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Pan C, Li YX, Yang K, Famous E, Ma Y, He X, Geng Q, Liu M, Tian J. The Molecular Mechanism of Perillaldehyde Inducing Cell Death in Aspergillus flavus by Inhibiting Energy Metabolism Revealed by Transcriptome Sequencing. Int J Mol Sci 2020; 21:ijms21041518. [PMID: 32102190 PMCID: PMC7073185 DOI: 10.3390/ijms21041518] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 01/01/2023] Open
Abstract
Perillaldehyde (PAE), an essential oil in Perilla plants, serves as a safe flavor ingredient in foods, and shows an effectively antifungal activity. Reactive oxygen species (ROS) accumulation in Aspergillus flavus plays a critical role in initiating a metacaspase-dependent apoptosis. However, the reason for ROS accumulation in A. flavus is not yet clear. Using transcriptome sequencing of A. flavus treated with different concentrations of PAE, our data showed that the ROS accumulation might have been as a result of an inhibition of energy metabolism with less production of reducing power. By means of GO and KEGG enrichment analysis, we screened four key pathways, which were divided into two distinct groups: a downregulated group that was made up of the glycolysis and pentose phosphate pathway, and an upregulated group that consisted of MAPK signaling pathway and GSH metabolism pathway. The inhibition of dehydrogenase gene expression in two glycometabolism pathways might play a crucial role in antifungal mechanism of PAE. Also, in our present study, we systematically showed a gene interaction network of how genes of four subsets are effected by PAE stress on glycometabolism, oxidant damage repair, and cell cycle control. This research may contribute to explaining an intrinsic antifungal mechanism of PAE against A. flavus.
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Affiliation(s)
- Chao Pan
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Yong-Xin Li
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Kunlong Yang
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Erhunmwunsee Famous
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Yan Ma
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Xiaona He
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Qingru Geng
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
| | - Man Liu
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
- Correspondence: (M.L.); (J.T.); Tel.: +86-516-83403172 (J.T.)
| | - Jun Tian
- College of Life Science, Jiangsu Normal University, Xuzhou 221116, China; (C.P.); (Y.-X.L.); (K.Y.); (E.F.)
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing100048, China
- Correspondence: (M.L.); (J.T.); Tel.: +86-516-83403172 (J.T.)
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2
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Foutz KR, Woloshuk CP, Payne GA. Cloning and assignment of linkage group loci to a karyotypic map of the filamentous fungusAspergillus flavus. Mycologia 2018. [DOI: 10.1080/00275514.1995.12026600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Kirk R. Foutz
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695-7616
| | - Charles P. Woloshuk
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
| | - Gary A. Payne
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695-7616
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3
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Martínez-Cruz J, Romero D, de Vicente A, Pérez-García A. Transformation of the cucurbit powdery mildew pathogen Podosphaera xanthii by Agrobacterium tumefaciens. THE NEW PHYTOLOGIST 2017; 213:1961-1973. [PMID: 27864969 DOI: 10.1111/nph.14297] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/21/2016] [Indexed: 06/06/2023]
Abstract
The obligate biotrophic fungal pathogen Podosphaera xanthii is the main causal agent of powdery mildew in cucurbit crops all over the world. A major limitation of molecular studies of powdery mildew fungi (Erysiphales) is their genetic intractability. In this work, we describe a robust method based on the promiscuous transformation ability of Agrobacterium tumefaciens for reliable transformation of P. xanthii. The A. tumefaciens-mediated transformation (ATMT) system yielded transformants of P. xanthii with diverse transferred DNA (T-DNA) constructs. Analysis of the resultant transformants showed the random integration of T-DNA into the P. xanthii genome. The integrations were maintained in successive generations in the presence of selection pressure. Transformation was found to be transient, because in the absence of selection agent, the introduced genetic markers were lost due to excision of T-DNA from the genome. The ATMT system represents a potent tool for genetic manipulation of P. xanthii and will likely be useful for studying other biotrophic fungi. We hope that this method will contribute to the development of detailed molecular studies of the intimate interaction established between powdery mildew fungi and their host plants.
