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Wang N, Arling M, Hoerster G, Ryan L, Wu E, Lowe K, Gordon-Kamm W, Jones TJ, Chilcoat ND, Anand A. An Efficient Gene Excision System in Maize. FRONTIERS IN PLANT SCIENCE 2020; 11:1298. [PMID: 32983193 PMCID: PMC7492568 DOI: 10.3389/fpls.2020.01298] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/11/2020] [Indexed: 05/25/2023]
Abstract
Use of the morphogenic genes Baby Boom (Bbm) and Wuschel2 (Wus2), along with new ternary constructs, has increased the genotype range and the type of explants that can be used for maize transformation. Further optimizing the expression pattern for Bbm/Wus2 has resulted in rapid maize transformation methods that are faster and applicable to a broader range of inbreds. However, expression of Bbm/Wus2 can compromise the quality of regenerated plants, leading to sterility. We reasoned excising morphogenic genes after transformation but before regeneration would increase production of fertile T0 plants. We developed a method that uses an inducible site-specific recombinase (Cre) to excise morphogenic genes. The use of developmentally regulated promoters, such as Ole, Glb1, End2, and Ltp2, to drive Cre enabled excision of morphogenic genes in early embryo development and produced excised events at a rate of 25-100%. A different strategy utilizing an excision-activated selectable marker produced excised events at a rate of 53-68%; however, the transformation frequency was lower (13-50%). The use of inducible heat shock promoters (e.g. Hsp17.7, Hsp26) to express Cre, along with improvements in tissue culture conditions and construct design, resulted in high frequencies of T0 transformation (29-69%), excision (50-97%), usable quality events (4-15%), and few escapes (non-transgenic; 14-17%) in three elite maize inbreds. Transgenic events produced by this method are free of morphogenic and marker genes.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Ajith Anand
- Crop Genome Engineering, Applied Science and Technology, Corteva Agriscience, Johnston, IA, United States
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Damaj MB, Jifon JL, Woodard SL, Vargas-Bautista C, Barros GOF, Molina J, White SG, Damaj BB, Nikolov ZL, Mandadi KK. Unprecedented enhancement of recombinant protein production in sugarcane culms using a combinatorial promoter stacking system. Sci Rep 2020; 10:13713. [PMID: 32792533 PMCID: PMC7426418 DOI: 10.1038/s41598-020-70530-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 07/21/2020] [Indexed: 11/09/2022] Open
Abstract
Plants represent a safe and cost-effective platform for producing high-value proteins with pharmaceutical properties; however, the ability to accumulate these in commercially viable quantities is challenging. Ideal crops to serve as biofactories would include low-input, fast-growing, high-biomass species such as sugarcane. The objective of this study was to develop an efficient expression system to enable large-scale production of high-value recombinant proteins in sugarcane culms. Bovine lysozyme (BvLz) is a potent broad-spectrum antimicrobial enzyme used in the food, cosmetics and agricultural industries. Here, we report a novel strategy to achieve high-level expression of recombinant proteins using a combinatorial stacked promoter system. We demonstrate this by co-expressing BvLz under the control of multiple constitutive and culm-regulated promoters on separate expression vectors and combinatorial plant transformation. BvLz accumulation reached 1.4% of total soluble protein (TSP) (10.0 mg BvLz/kg culm mass) in stacked multiple promoter:BvLz lines, compared to 0.07% of TSP (0.56 mg/kg) in single promoter:BvLz lines. BvLz accumulation was further boosted to 11.5% of TSP (82.5 mg/kg) through event stacking by re-transforming the stacked promoter:BvLz lines with additional BvLz expression vectors. The protein accumulation achieved with the combinatorial promoter stacking expression system was stable in multiple vegetative propagations, demonstrating the feasibility of using sugarcane as a biofactory for producing high-value proteins and bioproducts.
