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12 pages, 1459 KiB

Open AccessArticle

Entomopathogenic Fungi as a Potential Management Tool for the Control of Urban Malaria Vector, Anopheles stephensi (Diptera: Culicidae)

by Siddaramegowda Renuka, Chalageri Vani H and Eapen Alex

J. Fungi 2023, 9(2), 223; https://doi.org/10.3390/jof9020223 - 08 Feb 2023

Cited by 5 | Viewed by 2737

Abstract

Anopheles stephensi (Diptera: Culicidae) is the vector of urban malaria in India and has a significant impact in transmitting infection in cities and towns. Further, WHO has also alarmed its invasive nature as a threat to African countries. Entomopathogenic fungi such as Beauveria [...] Read more.

Anopheles stephensi (Diptera: Culicidae) is the vector of urban malaria in India and has a significant impact in transmitting infection in cities and towns. Further, WHO has also alarmed its invasive nature as a threat to African countries. Entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae have been found to be highly effective in controlling vector mosquito populations and therefore could be used in integrated vector control programs. Before employing the entomopathogenic fungi into the control programs, an effective isolate must be selected. Two separate experiments were conducted to evaluate the efficacy of Beauveria bassiana (Bb5a and Bb-NBAIR) and Metarhizium anisopliae (Ma4 and Ma-NBAIR) isolates against An. stephensi. Cement and mud panels were treated with fungal conidia with the concentration of 1 × 10⁷ conidia/mL and adult An. stephensi mosquitoes were exposed to the treated panels (24 h after conidia were applied) by conducting WHO cone bioassay tests. The survival of the mosquitoes was monitored daily until the 10th day. In the second experiment, second instar larvae of An. stephensi were treated with fungal (Bb5a, Bb-NBAIR, Ma4 and Ma-NBAIR) conidia and blastospores with the spore concentration of 1 × 10⁷ spores/mL. The survival of larvae was monitored until pupation. All the fungal isolates tested caused mortality in the adult mosquitoes, with varying median survival times. The Bb5a isolate reported lesser median survival times on both cement and mud panels (6 days). The treated mosquitoes showed similar survival rates for each fungal isolate irrespective of the panel type. There was no mortality in the treated larvae; however, a delay in larval development to pupae was observed compared with the untreated control larvae. Ma4-treated larvae took 11 days (95% CI = 10.7–11.2) to become pupae when compared with the untreated control larvae (6 days [95% CI = 5.6–6.3]). The findings of this study will be useful to consider EPF as a tool for the management of vector mosquitoes. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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17 pages, 3926 KiB

Open AccessArticle

FgAP1^σ Is Critical for Vegetative Growth, Conidiation, Virulence, and DON Biosynthesis in Fusarium graminearum

by Congxian Wu, Huilin Chen, Mingyue Yuan, Meiru Zhang, Yakubu Saddeeq Abubakar, Xin Chen, Haoming Zhong, Wenhui Zheng, Huawei Zheng and Jie Zhou

J. Fungi 2023, 9(2), 145; https://doi.org/10.3390/jof9020145 - 21 Jan 2023

Cited by 5 | Viewed by 1582

Abstract

The AP1 complex is a highly conserved clathrin adaptor that plays important roles in regulating cargo protein sorting and intracellular vesicle trafficking in eukaryotes. However, the functions of the AP1 complex in the plant pathogenic fungi including the devastating wheat pathogen Fusarium graminearum [...] Read more.

The AP1 complex is a highly conserved clathrin adaptor that plays important roles in regulating cargo protein sorting and intracellular vesicle trafficking in eukaryotes. However, the functions of the AP1 complex in the plant pathogenic fungi including the devastating wheat pathogen Fusarium graminearum are still unclear. In this study, we investigated the biological functions of FgAP1^σ, a subunit of the AP1 complex in F. graminearum. Disruption of FgAP1^σ causes seriously impaired fungal vegetative growth, conidiogenesis, sexual development, pathogenesis, and deoxynivalenol (DON) production. The ΔFgap1^σ mutants were found to be less sensitive to KCl- and sorbitol-induced osmotic stresses but more sensitive to SDS-induced stress than the wild-type PH-1. Although the growth inhibition rate of the ΔFgap1^σ mutants was not significantly changed under calcofluor white (CFW) and Congo red (CR) stresses, the protoplasts released from ΔFgap1^σ hyphae were decreased compared with the wild-type PH-1, suggesting that FgAP1^σ is necessary for cell wall integrity and osmotic stresses in F. graminearum. Subcellular localization assays showed that FgAP1^σ was predominantly localized to endosomes and the Golgi apparatus. In addition, FgAP1^β-GFP, FgAP1^γ-GFP, and FgAP1^μ-GFP also localize to the Golgi apparatus. FgAP1^β interacts with FgAP1^σ, FgAP1^γ, and FgAP1^μ, while FgAP1^σ regulates the expression of FgAP1^β, FgAP1^γ, and FgAP1^μ in F. graminearum. Furthermore, the loss of FgAP1^σ blocks the transportation of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane and delays the internalization of FM4-64 dye into the vacuole. Taken together, our results demonstrate that FgAP1^σ plays vital roles in vegetative growth, conidiogenesis, sexual reproduction, DON production, pathogenicity, cell wall integrity, osmotic stress, exocytosis, and endocytosis in F. graminearum. These findings unveil the functions of the AP1 complex in filamentous fungi, most notably in F. graminearum, and lay solid foundations for effective prevention and control of Fusarium head blight (FHB). Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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11 pages, 3415 KiB

Open AccessArticle

Clonostachys rosea Promotes Root Growth in Tomato by Secreting Auxin Produced through the Tryptamine Pathway

by Zhengyuan Han, Hossein Ghanizadeh, Haotian Zhang, Xinmao Li, Tiantian Li, Qi Wang, Jiayin Liu and Aoxue Wang

J. Fungi 2022, 8(11), 1166; https://doi.org/10.3390/jof8111166 - 04 Nov 2022

Cited by 8 | Viewed by 1380

Abstract

Clonostachys rosea (Link) Schroers is a filamentous fungus that has been widely used for biological control, biological fermentation, biodegradation and bioenergy. In this research, we investigated the impact of this fungus on root growth in tomato and the underlying mechanisms. The results showed [...] Read more.