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Affiliation(s)
- Jesús Martínez-Cruz
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora' - Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, 29071, Spain
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga. Bulevar Louis Pasteur 31, Málaga, 29071, Spain
| | - Diego Romero
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora' - Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, 29071, Spain
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga. Bulevar Louis Pasteur 31, Málaga, 29071, Spain
| | - Antonio de Vicente
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora' - Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, 29071, Spain
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga. Bulevar Louis Pasteur 31, Málaga, 29071, Spain
| | - Alejandro Pérez-García
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora' - Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, 29071, Spain
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga. Bulevar Louis Pasteur 31, Málaga, 29071, Spain
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4
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Das S, Dash HR, Mangwani N, Chakraborty J, Kumari S. Understanding molecular identification and polyphasic taxonomic approaches for genetic relatedness and phylogenetic relationships of microorganisms. J Microbiol Methods 2014; 103:80-100. [PMID: 24886836 DOI: 10.1016/j.mimet.2014.05.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 05/22/2014] [Accepted: 05/22/2014] [Indexed: 12/29/2022]
Abstract
The major proportion of earth's biological diversity is inhabited by microorganisms and they play a useful role in diversified environments. However, taxonomy of microorganisms is progressing at a snail's pace, thus less than 1% of the microbial population has been identified so far. The major problem associated with this is due to a lack of uniform, reliable, advanced, and common to all practices for microbial identification and systematic studies. However, recent advances have developed many useful techniques taking into account the house-keeping genes as well as targeting other gene catalogues (16S rRNA, rpoA, rpoB, gyrA, gyrB etc. in case of bacteria and 26S, 28S, β-tubulin gene in case of fungi). Some uncultivable approaches using much advanced techniques like flow cytometry and gel based techniques have also been used to decipher microbial diversity. However, all these techniques have their corresponding pros and cons. In this regard, a polyphasic taxonomic approach is advantageous because it exploits simultaneously both conventional as well as molecular identification techniques. In this review, certain aspects of the merits and limitations of different methods for molecular identification and systematics of microorganisms have been discussed. The major advantages of the polyphasic approach have also been described taking into account certain groups of bacteria as case studies to arrive at a consensus approach to microbial identification.
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Affiliation(s)
- Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India.
| | - Hirak R Dash
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India
| | - Neelam Mangwani
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India
| | - Jaya Chakraborty
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India
| | - Supriya Kumari
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela 769 008, Odisha, India
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5
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Development and refinement of a high-efficiency gene-targeting system for Aspergillus flavus. J Microbiol Methods 2010; 81:240-6. [DOI: 10.1016/j.mimet.2010.03.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 02/19/2010] [Accepted: 03/04/2010] [Indexed: 10/19/2022]
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Chen CJ, Yu JJ, Bi CW, Zhang YN, Xu JQ, Wang JX, Zhou MG. Mutations in a beta-tubulin confer resistance of Gibberella zeae to benzimidazole fungicides. PHYTOPATHOLOGY 2009; 99:1403-1411. [PMID: 19900007 DOI: 10.1094/phyto-99-12-1403] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
ABSTRACT Wheat head blight caused by Gibberella zeae (anamorph: Fusarium graminearum) is a threat to food safety in China because of mycotoxin contamination of the harvested grain, the frequent occurrence of the disease, and the failure of chemical control in some areas due to benzimidazole resistance in the pathogen population. The molecular resistance mechanism, however, of G. zeae to benzimidazole fungicides (especially carbendazim; active ingredient: methyl benzimidazol-2-yl carbamate [MBC]) is poorly understood. DNA sequences of a beta-tubulin gene (beta(2)tub) (GenBank access number FG06611.1) in G. zeae were analyzed. Mutations in beta(2)tub in moderately resistant strains (MBC(MR)) included TTT (Phe)-->TAT (Tyr) at codon 167 or TTC (Phe)-->TAC (Tyr) at codon 200. A highly resistant strain (MBC(HR)) had two point mutations, one at codon 73, CAG (Gln)-->CGG (Arg), and the other at codon 198, GAG (Glu)-->CTG (Leu). To confirm that mutations in the beta(2)tub confer resistance to benzimidazole fungicides, the entire beta(2)tub locus was deleted from MBC(MR) and MBC(HR) strains of G. zeae. The resulting Deltabeta(2)tub mutants from both MBC(MR) and MBC(HR) strains grew normally on MBC-free potato dextrose agar medium and were supersensitive to MBC. Complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from their parent strains exhibited less resistance than the original strains, and complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from sensitive strains restored MBC sensitivity. The results indicated that the mutations in the beta(2)tub gene conferred resistance of G. zeae to benzimidazole fungicides and this gene can be used as a genetic marker in G. zeae.
