, and the remainder were the NIV chemotype. FHB severity and trichothecene analysis indicated that F. asiaticum isolates with the 3ADON chemotype were more aggressive than those with the NIV chemotype in wheat. 3ADON and NIV chemotypes of F. asiaticum isolated from weeds and wheat showed no significant differences in pathogenicity in wheat. All selected F. asiaticum isolates produced perithecia, with little difference between the 3ADON and NIV chemotypes. These results highlight the epidemiology of the FGSC isolated from weeds near wheat fields, with implications for reducing FHB inoculum in China.

The antioxidant methyl gallate inhibits fungal growth and deoxynivalenol production in Fusarium graminearum

Abstract

Production of the Fusarium toxin deoxynivalenol (DON) is associated with oxidative stress and has been indicated to be part of an adaptive response to oxidative stress in the important wheat fungus Fusarium graminearum. In this study, we found that the antioxidant methyl gallate (MG) displays inhibitory effects against mycelial growth, conidial formation and germination, and DON biosynthesis in F. graminearum in a dose-dependent manner. Treatment with 0.05% (w/v) MG resulted in an abnormal swollen conidial morphology. The expression of the TRI genes involved in DON biosynthesis was significantly reduced, and the induction of Tri1-GFP green fluorescence signals in the spherical and crescent-shaped toxisomes was abolished in the MG-treated mycelium. RNA-Seq analysis of MG-treated F. graminearum showed that 0.5% (w/v) MG inhibited DON production by possibly altering membrane functions and oxidoreductase activities. Coupled with the observations that MG treatment decreases catalase, POD and SOD activity in F. graminearum. The results of this study indicated that MG displays antifungal activity against DON production by modulating its oxidative response. Taken together, the current study revealed the potential of MG in inhibiting mycotoxins in F. graminearum.

Graphical abstract

Phylogenomic Analysis of a 55.1-kb 19-Gene Dataset Resolves a Monophyletic Fusarium that Includes the Fusarium solani Species Complex

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option available.

High-efficiency picosecond mode-locked laser using a thulium-doped nanoengineered yttrium-alumina-silica fiber as the gain medium

We report the theoretical and experimental investigation of a self-starting mode-locked fiber laser with a nanoengineered Tm³⁺-doped yttrium-alumina-silica (YAS) fiber as the gain medium. The YAS fiber exhibits a higher capability of Tm³⁺ cluster elimination than commercial silica fibers. The Tm³⁺ fluorescence properties and YAS dispersion are well characterized. As a result, an efficient picosecond mode-locked fiber laser is demonstrated with a slope efficiency of 14.14% and maximum pulse energy of 1.27 nJ. To the best of our knowledge, this is the first mode-locked fiber laser based on a Tm³⁺-doped YAS fiber. The experimental observation is also supported by the numerical analysis.

Randomized, double-blind, active-controlled, multicentre, phase III clinical trial with two stages to assess the safety and efficacy of letibotulinum toxin a vs. onabotulinum toxin a for subjects with moderate to severe crow's feet

BACKGROUND

Letibotulinum toxin A (LeBA) was approved by the Ministry of Food and Drug Safety (known as the Korea Food & Drug Administration) for cosmetic indications in 2012. However, the efficacy and safety of this newly introduced LeBA have not been investigated in crow's feet lines (CFL) treatment and standardization before its universal use.

OBJECTIVE

The aim of this multicentre, double-blind, randomized, parallel, active-controlled Phase III clinical trial with two stages (ClinicalTrials.gov identifier: NCT03408236) was to investigate the non-inferiority of LeBA vs. the existing onabotulinum toxin A (OnBA) for the treatment of CFL.

METHODS

A total of 240 subjects were randomized to either the test (LeBA) or control (OnBA) group. At the baseline and at weeks 4 while maximum smiling (primary efficacy assessment), 8, 12 and 16, investigator's on-site evaluation, independent evaluator, evaluation by the subjects, subjects' satisfaction assessment and safety assessment were performed.

RESULTS

At week 4, the response rate of primary efficacy assessment was 69.75% and 68.33% in the test (LeBA) and control (OnBA) groups, respectively, without a significant difference. Other minor secondary evaluation results showed significant differences suggesting that LeBA offered better improvement than OnBA, but the overall results did not show significant differences between the two groups.

CONCLUSION

This study showed that LeBA was as effective and safe as OnBA for the treatment of CFL at the same doses.

Extraction and purification of ustiloxin A from rice false smut balls by a combination of macroporous resin and high-speed countercurrent chromatography

Abstract

Rice false smut is an emerging plant disease worldwide. Ustiloxin A (UstA) is the major mycotoxin found in rice false smut balls, which are fungal colonies in rice florets. In this study, a new method consisting of macroporous resin column chromatography and high-speed countercurrent chromatography (HSCCC) was developed for UstA separation. UstA was extracted by a 3.81% HCOOH solution and adsorbed by XAD-4 resin. UstA was then eluted by a 40% methanol solution supplemented with 0.1% trifluoroacetic acid (TFA). Further purification was achieved by HSCCC using a two-phase solvent system consisting of n-butanol/TFA/H2O (1/0.05/1, v/v/v). Under the optimized conditions, 225 mg of UstA was obtained with a purity of 97.39% in a single run, with a final recovery of 65.2%. An inhibitory effect on seed germination of wheat and maize caused by UstA was observed in a preliminary phytotoxicity assay.