Clonostachys rosea (Link) Schroers is a filamentous fungus that has been widely used for biological control, biological fermentation, biodegradation and bioenergy. In this research, we investigated the impact of this fungus on root growth in tomato and the underlying mechanisms. The results showed that C. rosea can promote root growth in tomato, and tryptophan enhances its growth-promoting impacts. The results also showed that tryptophan increases the abundance of metabolites in C. rosea, with auxin (IAA) and auxin-related metabolites representing a majority of the highly abundant metabolites in the presence of tryptophan. It was noted that C. rosea could metabolize tryptophan into tryptamine (TRA) and indole-3-acetaldehyde (IAAId), and these two compounds are used by C. rosea to produce IAA through the tryptamine (TAM) pathway, which is one of the major pathways in tryptophan-dependent IAA biosynthesis. The IAA produced is used by C. rosea to promote root growth in tomato. To the best of our knowledge, this is the first report on IAA biosynthesis by C. rosea through the TAM pathway. More research is needed to understand the molecular mechanisms underlying IAA biosynthesis in C. rosea, as well as to examine the ability of this fungus to boost plant development in the field. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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15 pages, 2317 KiB

Open AccessArticle

Rad1 and Rad10 Tied to Photolyase Regulators Protect Insecticidal Fungal Cells from Solar UV Damage by Photoreactivation

by Lei Yu, Si-Yuan Xu, Xin-Cheng Luo, Sheng-Hua Ying and Ming-Guang Feng

J. Fungi 2022, 8(11), 1124; https://doi.org/10.3390/jof8111124 - 25 Oct 2022

Cited by 8 | Viewed by 1337

Abstract

Beauveria bassiana serves as a main source of global fungal insecticides, which are based on the active ingredient of formulated conidia vulnerable to solar ultraviolet (UV) irradiation and restrained for all-weather application in green agriculture. The anti-UV proteins Rad1 and Rad10 are required [...] Read more.

Beauveria bassiana serves as a main source of global fungal insecticides, which are based on the active ingredient of formulated conidia vulnerable to solar ultraviolet (UV) irradiation and restrained for all-weather application in green agriculture. The anti-UV proteins Rad1 and Rad10 are required for the nucleotide excision repair (NER) of UV-injured DNA in model yeast, but their anti-UV roles remain rarely exploredin filamentous fungi. Here, Rad1 and Rad10 orthologues that accumulated more in the nuclei than the cytoplasm of B. bassiana proved capable of reactivating UVB-impaired or UVB-inactivated conidia efficiently by 5h light exposure but incapable of doing so by 24 h dark incubation (NER) if the accumulated UVB irradiation was lethal. Each orthologue was found interacting with the other and two white collar proteins (WC1 and WC2), which proved to be regulators of two photolyases (Phr1 and Phr2) and individually more efficient in the photorepair of UVB-induced DNA lesions than either photolyase alone. The fungal photoreactivation activity was more or far more compromised when the protein–protein interactions were abolished in the absence of Rad1 or Rad10 than when either Phr1 or Phr2 lost function. The detected protein–protein interactions suggest direct links of either Rad1 or Rad10 to two photolyase regulators. In B. bassiana, therefore, Rad1 and Rad10 tied to the photolyase regulators have high activities in the photoprotection of formulated conidia from solar UV damage but insufficient NER activities in the field, where night (dark) time is too short, and no other roles in the fungal lifecycle in vitro and in vivo. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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20 pages, 6973 KiB

Open AccessArticle

Suppression of Chitin-Triggered Immunity by a New Fungal Chitin-Binding Effector Resulting from Alternative Splicing of a Chitin Deacetylase Gene

by Jesús M. Martínez-Cruz, Álvaro Polonio, Laura Ruiz-Jiménez, Alejandra Vielba-Fernández, Jesús Hierrezuelo, Diego Romero, Antonio de Vicente, Dolores Fernández-Ortuño and Alejandro Pérez-García

J. Fungi 2022, 8(10), 1022; https://doi.org/10.3390/jof8101022 - 28 Sep 2022

Cited by 3 | Viewed by 1873

Abstract

Phytopathogenic fungi have evolved mechanisms to manipulate plant defences, such as chitin-triggered immunity, a plant defensive response based on the recognition of chitin oligomers by plant-specific receptors. To cope with chitin resistance, fungal pathogens have developed different strategies to prevent chitin recognition, such [...] Read more.

Phytopathogenic fungi have evolved mechanisms to manipulate plant defences, such as chitin-triggered immunity, a plant defensive response based on the recognition of chitin oligomers by plant-specific receptors. To cope with chitin resistance, fungal pathogens have developed different strategies to prevent chitin recognition, such as binding, breaking, or modifying immunogenic oligomers. In powdery mildew fungi, the activity of chitin deacetylase (CDA) is crucial for this purpose, since silencing of the CDA gene leads to a rapid activation of chitin signalling and the subsequent suppression of fungal growth. In this work, we have identified an unusually short CDA transcript in Podosphaera xanthii, the cucurbit powdery mildew pathogen. This transcript, designated PxCDA3, appears to encode a truncated version of CDA resulting from an alternative splicing of the PxCDA gene, which lacked most of the chitin deacetylase activity domain but retained the carbohydrate-binding module. Experiments with the recombinant protein showed its ability to bind to chitin oligomers and prevent the activation of chitin signalling. Furthermore, the use of fluorescent fusion proteins allowed its localization in plant papillae at pathogen penetration sites. Our results suggest the occurrence of a new fungal chitin-binding effector, designated CHBE, involved in the manipulation of chitin-triggered immunity in powdery mildew fungi. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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11 pages, 1736 KiB

Open AccessArticle

Reference Genes Selection of Gymnosporangium yamadae during the Interaction with Apple Leaves

by Chenxi Shao, Wenhao Lao and Yingmei Liang

J. Fungi 2022, 8(8), 830; https://doi.org/10.3390/jof8080830 - 09 Aug 2022

Cited by 1 | Viewed by 1357

Abstract

Apple rust disease caused by Gymnosporangium yamadae is the one of the major threats to the development of the apple industry in China, but the pathogenic molecular mechanism of the disease remains unclear. It is imperative to screen out appropriate reference genes during [...] Read more.

Apple rust disease caused by Gymnosporangium yamadae is the one of the major threats to the development of the apple industry in China, but the pathogenic molecular mechanism of the disease remains unclear. It is imperative to screen out appropriate reference genes during the interaction between G. yamadae and apple leaves to analyze the gene expression patterns during the pathogenesis of G. yamadae. ACT, EF1, EF2, GAPDH, 40S, 60S, α-TUB, β-TUB and UBCE3 were selected as candidate reference genes based on the transcriptomic dataset of G. yamadae. The expression levels were tested by real-time quantitative PCR during time-course infection of apple leaves and the expression stabilities were evaluated by △Ct method as well as by three software (NormFinder, geNorm and BestKeeper) and one web-based analysis software (RefFinder). The expression stability of the candidate reference genes was further validated by using the effector candidate gene Cluster-3395.48660 as the target gene in RT-qPCR. According to the results by △Ct and BestKeeper, 40S, EF2 and EF1 were the most stable reference genes, while EF1, EF2 and GAPDH were the most stable reference genes based on the NormFinder analysis result. The geNorm recommended the most stable genes EF1, EF2 and α-TUB as reference genes. Comprehensive analysis results of the RefFinder indicated EF1, EF2 and α-TUB were the most suitable genes. Based on these results, EF1, EF2 and α-TUB were considered as reference genes for analyzing the gene expression profiles of Cluster-3395.48660 in different infection stages, and the results were consistent with the transcriptome data. All the results suggest that the combination of EF1, EF2 and α-TUB proved to be acceptable reference genes during the interaction between G. yamadae and apple leaves. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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16 pages, 4245 KiB

