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Ganguly S, Purohit A, Ghosh S, Chaudhuri RK, Das S, Chakraborti D. Clean gene technology to develop selectable marker-free pod borer-resistant transgenic pigeon pea events involving the constitutive expression of Cry1Ac. Appl Microbiol Biotechnol 2022; 106:3051-3067. [PMID: 35441877 DOI: 10.1007/s00253-022-11922-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 04/04/2022] [Accepted: 04/08/2022] [Indexed: 11/29/2022]
Abstract
The most crucial yield constraint of pigeon pea is susceptibility to the pod borer Helicoverpa armigera, which causes extensive damage and severe economic losses every year. The Agrobacterium-mediated plumular meristem transformation technique was applied for the development of cry1Ac transgenic pigeon pea. Bioactivity of the cry1Ac gene was compared based on integration and expression driven by two promoters, the constitutive CaMV35S promoter and the green-tissue-specific ats1A promoter, in those transgenic events. The transgenic events also contained the selectable marker gene nptII flanked by loxP sites. Independent transgenic events expressing the Cre recombinase gene along with a linked bar selection marker were also developed. Integration and expression patterns of both cry1Ac and cre were confirmed through Southern and western blot analysis of T1 events. The constitutive expression of the Cry1Ac protein was found to be more effective for conferring resistant activity against H. armigera larvae in comparison to green-tissue-specific expression. Constitutively expressing Cry1Ac T1 events were crossed with Cre recombinase expressing T1 events. The crossing-based Cre/lox-mediated marker gene elimination strategy was demonstrated to generate nptII-free Cry1Ac-expressing T2 events. These events were subsequently analyzed in the T3 generation for the segregation of cre and bar genes. Five Cry1Ac-expressing T3 transgenic pigeon pea events were devoid of the nptII marker as well as cre-bar genes. H. armigera larval mortality in those marker-free T3 events was found to be 80-100%. The development of such nptII selectable marker-free Cry1Ac-expressing pigeon pea transgenics for the first time would greatly support the sustainable biotechnological breeding program for pod borer resistance in pigeon pea. KEY POINTS: • Constitutive expression of Cry1Ac conferred complete resistance against Helicoverpa armigera • Green-tissue-specific expression of Cry1Ac conferred partial pest resistance • Cre/lox-mediated nptII elimination was successful in constitutively expressing Cry1Ac transgenic pigeon pea events.
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Affiliation(s)
- Shreeparna Ganguly
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata - 700016, West Bengal, India.,Department of Genetics, University of Calcutta, 35, Ballygunge Circular Road, Kolkata - 700019, West Bengal, India
| | - Arnab Purohit
- Department of Genetics, University of Calcutta, 35, Ballygunge Circular Road, Kolkata - 700019, West Bengal, India
| | - Sanatan Ghosh
- Department of Genetics, University of Calcutta, 35, Ballygunge Circular Road, Kolkata - 700019, West Bengal, India
| | - Rituparna Kundu Chaudhuri
- Department of Botany, Barasat Govt. College, 10, K.N.C. Road, Barasat, Kolkata - 700124, West Bengal, India
| | - Sampa Das
- Division of Plant Biology, Bose Institute, C.I.T. Scheme VII M, P1/12, Kankurgachi, Kolkata- 700054, West Bengal, India
| | - Dipankar Chakraborti
- Department of Genetics, University of Calcutta, 35, Ballygunge Circular Road, Kolkata - 700019, West Bengal, India.
