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Vivekanandhan P, Alahmadi TA, Ansari MJ. Pathogenicity of Metarhizium rileyi (Hypocreales: Clavicipitaceae) against Tenebrio molitor (Coleoptera: Tenebrionidae). J Basic Microbiol 2024; 64:e2300744. [PMID: 38466146 DOI: 10.1002/jobm.202300744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/11/2024] [Accepted: 02/24/2024] [Indexed: 03/12/2024]
Abstract
Tenebrio molitor L., also known as the mealworm, is a polyphagous insect pest that infests various stored grains worldwide. Both the adult and larval stages can cause significant damage to stored grains. The present study focused on isolating entomopathogenic fungi from an infected larval cadaver under environmental conditions. Fungal pathogenicity was tested on T. molitor larvae and pupae for 12 days. Entomopathogenic fungi were identified using biotechnological methods based on their morphology and the sequence of their nuclear ribosomal internal transcribed spacer (ITS). The results of the insecticidal activity indicate that the virulence of fungi varies between the larval and pupal stages. In comparison to the larval stage, the pupal stage is highly susceptible to Metarhizium rileyi, exhibiting 100% mortality rates after 12 days (lethal concentration 50 [LC50] = 7.8 × 106 and lethal concentration 90 (LC90) = 2.1 × 1013 conidia/mL), whereas larvae showed 92% mortality rates at 12 days posttreatment (LC50 = 1.0 × 106 and LC90 = 3.0 × 109 conidia/mL). The enzymatic analyses revealed a significant increase in the levels of the insect enzymes superoxide dismutase (4.76-10.5 mg-1) and glutathione S-transferase (0.46-6.53 mg-1) 3 days after exposure to M. rileyi conidia (1.5 × 105 conidia/mL) compared to the control group. The findings clearly show that M. rileyi is an environmentally friendly and effective microbial agent for controlling the larvae and pupae of T. molitor.
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Affiliation(s)
- Perumal Vivekanandhan
- Department of General Pathology, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India, Chennai, Tamil Nadu, India
| | - Tahani A Alahmadi
- Department of Pediatrics, College of Medicine and King Khalid University Hospital, King Saud University Medical City, Riyadh, Saudi Arabia
| | - Mohammad J Ansari
- Department of Botany, Hindu College Moradabad (Mahatma Jyotiba Phule Rohilkhand University Bareilly), Bareilly, Uttar Pradesh, India
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2
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Li X, Liu M, Dong C. Hydrophobin Gene Cmhyd4 Negatively Regulates Fruiting Body Development in Edible Fungi Cordyceps militaris. Int J Mol Sci 2023; 24:ijms24054586. [PMID: 36902017 PMCID: PMC10003708 DOI: 10.3390/ijms24054586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 03/03/2023] Open
Abstract
A deep understanding of the mechanism of fruiting body development is important for mushroom breeding and cultivation. Hydrophobins, small proteins exclusively secreted by fungi, have been proven to regulate the fruiting body development in many macro fungi. In this study, the hydrophobin gene Cmhyd4 was revealed to negatively regulate the fruiting body development in Cordyceps militaris, a famous edible and medicinal mushroom. Neither the overexpression nor the deletion of Cmhyd4 affected the mycelial growth rate, the hydrophobicity of the mycelia and conidia, or the conidial virulence on silkworm pupae. There was also no difference between the micromorphology of the hyphae and conidia in WT and ΔCmhyd4 strains observed by SEM. However, the ΔCmhyd4 strain showed thicker aerial mycelia in darkness and quicker growth rates under abiotic stress than the WT strain. The deletion of Cmhyd4 could promote conidia production and increase the contents of carotenoid and adenosine. The biological efficiency of the fruiting body was remarkably increased in the ΔCmhyd4 strain compared with the WT strain by improving the fruiting body density, not the height. It was indicated that Cmhyd4 played a negative role in fruiting body development. These results revealed that the diverse negative roles and regulatory effects of Cmhyd4 were totally different from those of Cmhyd1 in C. militaris and provided insights into the developmental regulatory mechanism of C. militaris and candidate genes for C. militaris strain breeding.
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Affiliation(s)
- Xiao Li
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- College of Horticulture, Hebei Agricultural University, Baoding 071001, China
| | - Mengqian Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Caihong Dong
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- Correspondence:
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3
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Sant Anna Iwanicki N, Delalibera Júnior I, de Carvalho LLB, Eilenberg J, De Fine Licht HH. Comparative transcriptomics of growth metabolism and virulence reveal distinct morphogenic profiles of yeast-like cells and hyphae of the fungus Metarhizium rileyi. Fungal Genet Biol 2023; 164:103766. [PMID: 36513262 DOI: 10.1016/j.fgb.2022.103766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Metarhizium rileyiis an entomopathogenic fungus with a narrow host range which distinguishes it from other Metarhiziumspecies with broad host ranges. This species is also unique because the initial yeast-like growth on solid media is only observed in liquid culture in other Metharizium species. A lack of knowledge about the metabolism and genetic signatures of M. rileyiduring this yeast-like phase on solid and in liquid media is a bottleneck for its large-scale production as a commercial biocontrol agent.In this study wefound that M. rileyiyeast-like cells produced on solid medium infected and killed the important insect pest Spodoptera frugiperda with comparable efficiency as yeast-like cells grown in liquid medium. Secondly, we used comparative transcriptomic analysis to investigate theactive genes and genomic signatures of the M. rileyi yeast-like morphotypes produced on solid and in liquid media. Yeast-like cells grown in liquid medium had upregulated genes relating specifically to signal transduction andparticular membrane transporters. Thirdly, we compared the transcriptomic profiles of yeast-like phases of M. rileyi with those of M. anisopliae. The yeast-like phase of M. rileyi grown on solid medium upregulated unique genes not found in otherMetarhiziumspecies including specific membrane proteins and several virulence factors. Orthologous genes associated with heat shock protein, iron permease, membrane proteins and key virulence traits (e.g. collagen-like protein Mcl1) were upregulated in both species. Comparative transcriptome analyses of gene expression showed more differences than similarities between M. anisopliae and M. rileyi yeast-like cells.
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Affiliation(s)
- Natasha Sant Anna Iwanicki
- Department of Entomology and Acarology, Escola Superior de Agricultura 'Luiz de Queiroz', University of São Paulo (ESALQ-USP), Av. Pádua Dias, 11, C.P. 9, Piracicaba, SP CEP 13418-900, Brazil.
| | - Italo Delalibera Júnior
- Department of Entomology and Acarology, Escola Superior de Agricultura 'Luiz de Queiroz', University of São Paulo (ESALQ-USP), Av. Pádua Dias, 11, C.P. 9, Piracicaba, SP CEP 13418-900, Brazil
| | - Lana L B de Carvalho
- Department of Entomology and Acarology, Escola Superior de Agricultura 'Luiz de Queiroz', University of São Paulo (ESALQ-USP), Av. Pádua Dias, 11, C.P. 9, Piracicaba, SP CEP 13418-900, Brazil
| | - Jørgen Eilenberg
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Henrik H De Fine Licht
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
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4
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Peng ZY, Huang ST, Chen JT, Li N, Wei Y, Nawaz A, Deng SQ. An update of a green pesticide: Metarhizium anisopliae. ALL LIFE 2022. [DOI: 10.1080/26895293.2022.2147224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Zhe-Yu Peng
- Department of Pathogen Biology, the Key Laboratory of Microbiology and Parasitology of Anhui Province, the Key Laboratory of Zoonoses of High Institutions in Anhui, School of Basic Medical Sciences, Anhui Medical University, Hefei, People’s Republic of China
| | - Shu-Ting Huang
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, People’s Republic of China
| | - Jia-Ting Chen
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, People’s Republic of China
| | - Ni Li
- Department of Pathogen Biology, the Key Laboratory of Microbiology and Parasitology of Anhui Province, the Key Laboratory of Zoonoses of High Institutions in Anhui, School of Basic Medical Sciences, Anhui Medical University, Hefei, People’s Republic of China
| | - Yong Wei
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, People’s Republic of China
| | - Asad Nawaz
- Department of Pathogen Biology, the Key Laboratory of Microbiology and Parasitology of Anhui Province, the Key Laboratory of Zoonoses of High Institutions in Anhui, School of Basic Medical Sciences, Anhui Medical University, Hefei, People’s Republic of China
| | - Sheng-Qun Deng
- Department of Pathogen Biology, the Key Laboratory of Microbiology and Parasitology of Anhui Province, the Key Laboratory of Zoonoses of High Institutions in Anhui, School of Basic Medical Sciences, Anhui Medical University, Hefei, People’s Republic of China
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5
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Host–Pathogen Interactions between Metarhizium spp. and Locusts. J Fungi (Basel) 2022; 8:jof8060602. [PMID: 35736085 PMCID: PMC9224550 DOI: 10.3390/jof8060602] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/26/2022] [Accepted: 05/31/2022] [Indexed: 01/27/2023] Open
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 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.