Open AccessEditor’s ChoiceArticle

The Fungal Protein Mes1 Is Required for Morphogenesis and Virulence in the Dimorphic Phytopathogen Ustilago maydis

by David Cánovas

J. Fungi 2022, 8(8), 759; https://doi.org/10.3390/jof8080759 - 22 Jul 2022

Cited by 1 | Viewed by 1842

Abstract

Polarized growth is a defining property of filamentous fungi, which plays an important role in different aspects of their biology, including virulence. However, little information is available about the determinants of cell surface organization and their role in polarized growth. The fungal protein [...] Read more.

Polarized growth is a defining property of filamentous fungi, which plays an important role in different aspects of their biology, including virulence. However, little information is available about the determinants of cell surface organization and their role in polarized growth. The fungal protein MesA was identified in a genetic screen in Aspergillus nidulans and is involved in the stabilization of the polarity axes, but it has no evident role in budding yeast. In this work, I present evidence that in the dimorphic fungal phytopathogen Ustilago maydis MesA/Mes1 is involved in cell wall stability and polarized growth. mes1 mutants were more sensitive to drugs provoking cell wall stress, and they displayed a temperature-sensitive phenotype. Actin cytoskeleton was disorganized in a mes1 mutant, suggesting that there is a connection between Mes1, the actin cytoskeleton and polarized morphogenesis. The septin ring was also absent from the bud tip, but not the bud neck. Deletion of mes1 provoked defects in endocytosis and vacuolar organization in the cells. Mes1 was essential for strong polarized growth in the hyphal form, but it was dispensable during low or moderate polarized growth in the yeast form in U. maydis at a permissive temperature. Consistently, mes1 mutants showed delayed mating and they were avirulent. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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16 pages, 1836 KiB

Open AccessArticle

A Perilipin Affects Lipid Droplet Homeostasis and Aerial Hyphal Growth, but Has Only Small Effects on Virulence in the Insect Pathogenic Fungus Beauveria bassiana

by Xiaoyun Wang, Yu Liu, Nemat O. Keyhani, Shengan Zhu, Jing Wang, Junyao Wang, Dan Jin and Yanhua Fan

J. Fungi 2022, 8(6), 634; https://doi.org/10.3390/jof8060634 - 15 Jun 2022

Cited by 3 | Viewed by 1737

Abstract

Lipid assimilation, storage, and turnover impact growth, development, and virulence in many microbial pathogens including fungi. Perilipins are proteins associated with lipid droplets (LDs) that mediate their assembly and turnover. Here, we characterized the Beauveria bassiana (BbPlin1) perilipin. BbPlin1 expression was [...] Read more.

Lipid assimilation, storage, and turnover impact growth, development, and virulence in many microbial pathogens including fungi. Perilipins are proteins associated with lipid droplets (LDs) that mediate their assembly and turnover. Here, we characterized the Beauveria bassiana (BbPlin1) perilipin. BbPlin1 expression was higher in minimal media than in rich media, and, using a BbPlin1::eGFP fusion protein, the protein was shown to be co–localized to LDs, with the high expression seen during infection and proliferation within the insect (Galleria mellonella) host that dramatically decreased to almost no expression during fungal outgrowth on cadavers including in conidia, but that BbPlin1 production resumed in the conidia once placed in nutrient–containing media allowing for germination and growth. Characterization of a targeted gene deletion strain (ΔBbPlin1) revealed a dramatic (>30%) reduction in cellular LD content, promotion of aerial hyphal growth, and a small decrease in virulence, with little to no effects on vegetative growth and stress responses. However, in the ΔBbPlin1 strain, expression of the complementary LD–associated caleosin gene, BbCal1, was enhanced under nutrient–poor conditions, although no changes in BbPlin1 expression were seen in a ΔBbCal1 strain and the expression of BbPlin1 in the ΔBbCal1 strain did not change LD patterns in cells. Transcriptome and RT–PCR analyses indicated increased expression of lipid metabolism–related genes, including triacylglyercol lipase 3, enoyl–CoA isomerase, and diacylglycerol–O–acetyl transferase in the BbPlin1 deletion mutant. Lipid profile analyses confirmed that the loss of BbPlin1 significantly reduced the cellular levels of contents of triacylglycerol, diacylglycerol, and phosphatidylethanolamine as compared to the wild–type strain. These results demonstrate the involvement of the B. bassiana perilipin in mediating lipid homeostasis, fungal aerial hyphal growth, and virulence, revealing critical cycling from high expression during nutrient utilization within host cadavers to low expression during growth on the surface of the cadaver during the infection process. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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14 pages, 1970 KiB

Open AccessArticle

Peroxins in Peroxisomal Receptor Export System Contribute to Development, Stress Response, and Virulence of Insect Pathogenic Fungus Beauveria bassiana

by Jia Hou, Haiyan Lin, Jinli Ding, Mingguang Feng and Shenghua Ying

J. Fungi 2022, 8(6), 622; https://doi.org/10.3390/jof8060622 - 10 Jun 2022

Cited by 5 | Viewed by 1653

Abstract

In filamentous fungi, recycling of receptors responsible for protein targeting to peroxisomes depends on the receptor export system (RES), which consists of peroxins Pex1, Pex6, and Pex26. This study seeks to functionally characterize these peroxins in the entomopathogenic fungus Beauveria bassiana. BbPex1, [...] Read more.