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Leng C, Sun B, Liu Z, Zhang L, Wei X, Zhou Y, Meng Y, Lai Y, Dai Y, Zhu Z. An optimized double T-DNA binary vector system for improved production of marker-free transgenic tobacco plants. Biotechnol Lett 2020; 42:641-655. [PMID: 31965394 DOI: 10.1007/s10529-020-02797-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/12/2020] [Indexed: 12/31/2022]
Abstract
OBJECTIVES In the plant transformation process, marker genes play a vital role in identifying transformed cells from non-transformed cells. However, once transgenic plants have been obtained, the presence of marker genes may provoke public concern about environmental or biosafety issues. In our previous study, a double T-DNA vector system has been developed to obtain marker-free transgenic plants, but the T-DNA left border (LB) and right border (RB) of the vector showed an RB-LB-RB-LB pattern and led to high linkage integration between the selectable marker gene (SMG) and the gene of interest (GOI). To improve this double T-DNA vector system, we inverted the first T-DNA direction such that a LB-RB-RB-LB pattern resulted to avoid transcriptional read-through at the LB and the subsequent linkage transfer of the SMG and GOI. RESULTS We separately inserted the green fluorescent protein (GFP) gene as the GOI and the neomycin phosphotransferase II (NPTII) gene as the SMG in both optimized and original vectors and carried out Agrobacterium-mediated tobacco transformation. Statistical analysis revealed that the linkage frequency was 25.6% in T0 plants transformed with the optimized vector, which is a 42.1% decrease compared with that of the original vector (44.2%). The frequency of obtaining marker-free transgenic plants was 66.7% in T1 plants transformed with the optimized vector, showing a 33.4% increase compared with that of the original vector (50.0%). CONCLUSION Our results demonstrate that the optimized double T-DNA binary vector system is a more effective, economical and time-saving approach for obtaining marker-free transgenic plants.
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Affiliation(s)
- Chunxu Leng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- Biotechnology Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Bing Sun
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Zheming Liu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lei Zhang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaoli Wei
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yun Zhou
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Ying Meng
- Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Yongcai Lai
- Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Yan Dai
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Zhen Zhu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
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Gray DJ, Li ZT, Dhekney SA. Precision breeding of grapevine (Vitis vinifera L.) for improved traits. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2014; 228:3-10. [PMID: 25438781 DOI: 10.1016/j.plantsci.2014.03.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 05/26/2023]
Abstract
This review provides an overview of recent technological advancements that enable precision breeding to genetically improve elite cultivars of grapevine (Vitis vinifera L.). Precision breeding, previously termed "cisgenic" or "intragenic" genetic improvement, necessitates a better understanding and use of genomic resources now becoming accessible. Although it is now a relatively simple task to identify genetic elements and genes from numerous "omics" databases, the control of major agronomic and enological traits often involves the currently unknown participation of many genes and regulatory machineries. In addition, genetic evolution has left numerous vestigial genes and sequences without tangible functions. Thus, it is critical to functionally test each of these genetic entities to determine their real-world functionality or contribution to trait attributes. Toward this goal, several diverse techniques now are in place, including cell culture systems to allow efficient plant regeneration, advanced gene insertion techniques, and, very recently, resources for genomic analyses. Currently, these techniques are being used for high-throughput expression analysis of a wide range of grapevine-derived promoters and disease-related genes. It is envisioned that future research efforts will be extended to the study of promoters and genes functioning to enhance other important traits, such as fruit quality and vigor.
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Affiliation(s)
- Dennis J Gray
- Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, University of Florida/IFAS, 2725 Binion Road, Apopka, FL 32703-8504 USA.
| | - Zhijian T Li
- Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, University of Florida/IFAS, 2725 Binion Road, Apopka, FL 32703-8504 USA
| | - Sadanand A Dhekney
- Department of Plant Sciences, Sheridan Research and Extension Center, University of Wyoming, 663 Wyarno Road, Sheridan, WY 82801 USA
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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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Li ZT, Kim KH, Jasinski JR, Creech MR, Gray DJ. Large-scale characterization of promoters from grapevine (Vitis spp.) using quantitative anthocyanin and GUS assay systems. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 196:132-42. [PMID: 23017908 DOI: 10.1016/j.plantsci.2012.08.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 08/10/2012] [Accepted: 08/11/2012] [Indexed: 06/01/2023]
Abstract
Successful implementation of cisgenic/intragenic/ingenic technology for crop improvement necessitates a better understanding of the function of native promoters for driving desired gene expression in host plant. Although the genome of grapevine (Vitis vinifera) has been determined, efforts to explore promoter resources for the development of cisgenics are still lacking. Particularly, there is a shortage of constitutive promoters for marker and/or target gene expression in this species. In this work, we utilized an anthocyanin-based color histogram analysis method to evaluate quantitatively a large number of promoters for their ability to activate transgene expression. Promoter fragments corresponding to known genes were amplified from various genotypes and used to drive the VvMybA1 gene of 'Merlot' for anthocyanin production in non-pigmented somatic embryo (SE) explants to infer transcriptional activity. Results revealed that among 15 tested promoters belonging to seven ubiquitin genes, at least three promoters generated constitutive activities reaching up to 100% value of the d35S promoter. In particular, the high activity levels of VvUb6-1 and VvUb7-2 promoters were verified by transient GUS quantitative assay as well as stable anthocyanin expression in sepal and corolla of transgenic tobacco. Variations in promoter activity of different ubiquitin genes in grapevine did not correlate with the presence and sizes of 5' UTR intron, but seemed to be related positively and negatively to the number of positive cis-acting elements and root-specific elements respectively. In addition, several of the 13 promoters derived from a PR1 gene and a PAL gene produced a higher basal activity as compared to previously reported inducible promoters and might be useful for further identification of strong inducible promoters. Our study contributed invaluable information on transcriptional activity of many previously uncharacterized native promoters that could be used for genetic engineering of grapevine.
