Efficient four fragment cloning for the construction of vectors for targeted gene replacement in filamentous fungi
TL;DR: The new vectors designed for USER Friendly cloning provided a fast reliable method to construct vectors for targeted gene manipulations in fungi.
Abstract: The rapid increase in whole genome fungal sequence information allows large scale functional analyses of target genes. Efficient transformation methods to obtain site-directed gene replacement, targeted over-expression by promoter replacement, in-frame epitope tagging or fusion of coding sequences with fluorescent markers such as GFP are essential for this process. Construction of vectors for these experiments depends on the directional cloning of two homologous recombination sequences on each side of a selection marker gene. Here, we present a USER Friendly cloning based technique that allows single step cloning of the two required homologous recombination sequences into different sites of a recipient vector. The advantages are: A simple experimental design, free choice of target sequence, few procedures and user convenience. The vectors are intented for Agrobacterium tumefaciens and protoplast based transformation technologies. The system has been tested by the construction of vectors for targeted replacement of 17 genes and overexpression of 12 genes in Fusarium graminearum. The results show that four fragment vectors can be constructed in a single cloning step with an average efficiency of 84% for gene replacement and 80% for targeted overexpression. The new vectors designed for USER Friendly cloning provided a fast reliable method to construct vectors for targeted gene manipulations in fungi.
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TL;DR: Results suggest that FvTox1 is a major virulence factor involved in foliar SDS development in soybean and it is expected that interference of the function of this toxin in transgenic soybean plants will lead to generation of SDS-resistant soybean cultivars.
Abstract: The soil borne fungus, Fusarium virguliforme, causes sudden death syndrome (SDS) in soybean, which is a serious foliar and root rot disease. The pathogen has never been isolated from the diseased foliar tissues; phytotoxins produced by the pathogen are believed to cause foliar SDS symptoms. One of these toxins, a 13.5-kDa acidic protein named FvTox1, has been hypothesized to interfere with photosynthesis in infected soybean plants and cause foliar SDS. The objective of this study is to determine if FvTox1 is involved in foliar SDS development. We created and studied five independent knockout fvtox1 mutants to study the function of FvTox1. We conducted Agrobacterium tumefaciens-mediated transformation to accomplish homologous recombination of FvTox1 with a hygromycin B resistance gene, hph, to generate the fvtox1 mutants. Approximately 40 hygromycin-resistant transformants were obtained from 10(6) conidial spores of the F. virguliforme Mont-1 isolate when the spores were co-cultivated with the A. tumefaciens EHA105 but not with LBA4044 strain carrying a recombinant binary plasmid, in which the hph gene encoding hygromycin resistance was flanked by 5'- and 3'-end FvTox1 sequences. We observed homologous recombination-mediated integration of hph into the FvTox1 locus among five independent fvtox1 mutants. In stem-cutting assays using cut soybean seedlings fed with cell-free F. virguliforme culture filtrates, the knockout fvtox1 mutants caused chlorophyll losses and foliar SDS symptoms, which were over twofold less than those caused by the virulent F. virguliforme Mont-1 isolate. Similarly, in root inoculation assays, more than a twofold reduction in foliar SDS development and chlorophyll losses was observed among the seedlings infected with the fvtox1 mutants as compared to the seedlings infected with the wild-type Mont-1 isolate. These results suggest that FvTox1 is a major virulence factor involved in foliar SDS development in soybean. It is expected that interference of the function of this toxin in transgenic soybean plants will lead to generation of SDS-resistant soybean cultivars.
59 citations
Cites background or methods from "Efficient four fragment cloning for..."
...The ATMT of F. virguliforme was based on a published protocol (Frandsen et al. 2008)....
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...ATMT has been widely applied in transforming Fusarium spp. (Frandsen 2011; Malz et al. 2005; Frandsen et al. 2008; Mullins et al. 2001)....
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...virguliforme was based on a published protocol (Frandsen et al. 2008)....
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...on defined Fusarium medium (DFM) (Frandsen et al. 2008) supplemented with 150 lg/ml of hygromycin B (Sigma, St....
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...In the present study, we successfully applied such a system (Frandsen et al. 2008) for creating knockout fvtox1 mutants....
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TL;DR: The technological challenges and successes in regard to heterologous host selection and DNA assembly behind the reconstruction of microbial secondary metabolite biosynthesis in Aspergillus spp.
57 citations
TL;DR: AreA appears to regulate production of some mycotoxins directly or indirectly independent on nitrogen status and plays a role in utilization of certain amino acids.
