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Franco FP, Santiago AC, Henrique-Silva F, de Castro PA, Goldman GH, Moura DS, Silva-Filho MC. The sugarcane defense protein SUGARWIN2 causes cell death in Colletotrichum falcatum but not in non-pathogenic fungi. PLoS One 2014; 9:e91159. [PMID: 24608349 PMCID: PMC3946703 DOI: 10.1371/journal.pone.0091159] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 02/10/2014] [Indexed: 11/18/2022] Open
Abstract
Plants respond to pathogens and insect attacks by inducing and accumulating a large set of defense-related proteins. Two homologues of a barley wound-inducible protein (BARWIN) have been characterized in sugarcane, SUGARWIN1 and SUGARWIN2 (sugarcane wound-inducible proteins). Induction of SUGARWINs occurs in response to Diatraea saccharalis damage but not to pathogen infection. In addition, the protein itself does not show any effect on insect development; instead, it has antimicrobial activities toward Fusarium verticillioides, an opportunistic fungus that usually occurs after D. saccharalis borer attacks on sugarcane. In this study, we sought to evaluate the specificity of SUGARWIN2 to better understand its mechanism of action against phytopathogens and the associations between fungi and insects that affect plants. We used Colletotrichum falcatum, a fungus that causes red rot disease in sugarcane fields infested by D. saccharalis, and Ceratocystis paradoxa, which causes pineapple disease in sugarcane. We also tested whether SUGARWIN2 is able to cause cell death in Aspergillus nidulans, a fungus that does not infect sugarcane, and in the model yeast Saccharomyces cerevisiae, which is used for bioethanol production. Recombinant SUGARWIN2 altered C. falcatum morphology by increasing vacuolization, points of fractures and a leak of intracellular material, leading to germling apoptosis. In C. paradoxa, SUGARWIN2 showed increased vacuolization in hyphae but did not kill the fungi. Neither the non-pathogenic fungus A. nidulans nor the yeast S. cerevisiae was affected by recombinant SUGARWIN2, suggesting that the protein is specific to sugarcane opportunistic fungal pathogens.
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Affiliation(s)
- Flávia P. Franco
- Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, Brazil
| | - Adelita C. Santiago
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | - Flávio Henrique-Silva
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | | | - Gustavo H. Goldman
- Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Campinas, SP, Brazil
| | - Daniel S. Moura
- Departamento de Ciências Biológicas, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, Brazil
| | - Marcio C. Silva-Filho
- Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, Brazil
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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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Transcription factor CCG-8 as a new regulator in the adaptation to antifungal azole stress. Antimicrob Agents Chemother 2013; 58:1434-42. [PMID: 24342650 DOI: 10.1128/aac.02244-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Antifungal azoles are widely used for controlling fungal infections. Fungi are able to change the expression of many genes when they adapt to azole stress, and increased expression of some of these genes can elevate resistance to azoles. However, the regulatory mechanisms behind transcriptional adaption to azoles in filamentous fungi are poorly understood. In this study, we found that deletion of the transcription factor gene ccg-8, which is known to be a clock-controlled gene, made Neurospora crassa hypersensitive to azoles. A comparative genome-wide analysis of the responses to ketoconazole of the wild type and the ccg-8 mutant revealed that the transcriptional responses to ketoconazole of 78 of the 488 transcriptionally ketoconazole-upregulated genes and the 427 transcriptionally ketoconazole-downregulated genes in the wild type were regulated by CCG-8. Ketoconazole sensitivity testing of all available knockout mutants for CCG-8-regulated genes revealed that CCG-8 contributed to azole adaption by regulating the ketoconazole responses of many genes, including the target gene (erg11), an azole transporter gene (cdr4), a hexose transporter gene (hxt13), a stress response gene (locus number NCU06317, named kts-1), two transcription factor genes (NCU01386 [named kts-2] and fsd-1/ndt80), four enzyme-encoding genes, and six unknown-function genes. CCG-8 also regulated phospholipid synthesis in N. crassa in a manner similar to that of its homolog in Saccharomyces cerevisiae, Opi1p. However, there was no cross talk between phospholipid synthesis and azole resistance in N. crassa. CCG-8 homologs are conserved and are common in filamentous fungi. Deletion of the CCG-8 homolog-encoding gene in Fusarium verticillioides (Fvccg-8) also made this fungus hypersensitive to antifungal azoles.
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Song XS, Li HP, Zhang JB, Song B, Huang T, Du XM, Gong AD, Liu YK, Feng YN, Agboola RS, Liao YC. Trehalose 6-phosphate phosphatase is required for development, virulence and mycotoxin biosynthesis apart from trehalose biosynthesis in Fusarium graminearum. Fungal Genet Biol 2013; 63:24-41. [PMID: 24291007 DOI: 10.1016/j.fgb.2013.11.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/19/2013] [Accepted: 11/20/2013] [Indexed: 12/11/2022]
Abstract
Trehalose 6-phosphate synthase (TPS1) and trehalose 6-phosphate phosphatase (TPS2) are required for trehalose biosynthesis in yeast and filamentous fungi, including Fusarium graminearum. Three null mutants Δtps1, Δtps2 and Δtps1-Δtps2, each carrying either a single deletion of TPS1 or TPS2 or a double deletion of TPS1-TPS2, were generated from a toxigenic F. graminearum strain and were not able to synthesize trehalose. In contrast to its reported function in yeasts and filamentous fungi, TPS1 appeared dispensable for development and virulence. However, deletion of TPS2 abolished sporulation and sexual reproduction; it also altered cell polarity and ultrastructure of the cell wall in association with reduced chitin biosynthesis. The cell polarity alteration was exhibited as reduced apical growth and increased lateral growth and branching with increased hyphal and cell wall widths. Moreover, the TPS2-deficient strain displayed abnormal septum development and nucleus distribution in its conidia and vegetative hyphae. The Δtps2 mutant also had 62% lower mycelial growth on potato dextrose agar and 99% lower virulence on wheat compared with the wild-type. The Δtps1, Δtps2 and Δtps1-Δtps2 mutants synthesized over 3.08-, 7.09- and 2.47-fold less mycotoxins, respectively, on rice culture compared with the wild-type. Comparative transcriptome analysis revealed that the Δtps1, Δtps2 and Δtps1-Δtps2 mutants had 486, 1885 and 146 genotype-specific genes, respectively, with significantly changed expression profiles compared with the wild-type. Further dissection of this pathway will provide new insights into regulation of fungal development, virulence and trichothecene biosynthesis.
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Affiliation(s)
- Xiu-Shi Song
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - He-Ping Li
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Jing-Bo Zhang
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Bo Song
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Tao Huang
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Xiao-Min Du
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - An-Dong Gong
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yi-Ke Liu
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yan-Ni Feng
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Rebecca S Agboola
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yu-Cai Liao
- Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; National Center of Plant Gene Research (Wuhan), Wuhan 430070, People's Republic of China.
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López-Berges MS, Schäfer K, Hera C, Di Pietro A. Combinatorial function of velvet and AreA in transcriptional regulation of nitrate utilization and secondary metabolism. Fungal Genet Biol 2013; 62:78-84. [PMID: 24240057 DOI: 10.1016/j.fgb.2013.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/29/2013] [Accepted: 11/03/2013] [Indexed: 12/11/2022]
Abstract
Velvet is a conserved protein complex that functions as a regulator of fungal development and secondary metabolism. In the soil-inhabiting pathogen Fusarium oxysporum, velvet governs mycotoxin production and virulence on plant and mammalian hosts. Here we report a previously unrecognized role of the velvet complex in regulation of nitrate metabolism. F. oxysporum mutants lacking VeA or LaeA, two key components of the complex, were impaired in growth on the non-preferred nitrogen sources nitrate and nitrite. Both velvet and the general nitrogen response GATA factor AreA were required for transcriptional activation of nitrate (nit1) and nitrite (nii1) reductase genes under de-repressing conditions, as well as for the nitrate-triggered increase in chromatin accessibility at the nit1 locus. AreA also contributed to chromatin accessibility and expression of two velvet-regulated gene clusters, encoding biosynthesis of the mycotoxin beauvericin and of the siderophore ferricrocin. Thus, velvet and AreA coordinately orchestrate primary and secondary metabolism as well as virulence functions in F. oxysporum.
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Affiliation(s)
- Manuel S López-Berges
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, 14071 Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
| | - Katja Schäfer
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, 14071 Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
| | - Concepción Hera
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, 14071 Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain
| | - Antonio Di Pietro
- Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, 14071 Córdoba, Spain; Campus de Excelencia Internacional Agroalimentario ceiA3, 14071 Córdoba, Spain.
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WetA is required for conidiogenesis and conidium maturation in the ascomycete fungus Fusarium graminearum. EUKARYOTIC CELL 2013; 13:87-98. [PMID: 24186953 DOI: 10.1128/ec.00220-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fusarium graminearum, a prominent fungal pathogen that infects major cereal crops, primarily utilizes asexual spores to spread disease. To understand the molecular mechanisms underlying conidiogenesis in F. graminearum, we functionally characterized the F. graminearum ortholog of Aspergillus nidulans wetA, which has been shown to be involved in conidiogenesis and conidium maturation. Deletion of F. graminearum wetA did not alter mycelial growth, sexual development, or virulence, but the wetA deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the F. graminearum wetA deletion mutants was reduced. The wetA deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidial dormancy by suppressing microcycle conidiation in F. graminearum. Transcriptome analyses demonstrated that most of the putative conidiation-related genes are expressed constitutively and that only a few genes are specifically involved in F. graminearum conidiogenesis. The conserved and distinct roles identified for WetA in F. graminearum provide new insights into the genetics of conidiation in filamentous fungi.