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Affiliation(s)
- Zhijian T Li
- Grape Biotechnology Core Laboratory, Mid-Florida Research and Education Center, University of Florida/IFAS, 2725 Binion Road, Apopka, FL 32703-8504, USA
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6
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Gene deletor: a new tool to address gene flow and food safety concerns over transgenic crop plants. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11515-012-1195-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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7
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Owen MDK, Young BG, Shaw DR, Wilson RG, Jordan DL, Dixon PM, Weller SC. Benchmark study on glyphosate-resistant crop systems in the United States. Part 2: Perspectives. PEST MANAGEMENT SCIENCE 2011; 67:747-57. [PMID: 21452168 DOI: 10.1002/ps.2159] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 01/03/2011] [Accepted: 01/30/2011] [Indexed: 05/30/2023]
Abstract
A six-state, 5 year field project was initiated in 2006 to study weed management methods that foster the sustainability of genetically engineered (GE) glyphosate-resistant (GR) crop systems. The benchmark study field-scale experiments were initiated following a survey, conducted in the winter of 2005-2006, of farmer opinions on weed management practices and their views on GR weeds and management tactics. The main survey findings supported the premise that growers were generally less aware of the significance of evolved herbicide resistance and did not have a high recognition of the strong selection pressure from herbicides on the evolution of herbicide-resistant (HR) weeds. The results of the benchmark study survey indicated that there are educational challenges to implement sustainable GR-based crop systems and helped guide the development of the field-scale benchmark study. Paramount is the need to develop consistent and clearly articulated science-based management recommendations that enable farmers to reduce the potential for HR weeds. This paper provides background perspectives about the use of GR crops, the impact of these crops and an overview of different opinions about the use of GR crops on agriculture and society, as well as defining how the benchmark study will address these issues.
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Affiliation(s)
- Micheal D K Owen
- Agronomy Department, Iowa State University, Ames, IA 50011, USA.
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8
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Ma XF, Wright E, Ge Y, Bell J, Xi Y, Bouton JH, Wang ZY. Improving phosphorus acquisition of white clover (Trifolium repens L.) by transgenic expression of plant-derived phytase and acid phosphatase genes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2009; 176:479-88. [PMID: 26493137 DOI: 10.1016/j.plantsci.2009.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 12/30/2008] [Accepted: 01/02/2009] [Indexed: 05/02/2023]
Abstract
Phosphate is one of the least available macronutrients restricting crop production in many ecosystems. A phytase gene (MtPHY1) and a purple acid phosphatase gene (MtPAP1), both isolated from the model legume Medicago truncatula, were introduced into white clover (Trifolium repens L.) by Agrobacterium-mediated transformation. The transgenes were driven by the constitutive CaMV35S promoter or the root-specific MtPT1 promoter. Transcripts were detected in roots of the transgenic plants. Phytase or acid phosphatase (APase) activities in root apoplasts of the transgenic plants were increased up to three-fold compared to the wild type control. After the plants were grown 80 days in sand pots supplied with organic phosphorus (Po) as the sole P source, dry weights of shoot tissues of the best performing transgenic plants almost doubled that of the control and were comparable to the counterparts supplied with inorganic phosphorus (Pi). Relative biomass production of the transgenics under Po treatment was over 90% and 80% of that from the Pi treatment when the plants were grown in hydroponics (40 days) and sand pots (80 days), respectively. In contrast, biomass of the wild type controls under Po treatment was only about 50% of the Pi treatment in either hydroponic cultures or sand pots. In addition, shoot P concentrations of the transgenic plants were significantly increased compared to the control. Transgenic plants accumulated much higher amounts of total P (up to 2.6-fold after 80 days of growth) than the control in Po supplied sand pots. The results showed that transgenic expression of MtPHY1 or MtPAP1 in white clover plants increased their abilities of utilizing organic phosphorus in response to P deficiency.
