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Sahab S, Taylor N. Studies on Pure Mlb ® (Multiple Left Border) Technology and Its Impact on Vector Backbone Integration in Transgenic Cassava. FRONTIERS IN PLANT SCIENCE 2022; 13:816323. [PMID: 35185986 PMCID: PMC8855067 DOI: 10.3389/fpls.2022.816323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Imperfect T-DNA processing is common during Agrobacterium-mediated transformation, which integrates vector backbone sequences into the plant genome. However, regulatory restrictions prevent such transgenic plants from being developed for commercial deployment. The binary vector pCAMBIA2300 was modified by incorporating multiple left border (Mlb®) repeats and was tested in BY2 cells, tobacco, and cassava plants to address this issue. PCR analyses confirmed a twofold increase in the vector backbone free events in the presence of triple left borders in all three systems tested. Vector backbone read-through past the LB was reduced significantly; however, the inclusion of Mlbs® did not effectively address the beyond right border read-through. Also, Mlbs® increased the frequency of single-copy and vector backbone free events (clean events) twice compared to a single LB construct. Here, we briefly narrate the strength and limitations of using Mlb® technology and reporter genes in reducing the vector backbone transfer in transgenic events.
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Affiliation(s)
- Sareena Sahab
- Agriculture Victoria Research, AgriBio, Centre for AgriBioscience, Bundoora, VIC, Australia
- Donald Danforth Plant Science Center, St. Louis, MO, United States
| | - Nigel Taylor
- Donald Danforth Plant Science Center, St. Louis, MO, United States
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2
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Lim WL, Collins HM, Singh RR, Kibble NAJ, Yap K, Taylor J, Fincher GB, Burton RA. Method for hull-less barley transformation and manipulation of grain mixed-linkage beta-glucan. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2018; 60:382-396. [PMID: 29247595 DOI: 10.1111/jipb.12625] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 12/13/2017] [Indexed: 05/18/2023]
Abstract
Hull-less barley is increasingly offering scope for breeding grains with improved characteristics for human nutrition; however, recalcitrance of hull-less cultivars to transformation has limited the use of these varieties. To overcome this limitation, we sought to develop an effective transformation system for hull-less barley using the cultivar Torrens. Torrens yielded a transformation efficiency of 1.8%, using a modified Agrobacterium transformation method. This method was used to over-express genes encoding synthases for the important dietary fiber component, (1,3;1,4)-β-glucan (mixed-linkage glucan), primarily present in starchy endosperm cell walls. Over-expression of the HvCslF6 gene, driven by an endosperm-specific promoter, produced lines where mixed-linkage glucan content increased on average by 45%, peaking at 70% in some lines, with smaller increases in transgenic HvCslH1 grain. Transgenic HvCslF6 lines displayed alterations where grain had a darker color, were more easily crushed than wild type and were smaller. This was associated with an enlarged cavity in the central endosperm and changes in cell morphology, including aleurone and sub-aleurone cells. This work provides proof-of-concept evidence that mixed-linkage glucan content in hull-less barley grain can be increased by over-expression of the HvCslF6 gene, but also indicates that hull-less cultivars may be more sensitive to attempts to modify cell wall composition.
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Affiliation(s)
- Wai Li Lim
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Helen M Collins
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Rohan R Singh
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Natalie A J Kibble
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Kuok Yap
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Jillian Taylor
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Geoffrey B Fincher
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Rachel A Burton
- ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
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An Insight into T-DNA Integration Events in Medicago sativa. Int J Mol Sci 2017; 18:ijms18091951. [PMID: 28895894 PMCID: PMC5618600 DOI: 10.3390/ijms18091951] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/24/2017] [Accepted: 09/06/2017] [Indexed: 11/16/2022] Open
Abstract
The molecular mechanisms of transferred DNA (T-DNA) integration into the plant genome are still not completely understood. A large number of integration events have been analyzed in different species, shedding light on the molecular mechanisms involved, and on the frequent transfer of vector sequences outside the T-DNA borders, the so-called vector backbone (VB) sequences. In this work, we characterized 46 transgenic alfalfa (Medicago sativa L.) plants (events), generated in previous works, for the presence of VB tracts, and sequenced several T-DNA/genomic DNA (gDNA) junctions. We observed that about 29% of the transgenic events contained VB sequences, within the range reported in other species. Sequence analysis of the T-DNA/gDNA junctions evidenced larger deletions at LBs compared to RBs and insertions probably originated by different integration mechanisms. Overall, our findings in alfalfa are consistent with those in other plant species. This work extends the knowledge on the molecular events of T-DNA integration and can help to design better transformation protocols for alfalfa.
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Kalbande BB, Patil AS. Plant tissue culture independent Agrobacterium tumefaciens mediated In-planta transformation strategy for upland cotton ( Gossypium hirsutum). J Genet Eng Biotechnol 2016; 14:9-18. [PMID: 30647592 PMCID: PMC6299899 DOI: 10.1016/j.jgeb.2016.05.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 04/21/2016] [Accepted: 05/01/2016] [Indexed: 11/17/2022]
Abstract
A new method of transgenic development called "In-planta" transformation method, where Agrobacterium is used to infect the plantlets but the steps of in vitro regeneration of plants is totally avoided. In this study, we have reported a simple In-planta method for efficient transformation of diploid cotton Gossypium hirsutum cv LRK-516 Anjali using Agrobacterium tumefaciens EHA-105 harbouring recombinant binary vector plasmid pBinAR with Arabidopsis At-NPR1 gene. Four day old plantlets were used for transformation. A vertical cut was made at the junction of cotyledonary leaves, moderately bisecting the shoot tip and exposing meristem cells at apical meristem. This site was infected with Agrobacterium inoculum. The transgenic events obtained were tested positive for the presence of At-NPR1 gene with promoter nptII gene. They are also tested negative for vector backbone integration and Agrobacterium contamination in T0 events. With this method a transformation frequency of 6.89% was reported for the cv LRK-516.