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Affiliation(s)
- Chang-Jun Chen
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China
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7
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Li M, Yang Q. Isolation and characterization of a beta-tubulin gene from Trichoderma harzianum. Biochem Genet 2007; 45:529-34. [PMID: 17551827 DOI: 10.1007/s10528-007-9094-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Accepted: 03/16/2007] [Indexed: 10/23/2022]
Affiliation(s)
- Min Li
- Department of Life Science and Engineering, Harbin Institute of Technology, West Da-Zhi Street 96, Harbin, Heilongjiang Province 150001, P.R. China
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8
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Malkus A, Reszka E, Chang CJ, Arseniuk E, Chang PFL, Ueng PP. Sequence diversity of beta-tubulin (tubA) gene in Phaeosphaeria nodorum and P. avenaria. FEMS Microbiol Lett 2005; 249:49-56. [PMID: 15972251 DOI: 10.1016/j.femsle.2005.05.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2004] [Revised: 04/12/2005] [Accepted: 05/28/2005] [Indexed: 11/20/2022] Open
Abstract
Full-length coding sequences of the beta-tubulin gene (tubA) were PCR-amplified and sequenced from 42 Phaeosphaeria isolates, including 16 P. nodorum and 23 P. avenaria species from cereals, two Polish isolates from rye (Secale cereale L.), and one isolate from dallis grass (Paspalum dilatatum Poir). A tubA gene of size 1556bp was identified in wheat- and barley-biotype P. nodorum (PN-w and PN-b), P. avenaria f. sp. avenaria (Paa), homothallic P. avenaria f. sp. triticea (P.a.t.) (Pat1) and the P.a.t. isolate (Pat3) from the State of Washington. The tubA gene length polymorphisms were detected in two P.a.t. isolates (Pat2) from foxtail barley (Hordeum jubatum L.), one from dallis grass and two Polish isolates from rye. These size differences were due to the variation of intron lengths among these three Phaeosphaeria species. All Phaeosphaeria isolates have identical 1344bp exons that can be translated into a 447 amino acid beta-tubulin. Like glyceraldehyde-3-phosphate dehydrogenase, the beta-tubulin amino acid sequence was identical in all Phaeosphaeria species used in this study, with the exception of the two Pat2 isolates. Six amino acid differences were evident in the beta-tubulin of these Pat2 isolates.
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Affiliation(s)
- Arkadiusz Malkus
- Department of Plant Pathology, Plant Breeding and Acclimatization Institute, Radzikow, Poland
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9
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Characterisation of a β-tubulin gene from Melampsora lini and comparison of fungal β-tubulin genes. ACTA ACUST UNITED AC 2001. [DOI: 10.1017/s0953756201004245] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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10
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Molecular transformation, gene cloning, and gene expression systems for filamentous fungi. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1874-5334(01)80010-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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11
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Meyers DM, Obrian G, Du WL, Bhatnagar D, Payne GA. Characterization of aflJ, a gene required for conversion of pathway intermediates to aflatoxin. Appl Environ Microbiol 1998; 64:3713-7. [PMID: 9758789 PMCID: PMC106528 DOI: 10.1128/aem.64.10.3713-3717.1998] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genes encoding the aflatoxin biosynthetic pathway enzymes have been localized as a cluster to a 75-kb DNA fragment. The enzymatic functions of the products of most of the genes in the cluster are known, but there are a few genes that have not yet been characterized. We report here the characterization of one of these genes, a gene designated aflJ. This gene resides in the cluster adjacent to the pathway regulatory gene, aflR, and the two genes are divergently transcribed. Disruption of aflJ in Aspergillus flavus results in a failure to produce aflatoxins and a failure to convert exogenously added pathway intermediates norsolorinic acid, sterigmatocystin, and O-methylsterigmatocystin to aflatoxin. The disrupted strain does, however, accumulate pksA, nor-1, ver-1, and omtA transcripts under conditions conducive to aflatoxin biosynthesis. Therefore, disruption of aflJ does not affect transcription of these genes, and aflJ does not appear to have a regulatory function similar to that of aflR. Sequence analysis of aflJ and its putative peptide, AflJ, did not reveal any enzymatic domains or significant similarities to proteins of known function. The putative peptide does contain three regions predicted to be membrane-spanning domains and a microbodies C-terminal targeting signal.