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57
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Karakkat BB, Gold SE, Covert SF. Two members of the Ustilago maydis velvet family influence teliospore development and virulence on maize seedlings. Fungal Genet Biol 2013; 61:111-9. [PMID: 24064149 DOI: 10.1016/j.fgb.2013.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/26/2013] [Accepted: 09/13/2013] [Indexed: 11/26/2022]
Abstract
Members of the fungal-specific velvet protein family regulate sexual and asexual spore production in the Ascomycota. We predicted, therefore, that velvet homologs in the basidiomycetous plant pathogen Ustilago maydis would regulate sexual spore development, which is also associated with plant disease progression in this fungus. To test this hypothesis, we studied the function of three U. maydis velvet genes, umv1, umv2 and umv3. Using a gene replacement strategy, deletion mutants were made in all three genes in compatible haploid strains, and additionally for umv1 and umv2 in the solopathogenic strain, SG200. None of the mutants showed novel morphological phenotypes during yeast-like, in vitro growth. However, the Δumv1 mutants failed to induce galls or teliospores in maize. Chlorazol black E staining of leaves infected with Δumv1 dikaryons revealed that the Δumv1 hyphae did not proliferate normally and were blocked developmentally before teliospore formation. The Δumv2 mutants were able to induce galls and teliospores in maize, but were slow to do so and thus reduced in virulence. The Δumv3 mutants were not affected in teliospore formation or disease progression. Complementation of the Δumv1 and Δumv2 mutations in the SG200 background produced disease indices similar to those of SG200. These results indicate that two U. maydis velvet family members, umv1 and umv2, are important for normal teliospore development and disease progression in maize seedlings.
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Affiliation(s)
- Brijesh B Karakkat
- Department of Plant Pathology, University of Georgia, Athens, GA 30602, USA
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Wang J, Du Y, Zhang H, Zhou C, Qi Z, Zheng X, Wang P, Zhang Z. The actin-regulating kinase homologue MoArk1 plays a pleiotropic function in Magnaporthe oryzae. MOLECULAR PLANT PATHOLOGY 2013; 14:470-82. [PMID: 23384308 PMCID: PMC3642230 DOI: 10.1111/mpp.12020] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Endocytosis is an essential cellular process in eukaryotic cells that involves concordant functions of clathrin and adaptor proteins, various protein and lipid kinases, phosphatases and the actin cytoskeleton. In Saccharomyces cerevisiae, Ark1p is a member of the serine/threonine protein kinase (SPK) family that affects profoundly the organization of the cortical actin cytoskeleton. To study the function of MoArk1, an Ark1p homologue identified in Magnaporthe oryzae, we disrupted the MoARK1 gene and characterized the ΔMoark1 mutant strain. The ΔMoark1 mutant exhibited various defects ranging from mycelial growth and conidial formation to appressorium-mediated host infection. The ΔMoark1 mutant also exhibited decreased appressorium turgor pressure and attenuated virulence on rice and barley. In addition, the ΔMoark1 mutant displayed defects in endocytosis and formation of the Spitzenkörper, and was hyposensitive to exogenous oxidative stress. Moreover, a MoArk1-green fluorescent protein (MoArk1-GFP) fusion protein showed an actin-like localization pattern by localizing to the apical regions of hyphae. This pattern of localization appeared to be regulated by the N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins MoSec22 and MoVam7. Finally, detailed analysis revealed that the proline-rich region within the MoArk1 serine/threonine kinase (S_TKc) domain was critical for endocytosis, subcellular localization and pathogenicity. These results collectively suggest that MoArk1 exhibits conserved functions in endocytosis and actin cytoskeleton organization, which may underlie growth, cell wall integrity and virulence of the fungus.
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Affiliation(s)
- Jiamei Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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Shin JH, Kim JE, Malapi-Wight M, Choi YE, Shaw BD, Shim WB. Protein phosphatase 2A regulatory subunits perform distinct functional roles in the maize pathogen Fusarium verticillioides. MOLECULAR PLANT PATHOLOGY 2013; 14:518-29. [PMID: 23452277 PMCID: PMC6638791 DOI: 10.1111/mpp.12023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Fusarium verticillioides is a pathogen of maize causing ear rot and stalk rot. The fungus also produces fumonisins, a group of mycotoxins linked to disorders in animals and humans. A cluster of genes, designated FUM genes, plays a key role in the synthesis of fumonisins. However, our understanding of the regulatory mechanism of fumonisin biosynthesis is still incomplete. We have demonstrated previously that Cpp1, a protein phosphatase type 2A (PP2A) catalytic subunit, negatively regulates fumonisin production and is involved in cell shape maintenance. In general, three PP2A subunits, structural A, regulatory B and catalytic C, make up a heterotrimer complex to perform regulatory functions. Significantly, we identified two PP2A regulatory subunits in the F. verticillioides genome, Ppr1 and Ppr2, which are homologous to Saccharomyces cerevisiae Cdc55 and Rts1, respectively. In this study, we hypothesized that Ppr1 and Ppr2 are involved in the regulation of fumonisin biosynthesis and/or cell development in F. verticillioides, and generated a series of mutants to determine the functional role of Ppr1 and Ppr2. The PPR1 deletion strain (Δppr1) resulted in drastic growth defects, but increased microconidia production. The PPR2 deletion mutant strain (Δppr2) showed elevated fumonisin production, similar to the Δcpp1 strain. Germinating Δppr1 conidia formed abnormally swollen cells with a central septation site, whereas Δppr2 showed early hyphal branching during conidia germination. A kernel rot assay showed that the mutants were slow to colonize kernels, but this is probably a result of growth defects rather than a virulence defect. Results from this study suggest that two PP2A regulatory subunits in F. verticillioides carry out distinct roles in the regulation of fumonisin biosynthesis and fungal development.
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Affiliation(s)
- Joon-Hee Shin
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA
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Sun X, Wang W, Wang K, Yu X, Liu J, Zhou F, Xie B, Li S. Sterol C-22 Desaturase ERG5 Mediates the Sensitivity to Antifungal Azoles in Neurospora crassa and Fusarium verticillioides. Front Microbiol 2013; 4:127. [PMID: 23755044 PMCID: PMC3666115 DOI: 10.3389/fmicb.2013.00127] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/04/2013] [Indexed: 12/19/2022] Open
Abstract
Antifungal azoles inhibit ergosterol biosynthesis by interfering with lanosterol 14α-demethylase. In this study, seven upregulated and four downregulated ergosterol biosynthesis genes in response to ketoconazole treatment were identified in Neurospora crassa. Azole sensitivity test of knockout mutants for six ketoconazole-upregulated genes in ergosterol biosynthesis revealed that deletion of only sterol C-22 desaturase ERG5 altered sensitivity to azoles: the erg5 mutant was hypersensitive to azoles but had no obvious defects in growth and development. The erg5 mutant accumulated higher levels of ergosta 5,7-dienol relative to the wild type but its levels of 14α-methylated sterols were similar to the wild type. ERG5 homologs are highly conserved in fungal kingdom. Deletion of Fusarium verticillioides erg5 also increased ketoconazole sensitivity, suggesting that the roles of ERG5 homologs in azole resistance are highly conserved among different fungal species, and inhibition of ERG5 could reduce the usage of azoles and thus provide a new target for drug design.
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Affiliation(s)
- Xianyun Sun
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences Beijing, China
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Yang Q, Chen Y, Ma Z. Involvement of BcVeA and BcVelB in regulating conidiation, pigmentation and virulence in Botrytis cinerea. Fungal Genet Biol 2013; 50:63-71. [DOI: 10.1016/j.fgb.2012.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 10/16/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
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Bi Q, Wu D, Zhu X, Gillian Turgeon B. Cochliobolus heterostrophus Llm1 - a Lae1-like methyltransferase regulates T-toxin production, virulence, and development. Fungal Genet Biol 2012; 51:21-33. [PMID: 23261970 DOI: 10.1016/j.fgb.2012.11.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/27/2012] [Accepted: 11/27/2012] [Indexed: 12/18/2022]
Abstract
A Lae1-like methyltransferase, Llm1, was identified in maize pathogen Cochliobolus heterostrophus which is renowned for production of the secondary metabolite host-selective toxin, T-toxin, and is a model for mechanisms of reproduction of heterothallic Dothideomycetes. Previously, we determined that C. heterostrophus mutants lacking Lae1 and Vel1 proteins were decreased in ability to produce T-toxin when the fungus was grown in the dark, demonstrating that these proteins are positive regulators of toxin production. We showed also that Lae1 and Vel1 regulate resistance to oxidative stress and both sexual and asexual reproduction. Here, it is demonstrated that Llm1, one of nine Lae1-like methyltransferases in the C. heterostrophus genome, acts as a negative regulator of T-toxin production and thus impacts virulence to the host. In vitro, in the dark, and in planta, llm1 mutants make more T-toxin than do wild-type (WT) strains, while overexpressing strains make less than WT. Virulence (amount of chlorosis) to maize, due to T-toxin, follows accordingly. Expression of nine genes involved in T-toxin production is elevated in llm1 mutants and reduced in overexpressing strains. llm1 mutations cannot rescue deficiencies in T-toxin production of lae1 or vel1 mutants indicating that Llm1 represses T-toxin biosynthesis, and that vel1 and lae1 mutations are epistatic to llm1 mutations. Thus, increased T-toxin production, and presumably gene expression, in the llm1 mutant is dependent on the presence of Vel1 and Lae1 proteins. There is no evidence that Llm1 has an effect on oxidative stress tolerance. llm1 mutants are fully fertile in crosses to WT mating testers, while LLM1 overexpressing strains and llm1lae1 and llm1vel1 double mutants are unable to act as females. Overexpression of LLM1 leads to de-repression of asexual sporulation during sexual development, and of asexual sporulation in the light and the dark during vegetative growth, as is the case for vel1, llm1vel1, and llm1lae1-deletion strains. llm1vel1 and llm1lae1 double mutants are similar to lae1 single mutants and accumulate more hyphal melanin in liquid medium than do llm1 or vel1 single mutants, implying Llm1 plays a redundant role in regulating pigmentation with Vel1, while Lae1 plays a major role.