Graphical abstract

Analysis of Fusarium graminearum Species Complex from Freshly Harvested Rice in Jiangsu Province (China)

Members of Fusarium graminearum species complex (FGSC) are the major pathogens that cause Fusarium head blight (FHB) in cereals worldwide. Symptoms of FHB on rice, including dark staining or browning of rice glumes, were recently observed in Jiangsu Province, China. To improve our understanding of the pathogens involved, 201 FGSC isolates were obtained from freshly harvested rice samples and identified by phylogenetic analyses. Among the 201 FGSC isolates, 196 were F. asiaticum and the remaining 5 were F. graminearum. Trichothecene chemotype and chemical analyses showed that 68.4% of the F. asiaticum isolates were the 3-acetyldeoxynivalenol (3ADON) chemotype and the remainder were the nivalenol (NIV) chemotype. All of the F. graminearum isolates were the 15-acetyldeoxynivalenol chemotype. Pathogenicity assays showed that both the 3ADON and NIV chemotypes of F. asiaticum could infect wheat and rice spikes. FHB severity and trichothecene toxin analysis revealed that F. asiaticum with the NIV chemotype was less aggressive than that with the 3ADON chemotype in wheat, while the NIV-producing strains were more virulent than the 3ADON-producing strains in rice. F. asiaticum isolates with different chemotypes did not show significant differences in mycelial growth, sporulation, conidial dimensions, or perithecial production. These findings would provide useful information for developing management strategies for the control of FHB in China.

Fusarium fujikuroi Species Complex Associated With Rice, Maize, and Soybean From Jiangsu Province, China: Phylogenetic, Pathogenic, and Toxigenic Analysis

Species belonging to the Fusarium fujikuroi species complex (FFSC) are of vital importance and are a major concern for food quantity and quality worldwide, as they not only cause serious diseases in crops but also produce various mycotoxins. To characterize the population structure and evaluate the risk of poisonous secondary metabolites, a total of 237 candidate strains were isolated from rice, maize, and soybean samples in Jiangsu Province, China. Species identification of the individual strain was accomplished by sequencing the translation elongation factor 1α gene (TEF-1α) and the fumonisin (FB) synthetic gene (FUM1). The distribution of Fusarium species among the different crops was observed. The maize seeds were dominated by F. proliferatum (teleomorph, Gibberella intermedia) and F. verticillioides (teleomorph, G. moniliformis), whereas F. fujikuroi (teleomorph, G. fujikuroi) was the most frequently isolated species from rice and soybean samples. In addition, phylogenetic analyses of these strains were performed, and the results suggested clear groups showing no obvious relationship with the origin source. FFSC species pathogenicity and toxigenicity were studied. All of the species reduced the rice seed germination rate, with no significant differences. F. fujikuroi showed two distinct patterns of influencing the length of rice seedlings, which were correlated with FBs and gibberellic acid synthesis. FBs were mainly produced by F. verticillioides and F. proliferatum. F. proliferatum and F. fujikuroi also produced moniliformin and beauvericin. The toxigenicity of F. andiyazi (teleomorph, G. andiyazi) was extremely low. Further analysis indicated that the sequence variations in TEF-1α and the differences in the expression levels of the toxin synthesis genes were associated with the diversity of secondary metabolites in F. fujikuroi strains. These findings provide insight into the population-level characterization of the FFSC and might be helpful in the development of strategies for the management of diseases and mycotoxins.

Copper Tolerance Mediated by FgAceA and FgCrpA in Fusarium graminearum

All organisms must secure essential trace elements (e.g., Cu) for survival and reproduction. However, excess trace element accumulation in cells is highly toxic. The maintenance of copper (Cu) homeostasis has been extensively studied in mammals, bacteria, and yeast but not in plant pathogens. In this study, we investigated the molecular mechanisms of copper tolerance in Fusarium graminearum, the important wheat head scab fungus. RNA-seq revealed induced expression of the P-type ATPase transporter FgCrpA and metallothionein (MT) FgCrdA after excess Cu treatment. Deletion of FgCrpA but not FgCrdA resulted in reduced tolerance to Cu toxicity. The “Cu fist” transcription factor FgAceA was involved in Cu detoxification through activation of FgCrpA. △FgAceA was more sensitive to copper toxicity than △FgCrpA and overexpression of FgCrpA restored copper tolerance in △FgAceA. FgAceA negatively regulated aurofusarin production and its biosynthetic gene expression. △FgCrpA and △FgAceA were reduced in virulence in flowering wheat heads and synthesized decreased amounts of the mycotoxin deoxynivalenol when challenged with excess Cu. Taken together, these results suggest that mediation of Cu tolerance in F. graminearum mainly relies on the Cu efflux pump and that FgAceA governs Cu detoxification through activation of FgCrpA.

Characterization of the CCAAT-binding transcription factor complex in the plant pathogenic fungus Fusarium graminearum

The CCAAT sequence is a ubiquitous cis-element of eukaryotic promoters, and genes containing CCAAT sequences have been shown to be activated by the CCAAT-binding transcription factor complex in several eukaryotic model organisms. In general, CCAAT-binding transcription factors form heterodimers or heterotrimeric complexes that bind to CCAAT sequences within the promoters of target genes and regulate various cellular processes. To date, except Hap complex, CCAAT-binding complex has been rarely reported in fungi. In this study, we characterized two CCAAT-binding transcription factors (Fct1 and Fct2) in the plant pathogenic fungus Fusarium graminearum. Previously, FCT1 and FCT2 were shown to be related to DNA damage response among eight CCAAT-binding transcription factors in F. graminearum. We demonstrate that the nuclear CCAAT-binding complex of F. graminearum has important functions in various fungal developmental processes, not just DNA damage response but virulence and mycotoxin production. Moreover, the results of biochemical and genetic analyses revealed that Fct1 and Fct2 may form a complex and play distinct roles among the eight CCAAT-binding transcription factors encoded by F. graminearum. To the best of our knowledge, the results of this study represent a substantial advancement in our understanding of the molecular mechanisms underlying the functions of CCAAT-binding factors in eukaryotes.