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Sikdar MSI, Bowra S, Schmidt D, Dionisio G, Holm PB, Vincze E. Targeted modification of storage protein content resulting in improved amino acid composition of barley grain. Transgenic Res 2015; 25:19-31. [PMID: 26507269 DOI: 10.1007/s11248-015-9911-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/04/2015] [Indexed: 01/24/2023]
Abstract
C-hordein in barley and ω-gliadins in wheat are members of the prolamins protein families. Prolamins are the major component of cereal storage proteins and composed of non-essential amino acids (AA) such as proline and glutamine therefore have low nutritional value. Using double stranded RNAi silencing technology directed towards C-hordein we obtained transgenic barley lines with up to 94.7% reduction in the levels of C-hordein protein relative to the parental line. The composition of the prolamin fraction of the barley parental line cv. Golden Promise was resolved using SDS-PAGE electrophoresis, the protein band were excised and the proteins identified by quadrupole-time-of-flight mass spectrometry. Subsequent SDS-PAGE separation and analysis of the prolamin fraction of the transgenic lines revealed a reduction in the amounts of C-hordeins and increases in the content of other hordein family members. Analysis of the AA composition of the transgenic lines showed that the level of essential amino acids increased with a concomitant reduction in proline and glutamine. Both the barley C-hordein and wheat ω-gliadin genes proved successful for RNAi-gene mediated suppression of barley C-hordein level. All transgenic lines that exhibited a reduction for C-hordein showed off-target effects: the lines exhibited increased level of B/γ-hordein while D-hordein level was reduced. Furthermore, the multicopy insertions correlated negatively with silencing.
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Affiliation(s)
- Md S I Sikdar
- Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark.,Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dinajpur, 5200, Bangladesh
| | - S Bowra
- Verzyme (UK) Ltd., Plas Gogerddan, Aberystwyth, Wales, SY23 3EB, UK
| | - D Schmidt
- Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark.,Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, CEP 13418-900, Brazil
| | - G Dionisio
- Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark
| | - P B Holm
- Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark
| | - E Vincze
- Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark.
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Dedicova B, Bermudez C, Prias M, Zuniga E, Brondani C. High-throughput transformation pipeline for a Brazilian japonica rice with bar gene selection. PROTOPLASMA 2015; 252:1071-83. [PMID: 25488347 PMCID: PMC4491359 DOI: 10.1007/s00709-014-0741-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 11/27/2014] [Indexed: 06/04/2023]
Abstract
The goal of this work was to establish a transformation pipeline for upland Curinga rice (Oryza sativa L. ssp. japonica) with bar gene selection employing bialaphos and phosphinothricin as selection agents. The following genes of interest: AtNCED3, Lsi1, GLU2, LEW2, PLD-alpha, DA1, TOR, AVP1, and Rubisco were cloned into the binary vector p7i2x-Ubi and were transferred into Agrobacterium strain EHA 105. Embryogenic calli derived from the mature embryos were transformed, and transgenic cells and shoots were selected on the medium supplemented with bialaphos or phosphinothricin (PPT) using a stepwise selection scheme. Molecular analyses were established using polymerase chain reaction and Southern blot for the bar gene and the NOS terminator. Overall, 273 putative transgenic plants were analyzed by Southern blot with 134 events identified. In total, 77 events had a single copy of the transgene integrated in the plant genome while 29 events had two copies. We tested backbone integration in 101 transgenic plants from all constructs and found 60 transgenic plants having no additional sequence integrated in the plant genome. The bar gene activity was evaluated by the chlorophenol red test and the leaf painting test using phosphinothricin with several transgenic plants. The majority of T0 plants carrying the single copy of transgene produced T1 seeds in the screen house.
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Affiliation(s)
- B Dedicova
- International Center for Tropical Agriculture A.A. 6713, Cali, Colombia,
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Marthe C, Kumlehn J, Hensel G. Barley (Hordeum vulgare L.) transformation using immature embryos. Methods Mol Biol 2015; 1223:71-83. [PMID: 25300832 DOI: 10.1007/978-1-4939-1695-5_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Barley is a major crop species, and also has become a genetic model for the small grain temperate cereals. A draft barley genome sequence has recently been completed, opening many opportunities for candidate gene isolation and functionality testing. Thanks to the development of customizable endonucleases, also site-directed genome modification recently became feasible for higher plants, which marks the beginning of a new era of genetic engineering. The development of improved binary vectors and hypervirulent Agrobacterium tumefaciens strains has raised the efficiency of genetic transformation in barley to a level where the technique has become relatively routine. The transformation method described here involves immature barley embryos cocultivated with Agrobacterium after removal of their embryo axis. Critical adjustments to the protocol have included the supplementation of the cocultivation medium with the polyphenolic signaling compound acetosyringone at comparatively high concentration and the use of cysteine to reduce the extent of cellular oxidation upon agroinfection. In addition, the use of liquid, rather than solid, cocultivation medium promotes the throughput of the method. The protocol has delivered well over 10,000 transgenic barley plants over the past 10 years. Routine transformation efficiency, calculated on the basis of the recovery of independent transgenics per 100 explants, has reached about 25 % in cultivar (cv.) "Golden Promise". The protocol has proven effective for more than 20 barley cultivars, although some adjustments to the culture conditions have had to be made in some cases. The transformation efficiency of cv. "Golden Promise" remains higher than that of any other cultivar tested.