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Affiliation(s)
- Xue-Feng Ma
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Elane Wright
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Yaxin Ge
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Jeremey Bell
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Yajun Xi
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Joseph H Bouton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Zeng-Yu Wang
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA.
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9
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Weeks JT, Ye J, Rommens CM. Development of an in planta method for transformation of alfalfa (Medicago sativa). Transgenic Res 2007; 17:587-97. [PMID: 17851774 DOI: 10.1007/s11248-007-9132-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 08/13/2007] [Indexed: 11/30/2022]
Abstract
Conventional methods in transforming alfalfa (Medicago sativa) require multiple tissue culture manipulations that are time-consuming and expensive, while applicable only to a few highly regenerable genotypes. Here, we describe a simple in planta method that makes it possible to transform a commercial variety without employing selectable marker genes. Basically, young seedlings are cut at the apical node, cold-treated, and vigorously vortexed in an Agrobacterium suspension also containing sand. About 7% of treated seedlings produced progenies segregating for the T-DNA. The vortex-mediated seedling transformation method was applied to transform alfalfa with an all-native transfer DNA comprising a silencing construct for the caffeic acid o-methyltransferase (Comt) gene. Resulting intragenic plants accumulated reduced levels of the indigestible fiber component lignin that lowers forage quality. The absence of both selectable marker genes and other foreign genetic elements may expedite the governmental approval process for quality-enhanced alfalfa.
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Affiliation(s)
- J Troy Weeks
- J. R. Simplot Company, Simplot Plant Sciences, Boise, ID 83706, USA
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10
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Luo K, Duan H, Zhao D, Zheng X, Deng W, Chen Y, Stewart CN, McAvoy R, Jiang X, Wu Y, He A, Pei Y, Li Y. 'GM-gene-deletor': fused loxP-FRT recognition sequences dramatically improve the efficiency of FLP or CRE recombinase on transgene excision from pollen and seed of tobacco plants. PLANT BIOTECHNOLOGY JOURNAL 2007; 5:263-274. [PMID: 17309681 DOI: 10.1111/j.1467-7652.2006.00237.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Pollen- and seed-mediated transgene flow is a concern in plant biotechnology. We report here a highly efficient 'genetically modified (GM)-gene-deletor' system to remove all functional transgenes from pollen, seed or both. With the three pollen- and/or seed-specific gene promoters tested, the phage CRE/loxP or yeast FLP/FRT system alone was inefficient in excising transgenes from tobacco pollen and/or seed, with no transgenic event having 100% efficiency. When loxP-FRT fusion sequences were used as recognition sites, simultaneous expression of both FLP and CRE reduced the average excision efficiency, but the expression of FLP or CRE alone increased the average excision efficiency, with many transgenic events being 100% efficient based on more than 25,000 T(1) progeny examined per event. The 'GM-gene-deletor' reported here may be used to produce 'non-transgenic' pollen and/or seed from transgenic plants and to provide a bioconfinement tool for transgenic crops and perennials, with special applicability towards vegetatively propagated plants and trees.
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Affiliation(s)
- Keming Luo
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA
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Salyers AA, Moon K, Schlessinger D. The human intestinal tract – a hotbed of resistance gene transfer? Part II. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.clinmicnews.2007.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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12
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Arumugam N, Gupta V, Jagannath A, Mukhopadhyay A, Pradhan AK, Burma PK, Pental D. A passage through in vitro culture leads to efficient production of marker-free transgenic plants in Brassica juncea using the Cre-loxP system. Transgenic Res 2007; 16:703-12. [PMID: 17219247 DOI: 10.1007/s11248-006-9058-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Accepted: 11/20/2006] [Indexed: 11/30/2022]
Abstract
The Cre-loxP site-specific recombination system was deployed for removal of marker genes from Brassica juncea (Indian mustard). Excision frequencies, monitored by removal of nptII or gfp genes in F(1) plants of crosses between LOX and CRE lines, were high in quiescent, differentiated somatic tissues but extremely poor in the meristematic regions (and consequently the germinal cells) thus preventing identification and selection of marker-free transgenic events which are devoid of both the marker gene as well as the cre gene, in F(2) progeny. We show that a passage through in vitro culture of F(1 )leaf explants allows efficient development of marker-free transgenics in the F(2) generation addressing current limitations associated with efficient use of the Cre/loxP technology for marker gene removal.