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Affiliation(s)
- D M Meyers
- North Carolina State University, Raleigh, North Carolina 27695, USA
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Prieto R, Woloshuk CP. ord1, an oxidoreductase gene responsible for conversion of O-methylsterigmatocystin to aflatoxin in Aspergillus flavus. Appl Environ Microbiol 1997; 63:1661-6. [PMID: 9143099 PMCID: PMC168459 DOI: 10.1128/aem.63.5.1661-1666.1997] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Among the enzymatic steps in the aflatoxin biosynthetic pathway, the conversion of O-methylsterigmatocystin to aflatoxin has been proposed to be catalyzed by an oxidoreductase. Transformants of Aspergillus flavus 649WAF2 containing a 3.3-kb genomic DNA fragment and the aflatoxin biosynthesis regulatory gene aflR converted exogenously supplied O-methylsterigmatocystin to aflatoxin B1. A gene, ord1, corresponding to a transcript of about 2 kb was identified within the 3.3-kb DNA fragment. The promoter region presented a putative AFLR binding site and a TATA sequence. The nucleotide sequence of the gene revealed an open reading frame encoding a protein of 528 amino acids with a deduced molecular mass of 60.2 kDa. The gene contained six introns and seven exons. Heterologous expression of the ord1 open reading frame under the transcriptional control of the Saccharomyces cerevisiae galactose-inducible gal1 promoter results in the ability to convert O-methylsterigmatocystin to aflatoxin B1. The data indicate that ord1 is sufficient to accomplish the last step of the aflatoxin biosynthetic pathway. A search of various databases for similarity indicated that ord1 encodes a cytochrome P-450-type monooxygenase, and the gene has been assigned to a new P-450 gene family named CYP64.
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Affiliation(s)
- R Prieto
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
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13
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Liang SH, Wu TS, Lee R, Chu FS, Linz JE. Analysis of mechanisms regulating expression of the ver-1 gene, involved in aflatoxin biosynthesis. Appl Environ Microbiol 1997; 63:1058-65. [PMID: 9055421 PMCID: PMC168396 DOI: 10.1128/aem.63.3.1058-1065.1997] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Previous studies have shown that ver-1A encodes an enzyme which is directly involved in the conversion of versicolorin A to demethylsterigmatocystin during aflatoxin B1 (AFB1) biosynthesis in the filamentous fungus Aspergillus parasiticus. In this study, two different tools were utilized to study the regulation of ver-1A expression at the level of transcription and protein accumulation. First, a ver-1A cDNA was expressed in Escherichia coli with the vector pMAL-c2. The resulting maltose-binding protein-Ver-1A fusion protein was purified and used to generate polyclonal antibodies. Western blot analyses showed that these antibodies specifically recognized the Ver-1 protein (approximately 28 kDa) in cell extracts of Aspergillus parasiticus SU1. Second, a GUS (uidA; encodes beta-glucuronidase) reporter system was developed by fusing the ver-1A promoter and transcription terminator to the GUS gene. Reporter constructs were transformed into A. parasiticus, resulting in a single copy of the ver-1A-GUS reporter integrated adjacent to the wild-type ver-1A gene (3' end) in the chromosome. Western blot analysis, Northern hybridization analysis, and a GUS activity assay were used to analyze transformants. The timing of appearance and pattern of accumulation of GUS transcript and GUS protein in transformants were consistent with the timing of appearance and pattern of accumulation of ver-1 transcript and Ver-1 protein. These data suggested that the GUS gene was under the same regulatory control as the wild-type ver-1 gene and confirmed that transcriptional regulation plays an important role in ver-1A expression. Integration of the ver-1A-GUS reporter construct at the niaD locus resulted in 500-fold-lower GUS activity, but the temporal pattern of accumulation of GUS activity was not affected. Therefore, chromosomal location can play a role in determining the level of gene expression in A. parasiticus and should be an important consideration when analyzing promoter function in this organism.
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Affiliation(s)
- S H Liang
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing 48824, USA
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14
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Wu TS, Skory CD, Horng JS, Linz JE. Cloning and functional analysis of a beta-tubulin gene from a benomyl resistant mutant of Aspergillus parasiticus. Gene 1996; 182:7-12. [PMID: 8982061 DOI: 10.1016/s0378-1119(96)00382-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A genomic DNA library prepared from a benomyl resistant strain of Aspergillus parasiticus was screened with a Neurospora crassa beta-tubulin gene probe. A unique A. parasiticus genomic DNA fragment, thought to carry a mutant beta-tubulin gene (benr), was isolated. Two plasmids, pYT1 and pYTPYRG, carrying the putative benr gene or benr plus a second selectable marker (pyrG), respectively, were used to transform a benomyl sensitive strain of A. parasiticus (CS10) to determine if benr conferred benomyl resistance (BenR). BenR colonies were obtained with pYTPYRG, pYT1 or pYT1 cotransformed with pPG3J which carries a functional pyrG gene. No BenR colonies were obtained without added DNA or with pPG3J only (controls). Southern hybridization analysis of BenR and BenS transformants suggested that plasmid integration occurred most frequently at the chromosomal bens locus, however evidence for gene conversion and heterologous recombination was also observed. The predicted amino acid sequence of benr displayed a high degree of identity (> 93%) with other fungal beta-tubulin genes which confer benomyl resistance. Sequence analysis together with the genetic data suggested that benr encodes a functional mutant beta-tubulin.