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Song H, Bao Y, Zhang M, Liu S, Yu C, Dai J, Wu C, Tang D, Fang W. An inactivating mutation in the vacuolar arginine exporter gene Vae results in culture degeneration in the fungus Metarhizium robertsii. Environ Microbiol 2022; 24:2924-2937. [PMID: 35352870 DOI: 10.1111/1462-2920.15982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/03/2022] [Accepted: 03/20/2022] [Indexed: 02/04/2023]
Abstract
Culture degeneration usually results in great commercial losses in the economically important filamentous fungi, but the genetic causes of the degeneration remain elusive. In the fungus Metarhizium robertsii, we found that deletion of the vacuolar arginine exporter gene Vae caused culture degeneration. Compared to the WT strain, the mutant showed increased apoptosis, reactive oxygen species (ROS) level and mitochondrial membrane potential collapse, reduced conidial yield and abnormal lipid droplet formation. The extent of the degeneration in the mutant gradually increased over the successive subculturing, which eventually became irreversible; compared to the third subculture of the mutant, the seventh subculture showed a lower conidial yield and pathogenicity to insects, stronger apoptosis, higher ROS level and a smaller number of conidial lipid droplets. Incorporation of the genomic clone of Vae could not restore the WT phenotypes in the seventh subculture, but could in the third one. Loss-of-function in Vae resulted in vacuolar arginine accumulation and reduction in the cytosolic arginine. This downregulated the expression of the regulator CAG9 of G protein signalling pathway, which accounted for most of the phenotypic changes associated with the degeneration of the mutant. We identified a deleterious mutation that causes culture degeneration in a filamentous fugus.
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Affiliation(s)
- Hui Song
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Yuting Bao
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Mingxiang Zhang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Shuxing Liu
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Chaonan Yu
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Jin Dai
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Congcong Wu
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Dan Tang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Weiguo Fang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
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Zhang J, Zhang P, Zeng G, Wu G, Qi L, Chen G, Fang W, Yin WB. Transcriptional Differences Guided Discovery and Genetic Identification of Coprogen and Dimerumic Acid Siderophores in Metarhizium robertsii. Front Microbiol 2021; 12:783609. [PMID: 34899665 PMCID: PMC8656255 DOI: 10.3389/fmicb.2021.783609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 11/08/2021] [Indexed: 11/28/2022] Open
Abstract
Siderophores are small molecular iron chelators and participate in the multiple cellular processes in fungi. In this study, biosynthesis gene clusters of coprogens and dimerumic acids were identified by transcriptional level differences of genes related to iron deficiency conditions in Metarhizium robertsii. This leads to the characterization of new coprogen metachelin C (1) and five known siderophores metachelin A (2), metachelin A-CE (3), metachelin B (4), dimerumic acid 11-mannoside (5), and dimerumic acid (6). The structure of metachelin C (1) was elucidated by NMR spectroscopy and HR-ESI-MS analysis. Genetic deletions of mrsidA, and mrsidD abolished the production of compounds 1–6 that implied their involvement in the biosynthesis of coprogen and dimerumic acid. Interestingly, NRPS gene mrsidD is responsible for biosynthesis of both coprogen and dimerumic acid, thus we proposed plausible biosynthetic pathways for the synthesis of coprogen and dimerumic acid siderophores. Therefore, our study provides the genetic basis for understanding the biosynthetic pathway of coprogen and dimerumic acid in Metarhizium robertsii.
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Affiliation(s)
- Jinyu Zhang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Peng Zhang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Guohong Zeng
- College of Life Science, Institute of Microbiology, Zhejiang University, Hangzhou, China
| | - Guangwei Wu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Landa Qi
- Henan Academy of Science Institute of Biology, Zhengzhou, China
| | - Guocan Chen
- Henan Academy of Science Institute of Biology, Zhengzhou, China
| | - Weiguo Fang
- College of Life Science, Institute of Microbiology, Zhejiang University, Hangzhou, China
| | - Wen-Bing Yin
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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8
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Li X, Wang F, Liu M, Dong C. Hydrophobin CmHYD1 Is Involved in Conidiation, Infection and Primordium Formation, and Regulated by GATA Transcription Factor CmAreA in Edible Fungus, Cordyceps militaris. J Fungi (Basel) 2021; 7:jof7080674. [PMID: 34436213 PMCID: PMC8400498 DOI: 10.3390/jof7080674] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/13/2021] [Accepted: 08/19/2021] [Indexed: 12/30/2022] Open
Abstract
Hydrophobins are a family of small proteins exclusively secreted by fungi, and play a variety of roles in the life cycle. Cmhyd1, one of the hydrophobin class II members in Cordyceps militaris, has been shown to have a high transcript level during fruiting body development. Here, deletion of Cmhyd1 results in reduction in aerial mycelia, conidiation, hydrophobicity and infection ability, and complete inhibition of pigmentation and primordium differentiation. Cmhyd1 plays roles in conidiation and cuticle-bypassing infection by regulating the transcripts of frequency clock protein, Cmfrq, and velvet protein, Cmvosa, as well as primordium formation via the mitogen-activated protein kinase signaling pathway. Cmhyd1 also participates in stress response, including tolerance of mycelia to osmotic and oxidative stresses, and conidia to high or low temperatures. CmAreA, a transcription factor of nitrogen regulatory, is recruited to the promoter of Cmhyd1 and activates the transcription of Cmhyd1 with coactivator CmOTam using electrophoretic mobility shift assays and transient luciferase expression in tobacco. Furthermore, CmHYD1 is proved to regulate the transcription of Cmarea at different developmental stages via a positive feedback loop. These results reveal the diverse roles and regulation of Cmhyd1 in C. militaris, and provide insights into the developmental regulatory mechanism of mushrooms.
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Affiliation(s)
- Xiao Li
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (X.L.); (F.W.); (M.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fen Wang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (X.L.); (F.W.); (M.L.)
| | - Mengqian Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (X.L.); (F.W.); (M.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Caihong Dong
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (X.L.); (F.W.); (M.L.)
- Guizhou Key Laboratory of Edible Fungi Breeding, Guizhou Academy of Agricultural Sciences, Guiyang 550000, China
- Correspondence:
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9
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Dwivedi SA, Tomer A. Application of Mycobiocontrol Agent in Biodergradation and Pest Management. Fungal Biol 2021. [DOI: 10.1007/978-3-030-54422-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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González-Hernández GA, Padilla-Guerrero IE, Martínez-Vázquez A, Torres-Guzmán JC. Virulence Factors of the Entomopathogenic Genus Metarhizium. Curr Protein Pept Sci 2021; 21:324-330. [PMID: 31951168 DOI: 10.2174/1389203721666200116092407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 09/28/2019] [Accepted: 10/18/2019] [Indexed: 01/10/2023]
Abstract
The fungal genus Metarhizium has been used as an entomopathogen worldwide for approximately 140 years, and its mechanism of infection and its virulence factors have been studied. The present review is a compilation of virulence factors described in the literature to date and their participation in specific stages of the infection process.
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Affiliation(s)
- Gloria A González-Hernández
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Campus Guanajuato, Guanajuato, Mexico
| | - Israel E Padilla-Guerrero
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Campus Guanajuato, Guanajuato, Mexico
| | | | - Juan C Torres-Guzmán
- Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Campus Guanajuato, Guanajuato, Mexico
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11
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Shin TY, Lee MR, Park SE, Lee SJ, Kim WJ, Kim JS. Pathogenesis-related genes of entomopathogenic fungi. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 105:e21747. [PMID: 33029869 DOI: 10.1002/arch.21747] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
All living things on Earth experience various diseases such as those caused by viruses, bacteria, and fungi. Insects are no exception to this rule, and fungi that cause disease in insects are called entomopathogenic fungi. These fungi have been developed as microbial insecticides and are used to control various pests. Generally, the mode of action of entomopathogenic fungi is divided into the attachment of conidia, germination, penetration, growth, and generation of secondary infectious conidia. In each of these steps, that entomopathogenic fungi use genes in a complex manner (specific or diverse) has been shown by gene knock-out and RNA-sequencing analysis. In this review, the information mechanism of entomopathogenic fungi was divided into six steps: (1) attachment of conidia to host, (2) germination and appressorium, (3) penetration, (4) fungal growth in hemolymph, (5) conidia production on host, and (6) transmission and dispersal. The strategy used by the fungi in each step was described at the genetic level. In addition, an approach for studying the mode of action of the fungi is presented.
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Affiliation(s)
- Tae Young Shin
- Department of Agricultural Biology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Mi Rong Lee
- Department of Agricultural Biology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - So Eun Park
- Department of Agricultural Biology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Se Jin Lee
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Woo Jin Kim
- Department of Agricultural Biology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Jae Su Kim
- Department of Agricultural Biology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
- Department of Agricultural Convergence Technology, Jeonbuk National University, Jeonju, Republic of Korea
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12
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Grizanova EV, Coates CJ, Dubovskiy IM, Butt TM. Metarhizium brunneum infection dynamics differ at the cuticle interface of susceptible and tolerant morphs of Galleria mellonella. Virulence 2020; 10:999-1012. [PMID: 31724467 PMCID: PMC8647853 DOI: 10.1080/21505594.2019.1693230] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In order for entomopathogenic fungi to colonize an insect host, they must first attach to, and penetrate, the cuticle layers of the integument. Herein, we explored the interactions between the fungal pathogen Metarhizium brunneum ARSEF 4556 and two immunologically distinct morphs, melanic (M) and non-melanic (NM), of the greater wax moth Galleria mellonella. We first interrogated the cuticular compositions of both insect morphs to reveal substantial differences in their physiochemical properties. Enhanced melanin accumulation, fewer hydrocarbons, and higher L-dihydroxyphenylalanine (DOPA) decarboxylase activity were evident in the cuticle of the M larvae. This “hostile” terrain proved challenging for M. brunneum – reflected in poor conidial attachment and germination, and elevated expression of stress-associated genes (e.g., Hsp30, Hsp70). Lack of adherence to the cuticle impacted negatively on the speed of kill and overall host mortality; a dose of 107 conidia killed ~30% of M larvae over a 12-day period, whereas a 100-fold lower dose (105 conidia) achieved a similar result for NM larvae. Candidate gene expression patterns between the insect morphs indicated that M larvae are primed to “switch-on” immunity-associated genes (e.g., phenoloxidase) within 6–12 h of conidia exposure and can sustain a “defense” response. Critically, M. brunneum responds to the distinct physiochemical cues of both hosts and adjusts the expression of pathogenicity-related genes accordingly (e.g., Pr2, Mad1, Mad2). We reveal previously uncharacterized mechanisms of attack and defence in fungal-insect antibiosis.