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Affiliation(s)
- Mona B Damaj
- Texas A&M AgriLife Research and Extension Center, 2415 East US Highway 83, Weslaco, TX, 78596, USA.
| | - John L Jifon
- Texas A&M AgriLife Research and Extension Center, 2415 East US Highway 83, Weslaco, TX, 78596, USA
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, 77843-2133, USA
| | - Susan L Woodard
- National Center for Therapeutics Manufacturing, Texas A&M University, 100 Discovery Drive, College Station, TX, 77843-4482, USA
| | - Carol Vargas-Bautista
- Texas A&M AgriLife Research and Extension Center, 2415 East US Highway 83, Weslaco, TX, 78596, USA
- College of Medicine, Texas A&M University, 8447 Riverside Parkway, Bryan, TX, 77807, USA
| | - Georgia O F Barros
- BioSeparation Laboratory, Biological and Agricultural Engineering Department, College Station, TX, 77843-2117, USA
| | - Joe Molina
- Texas A&M AgriLife Research and Extension Center, 2415 East US Highway 83, Weslaco, TX, 78596, USA
| | - Steven G White
- BioSeparation Laboratory, Biological and Agricultural Engineering Department, College Station, TX, 77843-2117, USA
| | - Bassam B Damaj
- Innovus Pharmaceuticals, Inc., 8845 Rehco Road, San Diego, CA, 92121, USA
| | - Zivko L Nikolov
- BioSeparation Laboratory, Biological and Agricultural Engineering Department, College Station, TX, 77843-2117, USA
| | - Kranthi K Mandadi
- Texas A&M AgriLife Research and Extension Center, 2415 East US Highway 83, Weslaco, TX, 78596, USA.
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843-2132, USA.
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Wierzbicki MP, Maloney V, Mizrachi E, Myburg AA. Xylan in the Middle: Understanding Xylan Biosynthesis and Its Metabolic Dependencies Toward Improving Wood Fiber for Industrial Processing. FRONTIERS IN PLANT SCIENCE 2019; 10:176. [PMID: 30858858 PMCID: PMC6397879 DOI: 10.3389/fpls.2019.00176] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 02/04/2019] [Indexed: 05/14/2023]
Abstract
Lignocellulosic biomass, encompassing cellulose, lignin and hemicellulose in plant secondary cell walls (SCWs), is the most abundant source of renewable materials on earth. Currently, fast-growing woody dicots such as Eucalyptus and Populus trees are major lignocellulosic (wood fiber) feedstocks for bioproducts such as pulp, paper, cellulose, textiles, bioplastics and other biomaterials. Processing wood for these products entails separating the biomass into its three main components as efficiently as possible without compromising yield. Glucuronoxylan (xylan), the main hemicellulose present in the SCWs of hardwood trees carries chemical modifications that are associated with SCW composition and ultrastructure, and affect the recalcitrance of woody biomass to industrial processing. In this review we highlight the importance of xylan properties for industrial wood fiber processing and how gaining a greater understanding of xylan biosynthesis, specifically xylan modification, could yield novel biotechnology approaches to reduce recalcitrance or introduce novel processing traits. Altering xylan modification patterns has recently become a focus of plant SCW studies due to early findings that altered modification patterns can yield beneficial biomass processing traits. Additionally, it has been noted that plants with altered xylan composition display metabolic differences linked to changes in precursor usage. We explore the possibility of using systems biology and systems genetics approaches to gain insight into the coordination of SCW formation with other interdependent biological processes. Acetyl-CoA, s-adenosylmethionine and nucleotide sugars are precursors needed for xylan modification, however, the pathways which produce metabolic pools during different stages of fiber cell wall formation still have to be identified and their co-regulation during SCW formation elucidated. The crucial dependence on precursor metabolism provides an opportunity to alter xylan modification patterns through metabolic engineering of one or more of these interdependent pathways. The complexity of xylan biosynthesis and modification is currently a stumbling point, but it may provide new avenues for woody biomass engineering that are not possible for other biopolymers.