In filamentous fungi, recycling of receptors responsible for protein targeting to peroxisomes depends on the receptor export system (RES), which consists of peroxins Pex1, Pex6, and Pex26. This study seeks to functionally characterize these peroxins in the entomopathogenic fungus Beauveria bassiana. BbPex1, BbPex6, and BbPex26 are associated with peroxisomes and interact with each other. The loss of these peroxins did not completely abolish the peroxisome biogenesis. Three peroxins were all absolutely required for PTS1 pathway; however, only BbPex6 and BbPex26 were required for protein translocation via PTS2 pathway. Three gene disruption mutants displayed the similar phenotypic defects in assimilation of nutrients (e.g., fatty acid, protein, and chitin), stress response (e.g., oxidative and osmotic stress), and virulence. Notably, all disruptant displayed significantly enhanced sensitivity to linoleic acid, a polyunsaturated fatty acid. This study reinforces the essential roles of the peroxisome in the lifecycle of entomopathogenic fungi and highlights peroxisomal roles in combating the host defense system. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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14 pages, 3145 KiB

Open AccessArticle

Three Small Cysteine-Free Proteins (CFP1–3) Are Required for Insect-Pathogenic Lifestyle of Metarhizium robertsii

by Ya-Ni Mou, Kang Ren, Si-Yuan Xu, Sheng-Hua Ying and Ming-Guang Feng

J. Fungi 2022, 8(6), 606; https://doi.org/10.3390/jof8060606 - 06 Jun 2022

Cited by 3 | Viewed by 1702

Abstract

Unique CFP (cysteine-free protein; 120 aa) has been identified as an extraordinary virulence factor in Beauveria bassiana (Cordycipitaceae), a main source of wide-spectrum fungal insecticides. Its homologs exclusively exist in wide-spectrum insect pathogens of Hypocreales, suggesting their importance for a fungal insect-pathogenic lifestyle. [...] Read more.

Unique CFP (cysteine-free protein; 120 aa) has been identified as an extraordinary virulence factor in Beauveria bassiana (Cordycipitaceae), a main source of wide-spectrum fungal insecticides. Its homologs exclusively exist in wide-spectrum insect pathogens of Hypocreales, suggesting their importance for a fungal insect-pathogenic lifestyle. In this study, all three CFP homologs (CFP1–3, 128–145 aa) were proven essential virulence factors in Metarhizium robertsii (Clavicipitaceae). Despite limited effects on asexual cycles in vitro, knockout mutants of cfp1,cfp2 and cfp3 were severely compromised in their capability for normal cuticle infection, in which most tested Galleria mellonella larvae survived. The blocked cuticle infection concurred with reduced secretion of extracellular enzymes, including Pr1 proteases required cuticle penetration. Cuticle-bypassing infection by intrahemocoel injection of ~250 conidia per larva resulted in a greater reduction in virulence in the mutant of cfp1 (82%) than of cfp2 (21%) or cfp3 (25%) versus the parental wild-type. Transcriptomic analysis revealed dysregulation of 604 genes (up/down ratio: 251:353) in the Δcfp1 mutant. Many of them were involved in virulence-related cellular processes and events aside from 154 functionally unknown genes (up/down ratio: 56:98). These results reinforce the essential roles of small CFP homologs in hypocrealean fungal adaptation to insect-pathogenic lifestyle and their exploitability for the genetic improvement of fungal insecticidal activity. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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17 pages, 5420 KiB

Open AccessArticle

Transcription Factor Mavib-1 Negatively Regulates Conidiation by Affecting Utilization of Carbon and Nitrogen Source in Metarhizium acridum

by Xueling Su, Hong Liu, Yuxian Xia and Yueqing Cao

J. Fungi 2022, 8(6), 594; https://doi.org/10.3390/jof8060594 - 01 Jun 2022

Cited by 1 | Viewed by 1648

Abstract

Conidium is the main infection unit and reproductive unit of pathogenic fungi. Exploring the mechanism of conidiation and its regulation contributes to understanding the pathogenicity of pathogenic fungi. Vib-1, a transcription factor, was reported to participate in the conidiation process. However, the [...] Read more.

Conidium is the main infection unit and reproductive unit of pathogenic fungi. Exploring the mechanism of conidiation and its regulation contributes to understanding the pathogenicity of pathogenic fungi. Vib-1, a transcription factor, was reported to participate in the conidiation process. However, the regulation mechanism of Vib-1 in conidiation is still unclear. In this study, we analyzed the function of Vib-1 and its regulation mechanism in conidiation through knocking out and overexpression of Vib-1 in entomopathogenic fungus Metarhizium acridum. Results showed that the colonial growth of Mavib-1 disruption mutant (ΔMavib-1) was significantly decreased, and conidiation was earlier compared to wild type (WT), while overexpression of Mavib-1 led to a delayed conidiation especially when carbon or nitrogen sources were insufficient. Overexpression of Mavib-1 resulted in a conidiation pattern shift from microcycle conidiation to normal conidiation on nutrient-limited medium. These results indicated that Mavib-1 acted as a positive regulator in vegetative growth and a negative regulator in conidiation by affecting utilization of carbon and nitrogen sources in M. acridum. Transcription profile analysis demonstrated that many genes related to carbon and nitrogen source metabolisms were differentially expressed in ΔMavib-1 and OE strains compared to WT. Moreover, Mavib-1 affects the conidial germination, tolerance to UV-B and heat stresses, cell wall integrity, conidial surface morphology and conidial hydrophobicity in M. acridum. These findings unravel the regulatory mechanism of Mavib-1 in fungal growth and conidiation, and enrich the knowledge to conidiation pattern shift of filamentous fungi. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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13 pages, 3499 KiB

Open AccessArticle

MaOpy2, a Transmembrane Protein, Is Involved in Stress Tolerances and Pathogenicity and Negatively Regulates Conidial Yield by Shifting the Conidiation Pattern in Metarhizium acridum

by Zhiqiong Wen, Yu Fan, Yuxian Xia and Kai Jin

J. Fungi 2022, 8(6), 587; https://doi.org/10.3390/jof8060587 - 30 May 2022

Cited by 1 | Viewed by 1485

Abstract

Opy2 is an important membrane-anchored protein upstream of the HOG-MAPK signaling pathway and plays important roles in both the HOG-MAPK and Fus3/Kss1 MAPK. In this study, the roles of MaOpy2 in Metarhizium acridum were systematically elucidated. The results showed that the MaOpy2 disruption [...] Read more.

Opy2 is an important membrane-anchored protein upstream of the HOG-MAPK signaling pathway and plays important roles in both the HOG-MAPK and Fus3/Kss1 MAPK. In this study, the roles of MaOpy2 in Metarhizium acridum were systematically elucidated. The results showed that the MaOpy2 disruption significantly reduced fungal tolerances to UV, heat shock and cell-wall-disrupting agents. Bioassays showed that the decreased fungal pathogenicity by topical inoculation mainly resulted from the impaired penetration ability. However, the growth ability of ∆MaOpy2 was enhanced in insect hemolymph. Importantly, MaOpy2 deletion could significantly increase the conidial yield of M. acridum by shifting the conidiation pattern from normal conidiation to microcycle conidiation on the 1/4SDAY medium. Sixty-two differentially expressed genes (DEGs) during the conidiation pattern shift, including 37 up-regulated genes and 25 down-regulated genes in ∆MaOpy2, were identified by RNA-seq. Further analysis revealed that some DEGs were related to conidiation and hyphal development. This study will provide not only the theoretical basis for elucidating the regulation mechanism for improving the conidial yield and quality in M. acridum but also theoretical guidance for the molecular improvement of entomopathogenic fungi. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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14 pages, 1473 KiB

Open AccessArticle

Monitoring Mycoparasitism of Clonostachys rosea against Botrytis cinerea Using GFP

by Rakibul Hasan, Binna Lv, Md. Jamal Uddin, Yingying Chen, Lele Fan, Zhanbin Sun, Manhong Sun and Shidong Li

J. Fungi 2022, 8(6), 567; https://doi.org/10.3390/jof8060567 - 26 May 2022

Cited by 9 | Viewed by 3163

Abstract

Clonostachys rosea is an important mycoparasite, with great potential for controlling numerous plant fungal diseases. Understanding the mechanisms and modes of action will assist the development and application of this biocontrol fungus. In this study, the highly efficient C. rosea 67-1 strain was [...] Read more.