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Affiliation(s)
- Ekaterina V Grizanova
- Laboratory of Biological Plant Protection and Biotechnology, Novosibirsk State Agrarian University, Novosibirsk, Russia
| | | | - Ivan M Dubovskiy
- Laboratory of Biological Plant Protection and Biotechnology, Novosibirsk State Agrarian University, Novosibirsk, Russia.,Siberian Federal Scientific Centre of Agro-BioTechnologies, Russian Academy of Sciences, Krasnoobsk, Russia
| | - Tariq M Butt
- Department of Biosciences, College of Science, Swansea University, Swansea, UK
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13
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Tong Y, Wu H, Liu Z, Wang Z, Huang B. G-Protein Subunit Gα i in Mitochondria, MrGPA1, Affects Conidiation, Stress Resistance, and Virulence of Entomopathogenic Fungus Metarhizium robertsii. Front Microbiol 2020; 11:1251. [PMID: 32612588 PMCID: PMC7309505 DOI: 10.3389/fmicb.2020.01251] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 05/15/2020] [Indexed: 12/16/2022] Open
Abstract
G proteins are critical modulators or transducers in various transmembrane signaling systems. They play key roles in numerous biological processes in fungi, including vegetative growth, development of infection-related structures, asexual conidiation, and virulence. However, functions of G proteins in entomopathogenic fungi remain unclear. Here, we characterized the roles of MrGPA1, a G-protein subunit Gαi, in conidiation, stress resistance, and virulence in Metarhizium robertsii. MrGPA1 was localized in the mitochondria. MrGpa1 deletion resulted in a significant reduction (47%) in the conidiation capacity, and reduced expression of several key conidiation-related genes, including fluG, flbD, brlA, wetA, phiA, and stuA. Further, MrGpa1 disruption resulted in decreased fungal sensitivity to UV irradiation and thermal stress, as determined based on conidial germination of ΔMrGpa1 and wild-type (WT) strains. Chemical stress analysis indicated that MrGpa1 contributes to fungal antioxidant capacity and cell wall integrity, but is not involved in tolerance to antifungal drug and osmotic stress. Importantly, insect bioassays involving (topical inoculation and injection) of Galleria mellonella larvae revealed decreased virulence of ΔMrGpa1 strain after cuticle infection. This was accompanied by decreased rates of appressorium formation and reduced expression of several cuticle penetration-related genes. Further assays showed that MrGpa1 regulated intracellular cyclic AMP (cAMP) levels, but feeding with cAMP could not recover the appressorium formation rate of ΔMrGpa1. These observations suggest that MrGpa1 contributes to the regulation of conidiation, UV irradiation, thermal stress response, antioxidant capacity, and cell wall integrity in M. robertsii. This gene is also involved in insect cuticle penetration during infection. These findings raise the possibility of designing powerful strategies for genetic improvement of M. robertsii conidiation capacity and virulence for killing pests.
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Affiliation(s)
- Youmin Tong
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Hao Wu
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Zhenbang Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zhangxun Wang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
- School of Plant Protection, Anhui Agricultural University, Hefei, China
| | - Bo Huang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
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DNA methyltransferase implicated in the recovery of conidiation, through successive plant passages, in phenotypically degenerated Metarhizium. Appl Microbiol Biotechnol 2020; 104:5371-5383. [PMID: 32318770 DOI: 10.1007/s00253-020-10628-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/06/2020] [Accepted: 04/14/2020] [Indexed: 10/24/2022]
Abstract
Metarhizium robertsii is a fungus with two lifestyles; it is a plant root symbiont and an insect pathogen. A spontaneously phenotypically degenerated strain of M. robertsii strain ARSEF 2575 (M. robertsii lc-2575; lc = low conidiation) showed a reduction in conidiation and fungal virulence after successive subculturing on agar medium. In order to recover conidiation, we experimentally passaged M. robertsii lc-2575 through plant (soldier bean and switchgrass) root or insect (Galleria mellonella) larvae. After five passages, the resultant strains had significantly increased conidial yields on agar and increased virulence in insect bioassays. Concomitantly, DNA methyltransferase, MrDIM-2 expression was downregulated in BR5 (a strain after 5 bean root passages) and isolates after switchgrass and insect passages. Bisulfite sequencing showed little difference in overall genomic DNA methylation levels (~ 0.37%) between M. robertsii lc-2575 and BR5. However, a finer comparison of the different methylated regions (DMRs) showed that DMRs of BR5 were more abundant in the intergenic regions (69.32%) compared with that of M. robertsii lc-2575 (33.33%). The addition of DNA methyltransferase inhibitor, 5-azacytidine, to agar supported the role of DNA methyltransferases and resulted in an increase in conidiation of M. robertsii lc-2575. Differential gene expression was observed in selected DMRs in BR5 when compared with M. robertsii lc-2575. Here we implicated epigenetic regulation in the recovery of conidiation through the effects of DNA methyltransferase and that plant passage could be used as a method to recover fungal conidiation and virulence in a phenotypically degenerated M. robertsii. KEY POINTS: • Passage of Metarhizium through plant root or insect results in increased conidiation. • DNA methyltransferase is downregulated after host passage. • Bisulfite sequencing identified potentially methylated genes involved in conidiation.
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Beys-da-Silva WO, Rosa RL, Berger M, Coutinho-Rodrigues CJB, Vainstein MH, Schrank A, Bittencourt VREP, Santi L. Updating the application of Metarhizium anisopliae to control cattle tick Rhipicephalus microplus (Acari: Ixodidae). Exp Parasitol 2019; 208:107812. [PMID: 31809704 DOI: 10.1016/j.exppara.2019.107812] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/30/2019] [Accepted: 12/02/2019] [Indexed: 01/07/2023]
Abstract
The bovine tick, Rhipicephalus microplus, is the main ectoparasite of cattle and causes loss of billions of dollars worldwide in lost meat, milk, and leather production, as well as control expenses. In addition to systemically impacting the host during the parasitic act, this parasite is also an important disease vector. Traditionally, the main commercial control of the tick is achieved through application of chemical acaricides, which can leave residues in the meat and milk. Moreover, ticks can become resistant to these chemicals due to their massive and incorrect use. Many alternative methods have been tested including vaccines and natural products from plant origin. However, the efficacy of these treatments is variable and limited, especially when used alone. Arthropod-pathogenic fungi, such as Metarhizium anisopliae, are among the natural microbial agents with promising potential to be used alone or in association with other products, for example with chemical acaricides. This article discusses several aspects of bovine tick control related to the use of M. anisopliae, which is one of the most studied and viable alternative tools for effective tick control.
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Affiliation(s)
- Walter O Beys-da-Silva
- Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre, Brazil; Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
| | - Rafael L Rosa
- Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil
| | - Markus Berger
- Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre, Brazil
| | - Caio J B Coutinho-Rodrigues
- Departamento de Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Brazil
| | | | - Augusto Schrank
- Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil
| | - Vânia R E P Bittencourt
- Departamento de Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Brazil
| | - Lucélia Santi
- Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre, Brazil; Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Brazil.
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16
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Barelli L, Behie SW, Bidochka MJ. Availability of carbon and nitrogen in soil affects Metarhizium robertsii root colonization and transfer of insect-derived nitrogen. FEMS Microbiol Ecol 2019; 95:5567177. [PMID: 31504453 DOI: 10.1093/femsec/fiz144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 09/05/2019] [Indexed: 11/12/2022] Open
Abstract
The endophytic, insect pathogenic fungus, Metarhizium, exchanges insect-derived nitrogen for photosynthate as part of a symbiotic association similar to well-known mycorrhizal relationships. However, little is known about this nitrogen transfer in soils where there is an abundance of nitrogen and/or carbon. Here, we applied D-glucose and ammonium nitrate to soil to examine the effect on root colonization and transfer of labelled nitrogen (15N) from an insect (injected with 15N-ammonium sulfate) to Metarhizium robertsii, into leaves of the common bean, Phaseolus vulgaris, over the course of 28 days. Application of exogenous carbon and/or nitrogen to soils significantly reduced detectable 15N in plant leaves. Metarhizium root colonization, quantified with real-time PCR, revealed colonization persisted under all conditions but was significantly greater on roots in soil supplemented with glucose and significantly lower in soil supplemented with ammonium nitrate. Fungal gene expression analysis revealed differential expression of sugar and nitrogen transporters (mrt, st3, nrr1, nit1, mep2) when Metarhizium was grown in pure broth culture or in co-culture with plant roots under various carbon and nitrogen conditions. The observation that Metarhizium maintained root colonization in the absence of nitrogen transfer, and without evidence of plant harm, is intriguing and indicates additional benefits with ecological importance.