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Affiliation(s)
- Qing Bi
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, United States
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64
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López-Berges MS, Hera C, Sulyok M, Schäfer K, Capilla J, Guarro J, Di Pietro A. The velvet complex governs mycotoxin production and virulence of Fusarium oxysporum on plant and mammalian hosts. Mol Microbiol 2012; 87:49-65. [PMID: 23106229 DOI: 10.1111/mmi.12082] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2012] [Indexed: 01/10/2023]
Abstract
Fungal pathogens provoke devastating losses in agricultural production, contaminate food with mycotoxins and give rise to life-threatening infections in humans. The soil-borne ascomycete Fusarium oxysporum attacks over 100 different crops and can cause systemic fusariosis in immunocompromised individuals. Here we functionally characterized VeA, VelB, VelC and LaeA, four components of the velvet protein complex which regulates fungal development and secondary metabolism. Deletion of veA, velB and to a minor extent velC caused a derepression of conidiation as well as alterations in the shape and size of microconidia. VeA and LaeA were required for full virulence of F. oxysporum on tomato plants and on immunodepressed mice. A critical contribution of velvet consists in promoting chromatin accessibility and expression of the biosynthetic gene cluster for beauvericin, a depsipeptide mycotoxin that functions as a virulence determinant. These results reveal a conserved role of the velvet complex during fungal infection on plants and mammals.
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Zheng D, Zhang S, Zhou X, Wang C, Xiang P, Zheng Q, Xu JR. The FgHOG1 pathway regulates hyphal growth, stress responses, and plant infection in Fusarium graminearum. PLoS One 2012; 7:e49495. [PMID: 23166686 PMCID: PMC3498113 DOI: 10.1371/journal.pone.0049495] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 10/09/2012] [Indexed: 11/18/2022] Open
Abstract
Fusarium head blight (FHB) caused by Fusarium graminearum is a destructive disease of wheat and barley worldwide. In a previous study of systematic characterization of protein kinase genes in F. graminearum, mutants of three putative components of the osmoregulation MAP kinase pathway were found to have distinct colony morphology and hyphal growth defects on PDA plates. Because the osmoregulation pathway is not known to regulate aerial hyphal growth and branching, in this study we further characterized the functions of the FgHog1 pathway in growth, pathogenesis, and development. The Fghog1, Fgpbs2, and Fgssk2 mutants were all reduced in growth rate, aerial hyphal growth, and hyphal branching angle. These mutants were not only hypersensitive to osmotic stress but also had increased sensitivity to oxidative, cytoplasm membrane, and cell wall stresses. The activation of FgHog1 was blocked in the Fgpbs2 and Fgssk2 mutants, indicating the sequential activation of FgSsk2-FgPbs2-FgHog1 cascade. Interestingly, the FgHog1 MAPK pathway mutants appeared to be sensitive to certain compounds present in PDA. They were female sterile but retained male fertility. We also used the metabolomics profiling approach to identify compatible solutes that were accumulated in the wild type but not in the Fghog1 deletion mutant. Overall, our results indicate that the FgSsk2-FgPbs2-FgHog1 MAPK cascade is important for regulating hyphal growth, branching, plant infection, and hyperosmotic and general stress responses in F. graminearum.
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Affiliation(s)
- Dawei Zheng
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Shijie Zhang
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaoying Zhou
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (XZ); (JX)
| | - Chenfang Wang
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Ping Xiang
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Qian Zheng
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Jin-Rong Xu
- NWAFU-PU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (XZ); (JX)
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66
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Schumacher J, Pradier JM, Simon A, Traeger S, Moraga J, Collado IG, Viaud M, Tudzynski B. Natural variation in the VELVET gene bcvel1 affects virulence and light-dependent differentiation in Botrytis cinerea. PLoS One 2012; 7:e47840. [PMID: 23118899 PMCID: PMC3485325 DOI: 10.1371/journal.pone.0047840] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/21/2012] [Indexed: 12/14/2022] Open
Abstract
Botrytis cinerea is an aggressive plant pathogen causing gray mold disease on various plant species. In this study, we identified the genetic origin for significantly differing phenotypes of the two sequenced B. cinerea isolates, B05.10 and T4, with regard to light-dependent differentiation, oxalic acid (OA) formation and virulence. By conducting a map-based cloning approach we identified a single nucleotide polymorphism (SNP) in an open reading frame encoding a VELVET gene (bcvel1). The SNP in isolate T4 results in a truncated protein that is predominantly found in the cytosol in contrast to the full-length protein of isolate B05.10 that accumulates in the nuclei. Deletion of the full-length gene in B05.10 resulted in the T4 phenotype, namely light-independent conidiation, loss of sclerotial development and oxalic acid production, and reduced virulence on several host plants. These findings indicate that the identified SNP represents a loss-of-function mutation of bcvel1. In accordance, the expression of the B05.10 copy in T4 rescued the wild-type/B05.10 phenotype. BcVEL1 is crucial for full virulence as deletion mutants are significantly hampered in killing and decomposing plant tissues. However, the production of the two best known secondary metabolites, the phytotoxins botcinic acid and botrydial, are not affected by the deletion of bcvel1 indicating that other factors are responsible for reduced virulence. Genome-wide expression analyses of B05.10- and Δbcvel1-infected plant material revealed a number of genes differentially expressed in the mutant: while several protease- encoding genes are under-expressed in Δbcvel1 compared to the wild type, the group of over-expressed genes is enriched for genes encoding sugar, amino acid and ammonium transporters and glycoside hydrolases reflecting the response of Δbcvel1 mutants to nutrient starvation conditions.
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Affiliation(s)
- Julia Schumacher
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | | | | | - Stefanie Traeger
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Javier Moraga
- Organic Chemistry Department, Cádiz University, Puerto Real, Cádiz, Spain
| | | | - Muriel Viaud
- INRA, BIOGER, Grignon, France
- * E-mail: (MV); (BT)
| | - Bettina Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität Münster, Münster, Germany
- * E-mail: (MV); (BT)
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67
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VeA regulates conidiation, gliotoxin production, and protease activity in the opportunistic human pathogen Aspergillus fumigatus. EUKARYOTIC CELL 2012; 11:1531-43. [PMID: 23087369 DOI: 10.1128/ec.00222-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Invasive aspergillosis by Aspergillus fumigatus is a leading cause of infection-related mortality in immunocompromised patients. In this study, we show that veA, a major conserved regulatory gene that is unique to fungi, is necessary for normal morphogenesis in this medically relevant fungus. Although deletion of veA results in a strain with reduced conidiation, overexpression of this gene further reduced conidial production, indicating that veA has a major role as a regulator of development in A. fumigatus and that normal conidiation is only sustained in the presence of wild-type VeA levels. Furthermore, our studies revealed that veA is a positive regulator in the production of gliotoxin, a secondary metabolite known to be a virulent factor in A. fumigatus. Deletion of veA resulted in a reduction of gliotoxin production with respect to that of the wild-type control. This reduction in toxin coincided with a decrease in gliZ and gliP expression, which is necessary for gliotoxin biosynthesis. Interestingly, veA also influences protease activity in this organism. Specifically, deletion of veA resulted in a reduction of protease activity; this is the first report of a veA homolog with a role in controlling fungal hydrolytic activity. Although veA affects several cellular processes in A. fumigatus, pathogenicity studies in a neutropenic mouse infection model indicated that veA is dispensable for virulence.
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68
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Zheng W, Zhao X, Xie Q, Huang Q, Zhang C, Zhai H, Xu L, Lu G, Shim WB, Wang Z. A conserved homeobox transcription factor Htf1 is required for phialide development and conidiogenesis in Fusarium species. PLoS One 2012; 7:e45432. [PMID: 23029006 PMCID: PMC3448628 DOI: 10.1371/journal.pone.0045432] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/16/2012] [Indexed: 01/21/2023] Open
Abstract
Conidia are primary means of asexual reproduction and dispersal in a variety of pathogenic fungi, and it is widely recognized that they play a critical role in animal and plant disease epidemics. However, genetic mechanisms associated with conidiogenesis are complex and remain largely undefined in numerous pathogenic fungi. We previously showed that Htf1, a homeobox transcription factor, is required for conidiogenesis in the rice pathogen Magnaporthe oryzae. In this study, our aim was to characterize how Htf1 homolog regulates common and also distinctive conidiogenesis in three key Fusarium pathogens: F. graminearm, F. verticillioides, and F. oxysporum. When compared to wild-type progenitors, the gene-deletion mutants in Fusarium species failed to form conventional phialides. Rather, they formed clusters of aberrant phialides that resembled elongated hyphae segments, and it is conceivable that this led to the obstruction of conidiation in phialides. We also observed that mutants, as well as wild-type Fusaria, can initiate alternative macroconidia production directly from hyphae through budding-like mechanism albeit at low frequencies. Microscopic observations led us to conclude that proper basal cell division and subsequent foot cell development of macroconidia were negatively impacted in the mutants. In F. verticillioides and F. oxysporum, mutants exhibited a 2- to 5- microconidia complex at the apex of monophialides resulting in a floral petal-like shape. Also, prototypical microconidia chains were absent in F. verticillioides mutants. F. graminearum and F. verticillioides mutants were complemented by introducing its native HTF1 gene or homologs from other Fusarium species. These results suggest that Fusarium Htf1 is functionally conserved homeobox transcription factor that regulates phialide development and conidiogenesis via distinct signaling pathways yet to be characterized in fungi.