The novel bZIP transcription factor Fpo1 negatively regulates perithecial development by modulating carbon metabolism in the ascomycete fungus Fusarium graminearum

Fungal sexual reproduction requires complex cellular differentiation processes of hyphal cells. The plant pathogenic fungus Fusarium graminearum produces fruiting bodies called perithecia via sexual reproduction, and perithecia forcibly discharge ascospores into the air for disease initiation and propagation. Lipid metabolism and accumulation are closely related to perithecium formation, yet the molecular mechanisms that regulate these processes are largely unknown. Here, we report that a novel fungal specific bZIP transcription factor, F. graminearum perithecium overproducing 1 (Fpo1), plays a role as a global transcriptional repressor during perithecium production and maturation in F. graminearum. Deletion of FPO1 resulted in reduced vegetative growth, asexual sporulation and virulence and overproduced perithecium, which reached maturity earlier, compared with the wild type. Intriguingly, the hyphae of the fpo1 mutant accumulated excess lipids during perithecium production. Using a combination of molecular biological, transcriptomic and biochemical approaches, we demonstrate that repression of FPO1 after sexual induction leads to reprogramming of carbon metabolism, particularly fatty acid production, which affects sexual reproduction of this fungus. This is the first report of a perithecium-overproducing F. graminearum mutant, and the findings provide comprehensive insight into the role of modulation of carbon metabolism in the sexual reproduction of fungi.

Biodegradation of Deoxynivalenol by a Novel Microbial Consortium

Deoxynivalenol (DON), a common mycotoxin of type B trichothecene, is produced mainly by several Fusarium species. DON causes great losses in farming and poses severe safety risks to human and animal health. Thus, DON contamination in cereals and DON toxicity are of worldwide concern. In this study, we screened the bacterial consortium C20, which efficiently degraded almost 70 μg ml⁻¹ DON within 5 days. The bacterial consortium also had the ability to degrade 15-acetyl-DON, 3-acetyl-DON, and T-2 toxin. The bacterial consortium C20 was able to degrade DON under a wide range of pH and temperature conditions. The optimal temperature and pH for DON degradation were 30°C and pH 8.0, respectively. The bacterial consortium C20 comprised of different bacterial genera, and several strains were found to significantly increase when cultured in Mineral Medium with 100 μg ml⁻¹ DON based on the analysis of the sequences of the hypervariable V3-V4 region of the 16S rRNA gene. 3-keto-DON was confirmed as a degradation product of DON by liquid chromatography/time-of-flight/mass spectrometry (LC-TOF-MS) and nuclear magnetic resonance (NMR) analyses. The results indicated that the bacterial consortium C20 is a potential candidate for the biodegradation of DON in a safe and environmentally friendly manner.

Raman modes and dielectric relaxation properties of epitaxial BaBiO3 thin films

Perovskite BaBiO3 films are grown on MgO (100) substrate and SrTiO3 (001) and (110) substrates using pulsed laser deposition. The thickness of the films ranges from ∼10 nm up to 200 nm. X-ray diffraction and reciprocal space mapping show that the thin films are grown epitaxially but relaxed considerably particularly for the films on SrTiO3. The topography of the film surfaces are obtained with AFM and found to be atomically flat with the step and terrace structure of unit cell step height. Raman spectroscopy is performed on the BaBiO3 films in the temperature range from 50 K to 300 K. The phonon modes related to octahedral breathing, bond bending, and bond stretching are detected in the Raman spectra, and the distinctive features are found in the phonon modes below and above a structural transition around 140 K. Out-of-plane dielectric measurements are also carried out from 10 K to 400 K for the films on SrTiO3 with different orientations. In particular, the dielectric measurements demonstrate frequency as well as orientation dependent anisotropic dielectric relaxation behaviors in BaBiO3 films.

Intra-articular injection of magnesium chloride attenuates osteoarthritis progression in rats

OBJECTIVE

To explore the effects of Mg²⁺ on the expression of osteoarthritic markers in human cartilage and synovium tissue explants. To investigate the therapeutic effect of intra-articular injection of Mg²⁺ in an established rat OA (Osteoarthritis) model of anterior cruciate ligament transection with partial medial meniscectomy (ACLT + PMM).

DESIGN

Human cartilage and synovium explants were collected from total knee replacement surgeries and incubated with MgCl₂ (20 mmol/L) in vitro. A rat OA model was established by ACLT + PMM surgery in 450-500 g male Sprague Dawley (SD) rats. To select the optimal dose, intra-articular injections of MgCl₂ (0.05, 0.5, 5 mol/L) were performed at 4 weeks after the surgery every 3 days for 2 weeks. The effect of optimized MgCl₂ was further determined by histology, immunohistochemistry, and quantitative real-time polymerase chain reaction.