57 citations
TL;DR: These liquor starters are reported as a new functionally microbial resource, which can be used for discovering thermophilic and aerobic enzymes and for food and feed preservation.
Abstract: Traditional Chinese liquor (Baijiu) solid state fermentation technology has lasted for several thousand years. The microbial communities that enrich in liquor starter are important for fermentation. However, the microbial communities are still under-characterized. In this study, 454 pyrosequencing technology was applied to comprehensively analyze the microbial diversity, function and dynamics of two most-consumed liquor starters (Jiang- and Nong-flavor) during production. In total, 315 and 83 bacterial genera and 72 and 47 fungal genera were identified in Jiang- and Nong-flavor liquor starter, respectively. The relatively high diversity was observed when the temperature increased to 70 and 62 °C for Jiang- and Nong-flavor liquor starter, respectively. Some thermophilic fungi have already been isolated. Microbial communities that might contribute to ethanol fermentation, saccharification and flavor development were identified and shown to be core communities in correlation-based network analysis. The predictively functional profile of bacterial communities showed significant difference in energy, carbohydrate and amino acid metabolism and the degradation of aromatic compounds between the two kinds of liquor starters. Here we report these liquor starters as a new functionally microbial resource, which can be used for discovering thermophilic and aerobic enzymes and for food and feed preservation.
56 citations
TL;DR: This work demonstrates, that T. oleaginosus ATCC 20509 can be used as versatile biotechnology platform to transform industrial waste streams into designed, high value fatty acids.
49 citations
References
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TL;DR: These procedures, which can circumvent the need for large-scale phage or plasmid growths, preparative gel-electrophoresis and the screening of molecular clones, can facilitate the rapid study of sequence-specific interactions of proteins and DNA.
Abstract: Specific, end-labeled DNA fragments can be simply and rapidly prepared using the polymerase chain reaction (PCR). Such fragments are suitable for use in DNase I protection footprint assays, chemical sequencing reactions, and for the production and analysis of paused RNA polymerase transcription complexes. Moreover, a general means of introducing a specific mutation at any position along the length of such PCR-generated fragments is described. These procedures, which can circumvent the need for large-scale phage or plasmid growths, preparative gel-electrophoresis and the screening of molecular clones, can facilitate the rapid study of sequence-specific interactions of proteins and DNA. A rapid means of removing excess oligonucleotide primers from completed PCRs is also described.
2,471 citations
"Efficient four fragment cloning for..." refers methods in this paper
...Several laboratories have solved this problem by dividing the replacement constructs into two, a technique known as bipartite gene-targeting or split-marker recombination [6- 8]. In this technique, the two HRS's are fused with two thirds of either the 3' or 5'end of the selection marker gene, by fusion-PCR [ 9 ]....
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TL;DR: Questions are addressed, including which evolutionary pressures led to gene clustering, why closely related species produce different profiles of secondary metabolites, and whether fungal genomics will accelerate the discovery of new pharmacologically active natural products.
Abstract: Much of natural product chemistry concerns a group of compounds known as secondary metabolites. These low-molecular-weight metabolites often have potent physiological activities. Digitalis, morphine and quinine are plant secondary metabolites, whereas penicillin, cephalosporin, ergotrate and the statins are equally well known fungal secondary metabolites. Although chemically diverse, all secondary metabolites are produced by a few common biosynthetic pathways, often in conjunction with morphological development. Recent advances in molecular biology, bioinformatics and comparative genomics have revealed that the genes encoding specific fungal secondary metabolites are clustered and often located near telomeres. In this review, we address some important questions, including which evolutionary pressures led to gene clustering, why closely related species produce different profiles of secondary metabolites, and whether fungal genomics will accelerate the discovery of new pharmacologically active natural products.
1,488 citations
"Efficient four fragment cloning for..." refers background in this paper
...The use of Proofreading DNA polymerase is essential when making targeted genome modifications in fungi, due to the close spacing of fungal genes [26], which often means that the HRS extends into neighbouring genes or their regulatory sequences....
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TL;DR: A new procedure has been developed for the efficient cloning of complex PCR mixtures, resulting in libraries exclusively consisting of recombinant clones, and the procedure is applied for the cloning of inter-ALU fragments from hybrid cell-lines and human cosmid clones.