Clonostachys rosea is an important mycoparasite, with great potential for controlling numerous plant fungal diseases. Understanding the mechanisms and modes of action will assist the development and application of this biocontrol fungus. In this study, the highly efficient C. rosea 67-1 strain was marked with the green fluorescent protein (GFP), and the transformant possessed the same biological characteristics as the wild-type strain. Fungal interactions with Botrytis cinerea during co-culture and encounter on tomato leaves were assessed by fluorescence confocal and electron microscopy. The results indicated that once the two fungi met, the hyphae of C. rosea grew alongside those of B. cinerea, then attached tightly to the host and developed special structures, via which the biocontrol fungus penetrated the host and absorbed nutrients, eventually disintegrating the cells of the pathogen. Mycoparasitism to B. cinerea was also observed on tomato leaves, suggesting that C. rosea can colonize on plants and act following the invasion of the pathogenic fungus. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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14 pages, 2763 KiB

Open AccessArticle

The Entomopathogenic Fungus Metarhizium anisopliae Affects Feeding Preference of Sogatella furcifera and Its Potential Targets’ Identification

by Yirong Wang, Lijuan Han, Yuxian Xia and Jiaqin Xie

J. Fungi 2022, 8(5), 506; https://doi.org/10.3390/jof8050506 - 15 May 2022

Cited by 2 | Viewed by 1964

Abstract

The rice planthopper Sogatella furcifera is a unique vector of the southern rice black-streaked dwarf virus (SRBSDV). The feeding behavior of S. furcifera should directly affect the diffusion of this virus. In this study, we noted that the infection of Metarhizium anisopliae CQMa421 [...] Read more.

The rice planthopper Sogatella furcifera is a unique vector of the southern rice black-streaked dwarf virus (SRBSDV). The feeding behavior of S. furcifera should directly affect the diffusion of this virus. In this study, we noted that the infection of Metarhizium anisopliae CQMa421 on S. furcifera disturbed the feeding behavior of this pest to SRBSDV-infected rice, from preference to non-preference. Then, we further investigated the potential targets of M. anisopliae CQMa421 on the feeding behavior of S. furcifera after 0 h, 24 h and 48 h of infection by transcriptomic analysis via Illumina deep sequencing. A total of 93.27 GB of data was collected after sequencing, from which 91,125 unigenes were annotated, including 75 newly annotated genes. There were 1380 vs. 2187 and 137 vs. 106 upregulated and downregulated differentially expressed genes (DEGs) detected at 24 h and 48 h, respectively. The biological functions and associated metabolic processes of these genes were determined with the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The results suggested that major of DEGs are involved in energy metabolism, biosynthesis, immune response, the FoxO signaling pathway, the MAPK signaling pathway and apoptosis in response to the fungal infection. Noteworthily, several olfactory-related genes, including odorant receptors and odorant binding proteins, were screened from these differentially expressed genes, which played critical roles in regulating the olfactory behavior of insects. Taken together, these results provide new insights for understanding the molecular mechanisms underlying fungus and host insect interaction, especially for olfactory behavior regulated by fungus. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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20 pages, 53852 KiB

Open AccessArticle

The Arf-GAP Proteins AoGcs1 and AoGts1 Regulate Mycelial Development, Endocytosis, and Pathogenicity in Arthrobotrys oligospora

by Le Yang, Xuemei Li, Yuxin Ma, Keqin Zhang and Jinkui Yang

J. Fungi 2022, 8(5), 463; https://doi.org/10.3390/jof8050463 - 29 Apr 2022

Cited by 10 | Viewed by 1624

Abstract

Small GTPases from the ADP-ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) regulate mycelial development, endocytosis, and virulence in fungi. Here, we identified two orthologous Arf-GAP proteins, AoGcs1 and AoGts1, in a typical nematode-trapping fungus Arthrobotrys oligospora. The transcription of Aogcs1 [...] Read more.

Small GTPases from the ADP-ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) regulate mycelial development, endocytosis, and virulence in fungi. Here, we identified two orthologous Arf-GAP proteins, AoGcs1 and AoGts1, in a typical nematode-trapping fungus Arthrobotrys oligospora. The transcription of Aogcs1 and Aogts1 was highly expressed in the sporulation stage. The deletion of Aogcs1 and Aogts1 caused defects in DNA damage, endocytosis, scavenging of reactive oxygen species, lipid droplet storage, mitochondrial activity, autophagy, serine protease activity, and the response to endoplasmic reticulum stress. The combined effects resulted in slow growth, decreased sporulation capacity, increased susceptibility to chemical stressors and heat shock, and decreased pathogenicity of the mutants compared with the wild-type (WT) strain. Although deletion of Aogcs1 and Aogts1 produced similar phenotfypic traits, their roles varied in conidiation and proteolytic activity. The ΔAogts1 mutant showed a remarkable reduction in conidial yield compared with the WT strain but not in proteolytic activity; in contrast, the ΔAogcs1 mutant showed an increase in proteolytic activity but not in sporulation. In addition, the growth of ΔAogcs1 and ΔAogts1 mutants was promoted by rapamycin, and the ΔAogts1 mutant was sensitive to H-89. Collectively, the ΔAogts1 mutant showed a more remarkable difference compared with the WT strain than the ΔAogcs1 mutant. Our study further illustrates the importance of Arf-GAPs in the growth, development, and pathogenicity of nematode-trapping fungi. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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13 pages, 2738 KiB

Open AccessArticle

Unveiling a Novel Role of Cdc42 in Pyruvate Metabolism Pathway to Mediate Insecticidal Activity of Beauveria bassiana

by Yi Guan, Donghuang Wang, Xiaofeng Lin, Xin Li, Chao Lv, Dingyi Wang and Longbin Zhang

J. Fungi 2022, 8(4), 394; https://doi.org/10.3390/jof8040394 - 12 Apr 2022

Cited by 2 | Viewed by 1814

Abstract

The small GTPase Cdc42 acts as a molecular switch essential for cell cycles and polar growth in model yeast, but has not been explored in Beaurveria bassiana, an insect-pathogenic fungus serving as a main source of fungal formulations against arthropod pests. Here, [...] Read more.