RESULTS

The expressions of osteoarthritic markers in human cartilage and synovium explants were inhibited by Mg²⁺in vitro. Immunohistochemical analysis further suggested the inhibitory effects of Mg²⁺ on the expression of MMP-13 and IL-6 in the human tissue explants. Cartilage degeneration and synovitis in ACLT + PMM rats were significantly improved by intra-articular injections of Mg²⁺ (0.5 mol/L). Immunohistochemical analysis also showed the regulatory effects of Mg²⁺ on osteoarthritic markers in both cartilage and synovium in rats, consistent with in vitro results.

CONCLUSION

Intra-articular injections of Mg²⁺ at 0.5 mol/L attenuate the progression of OA in the ACLT + PMM rat model. Such effect was at least in part explained by the promotion of cartilage matrix synthesis and the suppression of synovial inflammation.

Preparative isolation and purification of B-type fumonisins by using macroporous resin column and high-speed countercurrent chromatography

B-type fumonisins (FBs) are water-soluble mycotoxins produced by Fusarium species, which are mainly found in maize products and threaten food safety. Toxicological studies and quantitative determinations of fumonisins require large amounts of pure toxins, and their high prices limit progress in FBs research. In this study, we used a macroporous resin column combined with high-speed countercurrent chromatography to separate large quantities of FBs. A fermented rice culture was extracted with 75% methanol. The dynamic adsorption capacity of FBs on XAD-2 resin was 27.5 mg/g resin at 25°C, pH 4.0, and then the FBs were desorbed with 60% methanol. The crude FBs were further purified using a biphasic system consisting of n-heptane/n-butanol/methanol/water (2:4:1:4, v/v/v/v). The method yielded 1.55 g of FB1 and 0.55 g of FB3 with purities of 96.8% and 95.6%, respectively, from 1 kg of rice culture, and the final overall yield of FBs was 74.8%.

ARS2 Plays Diverse Roles in DNA Damage Response, Fungal Development, and Pathogenesis in the Plant Pathogenic Fungus Fusarium graminearum

Arsenite-resistance protein 2 (Ars2) is an important nuclear protein involved in various RNA metabolisms in animals and plants, but no Ars2 ortholog has been studied in filamentous fungi. Although it is an essential gene in most model eukaryotes, FgARS2 null mutants were viable in the plant pathogenic fungus Fusarium graminearum. The deletion of FgARS2 resulted in pleiotropic defects in various fungal developmental processes. Fgars2 mutants were irregular in nuclear division, and conidial germination was significantly retarded, causing the fungus to manifest its hypersensitive phenotypes under DNA damage stress. While FgARS2 deletion caused abnormal morphologies of ascospores and defective ascospore discharge, our data revealed that FgARS2 was not closely involved in small-non-coding RNA production in F. graminearum. The dominant nuclear localization of FgArs2-green fluorescent proteins (GFP) and abnormal nuclear division in FgARS2 deletion mutant implicated that FgArs2 functions in the nucleus. Intriguingly, we found that FgArs2 established a robust physical interaction with the cap binding complex (CBC) to form a tertiary complex CBC-Ars2 (CBCA), and disruption of any CBCA complex subunit drastically attenuated the virulence of F. graminearum. The results of the study indicate that Ars2 regulates fungal development, stress response, and pathogenesis via interaction with CBC in F. graminearum and provide a novel insight into understanding of the biological functions of Ars2 in filamentous fungi.

Serum 25-Hydroxyvitamin D deficiency in Malaysian children with severe atopic dermatitis

BACKGROUND

Vitamin D deficiency has been shown to be a determinant of disease severity in patients with atopic dermatitis (AD). There is a lack of information on the prevalence of vitamin D deficiency in Malaysian children with AD. The objective of this study was to determine the association of vitamin D deficiency with AD severity, to compare vitamin D deficiency between children with and without AD and to determine prevalence of vitamin D deficiency in children with AD.

METHODS

A case-control study to examine serum 25- hydroxyvitamin D [25(OH)D] levels in children with and without AD was done. Serum 25-hydroxyvitamin D [25(OH)D] level was measured by immunoassay. AD severity was evaluated using the SCORing Atopic Dermatitis (SCORAD) index.

RESULTS

The serum levels of 25(OH)D, measured in 135 children with AD was not statistically different from 65 children without AD [median (IQR): 25.2ng/mL (15.45) vs 25.9ng/mL (15.87), p=0.616]. However, serum vitamin D levels were significantly lower in children with severe AD compared to those with mild-to-moderate AD [median (IQR): 16.0ng/mL (19.32) vs 26.3ng/mL (15.56), p=0.021]. The odds of having vitamin D deficiency in children with severe AD was 3.82 times that of children with non-severe AD (95% confidence level: 1.13, 12.87).

CONCLUSION

This study suggests that there is an inverse association between vitamin D level and the severity of AD in Malaysian children.

Efficacy and safety of PAC-14028 cream - a novel, topical, nonsteroidal, selective TRPV1 antagonist in patients with mild-to-moderate atopic dermatitis: a phase IIb randomized trial

Background

Transient receptor potential vanilloid subfamily, member 1 (TRPV1) may play an important role in pruritus and inflammation induction in atopic dermatitis (AD). The treatment effect of TRPV1 antagonist via topical application in patients with AD remains unknown.

Objectives

To assess the clinical efficacy and safety of PAC‐14028, a TRPV1 antagonist, via topical application in patients with AD.

Methods

In this 8‐week, phase IIb, randomized, double‐blind, multicentre, vehicle‐controlled study, patients with mild‐to‐moderate AD were randomized to receive PAC‐14028 cream 0·1%, 0·3%, 1·0% or vehicle cream twice daily. The primary efficacy end point was the Investigator's Global Assessment (IGA) success rate defined as the percentage of patients with an IGA score of 0 or 1 at week 8. The secondary efficacy end points included the severity Scoring of Atopic Dermatitis (SCORAD) index and Eczema Area and Severity Index (EASI) 75/90.