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Affiliation(s)
| | | | | | - Alexander A. Myburg
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
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4
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Brophy JAN, LaRue T, Dinneny JR. Understanding and engineering plant form. Semin Cell Dev Biol 2017; 79:68-77. [PMID: 28864344 DOI: 10.1016/j.semcdb.2017.08.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 11/18/2022]
Abstract
A plant's form is an important determinant of its fitness and economic value. Here, we review strategies for producing plants with altered forms. Historically, the process of changing a plant's form has been slow in agriculture, requiring iterative rounds of growth and selection. We discuss modern techniques for identifying genes involved in the development of plant form and tools that will be needed to effectively design and engineer plants with altered forms. Synthetic genetic circuits are highlighted for their potential to generate novel plant forms. We emphasize understanding development as a prerequisite to engineering and discuss the potential role of computer models in translating knowledge about single genes or pathways into a more comprehensive understanding of development.
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Affiliation(s)
- Jennifer A N Brophy
- Carnegie Institution for Science, Department of Plant Biology, Stanford, CA 94305, USA
| | - Therese LaRue
- Stanford University, Department of Biology, Stanford, CA 94305, USA
| | - José R Dinneny
- Carnegie Institution for Science, Department of Plant Biology, Stanford, CA 94305, USA.
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5
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von der Heyde EL, Klein B, Abram L, Hallmann A. The inducible nitA promoter provides a powerful molecular switch for transgene expression in Volvox carteri. BMC Biotechnol 2015; 15:5. [PMID: 25888095 PMCID: PMC4339647 DOI: 10.1186/s12896-015-0122-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 02/06/2015] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The multicellular green alga Volvox carteri represents an attractive model system to study various aspects of multicellularity like cellular differentiation, morphogenesis, epithelial folding and ECM biogenesis. However, functional and molecular analyses of such processes require a wide array of molecular tools for genetic engineering. So far there are only a limited number of molecular tools available in Volvox. RESULTS Here, we show that the promoter of the V. carteri nitrate reductase gene (nitA) is a powerful molecular switch for induction of transgene expression. Strong expression is triggered by simply changing the nitrogen source from ammonium to nitrate. We also show that the luciferase (g-luc) gene from the marine copepod Gaussia princeps, which previously was engineered to match the codon usage of the unicellular alga Chlamydomonas reinhardtii, is a suitable reporter gene in V. carteri. Emitted light of the chemiluminescent reaction can be easily detected and quantified with a luminometer. Long-term stability of inducible expression of the chimeric nitA/g-luc transgenes after stable nuclear transformation was demonstrated by transcription analysis and bioluminescence assays. CONCLUSION Two novel molecular tools for genetic engineering of Volvox are now available: the nitrate-inducible nitA promoter of V. carteri and the codon-adapted luciferase reporter gene of G. princeps. These novel tools will be useful for future molecular research in V. carteri.
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Affiliation(s)
- Eva Laura von der Heyde
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Benjamin Klein
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Lars Abram
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Armin Hallmann
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
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6
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Lombardo L. Genetic use restriction technologies: a review. PLANT BIOTECHNOLOGY JOURNAL 2014; 12:995-1005. [PMID: 25185773 DOI: 10.1111/pbi.12242] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 05/23/2023]
Abstract
Genetic use restriction technologies (GURTs), developed to secure return on investments through protection of plant varieties, are among the most controversial and opposed genetic engineering biotechnologies as they are perceived as a tool to force farmers to depend on multinational corporations' seed monopolies. In this work, the currently proposed strategies are described and compared with some of the principal techniques implemented for preventing transgene flow and/or seed saving, with a simultaneous analysis of the future perspectives of GURTs taking into account potential benefits, possible impacts on farmers and local plant genetic resources (PGR), hypothetical negative environmental issues and ethical concerns related to intellectual property that have led to the ban of this technology.