Abstract: A new procedure has been developed for the efficient cloning of complex PCR mixtures, resulting in libraries exclusively consisting of recombinant clones. Recombinants are generated between PCR products and a PCR-amplified plasmid vector. The procedure does not require the use of restriction enzymes, T4 DNA ligase or alkaline phosphatase. The 5'-ends of the primers used to generate the cloneable PCR fragments contain an additional 12 nucleotide (nt) sequence lacking dCMP. As a result, the amplification products include 12-nt sequences lacking dGMP at their 3'-ends. The 3'-terminal sequence can be removed by the action of the (3'----5') exonuclease activity of T4 DNA polymerase in the presence of dGTP, leading to fragments with 5'-extending single-stranded (ss) tails of a defined sequence and length. Similarly, the entire plasmid vector is amplified with primers homologous to sequences in the multiple cloning site. The vector oligos have additional 12-nt tails complementary to the tails used for fragment amplification, permitting the creation of ss-ends with T4 DNA polymerase in the presence of dCTP. Circularization can occur between vector molecules and PCR fragments as mediated by the 12-nt cohesive ends, but not in mixtures lacking insert fragments. The resulting circular recombinant molecules do not require in vitro ligation for efficient bacterial transformation. We have applied the procedure for the cloning of inter-ALU fragments from hybrid cell-lines and human cosmid clones.
1,185 citations
"Efficient four fragment cloning for..." refers methods in this paper
...Examples are the Xi-cloning, InFusion cloning, Ligase independent cloning (LIC-PCR), Recombinational cloning and USER Friendly cloning techniques [16-20]....
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TL;DR: This study describes a method for rapidly creating knockout mutants in which it makes use of yeast recombinational cloning, Neurospora mutant strains deficient in nonhomologous end-joining DNA repair, custom-written software tools, and robotics.
Abstract: The low rate of homologous recombination exhibited by wild-type strains of filamentous fungi has hindered development of high-throughput gene knockout procedures for this group of organisms. In this study, we describe a method for rapidly creating knockout mutants in which we make use of yeast recombinational cloning, Neurospora mutant strains deficient in nonhomologous end-joining DNA repair, custom-written software tools, and robotics. To illustrate our approach, we have created strains bearing deletions of 103 Neurospora genes encoding transcription factors. Characterization of strains during growth and both asexual and sexual development revealed phenotypes for 43% of the deletion mutants, with more than half of these strains possessing multiple defects. Overall, the methodology, which achieves high-throughput gene disruption at an efficiency >90% in this filamentous fungus, promises to be applicable to other eukaryotic organisms that have a low frequency of homologous recombination.
1,074 citations
"Efficient four fragment cloning for..." refers background or methods in this paper
...crassa, Colot and coworks [1], also allows for efficient four fragment cloning....
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...Contrary to Saccharomyces cerevisiae, where 30 bp is sufficient, many filamentous fungi require longer HRS [1], eg Fusarium graminearum needs 400 bp [2] 1500 bp is reported for Aspergillus niger [3] and around 1000 bp for Neurospora crassa [4]....
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...Vector construction for targeted replacement of genes is reduced to design of two primer pairs, which will permit automation of the experimental design as required for high-throughput knockout projects [1]....
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...Recombinational cloning of the two required HRS with a selection marker gene and a vector backbone is carried out in yeast, followed by PCR amplification of the two HRS and selection marker gene [1]....
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TL;DR: It is reported that A. tumefaciens can also transfer its T-DNA efficiently to the filamentous fungus Aspergillus awamori, demonstrating DNA transfer between a prokaryote and a filamentous fungi.
Abstract: Agrobacterium tumefaciens transfers part of its Ti plasmid, the T-DNA, to plant cells during tumorigenesis. It is routinely used for the genetic modification of a wide range of plant species. We report that A. tumefaciens can also transfer its T-DNA efficiently to the filamentous fungus Aspergillus awamori, demonstrating DNA transfer between a prokaryote and a filamentous fungus. We transformed both protoplasts and conidia with frequencies that were improved up to 600-fold as compared with conventional techniques for transformation of A. awamori protoplasts. The majority of the A. awamori transformants contained a single T-DNA copy randomly integrated at a chromosomal locus. The T-DNA integrated into the A. awamori genome in a manner similar to that described for plants. We also transformed a variety of other filamentous fungi, including Aspergillus niger, Fusarium venenatum, Trichoderma reesei, Colletotrichum gloeosporioides, Neurospora crassa, and the mushroom Agaricus bisporus, demonstrating that transformation using A. tumefaciens is generally applicable to filamentous fungi.
893 citations
"Efficient four fragment cloning for..." refers background in this paper
...The Agrobacterium tumefaciens mediated transformation (ATMT) technology [10] has the advantage of being independent of protoplast formation and can be used directly on a wide variety of fungal species and tissue types [11]....
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