Results

A total of 194 patients were enrolled. IGA success rates at week 8 were 14·58% for vehicle cream, 42·55% for PAC‐14028 cream 0·1% (P = 0·0025 vs. vehicle), 38·30% for PAC‐14028 cream 0·3% (P = 0·0087 vs. vehicle) and 57·45% for PAC‐14028 cream 1·0% (P < 0·001 vs. vehicle). In particular, statistically significant differences were found between the vehicle and treatment groups in the IGA success rates with two‐grade improvement. The SCORAD index, EASI 75/90, sleep disturbance score and pruritus visual analogue scale showed a trend towards improvement. No significant safety issues were reported.

Conclusions

PAC‐14028 cream may be an effective and safe treatment modality for the treatment of patients with mild‐to‐moderate AD.

What is already known about this topic?

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases characterized by pruritic erythematous skin lesions and barrier dysfunction.

Transient receptor potential vanilloid subfamily, member 1 (TRPV1) antagonists suppress the release of pruritic and proinflammatory mediators.

The preclinical results demonstrate the feasibility of TRPV1 as a potential therapeutic target for the treatment of AD.

What does this study add?

TRPV1 regulates inflammation and pruritus in patients with AD.

PAC‐14028 cream, a novel TRPV1 antagonist, was superior to vehicle in improving clinical symptoms and signs with a favourable safety profile in adults with mild‐to‐moderate AD.

TRPV1 antagonism may play a role as a promising nonsteroidal topical treatment target for AD with a new mechanism of action.

Linked Editorial:https://doi.org/10.1111/bjd.17777.

https://doi.org/10.1111/bjd.17802 available online

https://www.bjdonline.com/article/

Fungal Cytochrome P450s and the P450 Complement (CYPome) of Fusarium graminearum

Cytochrome P450s (CYPs), heme-containing monooxygenases, play important roles in a wide variety of metabolic processes important for development as well as biotic/trophic interactions in most living organisms. Functions of some CYP enzymes are similar across organisms, but some are organism-specific; they are involved in the biosynthesis of structural components, signaling networks, secondary metabolisms, and xenobiotic/drug detoxification. Fungi possess more diverse CYP families than plants, animals, or bacteria. Various fungal CYPs are involved in not only ergosterol synthesis and virulence but also in the production of a wide array of secondary metabolites, which exert toxic effects on humans and other animals. Although few studies have investigated the functions of fungal CYPs, a recent systematic functional analysis of CYP genes in the plant pathogen Fusarium graminearum identified several novel CYPs specifically involved in virulence, asexual and sexual development, and degradation of xenobiotics. This review provides fundamental information on fungal CYPs and a new platform for further metabolomic and biochemical studies of CYPs in toxigenic fungi.

Chemosensitization of Fusarium graminearum to Chemical Fungicides Using Cyclic Lipopeptides Produced by Bacillus amyloliquefaciens Strain JCK-12

Fusarium head blight (FHB) caused by infection with Fusarium graminearum leads to enormous losses to crop growers, and may contaminate grains with a number of Fusarium mycotoxins that pose serious risks to human and animal health. Antagonistic bacteria that are used to prevent FHB offer attractive alternatives or supplements to synthetic fungicides for controlling FHB without the negative effects of chemical management. Out of 500 bacterial strains isolated from soil, Bacillus amyloliquefaciens JCK-12 showed strong antifungal activity and was considered a potential source for control strategies to reduce FHB. B. amyloliquefaciens JCK-12 produces several cyclic lipopeptides (CLPs) including iturin A, fengycin, and surfactin. Iturin A inhibits spore germination of F. graminearum. Fengycin or surfactin alone did not display any inhibitory activity against spore germination at concentrations less than 30 μg/ml, but a mixture of iturin A, fengycin, and surfactin showed a remarkable synergistic inhibitory effect on F. graminearum spore germination. The fermentation broth and formulation of B. amyloliquefaciens JCK-12 strain reduced the disease incidence of FHB in wheat. Furthermore, co-application of B. amyloliquefaciens JCK-12 and chemical fungicides resulted in synergistic in vitro antifungal effects and significant disease control efficacy against FHB under greenhouse and field conditions, suggesting that B. amyloliquefaciens JCK-12 has a strong chemosensitizing effect. The synergistic antifungal effect of B. amyloliquefaciens JCK-12 and chemical fungicides in combination may result from the cell wall damage and altered cell membrane permeability in the phytopathogenic fungi caused by the CLP mixtures and subsequent increased sensitivity of F. graminearum to fungicides. In addition, B. amyloliquefaciens JCK-12 showed the potential to reduce trichothecenes mycotoxin production. The results of this study indicate that B. amyloliquefaciens JCK-12 could be used as an available biocontrol agent or as a chemosensitizer to chemical fungicides for controlling FHB disease and as a strategy for preventing the contamination of harvested crops with mycotoxins.