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Affiliation(s)
- Wenhui Zheng
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- The Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Xu Zhao
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Qiurong Xie
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Qingping Huang
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Chengkang Zhang
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Huanchen Zhai
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- College of Life Sciences, Henan University of Technology, Zhengzhou, Henan, Fujian, China
| | - Liping Xu
- The Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Guodong Lu
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Won-Bo Shim
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- * E-mail: (WBS); (ZW)
| | - Zonghua Wang
- Key Laboratory of Bio-pesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- The Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- * E-mail: (WBS); (ZW)
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69
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Laskowski-Peak MC, Calvo AM, Rohrssen J, Smulian AG. VEA1 is required for cleistothecial formation and virulence in Histoplasma capsulatum. Fungal Genet Biol 2012; 49:838-46. [PMID: 22841690 DOI: 10.1016/j.fgb.2012.07.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 06/30/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
Abstract
Histoplasma capsulatum is a pathogenic fungus dependent on dimorphism for virulence. Among the four described Velvet family genes, two of them, Ryp2 and Ryp3, have been shown to be required for dimorphism. It is known that Velvet A (VeA) is necessary for sexual development and toxin production in Aspergillus nidulans. However, the role of the VeA ortholog in H. capsulatum has not yet been explored. Vea1, H. capsulatum homolog of VeA, was studied to determine its role in cleistothecial formation, dimorphism, and virulence. H. capsulatum Vea1 restores cleistothecial formation and partially restores sterigmatocystin production in an A. nidulans veA deletion strain. Furthermore, silencing VEA1 in an H. capsulatum strain capable of forming cleistothecia abolishes cleistothecial formation. Silenced strains also switch to mycelial phase faster, and show impaired switching to the yeast phase once in mycelial phase. Virulence in mice and macrophages is attenuated in VEA1 silenced strains and silenced strains demonstrate increased sensitivity during growth under acidic conditions. These results indicate that H. capsulatum Vea1 shares a similar role in development as VeA. H. capsulatum is also more susceptible to growth in acidic conditions when VEA1 is silenced, which may contribute to the silenced strains' attenuated virulence in mice and macrophages.
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Affiliation(s)
- Meggan C Laskowski-Peak
- Infectious Disease Division, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0560, United States
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70
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Butchko RAE, Brown DW, Busman M, Tudzynski B, Wiemann P. Lae1 regulates expression of multiple secondary metabolite gene clusters in Fusarium verticillioides. Fungal Genet Biol 2012; 49:602-12. [PMID: 22713715 DOI: 10.1016/j.fgb.2012.06.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 06/01/2012] [Accepted: 06/10/2012] [Indexed: 11/18/2022]
Abstract
The filamentous fungus Fusarium verticillioides can cause disease of maize and is capable of producing fumonisins, a family of toxic secondary metabolites linked to esophageal cancer and neural tube defects in humans and lung edema in swine and leukoencephalomalacia in equines. The expression of fumonisin biosynthetic genes is influenced by broad-domain transcription factors (global regulators) and Fum21, a pathway-specific transcription factor. LaeA is a global regulator that in Aspergillus nidulans, affects the expression of multiple secondary metabolite gene clusters by modifying heterochromatin structure. Here, we employed gene deletion analysis to assess the effect of loss of a F. verticillioides laeA orthologue, LAE1, on genome-wide gene expression and secondary metabolite production. Loss of Lae1 resulted in reduced expression of gene clusters responsible for synthesis of the secondary metabolites bikaverin, fumonisins, fusaric acid and fusarins as well as two clusters for which the corresponding secondary metabolite is unknown. Analysis of secondary metabolites revealed that, in contrast to a previously described Fusarium fujikuroi lae1 mutant, bikaverin production is reduced. Fumonisin production is unchanged in the F. verticillioides lae1 mutant. Complementation of the F. verticillioides mutant resulted in increased fumonisin production.
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Affiliation(s)
- Robert A E Butchko
- National Center for Agricultural Utilization Research, Peoria, IL, United States.
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71
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FgVELB is associated with vegetative differentiation, secondary metabolism and virulence in Fusarium graminearum. Fungal Genet Biol 2012; 49:653-62. [PMID: 22713714 DOI: 10.1016/j.fgb.2012.06.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 06/03/2012] [Accepted: 06/10/2012] [Indexed: 12/22/2022]
Abstract
The velvet complex containing VeA, VelB and LaeA has been showed to play critical roles in the regulation of secondary metabolism and diverse cellular processes in Aspergillus spp. In this study, we identified FgVelB, a homolog of Aspergillus nidulans VelB, from Fusarium graminearum using the BLASTP program. Disruption of FgVELB gene led to several phenotypic defects, including suppression of aerial hyphae formation, reduced hyphal hydrophobicity and highly increased conidiation. The mutant showed increased resistance to osmotic stress and cell wall-damaging agents, which may be related to a high level of glycerol accumulation in the mutant. Additionally, the mutant exhibited increased sensitivity to the phenylpyrrole fungicide fludioxonil. Ultrastructural and histochemical analyses revealed that conidia of FgVELB deletion mutant contained numerous lipid droplets. Pathogenicity assays showed FgVELB deletion mutant was impaired in virulence on flowering wheat head, which is consistent with the observation that FgVelB is involved in the regulation of deoxynivalenol biosynthesis in F. graminearum. All of the defects were restored by genetic complementation of the mutant with wild-type FgVELB gene. Yeast two hybrid assays showed that FgVelB does not interact with FgVeA. Taken together, results of this study indicated that FgVelB plays a critical role in the regulation of various cellular processes in F. graminearum.
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72
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Merhej J, Urban M, Dufresne M, Hammond-Kosack KE, Richard-Forget F, Barreau C. The velvet gene, FgVe1, affects fungal development and positively regulates trichothecene biosynthesis and pathogenicity in Fusarium graminearum. MOLECULAR PLANT PATHOLOGY 2012; 13:363-74. [PMID: 22013911 PMCID: PMC6638759 DOI: 10.1111/j.1364-3703.2011.00755.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Trichothecenes are a group of toxic secondary metabolites produced mainly by Fusarium graminearum (teleomorph: Gibberella zeae) during the infection of crop plants, including wheat, maize, barley, oats, rye and rice. Some fungal genes involved in trichothecene biosynthesis have been shown to encode regulatory proteins. However, the global regulation of toxin biosynthesis is still enigmatic. In addition to the production of secondary metabolites belonging to the trichothecene family, F. graminearum produces the red pigment aurofusarin. The gene regulation underlying the production of aurofusarin is not well understood. The velvet gene (veA) is conserved in various genera of filamentous fungi. Recently, the veA gene from Aspergillus nidulans has been shown to be the key component of the velvet complex regulating development and secondary metabolism. Using blast analyses, we identified the velvet gene from F. graminearum, FgVe1. Disruption of FgVe1 causes several phenotypic effects. However, the complementation of this mutant with the FgVe1 gene restores the wild-type phenotypes. The in vitro phenotypes include hyperbranching of the mycelium, suppression of aerial hyphae formation, reduced hydrophobicity of the mycelium and highly reduced sporulation. Our data also show that FgVe1 modulates the production of the aurofusarin pigment and is essential for the expression of Tri genes and the production of trichothecenes. Pathogenicity studies performed on flowering wheat plants indicate that FgVe1 is a positive regulator of virulence in F. graminearum.
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Affiliation(s)
- Jawad Merhej
- INRA, UR1264 MycSA, 71, Avenue Edouard Bourleaux, BP81, F-33883 Villenave d'Ornon, France
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73
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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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74
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ChLae1 and ChVel1 regulate T-toxin production, virulence, oxidative stress response, and development of the maize pathogen Cochliobolus heterostrophus. PLoS Pathog 2012; 8:e1002542. [PMID: 22383877 PMCID: PMC3285592 DOI: 10.1371/journal.ppat.1002542] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 01/06/2012] [Indexed: 01/03/2023] Open
Abstract
LaeA and VeA coordinate secondary metabolism and differentiation in response to light signals in Aspergillus spp. Their orthologs, ChLae1 and ChVel1, were identified in the maize pathogen Cochliobolus heterostrophus, known to produce a wealth of secondary metabolites, including the host selective toxin, T-toxin. Produced by race T, T-toxin promotes high virulence to maize carrying Texas male sterile cytoplasm (T-cms). T-toxin production is significantly increased in the dark in wild type (WT), whereas Chvel1 and Chlae1 mutant toxin levels are much reduced in the dark compared to WT. Correspondingly, expression of T-toxin biosynthetic genes (Tox1) is up-regulated in the dark in WT, while dark-induced expression is much reduced/minimal in Chvel1 and Chlae1 mutants. Toxin production and Tox1 gene expression are increased in ChVEL1 overexpression (OE) strains grown in the dark and in ChLAE1 strains grown in either light or dark, compared to WT. These observations establish ChLae1 and ChVel1 as the first factors known to regulate host selective toxin production. Virulence of Chlae1 and Chvel1 mutants and OE strains is altered on both T-cms and normal cytoplasm maize, indicating that both T-toxin mediated super virulence and basic pathogenic ability are affected. Deletion of ChLAE1 or ChVEL1 reduces tolerance to H2O2. Expression of CAT3, one of the three catalase genes, is reduced in the Chvel1 mutant. Chlae1 and Chvel1 mutants also show decreased aerial hyphal growth, increased asexual sporulation and female sterility. ChLAE1 OE strains are female sterile, while ChVEL1 OE strains are more fertile than WT. ChLae1 and ChVel1 repress expression of 1,8-dihydroxynaphthalene (DHN) melanin biosynthesis genes, and, accordingly, melanization is enhanced in Chlae1 and Chvel1 mutants, and reduced in OE strains. Thus, ChLae1 and ChVel1 positively regulate T-toxin biosynthesis, pathogenicity and super virulence, oxidative stress responses, sexual development, and aerial hyphal growth, and negatively control melanin biosynthesis and asexual differentiation. Filamentous fungi produce chemically diverse metabolites that broker positive and negative interactions with other organisms, manage host pathogenicity/virulence, nutritional and environmental stresses, and differentiation of the fungus. The maize pathogen Cochliobolus heterostrophus is notorious as the causal agent of the most economically devastating epidemic to date, in 1970. Disease severity was associated with appearance of a new race, producing T-toxin, a host selective toxin promoting high virulence to Texas male sterile cytoplasm maize, widely planted at the time. LaeA and VeA are central regulators of secondary metabolism in Aspergillus, coordinating metabolite production and differentiation in response to light. Given the significance of effector-type host selective toxins in pathogenic interactions, we characterized ChLae1 and ChVel1 and found that deletion and overexpression affect T-toxin production in planta and in vitro. Both chlorosis due to T-toxin and necrotic lesion formation are altered, establishing these as the first factors known to regulate both super virulence conferred by T-toxin, and basic pathogenicity, due to unknown factors. The mutants are also altered in oxidative stress responses, key to success in the infection court, asexual and sexual development, essential for fungal dissemination in the field, aerial hyphal growth, and pigment biosynthesis, essential for survival in the field.