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Affiliation(s)
- T S Wu
- Department of Food Science and Human Nutrition, Michigan State University, E. Lansing 48824-1224, USA
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15
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Prieto R, Yousibova GL, Woloshuk CP. Identification of aflatoxin biosynthesis genes by genetic complementation in an Aspergillus flavus mutant lacking the aflatoxin gene cluster. Appl Environ Microbiol 1996; 62:3567-71. [PMID: 8967772 PMCID: PMC168161 DOI: 10.1128/aem.62.10.3567-3571.1996] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Aspergillus flavus mutant strain 649, which has a genomic DNA deletion of at least 120 kb covering the aflatoxin biosynthesis cluster, was transformed with a series of overlapping cosmids that contained DNA harboring the cluster of genes. The mutant phenotype of strain 649 was rescued by transformation with a combination of cosmid clones 5E6, 8B9, and 13B9, indicating that the cluster of genes involved in aflatoxin biosynthesis resides in the 90 kb of A. flavus genomic DNA carried by these clones. Transformants 5E6 and 20B11 and transformants 5E6 and 8B9 accumulated intermediate metabolites of the aflatoxin pathway, which were identified as averufanin and/or averufin, respectively. These data suggest that avf1, which is involved in the conversion of averufin to versiconal hemiacetal acetate, was present in the cosmid 13B9. Deletion analysis of 13B9 located the gene on a 7-kb DNA fragment of the cosmid. Transformants containing cosmid 8B9 converted exogenously supplied O-methylsterigmatocystin to aflatoxin, indicating that the oxidoreductase gene (ord1), which mediates the conversion of O-methylsterigmatocystin to aflatoxin, is carried by this cosmid. The analysis of transformants containing deletions of 8B9 led to the localization of ord1 on a 3.3-kb A. flavus genomic DNA fragment of the cosmid.
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Affiliation(s)
- R Prieto
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
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16
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Abstract
The disciplines traditionally used to investigate the mode of action of fungicides have been biochemistry and physiology. Over the past decade, classical and molecular genetics have been brought to bear on this problem with increasing success. Recently, genetic studies of fungicide resistance have led to advances in our understanding of the site of action of chemicals active against plant pathogens and, in some cases, to an appreciation of additional mechanisms of resistance to fungicide action.
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Affiliation(s)
- J J Steffens
- DuPont Agricultural Products, Wilmington, Delaware 19880-0402, USA.
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17
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Yu J, Chang PK, Cary JW, Wright M, Bhatnagar D, Cleveland TE, Payne GA, Linz JE. Comparative mapping of aflatoxin pathway gene clusters in Aspergillus parasiticus and Aspergillus flavus. Appl Environ Microbiol 1995; 61:2365-71. [PMID: 7793957 PMCID: PMC167508 DOI: 10.1128/aem.61.6.2365-2371.1995] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. Aflatoxins are synthesized by condensation of acetate units; their synthesis is estimated to involve at least 16 different enzymes. In this study we have shown that at least nine genes involved in the aflatoxin biosynthetic pathway are located within a 60-kb DNA fragment. Four of these genes, nor-1, aflR, ver-1, and omtA (previously named omt-1), have been cloned in A. flavus and A. parasiticus. In addition, five other genes, pksA, uvm8, aad, ord-1, and ord-2 have been recently cloned in A. parasiticus. The pksA, aad, and uvm8 genes exhibit sequence homologies to polyketide synthase, aryl-alcohol dehydrogenase, and fatty acid synthase genes, respectively. The cDNA sequences of ord-1 and ord-2 genes, which may be involved in later steps of aflatoxin biosynthesis, have been determined; the ord-1 gene product exhibits homology to cytochrome P-450-type enzymes. By characterizing the overlapping regions of the DNA inserts in different cosmid and lambda DNA clones, we have determined the order of these aflatoxin pathway genes within this 60-kb DNA region to be pksA, nor-1, uvm8, aflR, aad, ver-1, ord-1, ord-2, and omtA in A. parasiticus and nor-1, aflR, ver-1, ord-1, ord-2, and omtA in A. flavus. The order is related to the order in enzymatic steps required for aflatoxin biosynthesis. The physical distances (in kilobase pairs) and the directions of transcription of these genes have been determined for both aflatoxigenic species.