The small GTPase Cdc42 acts as a molecular switch essential for cell cycles and polar growth in model yeast, but has not been explored in Beaurveria bassiana, an insect-pathogenic fungus serving as a main source of fungal formulations against arthropod pests. Here, we show the indispensability of Cdc42 for fungal insecticidal activity. Deletion of cdc42 in B. bassiana resulted in a great loss of virulence to Galleria mellonella, a model insect, via normal cuticle infection as well as defects in conidial germination, radial growth, aerial conidiation, and conidial tolerance to heat and UVB irradiation. The deleted mutant’s hyphae formed fewer or more septa and produced unicellular blastospores with disturbed cell cycles under submerged-culture conditions. Transcriptomic analysis revealed differential expression of 746 genes and dysregulation of pyruvate metabolism and related pathways, which were validated by marked changes in intracellular pyruvate content, ATP content, related enzyme activities, and in extracellular beauvericin content and Pr1 protease activity vital for fungal virulence. These findings uncover a novel role for Cdc42 in the pathways of pyruvate metabolism and the pyruvate-involved tricarboxylic acid cycle (TCA cycle) and a linkage of the novel role with its indispensability for the biological control potential of B. bassiana against arthropod pests. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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18 pages, 4884 KiB

Open AccessArticle

Differential Roles of Five Fluffy Genes (flbA–flbE) in the Lifecycle In Vitro and In Vivo of the Insect–Pathogenic Fungus Beauveria bassiana

by Chong-Tao Guo, Xin-Cheng Luo, Sheng-Hua Ying and Ming-Guang Feng

J. Fungi 2022, 8(4), 334; https://doi.org/10.3390/jof8040334 - 23 Mar 2022

Cited by 8 | Viewed by 1843

Abstract

The fluffy genes flbA–flbE are well-known players in the upstream developmental activation pathway that activates the key gene brlA of central developmental pathway (CDP) to initiate conidiation in Aspergillus nidulans. Here, we report insignificant roles of their orthologs in radial [...] Read more.

The fluffy genes flbA–flbE are well-known players in the upstream developmental activation pathway that activates the key gene brlA of central developmental pathway (CDP) to initiate conidiation in Aspergillus nidulans. Here, we report insignificant roles of their orthologs in radial growth of Beauveria bassiana under normal culture conditions and different stresses although flbA and flbD were involved in respective responses to heat shock and H₂O₂. Aerial conidiation level was lowered in the deletion mutants of flbB and flbE (~15%) less than of flbA and flbC (~30%), in which the key CDP genes brlA and abaA were repressed consistently during normal incubation. The CDP-controlled blastospore production in submerged cultures mimicking insect hemolymph was abolished in the flbA mutant with brlA and abaA being sharply repressed, and decreased by 55% in the flbC mutant with only abaA being downregulated. The fungal virulence against a model insect was attenuated in the absence of flbA more than of flbC irrespective of normal cuticle infection or cuticle-bypassing infection (intrahemocoel injection). These findings unravel more important role of flbA than of flbC, but null roles of flbB/D/E, in B. bassiana’s insect–pathogenic lifecycle and a scenario distinctive from that in A.nidulans. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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11 pages, 1884 KiB

Open AccessArticle

SterylAcetyl Hydrolase 1 (BbSay1) Links Lipid Homeostasis to Conidiogenesis and Virulence in the Entomopathogenic Fungus Beauveria bassiana

by Yue-Jin Peng, Hao Zhang, Ming-Guang Feng and Sheng-Hua Ying

J. Fungi 2022, 8(3), 292; https://doi.org/10.3390/jof8030292 - 11 Mar 2022

Cited by 12 | Viewed by 1580

Abstract

Beauveria bassiana, as a well-studied entomopathogenic fungus, has a great potential for the biological control of insect pests. Lipid metabolism has been linked to the life cycle of B. bassiana; however, the underlying mechanisms remain unknown. In this study, a homolog [...] Read more.

Beauveria bassiana, as a well-studied entomopathogenic fungus, has a great potential for the biological control of insect pests. Lipid metabolism has been linked to the life cycle of B. bassiana; however, the underlying mechanisms remain unknown. In this study, a homolog of yeast steryl acetyl hydrolase 1 (Say1) was functionally characterized. The loss of B. bassianaSAY1 (BbSAY1) impaired the lipid homeostasis in conidia, with a significant reduction in oleic acid content. The ΔBbsay1 mutant strain displayed anelevated accumulation of lipid bodies and aweakened membrane permeability. As for phenotypic aspects, gene loss resulted in significant defects in germination, conidiation, and virulence. Our findings highlight that Say1, involved in lipid homeostasis, contributes to the cytomembrane integrity, development, and virulence in B. bassiana. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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16 pages, 43845 KiB

Open AccessArticle

AoSsk1, a Response Regulator Required for Mycelial Growth and Development, Stress Responses, Trap Formation, and the Secondary Metabolism in Arthrobotrys oligospora

by Ke-Xin Jiang, Qian-Qian Liu, Na Bai, Mei-Chen Zhu, Ke-Qin Zhang and Jin-Kui Yang

J. Fungi 2022, 8(3), 260; https://doi.org/10.3390/jof8030260 - 03 Mar 2022

Cited by 25 | Viewed by 2229

Abstract

Ssk1, a response regulator of the two-component signaling system, plays an important role in the cellular response to hyperosmotic stress in fungi. Herein, an ortholog of ssk1 (Aossk1) was characterized in the nematode-trapping fungus Arthrobotrys oligospora using gene disruption and [...] Read more.

Ssk1, a response regulator of the two-component signaling system, plays an important role in the cellular response to hyperosmotic stress in fungi. Herein, an ortholog of ssk1 (Aossk1) was characterized in the nematode-trapping fungus Arthrobotrys oligospora using gene disruption and multi-phenotypic comparison. The deletion of Aossk1 resulted in defective growth, deformed and swollen hyphal cells, an increased hyphal septum, and a shrunken nucleus. Compared to the wild-type (WT) strain, the number of autophagosomes and lipid droplets in the hyphal cells of the ΔAossk1 mutant decreased, whereas their volumes considerably increased. Aossk1 disruption caused a 95% reduction in conidial yield and remarkable defects in tolerance to osmotic and oxidative stress. Meanwhile, the transcript levels of several sporulation-related genes were significantly decreased in the ΔAossk1 mutant compared to the WT strain, including abaA, brlA, flbC, fluG, and rodA. Moreover, the loss of Aossk1 resulted in a remarkable increase in trap formation and predation efficiency. In addition, many metabolites were markedly downregulated in the ΔAossk1 mutant compared to the WT strain. Our results highlight that AoSsk1 is a crucial regulator of asexual development, stress responses, the secondary metabolism, and pathogenicity, and can be useful in probing the regulatory mechanism underlying the trap formation and lifestyle switching of nematode-trapping fungi. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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15 pages, 4562 KiB

Open AccessArticle

Identification and Characterization of Auxin/IAA Biosynthesis Pathway in the Rice Blast Fungus Magnaporthe oryzae

by Lihong Dong, Yuming Ma, Cheng-Yen Chen, Lizheng Shen, Wenda Sun, Guobing Cui, Naweed I. Naqvi and Yi Zhen Deng

J. Fungi 2022, 8(2), 208; https://doi.org/10.3390/jof8020208 - 21 Feb 2022

Cited by 12 | Viewed by 2743

Abstract

The rice blast fungus Magnaporthe oryzae has been known to produce the phytohormone auxin/IAA from its hyphae and conidia, but the detailed biological function and biosynthesis pathway is largely unknown. By sequence homology, we identified a complete indole-3-pyruvic acid (IPA)-based IAA biosynthesis pathway [...] Read more.