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75
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Influence of light on growth, conidiation and fumonisin production by Fusarium verticillioides. Fungal Biol 2012; 116:241-8. [DOI: 10.1016/j.funbio.2011.11.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 11/11/2011] [Accepted: 11/14/2011] [Indexed: 12/22/2022]
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76
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Myung K, Zitomer NC, Duvall M, Glenn AE, Riley RT, Calvo AM. The conserved global regulator VeA is necessary for symptom production and mycotoxin synthesis in maize seedlings by Fusarium verticillioides. PLANT PATHOLOGY 2012; 61:152-160. [PMID: 22247572 PMCID: PMC3256589 DOI: 10.1111/j.1365-3059.2011.02504.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The veA or velvet gene is necessary for biosynthesis of mycotoxins and other secondary metabolites in Aspergillus species. In addition, veA has also been demonstrated to be necessary for normal seed colonization in Aspergillus flavus and Aspergillus parasiticus. The present study shows that veA homologues are broadly distributed in fungi, particularly in Ascomycetes. The Fusarium verticillioides veA orthologue, FvVE1, is also required for the synthesis of several secondary metabolites, including fumonisin and fusarins. This study also shows that maize plants grown from seeds inoculated with FvVE1 deletion mutants did not show disease symptoms, while plants grown from seeds inoculated with the F. verticillioides wildtype and complementation strains clearly showed disease symptoms under the same experimental conditions. In this latter case, the presence of lesions coincided with accumulation of fumonisins in the plant tissues, and only these plant tissues had elevated levels of sphingoid bases and their 1-phosphate derivatives, indicating inhibition of ceramide synthase and disruption of sphingolipid metabolism. The results strongly suggest that FvVE1 is necessary for pathogenicity by F. verticillioides against maize seedlings. The conservation of veA homologues among ascomycetes suggests that veA could play a pivotal role in regulating secondary metabolism and associated pathogenicity in other fungi.
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Affiliation(s)
- K. Myung
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., DeKalb, Illinois 60115
| | - N. C. Zitomer
- Toxicology & Mycotoxin Research Unit, USDA-ARS, Russell Research Center, Athens, Georgia 30605, USA
| | - M. Duvall
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., DeKalb, Illinois 60115
| | - A. E. Glenn
- Toxicology & Mycotoxin Research Unit, USDA-ARS, Russell Research Center, Athens, Georgia 30605, USA
| | - R. T. Riley
- Toxicology & Mycotoxin Research Unit, USDA-ARS, Russell Research Center, Athens, Georgia 30605, USA
| | - A. M. Calvo
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., DeKalb, Illinois 60115
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Chettri P, Calvo AM, Cary JW, Dhingra S, Guo Y, McDougal RL, Bradshaw RE. The veA gene of the pine needle pathogen Dothistroma septosporum regulates sporulation and secondary metabolism. Fungal Genet Biol 2011; 49:141-51. [PMID: 22227160 DOI: 10.1016/j.fgb.2011.11.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 11/18/2011] [Accepted: 11/21/2011] [Indexed: 02/06/2023]
Abstract
Fungi possess genetic systems to regulate the expression of genes involved in complex processes such as development and secondary metabolite biosynthesis. The product of the velvet gene veA, first identified and characterized in Aspergillus nidulans, is a key player in the regulation of both of these processes. Since its discovery and characterization in many Aspergillus species, VeA has been found to have similar functions in other fungi, including the Dothideomycete Mycosphaerella graminicola. Another Dothideomycete, Dothistroma septosporum, is a pine needle pathogen that produces dothistromin, a polyketide toxin very closely related to aflatoxin (AF) and sterigmatocystin (ST) synthesized by Aspergillus spp. Dothistromin is unusual in that, unlike most other secondary metabolites, it is produced mainly during the early exponential growth phase in culture. It was therefore of interest to determine whether the regulation of dothistromin production in D. septosporum differs from the regulation of AF/ST in Aspergillus spp. To begin to address this question, a veA ortholog was identified and its function analyzed in D. septosporum. Inactivation of the veA gene resulted in reduced dothistromin production and a corresponding decrease in expression of dothistromin biosynthetic genes. Expression of other putative secondary metabolite genes in D. septosporum such as polyketide synthases and non-ribosomal peptide synthases showed a range of different responses to loss of Ds-veA. Asexual sporulation was also significantly reduced in the mutants, accompanied by a reduction in the expression of a putative stuA regulatory gene. The mutants were, however, able to infect Pinus radiata seedlings and complete their life cycle under laboratory conditions. Overall this work suggests that D. septosporum has a veA ortholog that is involved in the control of both developmental and secondary metabolite biosynthetic pathways.
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Affiliation(s)
- Pranav Chettri
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
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78
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Jiang J, Liu X, Yin Y, Ma Z. Involvement of a velvet protein FgVeA in the regulation of asexual development, lipid and secondary metabolisms and virulence in Fusarium graminearum. PLoS One 2011; 6:e28291. [PMID: 22140571 PMCID: PMC3226687 DOI: 10.1371/journal.pone.0028291] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Accepted: 11/05/2011] [Indexed: 01/15/2023] Open
Abstract
The velvet protein, VeA, is involved in the regulation of diverse cellular processes. In this study, we explored functions of FgVeA in the wheat head blight pathogen, Fusarium graminearum,using a gene replacement strategy. The FgVEA deletion mutant exhibited a reduction in aerial hyphae formation, hydrophobicity, and deoxynivalenol (DON) biosynthesis. Deletion of FgVEA gene led to an increase in conidial production, but a delay in conidial germination. Pathogencity assays showed that the mutant was impaired in virulence on flowering wheat head. Sensitivity tests to various stresses exhibited that the FgVEA deletion mutant showed increased resistance to osmotic stress and cell wall-damaging agents, but increased sensitivity to iprodione and fludioxonil fungicides. Ultrastructural and histochemical analyses revealed that conidia of FgVeA deletion mutant contained an unusually high number of large lipid droplets, which is in agreement with the observation that the mutant accumulated a higher basal level of glycerol than the wild-type progenitor. Serial analysis of gene expression (SAGE) in the FgVEA mutant confirmed that FgVeA was involved in various cellular processes. Additionally, six proteins interacting with FgVeA were identified by yeast two hybrid assays in current study. These results indicate that FgVeA plays a critical role in a variety of cellular processes in F. graminearum.
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MESH Headings
- Cell Wall/drug effects
- Colony Count, Microbial
- Drug Resistance, Fungal/drug effects
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Fungicides, Industrial/pharmacology
- Fusarium/genetics
- Fusarium/growth & development
- Fusarium/metabolism
- Fusarium/pathogenicity
- Gene Deletion
- Gene Expression Regulation, Fungal/drug effects
- Glycerol/metabolism
- Hyphae/drug effects
- Hyphae/growth & development
- Hyphae/metabolism
- Hyphae/ultrastructure
- Lipid Metabolism/drug effects
- Methyltransferases/chemistry
- Methyltransferases/metabolism
- Osmosis/drug effects
- Pigmentation/drug effects
- Protein Binding/drug effects
- Protein Structure, Tertiary
- Reproduction, Asexual/drug effects
- Sequence Analysis, Protein
- Spores, Fungal/drug effects
- Spores, Fungal/growth & development
- Spores, Fungal/ultrastructure
- Stress, Physiological/drug effects
- Trichothecenes/biosynthesis
- Virulence/drug effects
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Affiliation(s)
- Jinhua Jiang
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xin Liu
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yanni Yin
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Zhonghua Ma
- Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
- * E-mail:
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79
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Kamerewerd J, Zadra I, Kürnsteiner H, Kück U. PcchiB1, encoding a class V chitinase, is affected by PcVelA and PcLaeA, and is responsible for cell wall integrity in Penicillium chrysogenum. MICROBIOLOGY-SGM 2011; 157:3036-3048. [PMID: 21816879 DOI: 10.1099/mic.0.051896-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Penicillin production in Penicillium chrysogenum is controlled by PcVelA and PcLaeA, two components of the regulatory velvet-like complex. Comparative microarray analysis with mutants lacking PcVelA or PcLaeA revealed a set of 62 common genes affected by the loss of both components. A downregulated gene in both knockout strains is PcchiB1, potentially encoding a class V chitinase. Under nutrient-depleted conditions, transcript levels of PcchiB1 are strongly upregulated, and the gene product contributes to more than 50 % of extracellular chitinase activity. Functional characterization by generating PcchiB1-disruption strains revealed that PcChiB1 is responsible for cell wall integrity and pellet formation in P. chrysogenum. Further, fluorescence microscopy with a DsRed-labelled chitinase suggests a cell wall association of the protein. An unexpected phenotype occurred when knockout strains were grown on media containing N-acetylglucosamine as the sole C and N source, where, in contrast to the recipient, a penicillin producer strain, the mutants and an ancestral strain show distinct mycelial growth. We discuss the relevance of this class V chitinase for morphology in an industrially important fungus.