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Affiliation(s)
- Larissa Barelli
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, Canada, L2S 3A1
| | - Scott W Behie
- Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall, Berkeley, CA, USA, 94720
| | - Michael J Bidochka
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, Canada, L2S 3A1
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Yan Q, Zhang Z, Yang Y, Chen F, Shao Y. Proteome analysis reveals global response to deletion of mrflbA in Monascus ruber. J Microbiol 2018; 56:255-263. [DOI: 10.1007/s12275-018-7425-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/09/2018] [Accepted: 01/20/2018] [Indexed: 12/01/2022]
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Xu J, Wang X, Li Y, Zeng J, Wang G, Deng C, Guo W. Host-induced gene silencing of a regulator of G protein signalling gene (VdRGS1) confers resistance to Verticillium wilt in cotton. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1629-1643. [PMID: 29431919 PMCID: PMC6096726 DOI: 10.1111/pbi.12900] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/03/2018] [Indexed: 05/20/2023]
Abstract
Verticillium wilt (VW), caused by soil-borne fungi of the genus Verticillium, is a serious disease affecting a wide range of plants and leading to a constant and major challenge to agriculture worldwide. Cotton (Gossypium hirsutum) is the world's most important natural textile fibre and oil crop. VW of cotton is a highly devastating vascular disease; however, few resistant germplasms have been reported in cotton. An increasing number of studies have shown that RNA interference (RNAi)-based host-induced gene silencing (HIGS) is an effective strategy for improving plant resistance to pathogens by silencing genes essential for the pathogenicity of these pathogens. Here, we have identified and characterized multifunctional regulators of G protein signalling (RGS) in the Verticillium dahliae virulence strain, Vd8. Of eight VdRGS genes, VdRGS1 showed the most significant increase in expression in V. dahliae after treating with the roots of cotton seedlings. Based on the phenotype detection of VdRGS1 deletion and complementation mutants, we found that VdRGS1 played crucial roles in spore production, hyphal development, microsclerotia formation and pathogenicity. Tobacco rattle virus-mediated HIGS in cotton plants silenced VdRGS1 transcripts in invaded V. dahliae strains and enhanced broad-spectrum resistance to cotton VW. Our data demonstrate that VdRGS1 is a conserved and essential gene for V. dahliae virulence. HIGS of VdRGS1 provides effective control against V. dahliae infection and could obtain the durable disease resistance in cotton and in other VW-susceptible host crops by developing the stable transformants.
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Affiliation(s)
- Jun Xu
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Xinyu Wang
- College of Life SciencesNanjing Agricultural UniversityNanjingJiangsuChina
| | - Yongqing Li
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Jianguo Zeng
- College of Life SciencesNanjing Agricultural UniversityNanjingJiangsuChina
| | - Guilin Wang
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Chaoyang Deng
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Wangzhen Guo
- State Key Laboratory of Crop Genetics & Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
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Functional analysis of a regulator of G-protein signaling CgRGS1 in the rubber tree anthracnose fungus Colletotrichum gloeosporioides. Arch Microbiol 2017; 200:391-400. [PMID: 29177869 DOI: 10.1007/s00203-017-1455-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 11/12/2017] [Accepted: 11/14/2017] [Indexed: 01/02/2023]
Abstract
Colletotrichum gloeosporioides is the causal agent of rubber anthracnose, which is also one of the important biological factors threatening the development of natural rubber industry in the world. Regulators of G-protein signaling (RGS) are key negative regulators of G-proteins, which play important roles in growth, development and pathogenic processes of plant pathogens. In this study, a RGS gene CgRGS1 was functionally characterized in C. gloeosporioides. Compared to the wild type, the CgRGS1 deletion mutant had slow vegetative growth, reduced conidia with multi-end germination, low appressorium formation rate, high resistance to oxidative stress and SDS. Moreover, the mutant was sensitive to osmotic pressure and showed decreased virulence. In conclusion, CgRGS1 is involved in regulation of vegetative growth, conidiation, germination, appressorium formation, oxidative stress, osmotic pressure response and pathogenicity in C. gloeosporioides.
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Zeng G, Chen X, Zhang X, Zhang Q, Xu C, Mi W, Guo N, Zhao H, You Y, Dryburgh FJ, Bidochka MJ, St. Leger RJ, Zhang L, Fang W. Genome-wide identification of pathogenicity, conidiation and colony sectorization genes in Metarhizium robertsii. Environ Microbiol 2017; 19:3896-3908. [DOI: 10.1111/1462-2920.13777] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 04/17/2017] [Accepted: 04/17/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Guohong Zeng
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Xiaoxuan Chen
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Xing Zhang
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | | | - Chuan Xu
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Wubin Mi
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Na Guo
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Hong Zhao
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Yue You
- Institute of Microbiology; Zhejiang University; Hangzhou China
| | - Farah-Jade Dryburgh
- Department of Biological Sciences; Brock University; St. Catharines ON Canada
| | - Michael J. Bidochka
- Department of Biological Sciences; Brock University; St. Catharines ON Canada
| | | | - Lei Zhang
- School of Biological and Chemical Engineering; Zhejiang University of Science & Technology; Hangzhou China
| | - Weiguo Fang
- Institute of Microbiology; Zhejiang University; Hangzhou China
- Institute of Insect Sciences; Zhejiang University; Hangzhou China
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21
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García-Rico RO, Fierro F. [Role of G-protein alpha sub-units in the morphogenic processes of filamentous Ascomycota fungi]. Rev Iberoam Micol 2017; 34:1-9. [PMID: 28169110 DOI: 10.1016/j.riam.2016.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 03/30/2016] [Accepted: 06/21/2016] [Indexed: 01/04/2023] Open
Abstract
The phylum Ascomycota comprises about 75% of all the fungal species described, and includes species of medical, phytosanitary, agricultural, and biotechnological importance. The ability to spread, explore, and colonise new substrates is a feature of critical importance for this group of organisms. In this regard, basic processes such as conidial germination, the extension of hyphae and sporulation, make up the backbone of development in most filamentous fungi. These processes require specialised morphogenic machinery, coordinated and regulated by mechanisms that are still being elucidated. In recent years, substantial progress has been made in understanding the role of the signalling pathway mediated by heterotrimericG proteins in basic biological processes of many filamentous fungi. This review focuses on the role of the alpha subunits of heterotrimericG proteins in the morphogenic processes of filamentous Ascomycota.
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Affiliation(s)
- Ramón O García-Rico
- Departamento de Microbiología, Facultad de Ciencias Básicas, Universidad de Pamplona, Pamplona, Norte de Santander, Colombia.
| | - Francisco Fierro
- Departamento de Biotecnología, Universidad Autónoma Metropolitana-Unidad Iztapalapa, Ciudad de México, Distrito Federal, México
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22
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Butt TM, Coates CJ, Dubovskiy IM, Ratcliffe NA. Entomopathogenic Fungi: New Insights into Host-Pathogen Interactions. ADVANCES IN GENETICS 2016; 94:307-64. [PMID: 27131329 DOI: 10.1016/bs.adgen.2016.01.006] [Citation(s) in RCA: 189] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Although many insects successfully live in dangerous environments exposed to diverse communities of microbes, they are often exploited and killed by specialist pathogens. Studies of host-pathogen interactions (HPI) provide valuable insights into the dynamics of the highly aggressive coevolutionary arms race between entomopathogenic fungi (EPF) and their arthropod hosts. The host defenses are designed to exclude the pathogen or mitigate the damage inflicted while the pathogen responds with immune evasion and utilization of host resources. EPF neutralize their immediate surroundings on the insect integument and benefit from the physiochemical properties of the cuticle and its compounds that exclude competing microbes. EPF also exhibit adaptations aimed at minimizing trauma that can be deleterious to both host and pathogen (eg, melanization of hemolymph), form narrow penetration pegs that alleviate host dehydration and produce blastospores that lack immunogenic sugars/enzymes but facilitate rapid assimilation of hemolymph nutrients. In response, insects deploy an extensive armory of hemocytes and macromolecules, such as lectins and phenoloxidase, that repel, immobilize, and kill EPF. New evidence suggests that immune bioactives work synergistically (eg, lysozyme with antimicrobial peptides) to combat infections. Some proteins, including transferrin and apolipophorin III, also demonstrate multifunctional properties, participating in metabolism, homeostasis, and pathogen recognition. This review discusses the molecular intricacies of these HPI, highlighting the interplay between immunity, stress management, and metabolism. Increased knowledge in this area could enhance the efficacy of EPF, ensuring their future in integrated pest management programs.
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Affiliation(s)
- T M Butt
- Swansea University, Swansea, Wales, United Kingdom
| | - C J Coates
- Swansea University, Swansea, Wales, United Kingdom
| | | | - N A Ratcliffe
- Swansea University, Swansea, Wales, United Kingdom; Universidade Federal Fluminense, Niteroi, Rio de Janeiro, Brazil
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23
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Moonjely S, Barelli L, Bidochka MJ. Insect Pathogenic Fungi as Endophytes. ADVANCES IN GENETICS 2016; 94:107-35. [PMID: 27131324 DOI: 10.1016/bs.adgen.2015.12.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this chapter, we explore some of the evolutionary, ecological, molecular genetics, and applied aspects of a subset of insect pathogenic fungi that also have a lifestyle as endophytes and we term endophytic insect pathogenic fungi (EIPF). We focus particularly on Metarhizium spp. and Beauveria bassiana as EIPF. The discussion of the evolution of EIPF challenges a view that these fungi were first and foremost insect pathogens that eventually evolved to colonize plants. Phylogenetic evidence shows that the lineages of EIPF are most closely related to grass endophytes that diverged c. 100MYA. We discuss the relationship between genes involved in "insect pathogenesis" and those involved in "endophytism" and provide examples of genes with potential importance in lifestyle transitions toward insect pathogenicity. That is, some genes for insect pathogenesis may have been coopted from genes involved in endophytic colonization. Other genes may be multifunctional and serve in both lifestyle capacities. The interactions of EIPF with their host plants are discussed in some detail. The genetic basis for rhizospheric competence, plant communication, and nutrient exchange is examined and we highlight, with examples, the benefits of EIPF to plants, and the potential reservoir of secondary metabolites hidden within these beneficial symbioses.