The rice blast fungus Magnaporthe oryzae has been known to produce the phytohormone auxin/IAA from its hyphae and conidia, but the detailed biological function and biosynthesis pathway is largely unknown. By sequence homology, we identified a complete indole-3-pyruvic acid (IPA)-based IAA biosynthesis pathway in M. oryzae, consisting of the tryptophan aminotransferase (MoTam1) and the indole-3-pyruvate decarboxylase (MoIpd1). In comparison to the wild type, IAA production was significantly reduced in the motam1Δ mutant, and further reduced in the moipd1Δ mutant. Correspondingly, mycelial growth, conidiation, and pathogenicity were defective in the motam1Δ and the moipd1Δ mutants to various degrees. Targeted metabolomics analysis further confirmed the presence of a functional IPA pathway, catalyzed by MoIpd1, which contributes to IAA/auxin production in M. oryzae. Furthermore, the well-established IAA biosynthesis inhibitor, yucasin, suppressed mycelial growth, conidiation, and pathogenicity in M. oryzae. Overall, this study identified an IPA-dependent IAA synthesis pathway crucial for M. oryzae mycelial growth and pathogenic development. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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13 pages, 1699 KiB

Open AccessArticle

Casein Kinase 2 Mediates Degradation of Transcription Factor Pcf1 during Appressorium Formation in the Rice Blast Fungus

by Pengyun Huang, Yan Li, Jing Wang, Qing Wang, Zhicheng Huang, Xiaohong Liu, Fucheng Lin and Jianping Lu

J. Fungi 2022, 8(2), 144; https://doi.org/10.3390/jof8020144 - 30 Jan 2022

Cited by 3 | Viewed by 2678

Abstract

The appressorium is a specialized structure that is differentiated from Magnaporthe oryzae spores that can infect host cells. In the process of cellular transformation from spore to appressorium, the contents inside the spores are transferred into appressoria, accompanied by major differences in the [...] Read more.

The appressorium is a specialized structure that is differentiated from Magnaporthe oryzae spores that can infect host cells. In the process of cellular transformation from spore to appressorium, the contents inside the spores are transferred into appressoria, accompanied by major differences in the gene expression model. In this study, we reported a transcription factor (TF), Pcf1, which was depressed at the transcription level and degraded at the protein level in nuclei of incipient appressoria at four hpi (hours post inoculation). To investigate its degradation mechanism, the interacting proteins of Pcf1 were identified using an immunoprecipitation-mass spectrometry (IP-MS) assay. Yeast two-hybrid (Y2H) and co-IP (co-immunoprecipitation) assays confirmed that Pcf1 interacted with the casein kinase 2 (CK2) holoenzyme through direct combination with the CKb2 subunit. Moreover, Pcf1 was ubiquitinated in the hyphae. These changes in Pcf1 protein levels in nuclei provide a new clue of how TFs are degraded during appressorium formation: temporarily unnecessary TFs in spores are phosphorylated through interacting with CK2 enzyme and are then ubiquitinated and digested by the ubiquitin proteasome system (UPS). Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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13 pages, 2539 KiB

Open AccessArticle

Role of Two G-Protein α Subunits in Vegetative Growth, Cell Wall Integrity, and Virulence of the Entomopathogenic Fungus Metarhizium robertsii

by Youmin Tong, Hao Wu, Lili He, Jiaojiao Qu, Zhenbang Liu, Yulong Wang, Mingjun Chen and Bo Huang

J. Fungi 2022, 8(2), 132; https://doi.org/10.3390/jof8020132 - 28 Jan 2022

Cited by 1 | Viewed by 2352

Abstract

Heterotrimeric G-proteins are crucial for fungal growth and differentiation. The α subunits of heterotrimeric G-proteins play an essential role in controlling signal transduction. However, the function of G-protein α subunits in entomopathogenic fungi remains poorly understood. Two group II Gα subunits (MrGPA2 and [...] Read more.

Heterotrimeric G-proteins are crucial for fungal growth and differentiation. The α subunits of heterotrimeric G-proteins play an essential role in controlling signal transduction. However, the function of G-protein α subunits in entomopathogenic fungi remains poorly understood. Two group II Gα subunits (MrGPA2 and MrGPA4) were characterized in the entomopathogenic fungus, Metarhizium robertsii. Bioinformatics analysis showed that the relationship between MrGPA2 and MrGPA4 was closer than that of other MrGPAs. Both green fluorescent protein (GFP)-tagged MrGPA2 and MrGPA4 were localized at the cytoplasm. Furthermore, ∆MrGpa2∆MrGpa4 double mutants showed remarkably reduced vegetative growth compared to the wild-type and single-mutant strains, which was accompanied by the downregulation of several growth-related genes, such as ssk2, pbs2, stuA, hog1, and ac. Only the ∆MrGpa2∆MrGpa4 double mutant was sensitive to Congo red stress. The insect bioassay demonstrated significantly attenuated virulence for the ∆MrGpa2∆MrGpa4 double mutant compared to the wild-type and single-mutant strains. Further analysis indicated that double deletion of MrGpa2 and MrGpa4 had no effect on appressorium formation but suppressed the expression levels of several virulence-related genes in the insect hemocoel. These findings demonstrate that MrGpa2 and MrGpa4 exhibit functional redundancy and contribute to the vegetative growth, stress tolerance, and pest control potential in M. robertsii. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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13 pages, 5467 KiB

Open AccessArticle

A Putative D-Arabinono-1,4-lactone Oxidase, MoAlo1, Is Required for Fungal Growth, Conidiogenesis, and Pathogenicity in Magnaporthe oryzae

by Ming-Hua Wu, Lu-Yao Huang, Li-Xiao Sun, Hui Qian, Yun-Yun Wei, Shuang Liang, Xue-Ming Zhu, Lin Li, Jian-Ping Lu, Fu-Cheng Lin and Xiao-Hong Liu

J. Fungi 2022, 8(1), 72; https://doi.org/10.3390/jof8010072 - 11 Jan 2022

Cited by 3 | Viewed by 2009

Abstract

Magnaporthe oryzae is the causal agent of rice blast outbreaks. L-ascorbic acid (ASC) is a famous antioxidant found in nature. However, while ASC is rare or absent in fungi, a five-carbon analog, D-erythroascorbic acid (EASC), seems to appear to be a substitute for [...] Read more.