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Affiliation(s)
- Luca Lombardo
- Department of Crop Systems, Forestry and Environmental Sciences, University of Basilicata, Potenza, Italy
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Dutt M, Dhekney SA, Soriano L, Kandel R, Grosser JW. Temporal and spatial control of gene expression in horticultural crops. HORTICULTURE RESEARCH 2014; 1:14047. [PMID: 26504550 PMCID: PMC4596326 DOI: 10.1038/hortres.2014.47] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 07/19/2014] [Accepted: 08/06/2014] [Indexed: 05/05/2023]
Abstract
Biotechnology provides plant breeders an additional tool to improve various traits desired by growers and consumers of horticultural crops. It also provides genetic solutions to major problems affecting horticultural crops and can be a means for rapid improvement of a cultivar. With the availability of a number of horticultural genome sequences, it has become relatively easier to utilize these resources to identify DNA sequences for both basic and applied research. Promoters play a key role in plant gene expression and the regulation of gene expression. In recent years, rapid progress has been made on the isolation and evaluation of plant-derived promoters and their use in horticultural crops, as more and more species become amenable to genetic transformation. Our understanding of the tools and techniques of horticultural plant biotechnology has now evolved from a discovery phase to an implementation phase. The availability of a large number of promoters derived from horticultural plants opens up the field for utilization of native sequences and improving crops using precision breeding. In this review, we look at the temporal and spatial control of gene expression in horticultural crops and the usage of a variety of promoters either isolated from horticultural crops or used in horticultural crop improvement.
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Affiliation(s)
- Manjul Dutt
- Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
| | - Sadanand A Dhekney
- Department of Plant Sciences, Sheridan Research and Extension Center, University of Wyoming, Sheridan, WY 82801, USA
| | - Leonardo Soriano
- Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
- Universidade de Sao Paulo, Centro de Energia Nuclear na Agricultura, Piracicaba, Brazil
| | - Raju Kandel
- Department of Plant Sciences, Sheridan Research and Extension Center, University of Wyoming, Sheridan, WY 82801, USA
| | - Jude W Grosser
- Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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8
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Tavva VS, Dinkins RD, Palli SR, Collins GB. Development of a tightly regulated and highly inducible ecdysone receptor gene switch for plants through the use of retinoid X receptor chimeras. Transgenic Res 2007; 16:599-612. [PMID: 17139530 DOI: 10.1007/s11248-006-9054-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
Chemical inducible gene regulation systems provide essential tools for the precise regulation of transgene expression in plants and animals. Recent development of a two-hybrid ecdysone receptor (EcR) gene regulation system has solved some of the drawbacks that were associated with the monopartate gene switch. To further improve the versatility of the two-hybrid EcR gene switch for wide spread use in plants, chimeras between Homo sapiens retinoid X receptor (HsRXR) and insect, Locusta migratoria RXR (LmRXR) were tested in tobacco protoplasts as partners with Choristoneura fumiferana EcR (CfEcR) in inducing expression of the luciferase reporter gene. The RXR chimera 9 (CH9) along with CfEcR, in a two-hybrid format gave the best results in terms of low-background expression levels in the absence of ligand and high-induced expression levels of the reporter gene in the presence of nanomolar concentrations of the methoxyfenozide ligand. The performance of CH9 was further tested in corn and soybean protoplasts and the data obtained was compared with the other EcR switches that contained the wild-type LmRXR or HsRXR as EcR partners. In both transient expression studies and stable transformation experiments, the fold induction values obtained with the CH9 switch were several times higher than the values obtained with the other EcR switches containing LmRXR or HsRXR. The new CfEcR two-hybrid gene switch that uses the RXR CH9 as a partner in inducing reporter gene expression provides an efficient, ligand-sensitive and tightly regulated gene switch for plants.
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Affiliation(s)
- Venkata S Tavva
- Plant and Soil Sciences Department, University of Kentucky, 1405 Veterans Road, Lexington, KY 40546-0312, USA.