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Affiliation(s)
- S Moonjely
- Brock University, St. Catharines, ON, Canada
| | - L Barelli
- Brock University, St. Catharines, ON, Canada
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Chen X, Xu C, Qian Y, Liu R, Zhang Q, Zeng G, Zhang X, Zhao H, Fang W. MAPK cascade-mediated regulation of pathogenicity, conidiation and tolerance to abiotic stresses in the entomopathogenic fungus Metarhizium robertsii. Environ Microbiol 2016; 18:1048-62. [PMID: 26714892 DOI: 10.1111/1462-2920.13198] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 12/20/2015] [Accepted: 12/22/2015] [Indexed: 01/21/2023]
Abstract
Metarhizium robertsii has been used as a model to study fungal pathogenesis in insects, and its pathogenicity has many parallels with plant and mammal pathogenic fungi. MAPK (Mitogen-activated protein kinase) cascades play pivotal roles in cellular regulation in fungi, but their functions have not been characterized in M. robertsii. In this study, we identified the full complement of MAPK cascade components in M. robertsii and dissected their regulatory roles in pathogenesis, conidiation and stress tolerance. The nine components of the Fus3, Hog1 and Slt2-MAPK cascades are all involved in conidiation. The Fus3- and Hog1-MAPK cascades are necessary for tolerance to hyperosmotic stress, and the Slt2- and Fus3-MAPK cascades both mediate cell wall integrity. The Hog1 and Slt2-MAPK cascades contribute to pathogenicity; the Fus3-MAPK cascade is indispensable for fungal pathogenesis. During its life cycle, M. robertsii experiences multiple microenvironments as it transverses the cuticle into the haemocoel. RNA-seq analysis revealed that MAPK cascades collectively play a major role in regulating the adaptation of M. robertsii to the microenvironmental change from the cuticle to the haemolymph. The three MAPKs each regulate their own distinctive subset of genes during penetration of the cuticle and haemocoel colonization, but they function redundantly to regulate adaptation to microenvironmental change.
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Affiliation(s)
- Xiaoxuan Chen
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Chuan Xu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Ying Qian
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Ran Liu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Qiangqiang Zhang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Guohong Zeng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xin Zhang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Hong Zhao
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Weiguo Fang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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Genes involved in virulence of the entomopathogenic fungus Beauveria bassiana. J Invertebr Pathol 2016; 133:41-9. [DOI: 10.1016/j.jip.2015.11.011] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/18/2015] [Accepted: 11/24/2015] [Indexed: 01/13/2023]
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Garza-López PM, Suárez-Vergel G, Hamdan-Partida A, Loera O. Variations in oxygen concentration cause differential antioxidant response and expression of related genes in Beauveria bassiana. Fungal Biol 2015; 119:257-63. [PMID: 25813512 DOI: 10.1016/j.funbio.2014.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/17/2014] [Accepted: 12/23/2014] [Indexed: 10/24/2022]
Abstract
The entomopathogenic fungus Beauveria bassiana is widely used in pest biocontrol strategies. We evaluated both the antioxidant response mediated by compatible solutes, trehalose or mannitol, and the expression of related genes using oxygen pulses at three oxygen concentrations in solid state culture (SSC): normal atmosphere (21% O2), low oxygen (16% O2) and enriched oxygen (26% O2). Trehalose concentration decreased 75% after atmospheric modifications in the cultures, whereas mannitol synthesis was three-fold higher under the 16% O2 pulses relative to normal atmosphere (100 and 30 μg mannitol mg(-1) biomass, respectively). Confirming this result, expression of the mpd gene, coding for mannitol-1-P dehydrogenase (MPD), increased up to 1.4 times after O2 pulses. The expression of the bbrgs1 gene, encoding a regulatory G protein related to conidiation, was analysed to explain previously reported differences in conidial production. Surprisingly, expression of bbrgs1 decreased after atmospheric modification. Finally, principal component analysis (PCA) indicated that 83.39% of the variability in the data could be explained by two components. This analysis corroborated the positive correlation between mannitol concentration and mpd gene expression, as well as the negative correlation between conidial production and bbrgs1 gene expression. This study contributes to understanding of antioxidant and molecular response of B. bassiana induced under oxidant conditions.
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Affiliation(s)
- Paul Misael Garza-López
- Universidad Autónoma Metropolitana Iztapalapa, Departamento de Biotecnología, San Rafael Atlixco 186, Col. Vicentina, C. P. 09340, México D. F., Mexico
| | - Gerardo Suárez-Vergel
- Universidad Autónoma Metropolitana Iztapalapa, Departamento de Biotecnología, San Rafael Atlixco 186, Col. Vicentina, C. P. 09340, México D. F., Mexico
| | - Aida Hamdan-Partida
- Universidad Autónoma Metropolitana Xochimilco, Departamento de Sistemas Biológicos, Calz. del Hueso 1100, Col. Villa Quietud, C. P. 04960, México, D. F., Mexico
| | - Octavio Loera
- Universidad Autónoma Metropolitana Iztapalapa, Departamento de Biotecnología, San Rafael Atlixco 186, Col. Vicentina, C. P. 09340, México D. F., Mexico.
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Stress is the rule rather than the exception for Metarhizium. Curr Genet 2014; 61:253-61. [DOI: 10.1007/s00294-014-0447-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 08/07/2014] [Accepted: 08/17/2014] [Indexed: 01/20/2023]
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Xu C, Zhang X, Qian Y, Chen X, Liu R, Zeng G, Zhao H, Fang W. A high-throughput gene disruption methodology for the entomopathogenic fungus Metarhizium robertsii. PLoS One 2014; 9:e107657. [PMID: 25222118 PMCID: PMC4164657 DOI: 10.1371/journal.pone.0107657] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/14/2014] [Indexed: 11/19/2022] Open
Abstract
Systematic gene disruption is a direct way to interrogate a fungal genome to functionally characterize the full suite of genes involved in various biological processes. Metarhizium robertsii is extraordinarily versatile, and it is a pathogen of arthropods, a saprophyte and a beneficial colonizer of rhizospheres. Thus, M. robertsii can be used as a representative to simultaneously study several major lifestyles that are not shared by the "model" fungi Saccharomyces cerevisiae and Neurospora crassa; a systematic genetic analysis of M. robertsii will benefit studies in other fungi. In order to systematically disrupt genes in M. robertsii, we developed a high-throughput gene disruption methodology, which includes two technologies. One is the modified OSCAR-based, high-throughput construction of gene disruption plasmids. This technology involves two donor plasmids (pA-Bar-OSCAR with the herbicide resistance genes Bar and pA-Sur-OSCAR with another herbicide resistance gene Sur) and a recipient binary plasmid pPK2-OSCAR-GFP that was produced by replacing the Bar cassette in pPK2-bar-GFP with a ccdB cassette and recombination recognition sites. Using this technology, a gene disruption plasmid can be constructed in one cloning step in two days. The other is a highly efficient gene disruption technology based on homologous recombination using a Ku70 deletion mutant (ΔMrKu70) as the recipient strain. The deletion of MrKu70, a gene encoding a key component involved in nonhomologous end-joining DNA repair in fungi, dramatically increases the gene disruption efficiency. The frequency of disrupting the conidiation-associated gene Cag8 in ΔMrKu70 was 93% compared to 7% in the wild-type strain. Since ΔMrKu70 is not different from the wild-type strain in development, pathogenicity and tolerance to various abiotic stresses, it can be used as a recipient strain for a systematic gene disruption project to characterize the whole suite of genes involved in the biological processes of M. robertsii.
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Affiliation(s)
- Chuan Xu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xing Zhang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ying Qian
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaoxuan Chen
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ran Liu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Guohong Zeng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hong Zhao
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Weiguo Fang
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail:
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Zhao H, Xu C, Lu HL, Chen X, St. Leger RJ, Fang W. Host-to-pathogen gene transfer facilitated infection of insects by a pathogenic fungus. PLoS Pathog 2014; 10:e1004009. [PMID: 24722668 PMCID: PMC3983072 DOI: 10.1371/journal.ppat.1004009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/03/2014] [Indexed: 12/14/2022] Open
Abstract
Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen. Its entomopathogenicity is a characteristic that was acquired during evolution from a plant endophyte ancestor. This transition provides a novel perspective on how new functional mechanisms important for host switching and virulence have evolved. From a random T-DNA insertion library, we obtained a pathogenicity defective mutant that resulted from the disruption of a sterol carrier gene (Mr-npc2a). Phylogenetic analysis revealed that Metarhizium acquired Mr-npc2a from an insect by horizontal gene transfer (HGT). Mr-NPC2a binds to cholesterol, an animal sterol, rather than the fungal sterol ergosterol, indicating it retains the specificity of insect NPC2 proteins. Mr-NPC2a is an intracellular protein and is exclusively expressed in the hemolymph of living insects. The disruption of Mr-npc2a reduced the amount of sterol in cell membranes of the yeast-like hyphal bodies that facilitate dispersal in the host body. These were consequently more susceptible to insect immune responses than the wild type. Transgenic expression of Mr-NPC2a increased the virulence of Beauveria bassiana, an endophytic insect-pathogenic fungus that lacks a Mr-NPC2a homolog.