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Affiliation(s)
- N Arumugam
- Centre for Genetic Manipulation of Crop Plants, University of Delhi South Campus, Benito Juarez Road, New Delhi 110 021, India
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13
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Abstract
Selectable marker genes (SMGs) have been extraordinarily useful in enabling plant transformation because of the low efficiency of transgene integration. The most used SMGs encode proteins resistant to antibiotics or herbicides and use negative selection, i.e., by killing nontransgenic tissue. However, there are perceived risks in wide-scale deployment of SMG-transgenic plants, and therefore research has recently been performed to develop marker-free systems. In this review, transformation using markers not based on antibiotic or herbicide resistance genes, as well as different systems of marker gene deletion, are discussed.
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Affiliation(s)
- Behrooz Darbani
- Agriculture Biotechnology Research Institute for Northwest & West of Iran, Tabriz, Iran
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Mlynárová L, Conner AJ, Nap JP. Directed microspore-specific recombination of transgenic alleles to prevent pollen-mediated transmission of transgenes. PLANT BIOTECHNOLOGY JOURNAL 2006; 4:445-52. [PMID: 17177809 DOI: 10.1111/j.1467-7652.2006.00194.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A major challenge for future genetically modified (GM) crops is to prevent undesired gene flow of transgenes to plant material intended for another use. Recombinase-mediated auto excision of transgenes directed by a tightly controlled microspore-specific promoter allows efficient removal of either the selectable marker gene or of all introduced transgenes during microsporogenesis. This way, transgene removal becomes an integral part of the biology of pollen maturation, not requiring any external stimulus such as chemical induction by spraying. We here show the feasibility of engineering transgenic plants to produce pollen devoid of any transgene. Highly efficient excision of transgenes from tobacco pollen was achieved with a potential failure rate of at most two out of 16,800 seeds (0.024%). No evidence for either premature activation or absence of activation of the recombinase system was observed under stress conditions in the laboratory. This approach can prevent adventitious presence of transgenes in non-GM crops or related wild species by gene flow. Such biological containment may help the deployment and management of coexistence practices to support consumer choice and will promote clean molecular farming for the production of high-value compounds in plants.
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Affiliation(s)
- Ludmila Mlynárová
- Plant Sciences Group, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands
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15
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Bhalla PL. Genetic engineering of wheat--current challenges and opportunities. Trends Biotechnol 2006; 24:305-11. [PMID: 16682090 DOI: 10.1016/j.tibtech.2006.04.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 01/27/2006] [Accepted: 04/21/2006] [Indexed: 01/04/2023]
Abstract
Wheat is one of the major staple food crops grown worldwide; however, productivity in cereal crops has not kept pace with the world population growth. A significant increase in wheat production (>40% by 2020) is needed simply to keep up with the growing demand. This increase is unlikely to be achieved by conventional plant breeding methods because of the limited gene pool available. The application of recombinant techniques to improve wheat quality and yield is not only desirable but also has potential to open up new opportunities. Although there has been significant progress in developing gene-transformation technologies for improving these traits, this remains an important challenge for plant biotechnology. Obstacles to translate the full potential of the genomic era to wheat breeding include the need to develop elite wheat varieties without selectable markers, introducing minimal or nil intergenic DNA and social and market issues concerning genetically engineered food products.
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Affiliation(s)
- Prem L Bhalla
- Plant Molecular Biology and Biotechnology Laboratory, Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Melbourne, Parkville, Victoria 3010, Australia.