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Affiliation(s)
- Jens Kamerewerd
- Christian Doppler Laboratory for 'Fungal Biotechnology', Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Ivo Zadra
- Anti Infectives Microbiology, Sandoz GmbH, Biochemiestraße 10, 6250 Kundl, Austria
| | - Hubert Kürnsteiner
- Anti Infectives Microbiology, Sandoz GmbH, Biochemiestraße 10, 6250 Kundl, Austria
| | - Ulrich Kück
- Christian Doppler Laboratory for 'Fungal Biotechnology', Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
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80
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Bayram O, Braus GH. Coordination of secondary metabolism and development in fungi: the velvet family of regulatory proteins. FEMS Microbiol Rev 2011; 36:1-24. [PMID: 21658084 DOI: 10.1111/j.1574-6976.2011.00285.x] [Citation(s) in RCA: 376] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Filamentous fungi produce a number of small bioactive molecules as part of their secondary metabolism ranging from benign antibiotics such as penicillin to threatening mycotoxins such as aflatoxin. Secondary metabolism can be linked to fungal developmental programs in response to various abiotic or biotic external triggers. The velvet family of regulatory proteins plays a key role in coordinating secondary metabolism and differentiation processes such as asexual or sexual sporulation and sclerotia or fruiting body formation. The velvet family shares a protein domain that is present in most parts of the fungal kingdom from chytrids to basidiomycetes. Most of the current knowledge derives from the model Aspergillus nidulans where VeA, the founding member of the protein family, was discovered almost half a century ago. Different members of the velvet protein family interact with each other and the nonvelvet protein LaeA, primarily in the nucleus. LaeA is a methyltransferase-domain protein that functions as a regulator of secondary metabolism and development. A comprehensive picture of the molecular interplay between the velvet domain protein family, LaeA and other nuclear regulatory proteins in response to various signal transduction pathway starts to emerge from a jigsaw puzzle of several recent studies.
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Affiliation(s)
- Ozgür Bayram
- Institut für Mikrobiologie und Genetik, Abteilung Molekulare Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Göttingen, Germany
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81
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Yin W, Keller NP. Transcriptional regulatory elements in fungal secondary metabolism. J Microbiol 2011; 49:329-39. [PMID: 21717315 DOI: 10.1007/s12275-011-1009-1] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 03/15/2011] [Indexed: 01/19/2023]
Abstract
Filamentous fungi produce a variety of secondary metabolites of diverse beneficial and detrimental activities to humankind. The genes required for a given secondary metabolite are typically arranged in a gene cluster. There is considerable evidence that secondary metabolite gene regulation is, in part, by transcriptional control through hierarchical levels of transcriptional regulatory elements involved in secondary metabolite cluster regulation. Identification of elements regulating secondary metabolism could potentially provide a means of increasing production of beneficial metabolites, decreasing production of detrimental metabolites, aid in the identification of 'silent' natural products and also contribute to a broader understanding of molecular mechanisms by which secondary metabolites are produced. This review summarizes regulation of secondary metabolism associated with transcriptional regulatory elements from a broad view as well as the tremendous advances in discovery of cryptic or novel secondary metabolites by genomic mining.
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Affiliation(s)
- Wenbing Yin
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
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82
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Harris SD. Hyphal morphogenesis: an evolutionary perspective. Fungal Biol 2011; 115:475-84. [PMID: 21640312 DOI: 10.1016/j.funbio.2011.02.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/31/2011] [Accepted: 02/02/2011] [Indexed: 12/20/2022]
Abstract
Two modes of cellular morphogenesis predominate within the fungal kingdom; yeast growth and hyphal growth. The availability of complete genome sequences that span the kingdom has made possible the use of comparative approaches that address important questions regarding the evolution of these growth modes. These comparisons have also emphasized the point that not all hyphae are the same despite outward appearances. Topics considered here include the origins of hyphal growth, as well as the potential causes of and the consequences resulting from the loss of hyphal growth in yeast lineages. The mechanisms that enable distinct morphological outputs (i.e., yeast vs. hyphae) using an essentially identical inventory of gene products are also considered. Finally, processes implicated in the regulation of hyphal tip complexes are addressed from an evolutionary perspective.
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Affiliation(s)
- Steven D Harris
- Center for Plant Science Innovation and Department of Plant Pathology, University of Nebraska, E126 Beadle Center, Lincoln, NE 68506, USA.
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83
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Abstract
Aspergillus flavus is saprophytic soil fungus that infects and contaminates preharvest and postharvest seed crops with the carcinogenic secondary metabolite aflatoxin. The fungus is also an opportunistic animal and human pathogen causing aspergillosis diseases with incidence increasing in the immunocompromised population. Whole genome sequences of A. flavus have been released and reveal 55 secondary metabolite clusters that are regulated by different environmental regimes and the global secondary metabolite regulators LaeA and VeA. Characteristics of A. flavus associated with pathogenicity and niche specialization include secondary metabolite production, enzyme elaboration, and a sophisticated oxylipin host crosstalk associated with a quorum-like development program. One of the more promising strategies in field control involves the use of atoxic strains of A. flavus in competitive exclusion studies. In this review, we discuss A. flavus as an agricultural and medical threat and summarize recent research advances in genomics, elucidation of parameters of pathogenicity, and control measures.
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Affiliation(s)
- Saori Amaike
- Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin 53706, USA
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84
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Sarikaya Bayram Ö, Bayram Ö, Valerius O, Park HS, Irniger S, Gerke J, Ni M, Han KH, Yu JH, Braus GH. LaeA control of velvet family regulatory proteins for light-dependent development and fungal cell-type specificity. PLoS Genet 2010; 6:e1001226. [PMID: 21152013 PMCID: PMC2996326 DOI: 10.1371/journal.pgen.1001226] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 10/28/2010] [Indexed: 01/12/2023] Open
Abstract
VeA is the founding member of the velvet superfamily of fungal regulatory proteins. This protein is involved in light response and coordinates sexual reproduction and secondary metabolism in Aspergillus nidulans. In the dark, VeA bridges VelB and LaeA to form the VelB-VeA-LaeA (velvet) complex. The VeA-like protein VelB is another developmental regulator, and LaeA has been known as global regulator of secondary metabolism. In this study, we show that VelB forms a second light-regulated developmental complex together with VosA, another member of the velvet family, which represses asexual development. LaeA plays a key role, not only in secondary metabolism, but also in directing formation of the VelB-VosA and VelB-VeA-LaeA complexes. LaeA controls VeA modification and protein levels and possesses additional developmental functions. The laeA null mutant results in constitutive sexual differentiation, indicating that LaeA plays a pivotal role in inhibiting sexual development in response to light. Moreover, the absence of LaeA results in the formation of significantly smaller fruiting bodies. This is due to the lack of a specific globose cell type (Hülle cells), which nurse the young fruiting body during development. This suggests that LaeA controls Hülle cells. In summary, LaeA plays a dynamic role in fungal morphological and chemical development, and it controls expression, interactions, and modification of the velvet regulators.
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Affiliation(s)
- Özlem Sarikaya Bayram
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
| | - Özgür Bayram
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
| | - Oliver Valerius
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
| | - Hee Soo Park
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Stefan Irniger
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
| | - Jennifer Gerke
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
| | - Min Ni
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kap-Hoon Han
- Department of Pharmaceutical Engineering, Woosuk University, Wanju, Korea
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Gerhard H. Braus
- Institute of Microbiology and Genetics, Department of Molecular Microbiology and Genetics, Georg August University, Göttingen, Germany
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85
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MVE1, encoding the velvet gene product homolog in Mycosphaerella graminicola, is associated with aerial mycelium formation, melanin biosynthesis, hyphal swelling, and light signaling. Appl Environ Microbiol 2010; 77:942-53. [PMID: 21115702 DOI: 10.1128/aem.01830-10] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The ascomycete fungus Mycosphaerella graminicola is an important pathogen of wheat that causes Septoria tritici blotch. Despite the serious impact of M. graminicola on wheat production worldwide, knowledge about its molecular biology is limited. The velvet gene, veA, is one of the key regulators of diverse cellular processes, including development and secondary metabolism in many fungi. However, the species analyzed to date are not related to the Dothideomycetes, the largest class of plant-pathogenic fungi, and the function of veA in this group is not known. To test the hypothesis that the velvet gene has similar functions in the Dothideomycetes, a veA-homologous gene, MVE1, was identified and gene deletion mutations (Δmve1) were generated in M. graminicola. All of the MVE1 mutants exhibited consistent pleiotropic phenotypes, indicating the involvement of MVE1 in multiple signaling pathways. Δmve1 strains displayed albino phenotypes with significant reductions in melanin biosynthesis and less production of aerial mycelia on agar plates. In liquid culture, Δmve1 strains showed abnormal hyphal swelling, which was suppressed completely by osmotic stress or lower temperature. In addition, MVE1 gene deletion led to hypersensitivity to shaking, reduced hydrophobicity, and blindness to light-dependent stimulation of aerial mycelium production. However, pathogenicity was not altered in Δmve1 strains. Therefore, the light-signaling pathway associated with MVE1 does not appear to be important for Septoria tritici blotch disease. Our data suggest that the MVE1 gene plays crucial roles in multiple key signaling pathways and is associated with light signaling in M. graminicola.