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Affiliation(s)
- Cornelia Marthe
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Stadt Seeland, OT Gatersleben, Germany
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8
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Abstract
Agrobacterium-mediated transformation is a suitable method to transform different cultivars using different systems of A. tumefaciens strains and binary vectors as well as selection cassettes. We describe here a detailed protocol for two cultivars, one naked and one husked, using the AGL1 strain and the pGreen vector containing the nptII selection cassette ( http://www.pgreen.ac.uk/ ), suitable for oat as well as other cereals. The pGreen vector system was recently developed for pBract ( http://www.bract.org/ ) and its transformation ability for cereals was proved. Assuming our experience and the latest knowledge on Agrobacterium-mediated transformation of cereals, we suggest using in the protocol one of the newly developed pBract or pCAMBIA ( http://www.cambia.org/daisy/cambia/ ) vector systems which carry different selection cassettes. The commonly used selection genes nptII, bar, and hpt were proved to be applicable for oat transformation and might be used as needed.
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Affiliation(s)
- Sebastian Gasparis
- Department of Functional Genomics, Plant Breeding and Acclimatization Institute, National Research Institute, Radzikow, 05-870, Błonie, Poland
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9
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Dubouzet JG, Strabala TJ, Wagner A. Potential transgenic routes to increase tree biomass. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 212:72-101. [PMID: 24094056 DOI: 10.1016/j.plantsci.2013.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 05/05/2023]
Abstract
Biomass is a prime target for genetic engineering in forestry because increased biomass yield will benefit most downstream applications such as timber, fiber, pulp, paper, and bioenergy production. Transgenesis can increase biomass by improving resource acquisition and product utilization and by enhancing competitive ability for solar energy, water, and mineral nutrients. Transgenes that affect juvenility, winter dormancy, and flowering have been shown to influence biomass as well. Transgenic approaches have increased yield potential by mitigating the adverse effects of prevailing stress factors in the environment. Simultaneous introduction of multiple genes for resistance to various stress factors into trees may help forest trees cope with multiple or changing environments. We propose multi-trait engineering for tree crops, simultaneously deploying multiple independent genes to address a set of genetically uncorrelated traits that are important for crop improvement. This strategy increases the probability of unpredictable (synergistic or detrimental) interactions that may substantially affect the overall phenotype and its long-term performance. The very limited ability to predict the physiological processes that may be impacted by such a strategy requires vigilance and care during implementation. Hence, we recommend close monitoring of the resultant transgenic genotypes in multi-year, multi-location field trials.
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Magnusdottir A, Vidarsson H, Björnsson JM, Örvar BL. Barley grains for the production of endotoxin-free growth factors. Trends Biotechnol 2013; 31:572-80. [DOI: 10.1016/j.tibtech.2013.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/11/2013] [Accepted: 06/12/2013] [Indexed: 02/07/2023]
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Holme IB, Wendt T, Holm PB. Intragenesis and cisgenesis as alternatives to transgenic crop development. PLANT BIOTECHNOLOGY JOURNAL 2013; 11:395-407. [PMID: 23421562 DOI: 10.1111/pbi.12055] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/14/2013] [Accepted: 01/15/2013] [Indexed: 05/21/2023]
Abstract
One of the major concerns of the general public about transgenic crops relates to the mixing of genetic materials between species that cannot hybridize by natural means. To meet this concern, the two transformation concepts cisgenesis and intragenesis were developed as alternatives to transgenesis. Both concepts imply that plants must only be transformed with genetic material derived from the species itself or from closely related species capable of sexual hybridization. Furthermore, foreign sequences such as selection genes and vector-backbone sequences should be absent. Intragenesis differs from cisgenesis by allowing use of new gene combinations created by in vitro rearrangements of functional genetic elements. Several surveys show higher public acceptance of intragenic/cisgenic crops compared to transgenic crops. Thus, although the intragenic and cisgenic concepts were introduced internationally only 9 and 7 years ago, several different traits in a variety of crops have currently been modified according to these concepts. Five of these crops are now in field trials and two have pending applications for deregulation. Currently, intragenic/cisgenic plants are regulated as transgenic plants worldwide. However, as the gene pool exploited by intragenesis and cisgenesis are identical to the gene pool available for conventional breeding, less comprehensive regulatory measures are expected. The regulation of intragenic/cisgenic crops is presently under evaluation in the EU and in the US regulators are considering if a subgroup of these crops should be exempted from regulation. It is accordingly possible that the intragenic/cisgenic route will be of major significance for future plant breeding.
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Affiliation(s)
- Inger Bæksted Holme
- Department of Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, Research Centre Flakkebjerg, Slagelse, Denmark.
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12
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Kapusi E, Hensel G, Coronado MJ, Broeders S, Marthe C, Otto I, Kumlehn J. The elimination of a selectable marker gene in the doubled haploid progeny of co-transformed barley plants. PLANT MOLECULAR BIOLOGY 2013; 81:149-160. [PMID: 23180016 PMCID: PMC3527739 DOI: 10.1007/s11103-012-9988-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 11/07/2012] [Indexed: 05/23/2023]
Abstract
Following the production of transgenic plants, the selectable marker gene(s) used in the process are redundant, and their retention may be undesirable. They can be removed by exploiting segregation among the progeny of co-transformants carrying both the selectable marker gene and the effector transgene. Here we show that the doubled haploid technology widely used in conventional barley breeding programmes represents a useful means of fixing a transgene, while simultaneously removing the unwanted selectable marker gene. Primary barley co-transformants involving hpt::gfp (the selectable marker) and gus (a model transgene of interest) were produced via Agrobacterium-mediated gene transfer to immature embryos using two respective T-DNAs. These plants were then subjected to embryogenic pollen culture to separate independently integrated transgenes in doubled haploid progeny. A comparison between 14 combinations, involving two Agrobacterium strains carrying various plasmids, revealed that the highest rate of independent co-transformation was achieved when a single Agrobacterium clone carried two binary vectors. Using this principle along with Agrobacterium strain LBA4404, selectable marker-free, gus homozygous lines were eventually obtained from 1.5 per 100 immature embryos inoculated. Compared to the segregation of uncoupled T-DNAs in conventionally produced progeny, the incorporation of haploid technology improves the time and resource efficiency of producing true-breeding, selectable marker-free transgenic barley.