Roles of three Fusarium graminearum membrane Ca2+ channels in the formation of Ca2+ signatures, growth, development, pathogenicity and mycotoxin production

Similar to animals and plants, external stimuli cause dynamic spatial and temporal changes of cytoplasmic Ca²⁺ in fungi. Such changes are referred as the Ca²⁺ signature and control cellular responses by modulating the activity or location of diverse Ca²⁺-binding proteins (CBPs) and also indirectly affecting proteins that interact with CBPs. To understand the mechanism underpinning Ca²⁺ signaling, therefore, characterization of how Ca²⁺ moves to and from the cytoplasm to create Ca²⁺ signatures under different conditions is fundamental. Three genes encoding plasma membrane Ca²⁺ channels in a Fusarium graminearum strain that expresses a fluorescent protein-based Ca²⁺ indicator in the cytoplasm were mutagenized to investigate their roles in the generation of Ca²⁺ signatures under different growth conditions and genetic backgrounds. The genes disrupted include CCH1 and MID1, which encode a high affinity Ca²⁺ uptake system, and FIG1, encoding a low affinity Ca²⁺ channel. Resulting mutants were also analyzed for growth, development, pathogenicity and mycotoxin production to determine how loss of each of the genes alters these traits. To investigate whether individual genes influence the function and expression of other genes, phenotypes and Ca²⁺ signatures of their double and triple mutants, as well as their expression patterns, were analyzed.

Ex vivo magnetic resonance imaging using hyaluronic acid fillers: Differences between monophasic and biphasic fillers

BACKGROUND/PURPOSE

Hyaluronic acid (HA) is an anionic, non-sulfated glycosaminoglycan distributed throughout the human skin and injectable HA fillers are the most commonly used in aesthetic field. This study aimed to determine if differences in physical characteristics of HA products (monophasic or biphasic fillers) affect the patterns of magnetic resonance imaging (MRI).

METHODS

Twenty biphasic fillers and nine monophasic fillers were obtained from a commercial source, and examined with a 3.0 Tesla MRI scanner. Visual assessments and measurements of signal intensity for region of interest (ROI) were performed. A non-parametric Wilcoxon rank sum test was used to compare the ROI values.

RESULTS

Visual assessments by a radiologist did not show significant differences between the two types of fillers. While the signal intensity between the two types of filler did not differ significantly for T1-weighted images, the signal intensity of the biphasic filler was lower than that of the monophasic filler for T2-weighted images (P<.01).

CONCLUSION

Monophasic and biphasic HA fillers exhibited different MRI properties. Our findings may provide better insights into the use of in vivo MRI to evaluate aesthetic, procedure-related complications.

Comprehensive analysis of fungal diversity and enzyme activity in nuruk, a Korean fermenting starter, for acquiring useful fungi

Nuruk is a fermenting starter that is involved in the production of alcoholic beverages, and has been used in South Korea for a very long time. To analyze the fungal diversity, we collected a total of 59 nuruk samples from several companies and persons in 2013 to 2014, and obtained 364 isolates. All of the single isolated fungi were identified, both morphologically and molecularly, based on the sequences of ribosomal RNA gene [18S, ITS1-5.8S-ITS2, and 26S (D1/D2 region)]. In 46 nuruk samples out of 59 (78%), Saccharomycopsis fibuligera, a dimorphic yeast, was most frequently isolated. Among the filamentous fungi, Aspergillus and Lichtheimia were found in more than 50% of the samples with lower colony forming unit (CFU/g of sample) than those of yeasts. The yeasts S. fibuligera and Wickerhamomyces anomalus were counted with maximum 1.3-1.8 × 10⁸ CFU/g. Among Mucorales fungi, Lichtheimia and Mucor were isolated in much higher numbers than Rhizopus and Rhizomucor. Overall, the home-made nuruks tend to contain more diverse filamentous fungi than the commercial nuruks. To acquire industrially useful filamentous fungi and yeasts, we analyzed the enzyme activities of α-amylase, glucoamylase and acid protease associated with brewing properties for 131 strains. Aspergillus oryzae and S. fibuligera had high α- and glucoamylase activities and most isolates of Lichtheimia ramosa had high acid protease activity. For further applications, 27 fungal strains were chosen based on isolation frequencies from nuruk, and the ability to produce useful enzyme.

Functional characterization of cytochrome P450 monooxygenases in the cereal head blight fungus Fusarium graminearum

Fusarium graminearum is a prominent plant pathogenic fungus causing Fusarium head blight in major cereal crops worldwide. To understand the molecular mechanisms underlying fungal development and virulence, large collections of F. graminearum mutants have been constructed. Cytochrome P450 monooxygenases (P450s) are widely distributed in organisms and are involved in a diverse array of molecular/metabolic processes; however, no systematic functional analysis of P450s has been attempted in filamentous fungi. In this study, we constructed a genome-wide deletion mutant set covering 102 P450s and analyzed these mutants for changes in 38 phenotypic categories, including fungal development, stress responses and responses to several xenobiotics, to build a comprehensive phenotypic dataset. Most P450 mutants showing defective phenotypes were impaired in a single phenotypic trait, demonstrating that our mutant library is a good genetic resource for further fungal genetic studies. In particular, we identified novel P450s specifically involved in virulence (5) and both asexual (1) and sexual development (2). Most P450s seem to play redundant roles in the degradation of xenobiotics in F. graminearum. This study is the first phenome-based functional analysis of P450s, and it provides a valuable genetic resource for further basic and applied biological research in filamentous fungi and other plant pathogens.