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Affiliation(s)
- J Yu
- Southern Regional Research Center, USDA Agricultural Research Service, New Orleans, Louisiana 70179, USA
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18
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Kuriyama R, Levin A, Nelson D, Madl J, Frankfurter A, Kimble M. Monoclonal anti-dipeptide antibodies cross-react with detyrosinated and glutamylated forms of tubulins. CELL MOTILITY AND THE CYTOSKELETON 1995; 30:171-82. [PMID: 7538912 DOI: 10.1002/cm.970300302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Two monoclonal antibodies, GLU-1 and A1.6, raised against gamma-L-glutamyl-L-glutamic acid dipeptide (Glu-Glu) and Ca(2+)-dependent ATPase from Paramecium, respectively, recognized the dipeptide Glu-Glu sequence. Whereas the antibodies immunofluorescently stained very few, if any, cytoskeletal fibers in cultured mammalian cells, almost all interphase as well as mitotic spindle microtubules became visible after treatment of cells with carboxypeptidase A. Immunoblot analysis demonstrated intense cross-reaction of the antibodies to the alpha-tubulin subunit. alpha-Tubulin isotypes produced as fusion proteins in bacteria were labeled by both the antibodies only when the proteins did not contain a tyrosine residue at the C terminus, indicating that GLU-1 and A1.6 specifically recognize the detyrosinated form of alpha-tubulin. When microtubule protein purified from brain was probed, not only alpha-but also, to a lesser extent, beta-tubulin were revealed by the dipeptide antibodies. A synthetic tripeptide YED containing one glutamyl group linked to the second residue of the peptide via the gamma position was also recognized by the antibodies. Since this peptide sequence corresponds to the amino acid sequence of polyglutamyated class III beta isotype at amino acid position 437 to 439, it is suggested that GLU-1 and A1.6 are able to recognize the glutamylated form of beta-tubulin. These results indicate that the C-terminal Glu-Glu sequence displays strong antigenicity, and the antibodies recognize the sequence present in the C terminus of the detyrosinated form of alpha-tubulin and the glutamyl side chain of beta-tubulin. Particularly strong immunoreaction was detected with ciliary and flagellar microtubules; thus, stable axonemal microtubules appear to be rich in post-translationally modified tubulin subunits.
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Affiliation(s)
- R Kuriyama
- Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455, USA
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19
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Woloshuk CP, Foutz KR, Brewer JF, Bhatnagar D, Cleveland TE, Payne GA. Molecular characterization of aflR, a regulatory locus for aflatoxin biosynthesis. Appl Environ Microbiol 1994; 60:2408-14. [PMID: 8074521 PMCID: PMC201664 DOI: 10.1128/aem.60.7.2408-2414.1994] [Citation(s) in RCA: 250] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Aflatoxins belong to a family of decaketides that are produced as secondary metabolites by Aspergillus flavus and A. parasiticus. The aflatoxin biosynthetic pathway involves several enzymatic steps that appear to be regulated by the afl2 gene in A. flavus and the apa2 gene in A. parasiticus. Several lines of evidence indicate that these two genes are homologous. The DNA sequences of the two genes are highly similar, they both are involved in the regulation of aflatoxin biosynthesis, and apa2 can complement the afl2 mutation in A. flavus. Because of these similarities, we propose that these two genes are homologs, and because of the ability of these genes to regulate aflatoxin biosynthesis, we suggest that they be designated aflR. We report here the further characterization of aflR from A. flavus and show that aflR codes for a 2,078-bp transcript with an open reading frame of 1,311 nucleotides that codes for 437 amino acids and a putative protein of 46,679 daltons. Analysis of the predicted amino acid sequence indicated that the polypeptide contains a zinc cluster motif between amino acid positions 29 and 56. This region contains the consensus sequence Cys-Xaa2-Cys-Xaa6-Cys-Xaa6-Cys-Xaa2-Cys-Xaa6+ ++-Cys. This motif has been found in several fungal transcriptional regulatory proteins. DNA hybridization of the aflR gene with genomic digests of seven polyketide-producing fungi revealed similar sequences in three other species related to A. flavus: A. parasiticus, A. oryzae, and A. sojae. Finally, we present evidence for an antisense transcript (aflRas) derived from the opposite strand of aflR, suggesting that the aflR locus involves some form of antisense regulation.