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86
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Kalebina TS, Selyakh IO, Gorkovskii AA, Bezsonov EE, El’darov MA, Novak MI, Domracheva AG, Bartoshevich YE. Structure peculiarities of cell walls of Acremonium chrysogenum—an autotroph of cephalosporin C. APPL BIOCHEM MICRO+ 2010. [DOI: 10.1134/s0003683810060098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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87
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Suppressor mutagenesis identifies a velvet complex remediator of Aspergillus nidulans secondary metabolism. EUKARYOTIC CELL 2010; 9:1816-24. [PMID: 20935144 DOI: 10.1128/ec.00189-10] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fungal secondary metabolites (SM) are bioactive compounds that are important in fungal ecology and, moreover, both harmful and useful in human endeavors (e.g., as toxins and pharmaceuticals). Recently a nuclear heterocomplex termed the Velvet complex, characterized in the model ascomycete Aspergillus nidulans, was found to be critical for SM production. Deletion of two members of the Velvet complex, laeA and veA, results in near loss of SM and defective sexual spore production in A. nidulans and other species. Using a multicopy-suppressor genetics approach, we have isolated an Aspergillus nidulans gene named rsmA (remediation of secondary metabolism) based upon its ability to remediate secondary metabolism in ΔlaeA and ΔveA backgrounds. Overexpression of rsmA (OE::rsmA) restores production of sterigmatocystin (ST) (a carcinogenic SM) via transcriptional activation of ST biosynthetic genes. However, defects in sexual reproduction in either ΔlaeA or ΔveA strains cannot be overcome by OE::rsmA. An intact Velvet complex coupled with an OE::rsmA allele increases SM many fold over the wild-type level, but loss of rsmA does not decrease SM. RsmA encodes a putative bZIP basic leucine zipper-type transcription factor.
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88
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Zhang Y, Choi YE, Zou X, Xu JR. The FvMK1 mitogen-activated protein kinase gene regulates conidiation, pathogenesis, and fumonisin production in Fusarium verticillioides. Fungal Genet Biol 2010; 48:71-9. [PMID: 20887797 DOI: 10.1016/j.fgb.2010.09.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 09/10/2010] [Accepted: 09/20/2010] [Indexed: 10/19/2022]
Abstract
Fusarium verticillioides is one of the most important fungal pathogens to cause destructive diseases of maize worldwide. Fumonisins produced by the fungus are harmful to human and animal health. To date, our understanding of the molecular mechanisms associated with pathogenicity and fumonisin biosynthesis in F. verticillioides is limited. Because MAP kinase pathways have been implicated in regulating diverse processes important for plant infection in phytopathogenic fungi, in this study we identified and functionally characterized the FvMK1 gene in F. verticillioides. FvMK1 is orthologous to FMK1 in F. oxysporum and GPMK1 in F. graminearum. The Fvmk1 deletion mutant was reduced in vegetative growth and production of microconidia. However, it was normal in sexual reproduction and increased in the production of macroconidia. In infection assays with developing corn kernels, the Fvmk1 mutant was non-pathogenic and failed to colonize through wounding sites. It also failed to cause stalk rot symptoms beyond the inoculation sites on corn stalks, indicating that FvMK1 is essential for plant infection. Furthermore, the Fvmk1 mutant was significantly reduced in fumonisin production and expression levels of FUM1 and FUM8, two genes involved in fumonisin biosynthesis. The defects of the Fvmk1 mutant were fully complemented by re-introducing the wild type FvMK1 allele. These results demonstrate that FvMK1 plays critical roles in the regulation of vegetative growth, asexual reproduction, fumonisin biosynthesis, and pathogenicity.
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Affiliation(s)
- Yueping Zhang
- College of Longping, Graduate School of Central South University, Changsha, Hunan 410125, China.
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89
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Wiemann P, Brown DW, Kleigrewe K, Bok JW, Keller NP, Humpf HU, Tudzynski B. FfVel1 and FfLae1, components of a velvet-like complex in Fusarium fujikuroi, affect differentiation, secondary metabolism and virulence. Mol Microbiol 2010; 77:972-94. [PMID: 20572938 DOI: 10.1111/j.1365-2958.2010.07263.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Besides industrially produced gibberellins (GAs), Fusarium fujikuroi is able to produce additional secondary metabolites such as the pigments bikaverin and neurosporaxanthin and the mycotoxins fumonisins and fusarin C. The global regulation of these biosynthetic pathways is only poorly understood. Recently, the velvet complex containing VeA and several other regulatory proteins was shown to be involved in global regulation of secondary metabolism and differentiation in Aspergillus nidulans. Here, we report on the characterization of two components of the F. fujikuroi velvet-like complex, FfVel1 and FfLae1. The gene encoding this first reported LaeA orthologue outside the class of Eurotiomycetidae is upregulated in ΔFfvel1 microarray-studies and FfLae1 interacts with FfVel1 in the nucleus. Deletion of Ffvel1 and Fflae1 revealed for the first time that velvet can simultaneously act as positive (GAs, fumonisins and fusarin C) and negative (bikaverin) regulator of secondary metabolism, and that both components affect conidiation and virulence of F. fujikuroi. Furthermore, the velvet-like protein FfVel2 revealed similar functions regarding conidiation, secondary metabolism and virulence as FfVel1. Cross-genus complementation studies of velvet complex component mutants between Fusarium, Aspergillus and Penicillium support an ancient origin for this complex, which has undergone a divergence in specific functions mediating development and secondary metabolism.
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Affiliation(s)
- Philipp Wiemann
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Daren W Brown
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Karin Kleigrewe
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Jin Woo Bok
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Nancy P Keller
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Hans-Ulrich Humpf
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
| | - Bettina Tudzynski
- Institut für Botanik, Westfälische Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, GermanyInstitut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, D-48149 Münster, GermanyBacterial Foodborne Pathogens and Mycology Research, USDA/ARS, 1815 N University St, Peoria, IL 61604, USADepartment of Medical Microbiology and ImmunologyDepartment of Bacteriology, University of Wisconsin, 1550 Linden Dr, Madison, WI 53706-1521, USA
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90
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Two components of a velvet-like complex control hyphal morphogenesis, conidiophore development, and penicillin biosynthesis in Penicillium chrysogenum. EUKARYOTIC CELL 2010; 9:1236-50. [PMID: 20543063 DOI: 10.1128/ec.00077-10] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Penicillium chrysogenum is the industrial producer of the antibiotic penicillin, whose biosynthetic regulation is barely understood. Here, we provide a functional analysis of two major homologues of the velvet complex in P. chrysogenum, which we have named P. chrysogenum velA (PcvelA) and PclaeA. Data from array analysis using a DeltaPcvelA deletion strain indicate a significant role of PcVelA on the expression of biosynthesis and developmental genes, including PclaeA. Northern hybridization and high-performance liquid chromatography quantifications of penicillin titers clearly show that both PcVelA and PcLaeA play a major role in penicillin biosynthesis in a producer strain that underwent several rounds of UV mutagenesis during a strain improvement program. Both regulators are further involved in different developmental processes. While PcvelA deletion leads to light-independent conidial formation, dichotomous branching of hyphae, and pellet formation in shaking cultures, a DeltaPclaeA strain shows a severe impairment in conidiophore formation under both light and dark conditions. Bimolecular fluorescence complementation assays provide evidence for a velvet-like complex in P. chrysogenum, with structurally conserved components that have distinct developmental roles, illustrating the functional plasticity of these regulators in genera other than Aspergillus.
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91
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Reverberi M, Ricelli A, Zjalic S, Fabbri AA, Fanelli C. Natural functions of mycotoxins and control of their biosynthesis in fungi. Appl Microbiol Biotechnol 2010; 87:899-911. [PMID: 20495914 DOI: 10.1007/s00253-010-2657-5] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 04/28/2010] [Accepted: 04/29/2010] [Indexed: 12/31/2022]
Abstract
Mycotoxins are harmful secondary metabolites produced by a range of widespread fungi belonging in the main to Fusarium, Aspergillus and Penicillium genera. But why should fungi produce toxins? And how is the biosynthesis of these toxins regulated? Several separate factors are now known to be capable of modulating mycotoxin synthesis; however, in this study, focussing just on mycotoxins whose regulatory mechanisms have already been established, we introduce a further factor based on a novel consideration. Various different mycotoxin biosynthetic pathways appear to share a common factor in that they are all susceptible to the influence of reactive oxygen species. In fact, when a fungus receives an external stimulus, it reacts by activating, through a well-defined signal cascade, a profound change in its lifestyle. This change usually leads to the activation of global gene regulators and, in particular, of transcription factors which modulate mycotoxin gene cluster expression. Some mycotoxins have a clear-cut role both in generating a pathogenetic process, i.e. fumonisins and some trichothecenes, and in competing with other organisms, i.e. patulin. In other cases, such as aflatoxins, more than one role can be hypothesised. In this review, we suggest an "oxidative stress theory of mycotoxin biosynthesis" to explain the role and the regulation of some of the above mentioned toxins.
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Affiliation(s)
- Massimo Reverberi
- Department of Plant Biology, University Sapienza, L.go Cristina di Svezia 24, 00165, Rome, Italy.
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92
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Avalos J, Estrada AF. Regulation by light in Fusarium. Fungal Genet Biol 2010; 47:930-8. [PMID: 20460165 DOI: 10.1016/j.fgb.2010.05.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 05/04/2010] [Accepted: 05/04/2010] [Indexed: 01/05/2023]
Abstract
The genus Fusarium stands out as research model for pathogenesis and secondary metabolism. Light stimulates the production of some Fusarium metabolites, such as the carotenoids, and in many species it influences the production of asexual spores and sexual fruiting bodies. As found in other fungi with well-known photoresponses, the Fusarium genomes contain several genes for photoreceptors, among them a set of White Collar (WC) proteins, a cryptochrome, a photolyase, a phytochrome and two presumably photoactive opsins. The mutation of the opsin genes produced no apparent phenotypic alterations, but the loss of the only WC-1 orthologous protein eliminated the photoinduced expression of the photolyase and opsin genes. In contrast to other carotenogenic species, lack of the WC photoreceptor did not impede the light-induced accumulation of carotenoids, but produced alterations in conidiation, animal pathogenicity and nitrogen-regulated secondary metabolism. The regulation and functional role of other Fusarium photoreceptors is currently under investigation.