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Affiliation(s)
- Hong Zhao
- Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Chuan Xu
- Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Hsiao-Ling Lu
- Department of Entomology, University of Maryland, College Park, Maryland, United States of America
| | - Xiaoxuan Chen
- Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
| | - Raymond J. St. Leger
- Department of Entomology, University of Maryland, College Park, Maryland, United States of America
| | - Weiguo Fang
- Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China
- * E-mail:
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Shao Y, Lei M, Mao Z, Zhou Y, Chen F. Insights into Monascus biology at the genetic level. Appl Microbiol Biotechnol 2014; 98:3911-22. [PMID: 24633442 DOI: 10.1007/s00253-014-5608-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/10/2014] [Accepted: 02/10/2014] [Indexed: 12/24/2022]
Abstract
The genus of Monascus was nominated by van Tieghem in 1884, but its fermented product-red mold rice (RMR), namely red yeast rice, has been used as folk medicines, food colorants, and fermentation starters for more than thousands of years in oriental countries. Nowadays, RMR is widely developed as food supplements around the world due to its functional compounds such as monacolin K (MK, also called lovastatin) and γ-aminobutyric acid. But the usage of RMR also incurs controversy resulting from contamination of citrinin (a kind of mycotoxin) produced by some Monascus strains. In the past decade, it has made great progress to Monascus spp. at the genetic level with the application of molecular biology techniques to restrain the citrinin production and increase the yields of MK and pigment in RMR, as well as aid Monascus classification and phylogenesis. Up to now, hundreds of papers about Monascus molecular biology (MMB) have been published in the international primary journals. However, to our knowledge, there is no MMB review issued until now. In this review, current understanding of Monascus spp. from the view of molecular biology will be covered and insights into research areas that need to be further investigated will also be discussed.
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Affiliation(s)
- Yanchun Shao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
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Jung B, Kim S, Lee J. Microcyle conidiation in filamentous fungi. MYCOBIOLOGY 2014; 42:1-5. [PMID: 24808726 PMCID: PMC4004940 DOI: 10.5941/myco.2014.42.1.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 02/27/2014] [Accepted: 02/27/2014] [Indexed: 06/03/2023]
Abstract
The typical life cycle of filamentous fungi commonly involves asexual sporulation after vegetative growth in response to environmental factors. The production of asexual spores is critical in the life cycle of most filamentous fungi. Normally, conidia are produced from vegetative hyphae (termed mycelia). However, fungal species subjected to stress conditions exhibit an extremely simplified asexual life cycle, in which the conidia that germinate directly generate further conidia, without forming mycelia. This phenomenon has been termed as microcycle conidiation, and to date has been reported in more than 100 fungal species. In this review, first, we present the morphological properties of fungi during microcycle conidiation, and divide microcycle conidiation into four simple categories, even though fungal species exhibit a wide variety of morphological differences during microcycle conidiogenesis. Second, we describe the factors that influence microcycle conidiation in various fungal species, and present recent genetic studies that have identified the genes responsible for this process. Finally, we discuss the biological meaning and application of microcycle conidiation.
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Affiliation(s)
- Boknam Jung
- Department of Applied Biology, Dong-A University, Busan 604-714, Korea
| | - Soyeon Kim
- Department of Applied Biology, Dong-A University, Busan 604-714, Korea
| | - Jungkwan Lee
- Department of Applied Biology, Dong-A University, Busan 604-714, Korea
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Wang Y, Geng Z, Jiang D, Long F, Zhao Y, Su H, Zhang KQ, Yang J. Characterizations and functions of regulator of G protein signaling (RGS) in fungi. Appl Microbiol Biotechnol 2013; 97:7977-87. [DOI: 10.1007/s00253-013-5133-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 12/20/2022]
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Shin KS, Park HS, Kim YH, Yu JH. Comparative proteomic analyses reveal that FlbA down-regulates gliT expression and SOD activity in Aspergillus fumigatus. J Proteomics 2013; 87:40-52. [DOI: 10.1016/j.jprot.2013.05.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 05/05/2013] [Accepted: 05/09/2013] [Indexed: 10/26/2022]
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Stopiglia CDO, Heidrich D, Sorrentino JM, Vieira FJ, Landell MF, Valente P, Scroferneker ML. Susceptibility of species within theSporothrix schenckiicomplex to a panel of killer yeasts. J Basic Microbiol 2013; 54:578-84. [DOI: 10.1002/jobm.201200516] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 01/26/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Cheila Denise Ottonelli Stopiglia
- Programa de Pós-Graduação em Medicina: Ciências Médicas; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
- Departamento de Microbiologia, Imunologia e Parasitologia; ICBS, Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - Daiane Heidrich
- Programa de Pós-Graduação em Medicina: Ciências Médicas; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - Julia Medeiros Sorrentino
- Departamento de Microbiologia, Imunologia e Parasitologia; ICBS, Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - Fabiane Jamono Vieira
- Departamento de Microbiologia, Imunologia e Parasitologia; ICBS, Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - Melissa Fontes Landell
- Centro de Biotecnologia; Universidade Federal do Rio Grande do Sul; Campus do Vale, Porto Alegre RS Brazil
| | - Patrícia Valente
- Departamento de Microbiologia, Imunologia e Parasitologia; ICBS, Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
| | - Maria Lúcia Scroferneker
- Programa de Pós-Graduação em Medicina: Ciências Médicas; Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
- Departamento de Microbiologia, Imunologia e Parasitologia; ICBS, Universidade Federal do Rio Grande do Sul; Porto Alegre RS Brazil
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Liu Q, Ying SH, Li JG, Tian CG, Feng MG. Insight into the transcriptional regulation of Msn2 required for conidiation, multi-stress responses and virulence of two entomopathogenic fungi. Fungal Genet Biol 2013; 54:42-51. [PMID: 23466345 DOI: 10.1016/j.fgb.2013.02.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/12/2013] [Accepted: 02/21/2013] [Indexed: 01/28/2023]
Abstract
Msn2/4 transcription factors in some fungi have null effects on virulence and cellular stress responses. Here we found that the transcriptional regulation of Msn2 orthologs is vital for the conidiation, virulence and multi-stress responses of Beauveria bassiana (Bb) and Metarhizium robertsii (Mr), which lack Msn4 orthologs. Compared to wild-type and complemented strains of each fungus with all similar phenotypes, ΔBbmsn2 and ΔMrmsn2 showed remarkable defects in conidial yield (∼40% decrease) and virulence (∼25% decrease). Both delta mutants lost 20-65% of their tolerances to hyperosmolarity, oxidation, carbendazim, cell wall perturbing and high temperature at 34 °C during colony growth. Their conidia were also significantly (18-41%) less tolerant to oxidation, hyperosmolarity, wet-heat stress at 45 °C and UV-B irradiation. Accompanied with the defective phenotypes, several conidiation- and virulence-associated genes were greatly repressed in ΔBbmsn2 and ΔMrmsn2. Moreover, differentially expressed genes in the transcriptomes of ΔBbmsn2 versus wild type were ∼3% more under oxidative stress, but ∼12% fewer under heat shock, than those in the ΔMrmsn2 counterparts. Many stress-responsive effector genes and cellular signaling factors were remarkably downregulated. Taken together, the two entomopathogens could have evolved somewhat distinct stress-responsive mechanisms finely tuned by Msn2, highlighting the biological significance of Msn2 orthologs for filamentous fungi.
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Affiliation(s)
- Qian Liu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
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Large scale expressed sequence tag (EST) analysis of Metarhizium acridum infecting Locusta migratoria reveals multiple strategies for fungal adaptation to the host cuticle. Curr Genet 2012; 58:265-79. [DOI: 10.1007/s00294-012-0382-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 09/21/2012] [Accepted: 09/21/2012] [Indexed: 12/18/2022]
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Ramanujam R, Yishi X, Liu H, Naqvi NI. Structure-function analysis of Rgs1 in Magnaporthe oryzae: role of DEP domains in subcellular targeting. PLoS One 2012; 7:e41084. [PMID: 22927898 PMCID: PMC3426613 DOI: 10.1371/journal.pone.0041084] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Rgs1, a prototypical Regulator of G protein Signaling, negatively modulates the cyclic AMP pathway thereby influencing various aspects of asexual development and pathogenesis in the rice-blast fungus Magnaporthe oryzae. Rgs1 possesses tandem DEP motifs (termed DEP-A and DEP-B; for Dishevelled, Egl-10, Pleckstrin) at the N-terminus, and a Gα-GTP interacting RGS catalytic core domain at the C-terminus. In this study, we focused on gaining further insights into the mechanisms of Rgs1 regulation and subcellular localization by characterizing the role(s) of the individual domains and the full-length protein during asexual development and pathogenesis in Magnaporthe. METHODOLOGY/PRINCIPAL FINDINGS Utilizing western blot analysis and specific antisera against the N- and C-terminal halves of Rgs1, we identify and report the in vivo endoproteolytic processing/cleavage of full-length Rgs1 that yields an N-terminal DEP and a RGS core domain. Independent expression of the resultant DEP-DEP half (N-Rgs1) or RGS core (C-Rgs1) fragments, failed to complement the rgs1Δ defects in colony morphology, aerial hyphal growth, surface hydrophobicity, conidiation, appressorium formation and infection. Interestingly, the full-length Rgs1-mCherry, as well as the tagged N-terminal DEP domains (individually or in conjunction) localized to distinct punctate vesicular structures in the cytosol, while the catalytic RGS core motif was predominantly vacuolar. CONCLUSIONS/SIGNIFICANCE Based on our data from sequence alignments, immuno-blot and microscopic analysis, we propose that the post-translational proteolytic processing of Rgs1 and the vacuolar sequestration of the catalytic RGS domain represents an important means of down regulating Rgs1 function and thus forming an additional and alternative means of regulating G protein signaling in Magnaporthe. We further hypothesize the prevalence of analogous mechanisms functioning in other filamentous fungi. Furthermore, we conclusively assign a specific vesicular/membrane targeting function for the N-terminal DEP domains of Rgs1 in the rice-blast fungus.