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Affiliation(s)
- Eszter Kapusi
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
- Department for Applied Genetics and Cell Biology, University of Natural Resources and Applied Life Sciences, Muthgasse 11, Vienna, Austria
| | - Götz Hensel
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
| | - María-José Coronado
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
- Confocal Microscopy Unit, Hospital Universitario Puerta de Hierro de Majadahonda, Manuel de Falla 1, 28222 Madrid, Spain
| | - Sylvia Broeders
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
- EU, JRC, Institute for Reference Materials and Measurements, RM Unit, Retieseweg 111, 2440 Geel, Belgium
| | - Cornelia Marthe
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
| | - Ingrid Otto
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
| | - Jochen Kumlehn
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstr. 3, 06466 Gatersleben, Germany
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Mehrotra S, Goyal V. Evaluation of designer crops for biosafety--a scientist's perspective. Gene 2012; 515:241-8. [PMID: 23266812 DOI: 10.1016/j.gene.2012.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 10/26/2012] [Accepted: 12/04/2012] [Indexed: 01/16/2023]
Abstract
With the advent of transgenic technology, it has become possible to mobilize and express foreign genes into plants and to design crop varieties with better agronomic attributes and adaptability to challenging environmental conditions. Recent advances in transgenic technology have led to concerns about safety of transgenic crops to human and animal health and environment. Biosafety focuses on preventing, minimizing and eliminating risks associated with the research, production, and use of transgenic crops. Food biosafety involves studies of substantial equivalence related to compositional analysis, toxicity and allergenicity. Environmental biosafety involves glasshouse and field trials and study of unintended effects on non-target organisms. Transgenics are characterized at phenotypic and molecular levels for understanding the location of transgene insertion site, ploidy level, copy number, integrated vector sequences, protein expression and stability of the transgene. Various techniques employed for transgene characterization include flow cytometry, southern, northern and western analyses, real-time (qRT) PCR, competitive PCR, FISH, fiber-FISH, DNA micro-arrays, mRNA profiling, 2DE-MS, iTRAQ, FT-MS, NMR, GC-MS, CE-MS and biosensor-based approaches. Evaluation of transgene expression involves the application of integrated phenomics, transcriptomics, proteomics and metabolomics approaches. However, the relevance and application of these approaches may vary in different cases. The elaborate analysis of transgenic crops will facilitate the safety assessment and commercialization of transgenics and lead to global food security for the future.
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Affiliation(s)
- Shweta Mehrotra
- National Research Centre on Plant Biotechnology, Lal Bahadur Shastri Building, Pusa Campus, New Delhi-110012, India.
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Mikkelsen MD, Pedas P, Schiller M, Vincze E, Mills RF, Borg S, Møller A, Schjoerring JK, Williams LE, Baekgaard L, Holm PB, Palmgren MG. Barley HvHMA1 is a heavy metal pump involved in mobilizing organellar Zn and Cu and plays a role in metal loading into grains. PLoS One 2012; 7:e49027. [PMID: 23155447 PMCID: PMC3498361 DOI: 10.1371/journal.pone.0049027] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/03/2012] [Indexed: 12/11/2022] Open
Abstract
Heavy metal transporters belonging to the P(1B)-ATPase subfamily of P-type ATPases are key players in cellular heavy metal homeostasis. Heavy metal transporters belonging to the P(1B)-ATPase subfamily of P-type ATPases are key players in cellular heavy metal homeostasis. In this study we investigated the properties of HvHMA1, which is a barley orthologue of Arabidopsis thaliana AtHMA1 localized to the chloroplast envelope. HvHMA1 was localized to the periphery of chloroplast of leaves and in intracellular compartments of grain aleurone cells. HvHMA1 expression was significantly higher in grains compared to leaves. In leaves, HvHMA1 expression was moderately induced by Zn deficiency, but reduced by toxic levels of Zn, Cu and Cd. Isolated barley chloroplasts exported Zn and Cu when supplied with Mg-ATP and this transport was inhibited by the AtHMA1 inhibitor thapsigargin. Down-regulation of HvHMA1 by RNA interference did not have an effect on foliar Zn and Cu contents but resulted in a significant increase in grain Zn and Cu content. Heterologous expression of HvHMA1 in heavy metal-sensitive yeast strains increased their sensitivity to Zn, but also to Cu, Co, Cd, Ca, Mn, and Fe. Based on these results, we suggest that HvHMA1 is a broad-specificity exporter of metals from chloroplasts and serve as a scavenging mechanism for mobilizing plastid Zn and Cu when cells become deficient in these elements. In grains, HvHMA1 might be involved in mobilizing Zn and Cu from the aleurone cells during grain filling and germination.