Genome-wide exonic small interference RNA-mediated gene silencing regulates sexual reproduction in the homothallic fungus Fusarium graminearum

Various ascomycete fungi possess sex-specific molecular mechanisms, such as repeat-induced point mutations, meiotic silencing by unpaired DNA, and unusual adenosine-to-inosine RNA editing, for genome defense or gene regulation. Using a combined analysis of functional genetics and deep sequencing of small noncoding RNA (sRNA), mRNA, and the degradome, we found that the sex-specifically induced exonic small interference RNA (ex-siRNA)-mediated RNA interference (RNAi) mechanism has an important role in fine-tuning the transcriptome during ascospore formation in the head blight fungus Fusarium graminearum. Approximately one-third of the total sRNAs were produced from the gene region, and sRNAs with an antisense direction or 5'-U were involved in post-transcriptional gene regulation by reducing the stability of the corresponding gene transcripts. Although both Dicers and Argonautes partially share their functions, the sex-specific RNAi pathway is primarily mediated by FgDicer1 and FgAgo2, while the constitutively expressed RNAi components FgDicer2 and FgAgo1 are responsible for hairpin-induced RNAi. Based on our results, we concluded that F. graminearum primarily utilizes ex-siRNA-mediated RNAi for ascosporogenesis but not for genome defenses and other developmental stages. Each fungal species appears to have evolved RNAi-based gene regulation for specific developmental stages or stress responses. This study provides new insights into the regulatory role of sRNAs in fungi and other lower eukaryotes.

ISOLATION AND CHARACTERIZATION OF Fusarium solani CAUSING SOYBEAN SUDDEN DEATH SYNDROME IN KOREA

Soybean sudden death syndrome (SDS), caused by members of the Fusarium solani species complex, is an important disease leading to substantial yield reductions. The threat of soybean SDS is becoming serious in Korea, probably due to changes in the climate favoring the prevalence of this disease. In this study, after isolating Fusarium spp. from root rot-symptomatic soybean, we determined that F. solani was a causal agent of soybean SDS based on morphological and molecular characterization as well as Koch’s postulate. From 2009 to 2011, a total of nine isolates of Fusarium solani were collected from major soybean fields, Korea. Morphological and TEF-1α sequence analyses confirmed a variety of nine F. solani isolates. All F. solani isolates were close with F. solani species from Asia and mostly belonged to F. solani f. sp. pisi (SSLP14, 15, 16,19, and 20). Based on homology analysis of both ITS and TEF-1α, some isolates (SSLP2, 18, and 22) were similar to F. solani causing human eye keratitis, indicating a shared pathogenicity both on humans and plants. In a pathogenicity test, we observed hyphae in both xylem and phloem tissues from discolored roots and basal stems of plants exhibiting foliar SDS symptoms, indicating its contribution to foliar symptoms. Based on the differential reactions of soybean plant genotypes to F. solani isolates, one indigenous F. solani isolates, SSLP15 was identified having the highest levels of virulence. In addition, Danbaekkong and Jinpumkong 2 soybean were found to be resistant to SDS as demonstrated by slight symptom with less than 20% foliage affected. The evaluation of SDS resistance could be beneficial to support varietal improvement through extensive soybean breeding program in Korea.

A preliminary study of new single polymorphisms in the T helper type 17 pathway for psoriasis in the Korean population

Psoriasis is a polygenic and multi-factorial disease showing ethnic differences in terms of its severity and frequency. Therapies targeting interleukin (IL)-17A, IL-17 receptor (IL-17R) and Janus kinases (JAKs) are in clinical development for the treatment of psoriasis, and their success suggests the essential role of these molecules in psoriasis. To investigate the genetic susceptibility in T helper type 17 (Th17) cell signal transduction pathways for promoting psoriasis, we performed candidate gene and linkage disequilibrium analysis. In 208 patients and 266 normal controls, we analysed 31 single nucleotide polymorphisms in 12 genes (CAMP, IL17A, IL17F, IL17RA, IL22, JAK1, JAK2, JAK3, STAT3, TLR7, TLR9 and TYK2; abbreviations: CAMP, human cathelicidin antimicrobial peptide; STAT-3, signal transducer and activator of transcription 3; TLR, Toll-like receptor; TYK2, tyrosine kinase 2). Patients with psoriasis showed a strong association for IL17F rs763780 [odds ratio (OR) = 3·27, P = 0·04], which results in a histidine-to-arginine substitution, and JAK2 rs2274471 (OR = 2·66, P = 0·02). In addition, JAK2 rs7849191 showed a protective pattern, met the significance threshold (OR = 0·77, P = 0·05) and showed a tendency for an inverse association with the frequency of early-onset psoriasis under age 40 years (P = 0·07). In haplotype analysis, JAK1 rs310241A/rs2780889T showed a protective effect (OR = 0·73, P = 0·03) in psoriasis. In conclusion, we report two new psoriasis-susceptibility loci, in IL17F and JAK2, as well as a newly identified late-onset associated protective JAK2 locus and a protective JAK1 haplotype in the Korean population.

Whole-genome de novo sequencing, combined with RNA-Seq analysis, reveals unique genome and physiological features of the amylolytic yeast Saccharomycopsis fibuligera and its interspecies hybrid

BACKGROUND

Genomic studies on fungal species with hydrolytic activity have gained increased attention due to their great biotechnological potential for biomass-based biofuel production. The amylolytic yeast Saccharomycopsis fibuligera has served as a good source of enzymes and genes involved in saccharification. Despite its long history of use in food fermentation and bioethanol production, very little is known about the basic physiology and genomic features of S. fibuligera.