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Affiliation(s)
- Ravikrishna Ramanujam
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xu Yishi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
| | - Hao Liu
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Naweed I. Naqvi
- Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- * E-mail:
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Sevim A, Donzelli BGG, Wu D, Demirbag Z, Gibson DM, Turgeon BG. Hydrophobin genes of the entomopathogenic fungus, Metarhizium brunneum, are differentially expressed and corresponding mutants are decreased in virulence. Curr Genet 2012; 58:79-92. [PMID: 22388867 DOI: 10.1007/s00294-012-0366-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 02/02/2012] [Accepted: 02/04/2012] [Indexed: 10/28/2022]
Abstract
Hydrophobins are small, cysteine-rich, secreted proteins, ubiquitously produced by filamentous fungi that are speculated to function in fungal growth, cell surface properties, and development, although this has been rigorously tested for only a few species. Herein, we report identification of three hydrophobin genes from the entomopathogenic fungus, Metarhizium brunneum, and functional characterization of strains lacking these genes. One gene (HYD1/ssgA) encodes a class I hydrophobin identified previously. Two new genes, HYD3 and HYD2, encode a class I and class II hydrophobin, respectively. To examine function, we deleted all three separately, from the M. brunneum strain KTU-60 genome, using Agrobacterium tumefaciens-mediated transformation. Deletion strains were screened for alterations in developmental phenotypes including growth, sporulation, pigmentation, colony surface properties, and virulence to insects. All deletion strains were reduced in their ability to sporulate and showed alterations in wild-type pigmentation, but all retained wild-type hydrophobicity, except for one individual hyd3 mutant. Complementation with the wild-type HYD3 gene restored hydrophobicity. Each gene, present as a single copy in the genome, showed differential expression patterns dependent on the developmental stage of the fungus. When Spodoptera exigua (beet armyworm) larvae were treated with either conidia or blastospores of each hyd mutant, reductions in virulence and delayed mortality were observed as compared to WT. Together, these results suggest that hydrophobins are differentially expressed and may have distinct, but compensating roles, in conidiation, pigmentation, hydrophobicity, and virulence.
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Affiliation(s)
- Ali Sevim
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, 344 Plant Science Building, Ithaca, NY 14853, USA
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mrflbA, encoding a putative FlbA, is involved in aerial hyphal development and secondary metabolite production in Monascus ruber M-7. Fungal Biol 2012; 116:225-33. [DOI: 10.1016/j.funbio.2011.11.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 11/10/2011] [Accepted: 11/13/2011] [Indexed: 11/18/2022]
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40
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Zhang H, Tang W, Liu K, Huang Q, Zhang X, Yan X, Chen Y, Wang J, Qi Z, Wang Z, Zheng X, Wang P, Zhang Z. Eight RGS and RGS-like proteins orchestrate growth, differentiation, and pathogenicity of Magnaporthe oryzae. PLoS Pathog 2011; 7:e1002450. [PMID: 22241981 PMCID: PMC3248559 DOI: 10.1371/journal.ppat.1002450] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 11/05/2011] [Indexed: 11/18/2022] Open
Abstract
A previous study identified MoRgs1 as an RGS protein that negative regulates G-protein signaling to control developmental processes such as conidiation and appressorium formation in Magnaporthe oryzae. Here, we characterized additional seven RGS and RGS-like proteins (MoRgs2 through MoRgs8). We found that MoRgs1 and MoRgs4 positively regulate surface hydrophobicity, conidiation, and mating. Indifference to MoRgs1, MoRgs4 has a role in regulating laccase and peroxidase activities. MoRgs1, MoRgs2, MoRgs3, MoRgs4, MoRgs6, and MoRgs7 are important for germ tube growth and appressorium formation. Interestingly, MoRgs7 and MoRgs8 exhibit a unique domain structure in which the RGS domain is linked to a seven-transmembrane motif, a hallmark of G-protein coupled receptors (GPCRs). We have also shown that MoRgs1 regulates mating through negative regulation of Gα MoMagB and is involved in the maintenance of cell wall integrity. While all proteins appear to be involved in the control of intracellular cAMP levels, only MoRgs1, MoRgs3, MoRgs4, and MoRgs7 are required for full virulence. Taking together, in addition to MoRgs1 functions as a prominent RGS protein in M. oryzae, MoRgs4 and other RGS and RGS-like proteins are also involved in a complex process governing asexual/sexual development, appressorium formation, and pathogenicity.
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Affiliation(s)
- Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Wei Tang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Kaiyue Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Qian Huang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xin Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xia Yan
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Huajiachi Campus, Hangzhou, China
| | - Yue Chen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jiansheng Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhongqiang Qi
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhengyi Wang
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Huajiachi Campus, Hangzhou, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ping Wang
- Department of Pediatrics and the Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- * E-mail:
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Zhou G, Wang J, Qiu L, Feng MG. A Group III histidine kinase (mhk1) upstream of high-osmolarity glycerol pathway regulates sporulation, multi-stress tolerance and virulence of Metarhizium robertsii, a fungal entomopathogen. Environ Microbiol 2011; 14:817-29. [PMID: 22118192 DOI: 10.1111/j.1462-2920.2011.02643.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of Metarhizium robertsii Group III histidine kinase (mhk1) in regulating various phenotypes of the fungal entomopathogen and the transcripts of 25 downstream genes likely associated with the phenotypes were probed by constructing Δmhk1 and Δmhk1/mhk1 mutants. All examined Δmhk1 phenotypes except unchanged sensitivity to fungicide (dimethachlon) differed significantly from those of wild type and Δmhk1/mhk1, which were similar to each other. Significant phenotypic changes in Δmhk1 included increased conidial yields on two media, increased tolerance to H(2)O(2) , decreased tolerance to menadione, increased tolerance to hyperosmolarity, increased conidial thermotolerance, decreased conidial UV-B resistance and reduced virulence to Tenebrio molitor larvae. The mhk1 disruption elevated the transcripts of nine genes, including two associated with conidiation (flbC and hymA) and three encoding catalases but decreased seven other gene transcripts, including three for superoxide dismultases, under normal conditions. The high-osmolarity glycerol pathway MAPK phosphorylation level in Δmhk1 culture was increased 1.0- to 1.8-fold by KCl, sucrose and menadione stresses but reduced drastically by H(2)O(2) or heat (40°C) stress, accompanied with different transcript patterns of all examined genes under the stresses. Our results confirmed the crucial role of mhk1 in regulating the expression of the downstream genes and associated phenotypes important for the fungal biocontrol potential.
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Affiliation(s)
- Gang Zhou
- Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
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Lin L, Wang F, Wei D. Chlorimuron ethyl as a new selectable marker for disrupting genes in the insect-pathogenic fungus Metarhizium robertsii. J Microbiol Methods 2011; 87:241-3. [PMID: 21851837 DOI: 10.1016/j.mimet.2011.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 01/23/2023]
Abstract
A lack of selectable markers was a hindrance in investigating gene function in Metarhizium robertsii. A reliable Agrobacterium-mediated transformation system based on the use of chlorimuron ethyl as the selectable marker was developed which could serve as a useful tool to inactivate genes involved in insect pathogenicity.
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Affiliation(s)
- Liangcai Lin
- State key laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China
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43
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Carneiro-Leão MP, Andreote FD, Araújo WL, Oliveira NT. Differential expression of genes involved in entomopathogenicity of the fungi Metarhizium anisopliae var. anisopliae and M. anisopliae var. acridum (Clavicipitaceae). GENETICS AND MOLECULAR RESEARCH 2011; 10:769-78. [PMID: 21563071 DOI: 10.4238/vol10-2gmr1094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Expression analysis of the genes involved in germination, conidiogenisis and pathogenesis of Metarhizium anisopliae during its saprophytic and pathogenic life stages can help plan strategies to increase its efficacy as a biological control agent. We quantified relative expression levels of the nitrogen response regulator gene (nrr1) and a G-protein regulator of genes involved in conidiogenesis (cag8), using an RT-qPCR assay. Comparisons were made between M. anisopliae var. anisopliae and M. anisopliae var. acridum during germination and conidiogenesis and at different stages of pathogenesis. The cag8 gene was repressed during germination and induced during conidial development and the pathogenic phase, and the nrr1 gene was induced during germination, conidiogenesis and the pathogenic phase. Both genes were more expressed in M. anisopliae var. anisopliae, demonstrating that different varieties of M. anisopliae differ in activation of genes linked to virulence for certain environments and hosts. This suggests that differences among these varieties in the ability to adapt could be attributed not only to specific genomic regions and genes, but also to differential gene expression in this fungus, modulating its ability to respond to environmental stimuli.