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Affiliation(s)
- C P Woloshuk
- Purdue University, West Lafayette, Indiana 47907
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20
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Woloshuk CP, Payne GA. The alcohol dehydrogenase gene adh1 is induced in Aspergillus flavus grown on medium conducive to aflatoxin biosynthesis. Appl Environ Microbiol 1994; 60:670-6. [PMID: 8135521 PMCID: PMC201364 DOI: 10.1128/aem.60.2.670-676.1994] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
An Aspergillus flavus cDNA library was screened by differential hybridization to isolate clones corresponding to genes that are actively transcribed under culture conditions conducive to aflatoxin biosynthesis. One clone with a 1.28-kb insert was isolated, and its nucleotide sequence was determined. The nucleotide sequence of this clone had 75% DNA identity to those of the alcohol dehydrogenase genes from Aspergillus nidulans, and the putative polypeptide translated from the cDNA sequence had 82% similarity with the amino acid sequences of the A. nidulans proteins. Thus, this gene has been designated adh1. Southern hybridization analysis of genomic DNA from A. flavus indicated that there was one copy of the adh1 gene. Northern (RNA) hybridization analysis indicated that the adh1 transcript accumulated in culture medium conducive to aflatoxin production and the timing of accumulation of adh1 transcripts was similar to that for aflatoxin. Fusion of the promoter region of adh1 to a beta-glucuronidase reporter gene indicated that accumulation of the adh1 transcript was the result of transcriptional activation. These molecular data support previous physiological evidence that showed the importance of carbohydrate metabolism during aflatoxin biosynthesis.
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Affiliation(s)
- C P Woloshuk
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907
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21
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Goldman GH, Temmerman W, Jacobs D, Contreras R, Van Montagu M, Herrera-Estrella A. A nucleotide substitution in one of the beta-tubulin genes of Trichoderma viride confers resistance to the antimitotic drug methyl benzimidazole-2-yl-carbamate. MOLECULAR & GENERAL GENETICS : MGG 1993; 240:73-80. [PMID: 8341264 DOI: 10.1007/bf00276886] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We characterized a Trichoderma viride strain that is resistant to the antimitotic drug methyl benzimidazole-2-yl-carbamate (MBC). This species has two beta-tubulin genes (tub1 and tub2) and by reverse genetics we showed that a mutation in the tub2 gene confers MBC resistance in this strain. Comparison of the tub2 sequence of the mutant strain with that of the wild type revealed that a single amino acid substitution of tyrosine for histidine at a position 6 is responsible for the MBC tolerance. Furthermore, we showed that this gene can be used as a homologous dominant selectable marker in T. viride transformation. Both tubulin genes were completely sequenced. They differ by 48 residues and the degree of identity between their deduced amino acid sequences is 86.3%.
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Affiliation(s)
- G H Goldman
- Laboratorium voor Genetica, Universiteit Gent, Belgium
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22
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Cooley RN, Caten CE. Molecular analysis of the Septoria nodorum beta-tubulin gene and characterization of a benomyl-resistance mutation. MOLECULAR & GENERAL GENETICS : MGG 1993; 237:58-64. [PMID: 8455567 DOI: 10.1007/bf00282784] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The complete nucleotide sequence of a benomyl-resistant allele of the Septoria nodorum beta-tubulin gene (tubAR) has been determined including 745 and 1024 nucleotides 5' and 3' to the tubAR coding region, respectively. tubAR encodes a 447 amino acid polypeptide which shows a high degree of homology with other fungal beta-tubulins. The gene contains three introns at codons 4, 12 and 53, uses 48 of the possible 61 sense codons and has a GC content of 59.1% in its coding region. S1 nuclease mapping has identified two transcriptional start sites 80 bp and 83 bp upstream of the translation start, and a transcriptional termination site 192 bp downstream of the stop codon. The two transcriptional start sites lie just 8 bp and 5 bp downstream of a CT motif consisting of 18 pyrimidine nucleotides interrupted by a single adenine. The wild-type allele tubA+ has been cloned using the polymerase chain reaction and the mutation producing the benomyl-resistant phenotype of tubAR mapped to a C to T transition at the first position of codon 6, resulting in a histidine to tyrosine amino acid substitution.