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16
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Xiao K, Harrison MJ, Wang ZY. Transgenic expression of a novel M. truncatula phytase gene results in improved acquisition of organic phosphorus by Arabidopsis. PLANTA 2005; 222:27-36. [PMID: 15856283 DOI: 10.1007/s00425-005-1511-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Accepted: 02/08/2005] [Indexed: 05/02/2023]
Abstract
A full-length cDNA encoding an extracellular form of phytase was isolated from the model legume Medicago truncatula. The phytase cDNA (MtPHY1) has an open reading frame of 1,632 bp predicted to encode 543 amino acids including an N-terminal signal peptide of 27 amino acids. The MtPHY1 gene is 5,151 bp in length, containing 7 exons and 6 introns. MtPHY1 transcripts were detected in leaves and roots and levels elevated in roots during growth in low phosphate conditions. Transgenic Arabidopsis lines expressing MtPHY1 under the control of the root-specific MtPT1 promoter or the constitutive CaMV35S promoter were created. Phytase activities in root apoplast of the transgenic Arabidopsis were 12.3- to 16.2-fold higher than those of the control plants. The expressed phytase was secreted into the rhizosphere as demonstrated by enzyme activity staining and HPLC analysis of phytate degradation by root exudates. Transgenic expression of the MtPHY1 led to significant improvement in organic phosphorus utilization and plant growth. When phytate was supplied as the sole source of phosphorus, dry weight of the transgenic Arabidopsis lines were 3.1- to 4.0-fold higher than the control plants and total phosphorus contents were 4.1- to 5.5-fold higher than the control. Transgenic expression of phytase genes of plant origin has great potential for improving plant phosphorus acquisition and for phytoremediation.
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Affiliation(s)
- Kai Xiao
- Forage Improvement Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
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Hersch SM, Ferrante RJ. Translating therapies for Huntington's disease from genetic animal models to clinical trials. NeuroRx 2005; 1:298-306. [PMID: 15717031 PMCID: PMC534928 DOI: 10.1602/neurorx.1.3.298] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Genetic animal models of inherited neurological diseases provide an opportunity to test potential treatments and explore their promise for translation to humans experiencing these diseases. Therapeutic trials conducted in mouse models of Huntington's disease have identified a growing number of potential therapies that are candidates for clinical trials. Although it is very exciting to have these candidates, there has been increasing concern about the feasibility and desirability of taking all of the compounds that may work in mice and testing them in patients with HD. There is a need to begin to prioritize leads emerging from transgenic mouse studies; however, it is difficult to compare results between compounds and laboratories, and there are also many additional factors that can affect translation to humans. Among the important issues are what constitutes an informative genetic model, what principals should be followed in designing and conducting experiments using genetic animal models, how can results from different laboratories and in different models be compared, what body of evidence is desirable to fully inform clinical decision making, and what factors contribute to the equipoise in determining whether preclinical information about a therapy makes clinical study warranted. In the context of Huntington's disease, we will review the current state of genetic models and their successes in putting forward therapeutic leads, provide a guide to assessing studies in mouse models, and discuss some of the salient issues related to translation from mice to humans.
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Affiliation(s)
- Steven M Hersch
- Neurology Service, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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Halpin C. Gene stacking in transgenic plants--the challenge for 21st century plant biotechnology. PLANT BIOTECHNOLOGY JOURNAL 2005; 3:141-55. [PMID: 17173615 DOI: 10.1111/j.1467-7652.2004.00113.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
One of the major technical hurdles impeding the advance of plant genetic engineering and biotechnology is the fact that the expression or manipulation of multiple genes in plants is still difficult to achieve. Although a small proportion of commercial genetically modified (GM) crops present 'stacked' or 'pyramided' traits, only a handful of products have been developed by introducing three or more novel genes. On the research front, a variety of conventional and more novel methods have been employed to introduce multiple genes into plants, but all techniques suffer from certain drawbacks. In this review, the potential and problems of these various techniques and strategies are discussed, and the prospects for improving these technologies in the future are presented.
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Affiliation(s)
- Claire Halpin
- Plant Research Unit, School of Life Sciences, University of Dundee at SCRI, Invergowrie, Dundee DD2 5DA, UK.
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Rommens CM. All-native DNA transformation: a new approach to plant genetic engineering. TRENDS IN PLANT SCIENCE 2004; 9:457-64. [PMID: 15337496 DOI: 10.1016/j.tplants.2004.07.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Caius M Rommens
- J.R. Simplot Company, Simplot Plant Sciences, Boise, ID 83706, USA.