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9
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Tavva VS, Palli SR, Dinkins RD, Collins GB. Applications of EcR gene switch technology in functional genomics. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2007; 65:164-79. [PMID: 17570490 DOI: 10.1002/arch.20193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Genetic engineering of plants using transgenic technology is targeted to enhance agronomic performance or improved quality traits in a wide variety of plant species, and has become a fundamental tool for basic research in plant biotechnology. Constitutive promoters are presently the primary means used to express transgenes in plants. However, inducible gene regulation systems based on specific chemicals have many potential applications in agriculture and for enhancing the basic understanding of gene function. As a result, several gene switches have been developed. The ecdysone receptor gene switch is one of the best inducible gene regulation systems available, because the chemical, methoxyfenozide, required for its regulation is registered for field use. An EcR gene switch with a potential for use in large-scale field applications has been developed by adopting a two-hybrid format. In a two-hybrid switch format, the GAL4 DNA binding domain (GAL4 DBD) was fused to the ligand binding domain (LBD) of the Choristoneura fumiferana ecdysone receptor (CfEcR); and, the VP16 activation domain (VP16 AD) was fused to the LBD of Locust migratoria retinoid X receptor (LmRXR). The sensitivity of the CfEcR gene switch was improved from micromolar to nanomolar concentrations of ligand by using the CfEcR:LmRXR two-hybrid switch. In this report, we demonstrate the utility of CfEcR:LmRXR two-hybrid gene switch in functional genomics applications for regulating the expression of a Superman-like single zinc finger protein 11 (ZFP11) gene in both Arabidopsis and tobacco transgenic plants.
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Affiliation(s)
- Venkata S Tavva
- Department of Entomology, University of Kentucky, Lexington, KY 40546-0091, USA
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10
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Shindo T, Takahashi T, Nihira T, Yamada Y, Kato K, Shinmyo A. Streptomyces-derived induction system for gene expression in cultured plant cells. J Biosci Bioeng 2006; 102:552-9. [PMID: 17270721 DOI: 10.1263/jbb.102.552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Accepted: 09/21/2006] [Indexed: 11/17/2022]
Abstract
We have constructed an induction system for plant gene expression using an operator/repressor gene pair of Streptomyces virginiae. In this system, the repressor protein BarA dissociates from the operator sequence BARE in the presence of an inducer virginiae butanolide (VB), resulting in the induction of the transcription of the operator's downstream genes required for virginiamycin biosynthesis [Kinoshita et al., J. Bacteriol., 179, 6986-6993 ((1997))]. Two vectors were constructed: one was an effector plasmid, in which BarA was driven by plant promoters, and the other was a reporter plasmid, in which the BARE sequence was incorporated into the cauliflower mosaic virus 35S promoter to express the Escherichia coli beta-glucuronidase gene (GUS). An electroporation-mediated gene expression assay with cultured tobacco cells showed that GUS expression from the reporter plasmid was repressed upon coexpression with the effector plasmid and that the repression was relieved by VB. The result of electroporation to insert the reporter plasmid with various numbers and positions of BAREs into tobacco cells that had been transformed with the effector plasmid showed that the GUS induction by derepression increases with the number of BAREs and with BAREs downstream rather than upstream of the TATA box. Double transformants with the effector and reporter plasmids showed 30-fold induction with VB. The induction appeared within 8 h after VB addition, maximum induction being observed with 1 microM VB.