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Affiliation(s)
- Maria Dalgaard Mikkelsen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, Frederiksberg, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Pai Pedas
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Michaela Schiller
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Eva Vincze
- Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, Slagelse, Denmark
| | - Rebecca F. Mills
- Centre for Biological Sciences, University of Southampton, Southampton, Hampshire, United Kingdom
| | - Søren Borg
- Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, Slagelse, Denmark
| | - Annette Møller
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, Frederiksberg, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Jan K. Schjoerring
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Lorraine E. Williams
- Centre for Biological Sciences, University of Southampton, Southampton, Hampshire, United Kingdom
| | - Lone Baekgaard
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, Frederiksberg, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Preben Bach Holm
- Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, Slagelse, Denmark
| | - Michael G. Palmgren
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, Frederiksberg, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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15
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Singer K, Shiboleth YM, Li J, Tzfira T. Formation of complex extrachromosomal T-DNA structures in Agrobacterium tumefaciens-infected plants. PLANT PHYSIOLOGY 2012; 160:511-22. [PMID: 22797657 PMCID: PMC3440224 DOI: 10.1104/pp.112.200212] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Accepted: 07/12/2012] [Indexed: 05/09/2023]
Abstract
Agrobacterium tumefaciens is a unique plant pathogenic bacterium renowned for its ability to transform plants. The integration of transferred DNA (T-DNA) and the formation of complex insertions in the genome of transgenic plants during A. tumefaciens-mediated transformation are still poorly understood. Here, we show that complex extrachromosomal T-DNA structures form in A. tumefaciens-infected plants immediately after infection. Furthermore, these extrachromosomal complex DNA molecules can circularize in planta. We recovered circular T-DNA molecules (T-circles) using a novel plasmid-rescue method. Sequencing analysis of the T-circles revealed patterns similar to the insertion patterns commonly found in transgenic plants. The patterns include illegitimate DNA end joining, T-DNA truncations, T-DNA repeats, binary vector sequences, and other unknown "filler" sequences. Our data suggest that prior to T-DNA integration, a transferred single-stranded T-DNA is converted into a double-stranded form. We propose that termini of linear double-stranded T-DNAs are recognized and repaired by the plant's DNA double-strand break-repair machinery. This can lead to circularization, integration, or the formation of extrachromosomal complex T-DNA structures that subsequently may integrate.
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MESH Headings
- Agrobacterium tumefaciens/pathogenicity
- Ampicillin/pharmacology
- Cloning, Molecular
- DNA End-Joining Repair
- DNA, Bacterial/genetics
- DNA, Circular/genetics
- DNA, Single-Stranded/genetics
- Drug Resistance, Bacterial
- Escherichia coli/drug effects
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Genetic Vectors/genetics
- Plant Diseases/microbiology
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Plants, Genetically Modified/microbiology
- Plasmids/genetics
- Sequence Analysis, DNA/methods
- Nicotiana/genetics
- Nicotiana/metabolism
- Nicotiana/microbiology
- Transformation, Genetic
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Affiliation(s)
- Kamy Singer
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, USA.
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16
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Vector integration in triple R gene transformants and the clustered inheritance of resistance against potato late blight. Transgenic Res 2012; 22:315-25. [DOI: 10.1007/s11248-012-9644-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 08/11/2012] [Indexed: 10/27/2022]
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17
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Holme IB, Dionisio G, Brinch-Pedersen H, Wendt T, Madsen CK, Vincze E, Holm PB. Cisgenic barley with improved phytase activity. PLANT BIOTECHNOLOGY JOURNAL 2012; 10:237-47. [PMID: 21955685 DOI: 10.1111/j.1467-7652.2011.00660.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The cisgenesis concept implies that plants are transformed only with their own genetic materials or genetic materials from closely related species capable of sexual hybridization. Furthermore, foreign sequences such as selection genes and vector-backbone sequences should be absent. We used a barley phytase gene (HvPAPhy_a) expressed during grain filling to evaluate the cisgenesis concept in barley. The marker gene elimination method was used to obtain marker-free plant lines. Here, the gene of interest and the selection gene are flanked by their own T-DNA borders to allow unlinked integration of the two genes. We analysed the transformants for co-transformation efficiency, increased phytase activities in the grain, integration of the kanamycin resistance gene of the vector-backbone and segregation between the HvPAPhy_a insert and the hygromycin resistance gene. The frequencies of the four parameters imply that it should be possible to select 11 potentially cisgenic T(1) -lines out of the 72 T(0) -lines obtained, indicating that the generation of cisgenic barley is possible at reasonable frequencies with present methods. We selected two potential cisgenic lines with a single extra copy of the HvPAPhy_a insert for further analysis. Seeds from plants homozygous for the insert showed 2.6- and 2.8-fold increases in phytase activities and the activity levels were stable over the three generations analysed. In one of the selected lines, the flanking sequences from both the left and right T-DNA borders were analysed. These sequences confirmed the absence of truncated vector-backbone sequences linked to the borders. The described line should therefore be classified as cisgenic.
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Affiliation(s)
- Inger B Holme
- Faculty of Science and Technology, Department of Molecular Biology and Genetics, Research Centre Flakkebjerg, Aarhus University, Slagelse, Denmark.
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18
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Gase K, Weinhold A, Bozorov T, Schuck S, Baldwin IT. Efficient screening of transgenic plant lines for ecological research. Mol Ecol Resour 2011; 11:890-902. [PMID: 21518300 DOI: 10.1111/j.1755-0998.2011.03017.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plants stably transformed to manipulate the expression of genes mediating ecological performance have profoundly altered research in plant ecology. Agrobacterium-mediated transformation remains the most effective method of creating plants harbouring a limited number of transgene integrations of low complexity. For ecological/physiological research, the following requirements must be met: (i) the regenerated plants should have the same ploidy level as the corresponding wild-type plant and (ii) contain a single transgene copy in a homozygous state; (iii) the T-DNA must be completely inserted without vector backbone sequence and all its elements functional; and (iv) the integration should not change the phenotype of the plant by interrupting chromosomal genes or by mutations occurring during the regeneration procedure. The screening process to obtain transformed plants that meet the above criteria is costly and time-consuming, and an optimized screening procedure is presented. We developed a flow chart that optimizes the screening process to efficiently select transformed plants for ecological research. It consists of segregational analyses, which select transgenic T₁ and T₂ generation plants with single T-DNA copies that are homozygous. Indispensable molecular genetic tests (flow cytometry, diagnostic PCRs and Southern blotting) are performed at the earliest and most effective times in the screening process. qPCR to quantify changes in transcript accumulation to confirm gene silencing or overexpression is the last step in the selection process. Because we routinely transform the wild tobacco, Nicotiana attenuata, with constructs that silence or ectopically overexpress ecologically relevant genes, the proposed protocol is supported by examples from this system.