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Affiliation(s)
- M P Carneiro-Leão
- Departamento de Micologia, Universidade Federal de Pernambuco, Recife, PE, Brasil.
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44
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Zhang C, Xia Y, Li Z. Identification of Genes Differentially Expressed by Metarhizium anisopliae Growing on Locusta migratoria Wings Using Suppression Subtractive Hybridization. Curr Microbiol 2011; 62:1649-55. [DOI: 10.1007/s00284-011-9909-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 02/23/2011] [Indexed: 11/30/2022]
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Flexible metabolism in Metarhizium anisopliae and Beauveria bassiana: role of the glyoxylate cycle during insect pathogenesis. Microbiology (Reading) 2011; 157:199-208. [DOI: 10.1099/mic.0.042697-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insect pathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana have an increasing role in the control of agricultural insect pests and vectors of human diseases. Many of the virulence factors are well studied but less is known of the metabolism of these fungi during the course of insect infection or saprobic growth. Here, we assessed enzyme activity and gene expression in the central carbon metabolic pathway, including isocitrate dehydrogenase, aconitase, citrate synthase, malate synthase (MLS) and isocitrate lyase (ICL), with particular attention to the glyoxylate cycle when M. anisopliae and B. bassiana were grown under various conditions. We observed that ICL and MLS, glyoxylate cycle intermediates, were upregulated during growth on 2-carbon compounds (acetate and ethanol) as well as in insect haemolymph. We fused the promoter of the M. anisopliae ICL gene (Ma-icl) to a marker gene (mCherry) and showed that Ma-icl was upregulated when M. anisopliae was grown in the presence of acetate. Furthermore, Ma-icl was upregulated when fungi were engulfed by insect haemocytes as well as during appressorium formation. Addition of the ICL inhibitor 3-nitroproprionate delayed conidial germination and inhibited appressorium formation. These results show that these insect pathogenic fungi have a flexible metabolism that includes the glyoxylate cycle as an integral part of germination, pathogenesis and saprobic growth.
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46
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Schrank A, Vainstein MH. Metarhizium anisopliae enzymes and toxins. Toxicon 2010; 56:1267-74. [DOI: 10.1016/j.toxicon.2010.03.008] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/18/2010] [Accepted: 03/08/2010] [Indexed: 10/19/2022]
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47
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Omann M, Zeilinger S. How a mycoparasite employs g-protein signaling: using the example of trichoderma. JOURNAL OF SIGNAL TRANSDUCTION 2010; 2010:123126. [PMID: 21637351 PMCID: PMC3100592 DOI: 10.1155/2010/123126] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/06/2010] [Accepted: 07/20/2010] [Indexed: 12/04/2022]
Abstract
Mycoparasitic Trichoderma spp. act as potent biocontrol agents against a number of plant pathogenic fungi, whereupon the mycoparasitic attack includes host recognition followed by infection structure formation and secretion of lytic enzymes and antifungal metabolites leading to the host's death. Host-derived signals are suggested to be recognized by receptors located on the mycoparasite's cell surface eliciting an internal signal transduction cascade which results in the transcription of mycoparasitism-relevant genes. Heterotrimeric G proteins of fungi transmit signals originating from G-protein-coupled receptors mainly to the cAMP and the MAP kinase pathways resulting in regulation of downstream effectors. Components of the G-protein signaling machinery such as Gα subunits and G-protein-coupled receptors were recently shown to play crucial roles in Trichoderma mycoparasitism as they govern processes such as the production of extracellular cell wall lytic enzymes, the secretion of antifungal metabolites, and the formation of infection structures.
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Affiliation(s)
- Markus Omann
- Research Area of Gene Technology and Applied Biochemistry, Working Group Molecular Biochemistry of Fungi, Institute for Chemical Engineering, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Susanne Zeilinger
- Research Area of Gene Technology and Applied Biochemistry, Working Group Molecular Biochemistry of Fungi, Institute for Chemical Engineering, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
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48
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Chitosan increases conidiation in fungal pathogens of invertebrates. Appl Microbiol Biotechnol 2010; 87:2237-45. [PMID: 20532757 DOI: 10.1007/s00253-010-2693-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 05/17/2010] [Accepted: 05/18/2010] [Indexed: 10/19/2022]
Abstract
Antifungal activity of chitosan on plant pathogenic fungi has been widely studied, but little is known about the effect of chitosan on fungal biocontrol agents. In this work, we characterize the increase of conidiation induced by chitosan in fungal pathogens of invertebrates (FPI). Chitosan increased conidiation of FPI, including Beauveria bassiana, widely used as mycoinsecticide, and did not affect conidia viability or pathogenicity. Increased conidiation induced by chitosan is shown to be concentration dependent and is not associated to growth inhibition as observed for the mycoparasitic fungus Trichoderma harzianum. Real-time reverse transcription polymerase chain reaction was used to study transcript levels of two genes involved in conidiation in B. bassiana, the regulatory G protein signaling gene Bbrgs1 and the hydrophobin gene hyd1, at different chitosan concentrations. Higher levels of Bbrgs1 and hyd1 transcripts were detected on chitosan-amended media. No correlation with chitosan concentration was observed for expression of Bbrgs1 unlike hyd1. Bbrgs1 deletion mutant Bbrgs1 showed that chitosan-induced conidiation is independent of Bbrgs1, suggesting an alternative mechanism controlling conidiation in B. bassiana. Our data supports that sporulation increases by chitosan, with spores retaining their viability and pathogenicity, which makes chitosan a suitable compound to increase conidia production in fungi with applications in fungal biotechnology.
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Liu J, Cao Y, Xia Y. Mmc, a gene involved in microcycle conidiation of the entomopathogenic fungus Metarhizium anisopliae. J Invertebr Pathol 2010; 105:132-8. [PMID: 20546749 DOI: 10.1016/j.jip.2010.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 04/20/2010] [Accepted: 05/14/2010] [Indexed: 10/19/2022]
Abstract
Microcycle conidiation is a survival mechanism for some fungi encountering unfavorable conditions, in which asexual spores germinate secondary spores directly without formation of mycelium. Here, we isolated a microcycle conidiation associated gene, Mmc, from Metarhizium anisopliae and obtained its full length of cDNA and DNA sequence. To clarify its roles in conidiation, we constructed an Mmc RNA interference (RNAi) vector with dual promoter system to knockdown Mmc transcript level, and then analyzed RNAi mutant phenotypes. On microcycle conidiation medium, the RNAi mutant performed normal conidiation instead of microcycle conidiation with significantly reduced growth speed and conidia yield of 5.29-fold and 3.18-fold lower, respectively, than that of the wild-type. Meanwhile, on normal conidiation medium, no significant difference was found in conidiation speed and total yield between the wild-type and RNAi mutant. These data demonstrated that the Mmc gene regulated microcycle conidiation but did not affect normal conidiation. In addition, results of heat treatment, UV-B radiation and bioassays of RNAi mutant indicated that Mmc was also involved in heat resistance but irrelevant to UV-B tolerance and virulence of M. anisopliae. This study helped understanding the regulation of sporulation of the entomopathogenic fungus M. anisopliae.
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Affiliation(s)
- Jing Liu
- Genetic Engineering Research Center, College of Bioengineering, Chongqing University, Chongqing Engineering Research Center for Fungal Insecticides and Key Lab of Functional Gene and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing, 400030, PR China
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50
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Fang W, Fernandes EKK, Roberts DW, Bidochka MJ, St Leger RJ. A laccase exclusively expressed by Metarhizium anisopliae during isotropic growth is involved in pigmentation, tolerance to abiotic stresses and virulence. Fungal Genet Biol 2010; 47:602-7. [PMID: 20382249 DOI: 10.1016/j.fgb.2010.03.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 03/01/2010] [Accepted: 03/30/2010] [Indexed: 11/30/2022]
Abstract
Insect pathogenic fungi including Metarhizium anisopliae offer an environmentally friendly alternative to chemical pesticides. However, their use has been limited by their relatively slow killing speed compared to chemicals and low tolerance to abiotic stresses. We report here on a class 1 laccase (MLAC1) that is involved in both virulence and tolerance to environmental stresses. Mlac1 is expressed during isotropic growth (swelling) but not during polarized growth (e.g., germ tubes and hyphae); Mlac1 is therefore expressed exclusively in the later stages of conidiation and in blastospores when M. anisopliae is living as a saprophyte. During infection processes, Mlac1 is also expressed by appressoria (infection structures) on the cuticle surface and hyphal bodies inside the insect haemocoel. Disrupting Mlac1 reduced virulence to caterpillars because of impaired appressoria and delayed post-infection events. It also produced a yellow-conidia phenotype with increased conidial susceptibility to heat shock (45 degrees C for 2h) and UV-B stress. The relationship between M. anisopliae's pigment-synthesis pathway and its adaptation to diverse natural habitats is discussed.
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Affiliation(s)
- Weiguo Fang
- University of Maryland, Department of Entomology, 4112 Plant Sciences Building, College Park, MD 20742, USA.
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