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Affiliation(s)
- Takuya Shindo
- Life Science Research Laboratories, Life Science RD Center, Kaneka Corporation, 1-8 Miyamae-machi, Takasago-cho, Takasago, Hyogo 676-8688, Japan
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Samalova M, Brzobohaty B, Moore I. pOp6/LhGR: a stringently regulated and highly responsive dexamethasone-inducible gene expression system for tobacco. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 41:919-35. [PMID: 15743454 DOI: 10.1111/j.1365-313x.2005.02341.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We describe pOp/LhGR, a dexamethasone-inducible derivative of the pOp/LhG4 transcription activation system, and its use in tobacco to regulate expression of uidA (encoding beta-glucuronidase; GUS) and the cytokinin-biosnythetic gene ipt. The pOp/LhGR system exhibited stringent regulation and strong induced phenotypes in soil and tissue culture. In conjunction with an improved target promoter, pOp6, that carries six copies of an optimized lac operator sequence the pOp6/LhGR system directed induced GUS activities that exceeded those obtained with pOp/LhG4 or the CaMV 35S promoter but without increased uninduced activity. A single dose of dexamethasone was sufficient to direct cytotoxic levels of ipt expression in soil-grown plants although uninduced plants grew normally throughout a complete life cycle. In vitro, induced transcripts were detectable within an hour of dexamethasone application and 1 nM dexamethasone was sufficient for half maximal induction of GUS activity. Various methods of dexamethasone application were successfully applied under tissue culture and greenhouse conditions. We observed no inhibitory effects of dexamethasone or LhGR on plant development even with the highest concentrations of inducer, although tobacco seedlings were adversely affected by ethanol used as a solvent for dexamethasone stock solutions. The pOp/LhGR system provides a highly sensitive, efficient, and tightly regulated chemically inducible transgene expression system for tobacco plants.
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Affiliation(s)
- Marketa Samalova
- Department of Plant Sciences, University of Oxford, South Parks Rd, Oxford OX1 3RB, UK
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12
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Abstract
Chemically inducible systems that activate or inactivate gene expression have many potential applications in the determination of gene function and in plant biotechnology. The precise timing and control of gene expression are important aspects of chemically inducible systems. Several systems have been developed and used to analyze gene function, marker-free plant transformation, site-specific DNA excision, activation tagging, conditional genetic complementation, and restoration of male fertility. Chemicals that are used to regulate transgene expression include the antibiotic tetracycline, the steroids dexamethasone and estradiol, copper, ethanol, the inducer of pathogen-related proteins benzothiadiazol, herbicide safeners, and the insecticide methoxyfenozide. Systems that are suitable for field application are particularly useful for experimental systems and have potential applications in biotechnology.
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Affiliation(s)
- Malla Padidam
- RHeoGene/Rohm and Haas, PO Box 949, Spring House, Pennsylvania 19477-0949, USA
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13
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Shimizu-Sato S, Huq E, Tepperman JM, Quail PH. A light-switchable gene promoter system. Nat Biotechnol 2002; 20:1041-4. [PMID: 12219076 DOI: 10.1038/nbt734] [Citation(s) in RCA: 432] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2002] [Accepted: 05/07/2002] [Indexed: 11/09/2022]
Abstract
Regulatable transgene systems providing easily controlled, conditional induction or repression of expression are indispensable tools in biomedical and agricultural research and biotechnology. Several such systems have been developed for eukaryotes. Most of these rely on the administration of either exogenous chemicals or heat shock. Despite the general success of many of these systems, the potential for problems, such as toxic, unintended, or pleiotropic effects of the inducing chemical or treatment, can impose limitations on their use. We have developed a promoter system that can be induced, rapidly and reversibly, by short pulses of light. This system is based on the known red light-induced binding of the plant photoreceptor phytochrome to the protein PIF3 and the reversal of this binding by far-red light. We show here that yeast cells expressing two chimeric proteins, a phytochrome-GAL4-DNA-binding-domain fusion and a PIF3-GAL4-activation-domain fusion, are induced by red light to express selectable or "scorable" marker genes containing promoters with a GAL4 DNA-binding site, and that this induction is rapidly abrogated by subsequent far-red light. We further show that the extent of induction can be controlled precisely by titration of the number of photons delivered to the cells by the light pulse. Thus, this system has the potential to provide rapid, noninvasive, switchable control of the expression of a desired gene to a preselected level in any suitable cell by simple exposure to a light signal.