RESULTS

We performed whole-genome (WG) de novo sequencing and complete assembly of S. fibuligera KJJ81 and KPH12, two isolates from wheat-based Nuruk in Korea. Intriguingly, the KJJ81 genome (~38 Mb) was revealed as a hybrid between the KPH12 genome (~18 Mb) and another unidentified genome sharing 88.1% nucleotide identity with the KPH12 genome. The seven chromosome pairs of KJJ81 subgenomes exhibit highly conserved synteny, indicating a very recent hybridization event. The phylogeny inferred from WG comparisons showed an early divergence of S. fibuligera before the separation of the CTG and Saccharomycetaceae clades in the subphylum Saccharomycotina. Reconstructed carbon and sulfur metabolic pathways, coupled with RNA-Seq analysis, suggested a marginal Crabtree effect under high glucose and activation of sulfur metabolism toward methionine biosynthesis under sulfur limitation in this yeast. Notably, the lack of sulfate assimilation genes in the S. fibuligera genome reflects a unique phenotype for Saccharomycopsis clades as natural sulfur auxotrophs. Extended gene families, including novel genes involved in saccharification and proteolysis, were identified. Moreover, comparative genome analysis of S. fibuligera ATCC 36309, an isolate from chalky rye bread in Germany, revealed that an interchromosomal translocation occurred in the KPH12 genome before the generation of the KJJ81 hybrid genome.

CONCLUSIONS

The completely sequenced S. fibuligera genome with high-quality annotation and RNA-Seq analysis establishes an important foundation for functional inference of S. fibuligera in the degradation of fermentation mash. The gene inventory facilitates the discovery of new genes applicable to the production of novel valuable enzymes and chemicals. Moreover, as the first gapless genome assembly in the genus Saccharomycopsis including members with desirable traits for bioconversion, the unique genomic features of S. fibuligera and its hybrid will provide in-depth insights into fungal genome dynamics as evolutionary adaptation.

Heat shock protein 90 is required for sexual and asexual development, virulence, and heat shock response in Fusarium graminearum

Eukaryotic cells repress global translation and selectively upregulate stress response proteins by altering multiple steps in gene expression. In this study, genome-wide transcriptome analysis of cellular adaptation to thermal stress was performed on the plant pathogenic fungus Fusarium graminearum. The results revealed that profound alterations in gene expression were required for heat shock responses in F. graminearum. Among these proteins, heat shock protein 90 (FgHsp90) was revealed to play a central role in heat shock stress responses in this fungus. FgHsp90 was highly expressed and exclusively localised to nuclei in response to heat stress. Moreover, our comprehensive functional characterisation of FgHsp90 provides clear genetic evidence supporting its crucial roles in the vegetative growth, reproduction, and virulence of F. graminearum. In particular, FgHsp90 performs multiple functions as a transcriptional regulator of conidiation. Our findings provide new insight into the mechanisms underlying adaptation to heat shock and the roles of Hsp90 in fungal development.

Transcription factor ART1 mediates starch hydrolysis and mycotoxin production in Fusarium graminearum and F. verticillioides

Molecular mechanisms underlying the responses to environmental factors, such as nitrogen, carbon and pH, involve components that regulate the production of secondary metabolites, including mycotoxins. In this study, we identified and characterized a gene in the FGSG_02083 locus, designated as FgArt1, which was predicted to encode a Zn(II)2 Cys6 zinc finger transcription factor. An FgArt1 deletion mutant of Fusarium graminearum exhibited impaired starch hydrolysis as a result of significantly reduced α-amylase gene expression. The deletion strain was unable to produce trichothecenes and exhibited low Tri5 and Tri6 expression levels, whereas the complemented strain showed a similar ability to produce trichothecenes as the wild-type strain. In addition, FgArt1 deletion resulted in impairment of germination in starch liquid medium and reduced pathogenicity on flowering wheat heads. To investigate the roles of the FgArt1 homologue in F. verticillioides, we deleted the FVEG_02083 gene, and the resulting strain showed defects in starch hydrolysis, similar to the FgArt1 deletion strain, and produced no detectable level of fumonisin B1 . Fum1 and Fum12 expression levels were undetectable in the deletion strain. However, when the FvArt1-deleted F. verticillioides strain was complemented with FgArt1, the resulting strain was unable to recover the production of fumonisin B1 , although FgArt1 expression and starch hydrolysis were induced. Thus, our results suggest that there are different regulatory pathways governed by each ART1 transcription factor in trichothecene and fumonisin biosynthesis. Taken together, we suggest that ART1 plays an important role in both trichothecene and fumonisin biosynthesis by the regulation of genes involved in starch hydrolysis.

Utilization of a Conidia-Deficient Mutant to Study Sexual Development in Fusarium graminearum

Transcriptome analysis is a widely used approach to study the molecular mechanisms underlying development and the responses of fungi to environmental cues. However, it is difficult to obtain cells with a homogeneous status from the sexually-induced culture of the plant pathogenic fungus Fusarium graminearum. In this study, we provided phenotypic and genetic evidence to show that the current conditions applied for perithecia induction inevitably highly induced asexual sporulation in this fungus. We also found that hundreds of genes under the control of the conidiation-specific gene ABAA were unnecessarily upregulated after perithecia induction. Deletion of ABAA specifically blocked conidia production in both the wild-type strain and sexually-defective mutants during sexual development. Taken together, our results suggest that the abaA strain could be used as a background strain for studies of the initial stages of perithecia production in F. graminearum. Further comparative transcriptome analysis between the abaA mutant and the sexually-defective transcription factor mutant carrying the ABAA deletion would contribute to the construction of the genetic networks involved in perithecia development in F. graminearum.