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Kuiper HA, König A, Kleter GA, Hammes WP, Knudsen I. Concluding remarks. Food Chem Toxicol 2004; 42:1195-202. [PMID: 15123387 DOI: 10.1016/j.fct.2004.02.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2003] [Accepted: 02/04/2004] [Indexed: 11/23/2022]
Abstract
The most important results from the EU-sponsored ENTRANSFOOD Thematic Network project are reviewed, including the design of a detailed step-wise procedure for the risk assessment of foods derived from genetically modified crops based on the latest scientific developments, evaluation of topical risk assessment issues, and the formulation of proposals for improved risk management and public involvement in the risk analysis process.
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Affiliation(s)
- H A Kuiper
- RIKILT-Institute of Food Safety, Wageningen University & Research Centre, Bornsesteeg 45, PO Box 230, NL-6700 AE Wageningen, The Netherlands.
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König A, Cockburn A, Crevel RWR, Debruyne E, Grafstroem R, Hammerling U, Kimber I, Knudsen I, Kuiper HA, Peijnenburg AACM, Penninks AH, Poulsen M, Schauzu M, Wal JM. Assessment of the safety of foods derived from genetically modified (GM) crops. Food Chem Toxicol 2004; 42:1047-88. [PMID: 15123382 DOI: 10.1016/j.fct.2004.02.019] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2003] [Accepted: 02/04/2004] [Indexed: 11/25/2022]
Abstract
This paper provides guidance on how to assess the safety of foods derived from genetically modified crops (GM crops); it summarises conclusions and recommendations of Working Group 1 of the ENTRANSFOOD project. The paper provides an approach for adapting the test strategy to the characteristics of the modified crop and the introduced trait, and assessing potential unintended effects from the genetic modification. The proposed approach to safety assessment starts with the comparison of the new GM crop with a traditional counterpart that is generally accepted as safe based on a history of human food use (the concept of substantial equivalence). This case-focused approach ensures that foods derived from GM crops that have passed this extensive test-regime are as safe and nutritious as currently consumed plant-derived foods. The approach is suitable for current and future GM crops with more complex modifications. First, the paper reviews test methods developed for the risk assessment of chemicals, including food additives and pesticides, discussing which of these methods are suitable for the assessment of recombinant proteins and whole foods. Second, the paper presents a systematic approach to combine test methods for the safety assessment of foods derived from a specific GM crop. Third, the paper provides an overview on developments in this area that may prove of use in the safety assessment of GM crops, and recommendations for research priorities. It is concluded that the combination of existing test methods provides a sound test-regime to assess the safety of GM crops. Advances in our understanding of molecular biology, biochemistry, and nutrition may in future allow further improvement of test methods that will over time render the safety assessment of foods even more effective and informative.
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Affiliation(s)
- A König
- Harvard Center for Risk Analysis, Harvard School of Public Health, Harvard University, 718 Huntington Avenue, Boston, MA 02115, USA.
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Rommens CM, Humara JM, Ye J, Yan H, Richael C, Zhang L, Perry R, Swords K. Crop improvement through modification of the plant's own genome. PLANT PHYSIOLOGY 2004; 135:421-31. [PMID: 15133156 PMCID: PMC429395 DOI: 10.1104/pp.104.040949] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Revised: 03/10/2004] [Accepted: 03/12/2004] [Indexed: 05/17/2023]
Abstract
Plant genetic engineering has, until now, relied on the incorporation of foreign DNA into plant genomes. Public concern about the extent to which transgenic crops differ from their traditionally bred counterparts has resulted in molecular strategies and gene choices that limit, but not eliminate, the introduction of foreign DNA. Here, we demonstrate that a plant-derived (P-) DNA fragment can be used to replace the universally employed Agrobacterium transfer (T-) DNA. Marker-free P-DNAs are transferred to plant cell nuclei together with conventional T-DNAs carrying a selectable marker gene. By subsequently linking a positive selection for temporary marker gene expression to a negative selection against marker gene integration, 29% of derived regeneration events contain P-DNA insertions but lack any copies of the T-DNA. Further refinements are accomplished by employing Omega-mutated virD2 and isopentenyl transferase cytokinin genes to impair T-DNA integration and select against backbone integration, respectively. The presented methods are used to produce hundreds of marker-free and backbone-free potato (Solanum tuberosum) plants displaying reduced expression of a tuber-specific polyphenol oxidase gene in potato. The modified plants represent the first example of genetically engineered plants that only contain native DNA.
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Affiliation(s)
- Caius M Rommens
- J.R. Simplot Company, Simplot Plant Sciences, Boise, Idaho 83706, USA.
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