Magnaporthe oryzae is the causal agent of rice blast outbreaks. L-ascorbic acid (ASC) is a famous antioxidant found in nature. However, while ASC is rare or absent in fungi, a five-carbon analog, D-erythroascorbic acid (EASC), seems to appear to be a substitute for ASC. Although the antioxidant function of ASC has been widely described, the specific properties and physiological functions of EASC remain poorly understood. In this study, we identified a D-arabinono-1,4-lactone oxidase (ALO) domain-containing protein, MoAlo1, and found that MoAlo1 was localized to mitochondria. Disruption of MoALO1 (ΔMoalo1) exhibited defects in vegetative growth as well as conidiogenesis. The ΔMoalo1 mutant was found to be more sensitive to exogenous H₂O₂. Additionally, the pathogenicity of conidia in the ΔMoalo1 null mutant was reduced deeply in rice, and defective penetration of appressorium-like structures (ALS) formed by the hyphal tips was also observed in the ΔMoalo1 null mutant. When exogenous EASC was added to the conidial suspension, the defective pathogenicity of the ΔMoalo1 mutant was restored. Collectively, MoAlo1 is essential for growth, conidiogenesis, and pathogenicity in M. oryzae. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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Review

Jump to: Research

17 pages, 1093 KiB

Open AccessReview

Host–Pathogen Interactions between Metarhizium spp. and Locusts

by Jun Li and Yuxian Xia

J. Fungi 2022, 8(6), 602; https://doi.org/10.3390/jof8060602 - 03 Jun 2022

Cited by 13 | Viewed by 2641

Abstract

The progress in research on the interactions between Metarhizium spp. and locusts has improved our understanding of the interactions between fungal infection and host immunity. A general network of immune responses has been constructed, and the pathways regulating fungal pathogenicity have also been [...] Read more.

The progress in research on the interactions between Metarhizium spp. and locusts has improved our understanding of the interactions between fungal infection and host immunity. A general network of immune responses has been constructed, and the pathways regulating fungal pathogenicity have also been explored in depth. However, there have been no systematic surveys of interaction between Metarhizium spp. and locusts. The pathogenesis of Metarhizium comprises conidial attachment, germination, appressorial formation, and colonization in the body cavity of the host locusts. Meanwhile, the locust resists fungal infection through humoral and cellular immunity. Here, we summarize the crucial pathways that regulate the pathogenesis of Metarhizium and host immune defense. Conidial hydrophobicity is mainly affected by the contents of hydrophobins and chitin. Appressorial formation is regulated by the pathways of MAPKs, cAMP/PKA, and Ca²⁺/calmodulin. Lipid droplets degradation and secreted enzymes contributed to fungal penetration. The humoral response of locust is coordinated by the Toll pathway and the ecdysone. The regulatory mechanism of hemocyte differentiation and migration is elusive. In addition, behavioral fever and density-dependent population immunity have an impact on the resistance of hosts against fungal infection. This review depicts a prospect to help us understand host–pathogen interactions and provides a foundation for the engineering of entomopathogenic fungi and the discovery of insecticidal targets to control insect pests. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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23 pages, 1675 KiB

Open AccessReview

Regulatory Roles of Histone Modifications in Filamentous Fungal Pathogens

by Yiling Lai, Lili Wang, Weilu Zheng and Sibao Wang

J. Fungi 2022, 8(6), 565; https://doi.org/10.3390/jof8060565 - 25 May 2022

Cited by 17 | Viewed by 3352

Abstract

Filamentous fungal pathogens have evolved diverse strategies to infect a variety of hosts including plants and insects. The dynamic infection process requires rapid and fine-tuning regulation of fungal gene expression programs in response to the changing host environment and defenses. Therefore, transcriptional reprogramming [...] Read more.

Filamentous fungal pathogens have evolved diverse strategies to infect a variety of hosts including plants and insects. The dynamic infection process requires rapid and fine-tuning regulation of fungal gene expression programs in response to the changing host environment and defenses. Therefore, transcriptional reprogramming of fungal pathogens is critical for fungal development and pathogenicity. Histone post-translational modification, one of the main mechanisms of epigenetic regulation, has been shown to play an important role in the regulation of gene expressions, and is involved in, e.g., fungal development, infection-related morphogenesis, environmental stress responses, biosynthesis of secondary metabolites, and pathogenicity. This review highlights recent findings and insights into regulatory mechanisms of histone methylation and acetylation in fungal development and pathogenicity, as well as their roles in modulating pathogenic fungi–host interactions. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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14 pages, 862 KiB

Open AccessReview

Regulatory Mechanism of Trap Formation in the Nematode-Trapping Fungi

by Mei-Chen Zhu, Xue-Mei Li, Na Zhao, Le Yang, Ke-Qin Zhang and Jin-Kui Yang

J. Fungi 2022, 8(4), 406; https://doi.org/10.3390/jof8040406 - 16 Apr 2022

Cited by 25 | Viewed by 3203

Abstract

Nematode-trapping (NT) fungi play a significant role in the biological control of plant- parasitic nematodes. NT fungi, as a predator, can differentiate into specialized structures called “traps” to capture, kill, and consume nematodes at a nutrient-deprived condition. Therefore, trap formation is also an [...] Read more.

Nematode-trapping (NT) fungi play a significant role in the biological control of plant- parasitic nematodes. NT fungi, as a predator, can differentiate into specialized structures called “traps” to capture, kill, and consume nematodes at a nutrient-deprived condition. Therefore, trap formation is also an important indicator that NT fungi transition from a saprophytic to a predacious lifestyle. With the development of gene knockout and multiple omics such as genomics, transcriptomics, and metabolomics, increasing studies have tried to investigate the regulation mechanism of trap formation in NT fungi. This review summarizes the potential regulatory mechanism of trap formation in NT fungi based on the latest findings in this field. Signaling pathways have been confirmed to play an especially vital role in trap formation based on phenotypes of various mutants and multi-omics analysis, and the involvement of small molecule compounds, woronin body, peroxisome, autophagy, and pH-sensing receptors in the formation of traps are also discussed. In addition, we also highlight the research focus for elucidating the mechanism underlying trap formation of NT fungi in the future. Full article

(This article belongs to the Special Issue Interactions between Filamentous Fungal Pathogens and Hosts)

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