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Affiliation(s)
- Klaus Gase
- Department of Molecular Ecology, Max-Planck-Institute for Chemical Ecology, Hans-Knoell-Strasse 8, 07745 Jena, Germany
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19
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Cullen D, Harwood W, Smedley M, Davies H, Taylor M. Comparison of DNA Walking Methods for Isolation of Transgene-Flanking Regions in GM Potato. Mol Biotechnol 2011; 49:19-31. [DOI: 10.1007/s12033-010-9371-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Biolistic-mediated transformation protocols for maize and pearl millet using pre-cultured immature zygotic embryos and embryogenic tissue. Methods Mol Biol 2011; 710:343-54. [PMID: 21207279 DOI: 10.1007/978-1-61737-988-8_23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Maize (Zea mays L.) is the most important cereal food crop in sub-Saharan Africa and Latin America, and a key feed crop in Asia, whereas pearl millet (Pennisetum glaucum (L.) R. Br.) is a staple food that supplies a major proportion of calories and protein to large segments of the populations living in the semi-arid tropical regions of Africa and Asia. The limitations of biological gene transfer with Agrobacterium tumefaciens specifically related to recalcitrant cereal crops, led to the development of alternative methods of which high-velocity microprojectiles, biolistic genetic transfer is the most successful and also the most widely employed. Agrobacterium facilitated transformation is the method of choice especially for deregulation of commercial transgenic food crop products, but biolistic-mediated transformation is still valid for proof of concept and functional genomics applications. Biolistic-mediated transformation and the production of transgenic plantlets via somatic embryogenesis of two maize strains viz. Hi-II (a laboratory strain) and M37W (a South African elite white maize genotype) as well as a pearl millet strain (842B) are described in this chapter. The stages described include: (1) proliferation of immature zygotic embryos for biolistic-mediated transformation, (2) induction and maintenance of transgenic embryogenic tissue on selection medium; (3) maturation (both morphological and physiological) of transgenic somatic embryos; and (4) germination of the somatic embryos to putative transgenic primary events. Maize and pearl millet cultures were regenerated via somatic embryogenesis as they are bipolar structures that shoot and root simultaneously. The culture media described in this chapter rarely induced or regenerated plantlets via organogenesis.
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21
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Confalonieri M, Borghetti R, Macovei A, Testoni C, Carbonera D, Fevereiro MPS, Rommens C, Swords K, Piano E, Balestrazzi A. Backbone-free transformation of barrel medic (Medicago truncatula) with a Medicago-derived transfer DNA. PLANT CELL REPORTS 2010; 29:1013-1021. [PMID: 20571798 DOI: 10.1007/s00299-010-0887-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 05/31/2010] [Accepted: 06/14/2010] [Indexed: 05/29/2023]
Abstract
In the present work, Agrobacterium tumefaciens-mediated genetic transformation of the model legume Medicago truncatula Gaertn. (barrel medic) was carried out using the pSIM843 vector that contains a Medicago-derived transfer DNA, delineated by a 25-bp sequence homologous to bacterial T-DNA borders. The transfer DNA contains an expression cassette for the nptII (neomycin phosphotransferase) gene and is flanked by an expression cassette for the backbone integration marker gene ipt (isopentenyl transferase). Our results demonstrate that the Medicago-derived RB-like elements efficiently support DNA mobilization from A. tumefaciens to M. truncatula. Kanamycin-resistant shoots with normal phenotype and ipt-shooty lines were recovered at a frequency of 11.7 and 7.8%, respectively. Polymerase chain reaction (PCR) analyses demonstrated that 44.4% of the independent transgenic lines were backbone-free and evidenced the occurrence of backbone-transfer events.
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Affiliation(s)
- Massimo Confalonieri
- C.R.A.-Centro di Ricerca per le Produzioni Foraggere e Lattiero-Casearie, viale Piacenza 29, 26900, Lodi, Italy
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22
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Generation of marker-free Bt transgenicindica rice and evaluation of its yellow stem borer resistance. J Appl Genet 2010; 51:243-57. [DOI: 10.1007/bf03208854] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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Permyakova NV, Shumnyi VK, Deineko EV. Agrobacterium-mediated transformation of plants: Transfer of vector DNA fragments in the plant genome. RUSS J GENET+ 2009. [DOI: 10.1134/s1022795409030028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Petti C, Wendt T, Meade C, Mullins E. Evidence of genotype dependency within Agrobacterium tumefaciens in relation to the integration of vector backbone sequence in transgenic Phytophthora infestans-tolerant potato. J Biosci Bioeng 2009; 107:301-6. [DOI: 10.1016/j.jbiosc.2008.11.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 11/06/2008] [Indexed: 11/29/2022]
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25
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Abstract
Ever since the first developments in plant transformation technology using model plant species in the early 1980s, there has been a body of plant science research devoted to adapting these techniques to the transformation of crop plants. For some crop species progress was relatively rapid, but in other crop groups such as the small grain cereals, which were not readily amenable to culture in vitro and were not natural hosts to Agrobacterium, it has taken nearly two decades to develop reliable and robust transformation methods.In the following chapters of this book, transformation procedures for small grain cereals are presented, together with methods for gene and protein expression and the characterization of transgenic plants. In this introductory chapter we try to put these later chapters into context, giving an overview of the development of transformation technology for small grain cereals, discussing some of the pros and cons of the techniques and what limitations still exist.