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Affiliation(s)
- Sae Shimizu-Sato
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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14
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Schaefer DG. A new moss genetics: targeted mutagenesis in Physcomitrella patens. ANNUAL REVIEW OF PLANT BIOLOGY 2002; 53:477-501. [PMID: 12221986 DOI: 10.1146/annurev.arplant.53.100301.135202] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The potential of moss as a model system to study plant biology is associated with their relatively simple developmental pattern that nevertheless resembles the basic organization of the body plan of land plants, the direct access to cell-lineage analysis, their similar responses to plant growth factors and environmental stimuli as those observed in other land plants, and the dominance of the gametophyte in the life cycle that facilitates genetic approaches. Transformation studies in the moss Physcomitrella patens have revealed a totally unique feature for plants, i.e., that foreign DNA sequences integrate in the genome preferentially at targeted locations by homologous recombination, enabling for the first time in plants the application of the powerful molecular genetic approaches used routinely in bacteria, yeast, and since 1989, the mouse embryonic stem cells. This article reviews our current knowledge of Physcomitrella patens transformation and its unique suitability for functional genomic studies.
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Affiliation(s)
- Didier G Schaefer
- Institut d'Ecologie, Laboratoire de Phytogénétique Cellulaire, Bâtiment de Biologie, Université de Lausanne, CH-1015 Lausanne, Switzerland.
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15
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Baroux C, Blanvillain R, Moore IR, Gallois P. Transactivation of BARNASE under the AtLTP1 promoter affects the basal pole of the embryo and shoot development of the adult plant in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2001; 28:503-515. [PMID: 11849591 DOI: 10.1046/j.1365-313x.2001.01174.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Genetically controlled expression of a toxin provides a tool to remove a specific structure and consequently study its role during a developmental process. The availability of many tissue-specific promoters is a good argument for the development of such a strategy in plants. We have developed a conditional system for targeted toxin expression and demonstrated its use for generating embryo phenotypes that can bring valuable information about signalling during embryogenesis. The BARNASE gene was expressed in the Arabidopsis embryo under the control of two promoters, one from the cyclin AtCYCB1 gene and one from the AtLTP1 gene (Lipid Transfer Protein 1). One-hundred percent seed abortion was obtained with the cyclin promoter. Surprisingly however, the embryos displayed a range of lethal phenotypes instead of a single arrested stage as expected from this promoter. We also show that BARNASE expression under the control of the AtLTP1 promoter affects the basal pole of the globular embryo. Together with reporter expression studies, this result suggests a role of the epidermis in controlling the development of the lower tier of the embryo. This defect was not embryo-lethal and we show that the seedlings displayed a severe shoot phenotype correlated to epidermal defects. Therefore, the epidermis does not play an active role during organogenesis in seedlings but is important for the postgermination development of a viable plant.
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Affiliation(s)
- C Baroux
- Laboratoire Génome et Développement des Plantes, CNRS-UMR 5096, 52 avenue de Villeneuve, 66 000 Perpignan, France
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De Veylder L, Beeckman T, Van Montagu M, Inzé D. Increased leakiness of the tetracycline-inducible Triple-Op promoter in dividing cells renders it unsuitable for high inducible levels of a dominant negative CDC2aAt gene. JOURNAL OF EXPERIMENTAL BOTANY 2000; 51:1647-1653. [PMID: 11053453 DOI: 10.1093/jexbot/51.351.1647] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A tetracycline-inducible promoter system was used to generate transgenic tobacco plants that confer inducible expression of the wild type or a dominant negative allele of the gene coding for the cyclin-dependent kinase (CDK) of Arabidopsis thaliana CDC2aAt. Although the total extractable CDK activity was doubled, the induced expression of the wild-type CDC2aAt did not correlate with any change of the cell cycle kinetics. An increase of CDK activity upon CDC2aAt expression was only seen in dividing cell populations, demonstrating that CDC2aAt expression itself is not sufficient to induce CDK activation. Induced expression of the dominant negative CDC2aAt.N146 correlated with a reduction of CDK activity to 66% of the level found in non-induced cells. This decrease was not sufficient to block cell division. The isolation of plants showing only low inducible levels of CDC2aAt.N146 suggests that a counterselection against strong inducible lines had occurred. Accordingly, Triple-Op promoter activity was found in dividing cells in the absence of tetracycline.