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Affiliation(s)
- Javier Avalos
- Department of Genetics, Faculty of Biology, University of Seville, E-41080 Seville, Spain.
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93
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Choi YE, Xu JR. The cAMP signaling pathway in Fusarium verticillioides is important for conidiation, plant infection, and stress responses but not fumonisin production. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:522-33. [PMID: 20192838 DOI: 10.1094/mpmi-23-4-0522] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Fusarium verticillioides is one of the most important fungal pathogens of maize. Mycotoxin, fumonisins produced by this pathogen pose a threat to human and animal health. Because cAMP signaling has been implicated in regulating diverse developmental and infection processes in fungal pathogens, in this study, we aimed to elucidate the function of the cAMP-protein kinase A (PKA) pathway in toxin production and plant infection in F. verticillioides. Targeted deletion mutants were generated for the CPK1 and FAC1 genes that encode a catalytic subunit of PKA and the adenylate cyclase, respectively. Defects in radial growth and macroconidiation were observed in both the cpk1 and fac1 deletion mutants. The fac1 mutant also was significantly reduced in virulence and microconidiation but increased in tolerance to heat and oxidative stresses. These phenotypes were not observed in the cpk1 mutant, indicating that additional catalytic subunit of PKA must exist and function downstream from FAC1. The fac1 mutant formed microconidia mainly in false heads. The expression levels of the hydrophobin genes HYD1 and HYD2, which are known to be associated with change in formation of microconidia, were significantly reduced in the fac1 mutant. Expression of F. verticillioides GSY2 and HSP26 genes, two other putative downstream targets of FAC1, was increased in the fac1 mutant and may be associated with its enhanced stress tolerance. Although fumonisin production was normal, biosynthesis of bikaverin was increased in the fac1 mutant, suggesting that FAC1 and cAMP signaling may have pathway-or metabolite-specific regulatory roles in secondary metabolism. Overall, the pleiotropic defects of the fac1 deletion mutant indicate that the cAMP-PKA pathway is involved in growth, conidiation, bikaverin production, and plant infection in F. verticillioides.
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Affiliation(s)
- Yoon-E Choi
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
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94
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Abstract
Human fungal pathogens are associated with diseases ranging from dandruff and skin colonization to invasive bloodstream infections. The major human pathogens belong to the Candida, Aspergillus, and Cryptococcus clades, and infections have high and increasing morbidity and mortality. Many human fungal pathogens were originally assumed to be asexual. However, recent advances in genome sequencing, which revealed that many species have retained the genes required for the sexual machinery, have dramatically influenced our understanding of the biology of these organisms. Predictions of a rare or cryptic sexual cycle have been supported experimentally for some species. Here, I examine the evidence that human pathogens reproduce sexually. The evolution of the mating-type locus in ascomycetes (including Candida and Aspergillus species) and basidiomycetes (Malassezia and Cryptococcus) is discussed. I provide an overview of how sex is suppressed in different species and discuss the potential associations with pathogenesis.
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95
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Regulation of morphogenesis and biocontrol properties in Trichoderma virens by a VELVET protein, Vel1. Appl Environ Microbiol 2010; 76:2345-52. [PMID: 20154111 DOI: 10.1128/aem.02391-09] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species.
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96
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Tisch D, Schmoll M. Light regulation of metabolic pathways in fungi. Appl Microbiol Biotechnol 2009; 85:1259-77. [PMID: 19915832 PMCID: PMC2807966 DOI: 10.1007/s00253-009-2320-1] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 10/14/2009] [Accepted: 10/14/2009] [Indexed: 12/17/2022]
Abstract
Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes.
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Affiliation(s)
- Doris Tisch
- Research Area Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria.
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97
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MYUNG KYUNG, LI SHAOJIE, BUTCHKO ROBERTA, BUSMAN MARK, PROCTOR ROBERTH, ABBAS HAMEDK, CALVO ANAM. FvVE1 regulates biosynthesis of the mycotoxins fumonisins and fusarins in Fusarium verticillioides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:5089-94. [PMID: 19382792 PMCID: PMC2692565 DOI: 10.1021/jf900783u] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The veA gene positively regulates sterigmatocystin production in Aspergillus nidulans and aflatoxin production in Aspergillus parasiticus and Aspergillus flavus . Whether veA homologues have a role in regulating secondary metabolism in other fungal genera is unknown. In this study, we examined the role of the veA homologue, FvVE1, on the production of two mycotoxin families, fumonisins and fusarins, in the important corn pathogen Fusarium verticillioides . We found that FvVE1 deletion completely suppressed fumonisin production on two natural substrates, corn and rice. Furthermore, our results revealed that FvVE1 is necessary for the expression of the pathway-specific regulatory gene FUM21 and structural genes in the fumonisin biosynthetic gene (FUM) cluster. FvVE1 deletion also blocked production of fusarins. The effects of FvVE1 deletion on the production of these toxins were found to be the same in two separate mating types. Our results strongly suggest that FvVE1 plays an important role in regulating mycotoxin production in F. verticillioides .
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Affiliation(s)
- KYUNG MYUNG
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., Dekalb, Illinois 60115. USA
| | - SHAOJIE LI
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., Dekalb, Illinois 60115. USA
| | - ROBERT A.E. BUTCHKO
- Mycotoxin Research Unit, US Department of Agriculture-ARS, 1815 N. University Street, Peoria, Illinois 61604, USA
| | - MARK BUSMAN
- Mycotoxin Research Unit, US Department of Agriculture-ARS, 1815 N. University Street, Peoria, Illinois 61604, USA
| | - ROBERT H PROCTOR
- Mycotoxin Research Unit, US Department of Agriculture-ARS, 1815 N. University Street, Peoria, Illinois 61604, USA
| | - HAMED K. ABBAS
- Crop Genetics and Production Research Unit, US Department of Agriculture-ARS, CG&PRU, P.O. Box 345 Stoneville, Mississippi 38776, USA
| | - ANA M. CALVO
- Department of Biological Sciences, Northern Illinois University, 1425 W. Lincoln Hwy., Dekalb, Illinois 60115. USA
- Author to whom correspondence should be addressed [telephone: (815) 753−0451; fax (815) 753−0461; e-mail ]
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98
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Abstract
Penicillins and cephalosporins are β‐lactam antibiotics widely used in human medicine. The biosynthesis of these compounds starts by the condensation of the amino acids l‐α‐aminoadipic acid, l‐cysteine and l‐valine to form the tripeptide δ‐l‐α‐aminoadipyl‐l‐cysteinyl‐d‐valine catalysed by the non‐ribosomal peptide ‘ACV synthetase’. Subsequently, this tripeptide is cyclized to isopenicillin N that in Penicillium is converted to hydrophobic penicillins, e.g. benzylpenicillin. In Acremonium and in streptomycetes, isopenicillin N is later isomerized to penicillin N and finally converted to cephalosporin. Expression of genes of the penicillin (pcbAB, pcbC, pendDE) and cephalosporin clusters (pcbAB, pcbC, cefD1, cefD2, cefEF, cefG) is controlled by pleitropic regulators including LaeA, a methylase involved in heterochromatin rearrangement. The enzymes catalysing the last two steps of penicillin biosynthesis (phenylacetyl‐CoA ligase and isopenicillin N acyltransferase) are located in microbodies, as shown by immunoelectron microscopy and microbodies proteome analyses. Similarly, the Acremonium two‐component CefD1–CefD2 epimerization system is also located in microbodies. This compartmentalization implies intracellular transport of isopenicillin N (in the penicillin pathway) or isopenicillin N and penicillin N in the cephalosporin route. Two transporters of the MFS family cefT and cefM are involved in transport of intermediates and/or secretion of cephalosporins. However, there is no known transporter of benzylpenicillin despite its large production in industrial strains.
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Affiliation(s)
- Juan F Martín
- Institute of Biotechnology of León, Science Park, Avda. Real 1, 24006 León, Spain.
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Kim HY, Han KH, Lee M, Oh M, Kim HS, Zhixiong X, Han DM, Jahng KY, Kim JH, Chae KS. The veA gene is necessary for the negative regulation of the veA expression in Aspergillus nidulans. Curr Genet 2009; 55:391-7. [PMID: 19479257 DOI: 10.1007/s00294-009-0253-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 05/07/2009] [Accepted: 05/10/2009] [Indexed: 02/04/2023]
Abstract
The veA gene is one of the key genes in regulating sexual development of Aspergillus nidulans. During the study on the veA gene, it was observed that the veA expression level is slightly higher in a veA1 mutant than in a wild type at 37 degrees C, suggesting that the wild type veA gene is necessary for the negative regulation of the veA expression. In the veA1 mutant, the veA expression was higher than in a wild type grown at 42 degrees C but equal at 30 degrees C. Furthermore, in a veA deletion mutant having its own promoter and the N-terminus of the VeA ORF, expression of the N-terminus by the veA promoter was highly up-regulated, supporting the possibility that the veA gene is important for the negative regulation of the veA expression. Analyses of the lacZ transcript and the beta-galactosidase activity from the reporter strains in the veA1 background, which were constructed by transformation of the lacZ reporter plasmids containing the lacZ gene under the control of the intact or the truncated veA promoters from the -943 to +262 bp region, showed that the truncated promoters produced more veA transcript and higher beta-galactosidase activity than the intact one at 30 degrees C, but equal at 42 degrees C. In addition, the serial-deletion analysis of the veA promoter identified a crucial region in the promoter from -943 to -740 bp for this derepression of the veA expression. Taken together, these results indicated that the veA gene is necessary for the negative regulation of the veA expression. Moreover, the veA expression was derepressed in the light-illuminated condition, where the VeA protein is hardly transported into the nucleus.
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Affiliation(s)
- Hyoun-Young Kim
- Division of Biological Sciences, Basic Science Research Institute, Chonbuk National University, Chonju, 561-756, Republic of Korea
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