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26
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Hensel G, Kastner C, Oleszczuk S, Riechen J, Kumlehn J. Agrobacterium-mediated gene transfer to cereal crop plants: current protocols for barley, wheat, triticale, and maize. INTERNATIONAL JOURNAL OF PLANT GENOMICS 2009; 2009:835608. [PMID: 19584907 PMCID: PMC2699555 DOI: 10.1155/2009/835608] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 04/17/2009] [Indexed: 05/20/2023]
Abstract
The development of powerful "omics" technologies has enabled researchers to identify many genes of interest for which comprehensive functional analyses are highly desirable. However, the production of lines which ectopically express recombinant genes, or those in which endogenous genes are knocked down via stable transformation, remains a major bottleneck for the association between genetics and gene function in monocotyledonous crops. Methods of effective DNA transfer into regenerable cells of immature embryos from cereals by means of Agrobacterium tumefaciens have been modified in a stepwise manner. The effect of particular improvement measures has often not been significantly evident, whereas their combined implementation has resulted in meaningful advances. Here, we provide updated protocols for the Agrobacterium-mediated generation of stably transgenic barley, wheat, triticale and maize. Based upon these methods, several hundred independent transgenic lines have been delivered, with efficiencies of inoculated embryos leading to stably transgenic plants reaching 86% in barley, 10% in wheat, 4% in triticale, and 24% in maize.
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Affiliation(s)
- Goetz Hensel
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466 Gatersleben, Germany
- *Goetz Hensel:
| | - Christine Kastner
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466 Gatersleben, Germany
| | - Sylwia Oleszczuk
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466 Gatersleben, Germany
- Plant Breeding and Acclimatization Institute, Radzików, 05-870 Blonie, Poland
| | - Jan Riechen
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466 Gatersleben, Germany
| | - Jochen Kumlehn
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466 Gatersleben, Germany
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27
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Abstract
Following the success of transgenic maize and rice, methods have now been developed for the efficient introduction of genes into wheat, barley and oats. This review summarizes the present position in relation to these three species, and also uses information from field trial databases and the patent literature to assess the future trends in the exploitation of transgenic material. This analysis includes agronomic traits and also discusses opportunities in expanding areas such as biofuels and biopharming.
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Affiliation(s)
- Jim M Dunwell
- School of Biological Sciences, University of Reading, Reading, Berkshire, UK
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28
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Sandhu S, Altpeter F. Co-integration, co-expression and inheritance of unlinked minimal transgene expression cassettes in an apomictic turf and forage grass (Paspalum notatum Flugge). PLANT CELL REPORTS 2008; 27:1755-65. [PMID: 18758782 DOI: 10.1007/s00299-008-0599-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 08/11/2008] [Accepted: 08/18/2008] [Indexed: 05/05/2023]
Abstract
Bahiagrass (Paspalum notatum Flugge) is an important turf and forage grass in the southeastern United States and other subtropical regions. Biolistic co-transfer of two unlinked, minimal, linear transgene expression cassettes (MCs) into the apomictic bahiagrass cv. Argentine was carried out to evaluate co-integration, quantify co-expression and analyze inheritance to apomictic seed progeny. Gold projectiles were coated with minimal unlinked nptII and bar expression cassettes in a 1:2 molar ratio. Complexity of transgene loci correlated with the amount of DNA used during gene transfer. Transgenic plants displayed a simple nptII integration pattern with 1-4 hybridization signals compared to the non-selected bar gene with 2 to more than 5 hybridization signals per transgenic line. Co-expression of unlinked nptII and bar genes occurred in 19 of the 20 co-transformed lines (95% co-expression frequency). Protein quantification revealed that several lines with complex integration patterns displayed a higher transgene expression than lines with simple transgene integration patterns. Several transgenic lines displayed hybridization signals indicative of concatemerization. Concatemers were confirmed following PCR amplification and sequence analysis of transgene loci. The obligate apomictic bahiagrass cv. Argentine produced uniform seed progeny without segregation of simple or complex transgene loci. NPTII- and PAT-ELISA, as well as herbicide application, confirmed stable expression of the nptII and bar gene at levels similar to the primary transformants. These results demonstrate that biolistic transfer of MCs support stable and high level co-expression of transgenes in bahiagrass.
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Affiliation(s)
- Sukhpreet Sandhu
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
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29
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Hensel G, Valkov V, Middlefell-Williams J, Kumlehn J. Efficient generation of transgenic barley: the way forward to modulate plant-microbe interactions. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:71-82. [PMID: 17905476 DOI: 10.1016/j.jplph.2007.06.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 06/06/2007] [Accepted: 06/10/2007] [Indexed: 05/03/2023]
Abstract
Stable genetic transformation represents the gold standard approach to the detailed elucidation of plant gene functions. This is particularly relevant in barley, an important experimental model widely employed in applied molecular, genetic and cell biological research, and biotechnology. Presented are details of the establishment of a protocol for Agrobacterium-mediated gene transfer to immature embryos, which enables the highly efficient generation of transgenic barley. Advancements were achieved through comparative experiments on the influence of various explant treatments and co-cultivation conditions. The analysis of representative numbers of transgenic lines revealed that the obtained T-DNA copy numbers are typically low, the generative transmission of the recombinant DNA is in accordance with the Mendelian rules and the vast majority of the primary transgenics produce progeny that expresses the respective transgene product. Moreover, the newly established protocol turned out to be useful to transform not only the highly amenable cultivar (cv.) 'Golden Promise' but also other spring and winter barley genotypes, albeit with substantially lower efficiency. As a major result of this study, a very useful tool is now available for future functional gene analyses as well as genetic engineering approaches. With the aim to modify the expression of barley genes putatively involved in plant-fungus interactions, numerous transgenic plants have been generated using diverse expression cassettes. These plants represent an example of how transformation technology may contribute to further our understanding of important biological processes.
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Affiliation(s)
- Goetz Hensel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Plant Reproductive Biology, Corrensstr. 3, 06466 Gatersleben, Germany.