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Affiliation(s)
- L De Veylder
- Departments of Molecular and Plant Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
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Affiliation(s)
- J Hammond
- United States Department of Agriculture, United States National Arboretum, Beltsville, MD 20705-2350, USA
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Guyer D, Tuttle A, Rouse S, Volrath S, Johnson M, Potter S, Görlach J, Goff S, Crossland L, Ward E. Activation of latent transgenes in Arabidopsis using a hybrid transcription factor. Genetics 1998; 149:633-9. [PMID: 9611179 PMCID: PMC1460168 DOI: 10.1093/genetics/149.2.633] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A hybrid transcription factor comprising a fusion of the DNA-binding domain of Saccharomyces cerevisiae GAL4 and the transcription activation domain of maize C1 was expressed in stably transformed Arabidopsis. Additional transgenic lines were created containing test genes controlled by a synthetic promoter consisting of concatemeric copies of the cis-acting site recognized by GAL4 (UASG) fused to a minimal promoter. The GAL4/C1 effector line was crossed to two lines containing a synthetic promoter/GUS fusion. Both histochemical staining and GUS activity assays indicate strong activation of GUS expression was achieved only after crossing. The GAL4/C1 effector line was also crossed to 15 lines containing a synthetic promoter/antisense adenylosuccinate synthetase gene. Severely retarded growth, and in some cases lethality, was observed in 40% of the F1 lines. This system of activation by crossing is generally useful for activating expression of test transgenes.
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Affiliation(s)
- D Guyer
- Novartis Agricultural Biotechnology Research, Research Triangle Park, North Carolina 27709, USA
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21
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Caddick MX, Greenland AJ, Jepson I, Krause KP, Qu N, Riddell KV, Salter MG, Schuch W, Sonnewald U, Tomsett AB. An ethanol inducible gene switch for plants used to manipulate carbon metabolism. Nat Biotechnol 1998; 16:177-80. [PMID: 9487526 DOI: 10.1038/nbt0298-177] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Many transgenic plant studies use constitutive promoters to express transgenes. For certain genes, deleterious effects arise from constant expression in all tissues throughout development. We describe a chemically inducible plant gene expression system, with negligible background activity, that obviates this problem. We demonstrate its potential by showing inducible manipulation of carbon metabolism in transgenic plants. Upon rapid induction of yeast cytosolic invertase, a marked phenotype appears in developing leaves that is absent from leaves that developed before induction or after it has ceased.
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Affiliation(s)
- M X Caddick
- School of Biological Sciences, University of Liverpool, Donnan Laboratories, UK
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Moore I, Gälweiler L, Grosskopf D, Schell J, Palme K. A transcription activation system for regulated gene expression in transgenic plants. Proc Natl Acad Sci U S A 1998; 95:376-81. [PMID: 9419383 PMCID: PMC18229 DOI: 10.1073/pnas.95.1.376] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A widely applicable promoter system is described that allows a gene of interest to be activated in specific plant tissues after a cross between defined transgenic lines. The promoter, pOp, consists of lac operators cloned upstream of a minimal promoter. No expression was detected from this promoter when placed upstream of a beta-glucuronidase (GUS) reporter gene in transgenic plants. Transcription from the promoter was activated by crossing reporter plants with activator lines that expressed a chimeric transcription factor, LhG4. This factor comprised transcription-activation domain-II from Gal4 of Saccharomyces cerevisiae fused to a mutant lac-repressor that binds its operator with increased affinity. When LhG4 was expressed from the CaMV 35S promoter, the spatial and quantitative expression characteristics of the 35S promoter were exhibited by the GUS reporter. The LhG4/pOp system may be used to study toxic or deleterious gene products, to coordinate the expression of multiple gene products, to restrict transgene phenotypes to the F1 generation, and to generate hybrid seed. The LhG4 system offers spatially regulated gene expression in the tissues of whole plants growing under normal conditions without the need for external intervention. It complements inducible expression systems that offer temporal control of gene expression in tissues that can be treated with inducing chemicals.
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Affiliation(s)
- I Moore
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, United Kingdom.
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