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Affiliation(s)
- R N Cooley
- School of Biological Sciences, University of Birmingham, Edgbaston, UK
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23
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Payne GA, Nystrom GJ, Bhatnagar D, Cleveland TE, Woloshuk CP. Cloning of the afl-2 gene involved in aflatoxin biosynthesis from Aspergillus flavus. Appl Environ Microbiol 1993; 59:156-62. [PMID: 8439147 PMCID: PMC202071 DOI: 10.1128/aem.59.1.156-162.1993] [Citation(s) in RCA: 182] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Aflatoxins are extremely potent carcinogens produced by Aspergillus flavus and Aspergillus parasiticus. Cloning of genes in the aflatoxin pathway provides a specific approach to understanding the regulation of aflatoxin biosynthesis and, subsequently, to the control of aflatoxin contamination of food and feed. This paper reports the isolation of a gene involved in aflatoxin biosynthesis by complementation of an aflatoxin-nonproducing mutant with a wild-type genomic cosmid library of A. flavus. Strain 650-33, blocked in aflatoxin biosynthesis at the afl-2 allele, was complemented by a 32-kb cosmid clone (B9), resulting in the production of aflatoxin. The onset and profile of aflatoxin accumulation was similar for the transformed strain and the wild-type strain (NRRL 3357) of the fungus, indicating that the integrated gene is under the same control as in wild-type strains. Complementation analyses with DNA fragments from B9 indicated that the gene resides within a 2.2-kb fragment. Because this gene complements the mutated afl-2 allele, it was designated afl-2. Genetic evidence obtained from a double mutant showed that afl-2 is involved in aflatoxin biosynthesis before the formation of norsolorinic acid, the first stable intermediate identified in the pathway. Further, metabolite feeding studies with the mutant, transformed, and wild-type cultures and enzymatic activity measurements in cell extracts of these cultures suggest that afl-2 regulates gene expression or the activity of other aflatoxin pathway enzymes. This is the first reported isolation of a gene for aflatoxin biosynthesis in A. flavus.
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Affiliation(s)
- G A Payne
- Department of Plant Pathology, North Carolina State University, Raleigh, 27695-7616
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24
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Chevalet L, Tiraby G, Cabane B, Loison G. Transformation of Aspergillus flavus: construction of urate oxidase-deficient mutants by gene disruption. Curr Genet 1992; 21:447-53. [PMID: 1617733 DOI: 10.1007/bf00351654] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A transformation procedure based on the complementation of a genetic defect was developed using a nitrate reductase-deficient mutant of Aspergillus flavus. The initial transformation efficiency was improved 40-fold by combining factors in a planned experimental program. Although low, this transformation rate was sufficient to obtain transformants in which the urate oxidase-encoding gene (uaZ) was disrupted in a gene replacement experiment. These new uaZ- strains were unable to utilize uric acid as the unique nitrogen source and could be reversed directly to the wild-type phenotype in second order transformation experiments using a urate oxidase-expressing vector.
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Affiliation(s)
- L Chevalet
- SANOFI-Chimie, Département Développement Biotechnologie, Aramon, France
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25
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Keller NP, Cleveland TE, Bhatnagar D. Variable electrophoretic karyotypes of members of Aspergillus Section Flavi. Curr Genet 1992. [DOI: 10.1007/bf00351697] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Upchurch RG, Ehrenshaft M, Walker DC, Sanders LA. Genetic Transformation System for the Fungal Soybean Pathogen
Cercospora kikuchii. Appl Environ Microbiol 1991; 57:2935-9. [PMID: 16348566 PMCID: PMC183900 DOI: 10.1128/aem.57.10.2935-2939.1991] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An altered β-tubulin gene that confers resistance to the fungicide benomyl was isolated from a genomic library of a UV-induced mutant of
Cercospora kikuchii
and used as a selectable marker for transformation. The level of benomyl resistance conferred to the transformants was at least 150-fold greater than the intrinsic resistance of the
C. kikuchii
recipient protoplasts. In the majority of cases, the tubulin fragment was integrated at the native β-tubulin locus, apparently by gene replacement or gene conversion. The frequency of transformation ranged from 0.2 to 6 transformants per μg of DNA, depending on the recipient strain. Transformation with linearized plasmid resulted in a higher frequency, without changing the type of integration event. Transformants were phenotypically stable after eight consecutive transfers on medium without benomyl. This is the first report of a genetic transformation system for a
Cercospora
species.
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Affiliation(s)
- R G Upchurch
- Agricultural Research Service, U.S. Department of Agriculture, and Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695-7616
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27
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New nucleotide sequence data on the EMBL File Server. Nucleic Acids Res 1991; 19:1967-70. [PMID: 2030988 PMCID: PMC328160 DOI: 10.1093/nar/19.8.1967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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