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30
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Zhang J, Cai L, Cheng J, Mao H, Fan X, Meng Z, Chan KM, Zhang H, Qi J, Ji L, Hong Y. Transgene integration and organization in cotton (Gossypium hirsutum L.) genome. Transgenic Res 2007; 17:293-306. [PMID: 17549600 DOI: 10.1007/s11248-007-9101-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 04/18/2007] [Indexed: 11/28/2022]
Abstract
While genetically modified upland cotton (Gossypium hirsutum L.) varieties are ranked among the most successful genetically modified organisms (GMO), there is little knowledge on transgene integration in the cotton genome, partly because of the difficulty in obtaining large numbers of transgenic plants. In this study, we analyzed 139 independently derived T0 transgenic cotton plants transformed by Agrobacterium tumefaciens strain AGL1 carrying a binary plasmid pPZP-GFP. It was found by PCR that as many as 31% of the plants had integration of vector backbone sequences. Of the 110 plants with good genomic Southern blot results, 37% had integration of a single T-DNA, 24% had two T-DNA copies and 39% had three or more copies. Multiple copies of the T-DNA existed either as repeats in complex loci or unlinked loci. Our further analysis of two T1 populations showed that segregants with a single T-DNA and no vector sequence could be obtained from T0 plants having multiple T-DNA copies and vector sequence. Out of the 57 T-DNA/T-DNA junctions cloned from complex loci, 27 had canonical T-DNA tandem repeats, the rest (30) had deletions to T-DNAs or had inclusion of vector sequences. Overlapping micro-homology was present for most of the T-DNA/T-DNA junctions (38/57). Right border (RB) ends of the T-DNA were precise while most left border (LB) ends (64%) had truncations to internal border sequences. Sequencing of collinear vector integration outside LB in 33 plants gave evidence that collinear vector sequence was determined in agrobacterium culture. Among the 130 plants with characterized flanking sequences, 12% had the transgene integrated into coding sequences, 12% into repetitive sequences, 7% into rDNAs. Interestingly, 7% had the transgene integrated into chloroplast derived sequences. Nucleotide sequence comparison of target sites in cotton genome before and after T-DNA integration revealed overlapping microhomology between target sites and the T-DNA (8/8), deletions to cotton genome in most cases studied (7/8) and some also had filler sequences (3/8). This information on T-DNA integration in cotton will facilitate functional genomic studies and further crop improvement.
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MESH Headings
- Agrobacterium tumefaciens/genetics
- Base Sequence
- Blotting, Southern
- DNA Primers
- DNA, Bacterial/genetics
- DNA, Plant/genetics
- Genetic Vectors
- Genome, Plant
- Gossypium/genetics
- Gossypium/growth & development
- Molecular Sequence Data
- Plants, Genetically Modified
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Recombination, Genetic
- Repetitive Sequences, Nucleic Acid
- Reverse Transcriptase Polymerase Chain Reaction
- Transformation, Genetic
- Transgenes/physiology
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Affiliation(s)
- Jun Zhang
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore
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31
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Holme IB, Brinch-Pedersen H, Lange M, Holm PB. Transformation of barley (Hordeum vulgare L.) by Agrobacterium tumefaciens infection of in vitro cultured ovules. PLANT CELL REPORTS 2006; 25:1325-35. [PMID: 16832622 DOI: 10.1007/s00299-006-0188-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 05/11/2006] [Accepted: 05/28/2006] [Indexed: 05/10/2023]
Abstract
We report on a novel transformation procedure for barley by Agrobacterium infection of in vitro cultured ovules. Ovules of the cultivar Golden Promise were isolated a few hours after pollination and infected with the Agrobacterium tumefaciens strain AGL0 carrying the binary vector pVec8-GFP. The vector harboured a hygromycin resistance gene and the green fluorescence protein (GFP) gene. GFP-expressing embryos were isolated from the ovules, regenerated to plants and investigated by Southern blot analysis. Transformation frequencies amounted to 3.1% with hygromycin selection and 0.8% without selection. Mendelian inheritance and stable expression of the GFP gene was confirmed in 18 independent lines over two generations. We conclude that the described technique allows for the rapid and direct generation of high quality transgenic plants.
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Affiliation(s)
- Inger Baeksted Holme
- Department of Genetics and Biotechnology, Danish Institute of Agricultural Sciences, Research Centre Flakkebjerg, 4200, Slagelse, Denmark.
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32
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Podevin N, De Buck S, De Wilde C, Depicker A. Insights into recognition of the T-DNA border repeats as termination sites for T-strand synthesis by Agrobacterium tumefaciens. Transgenic Res 2006; 15:557-71. [PMID: 16830227 DOI: 10.1007/s11248-006-9003-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 04/14/2006] [Indexed: 10/24/2022]
Abstract
The recognition of the T-DNA left border (LB) repeat is affected by its surrounding sequences. Here, the LB regions were further characterized by molecular analysis of transgenic plants, obtained after Agrobacterium tumefaciens-mediated transformation with T-DNA vectors that had been modified in this LB region. At least the 24-bp LB repeat by itself was insufficient to terminate the T-strand synthesis. Addition of the natural inner and/or outer border regions to at least the LB repeat, even when present at a distance, enhanced the correct recognition of the LB repeat, reducing the number of plants containing vector backbone sequences. In tandem occurrence of both the octopine and nopaline LB regions with their repeats terminated the T-strand synthesis most efficiently at the LB, yielding a reproducibly high number of plants containing only the T-DNA. Furthermore, T-strand synthesis did not terminate efficiently at the right border (RB) repeat, which might indicate that signals in the outer RB region inhibit the termination of T-strand synthesis at the RB repeat.
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Affiliation(s)
- Nancy Podevin
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, Technologiepark 927, B-9052 Gent, Belgium
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