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Zhao Y, Kim JY, Karan R, Jung JH, Pathak B, Williamson B, Kannan B, Wang D, Fan C, Yu W, Dong S, Srivastava V, Altpeter F. Generation of a selectable marker free, highly expressed single copy locus as landing pad for transgene stacking in sugarcane. PLANT MOLECULAR BIOLOGY 2019; 100:247-263. [PMID: 30919152 DOI: 10.1007/s11103-019-00856-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 03/15/2019] [Indexed: 05/23/2023]
Abstract
A selectable marker free, highly expressed single copy locus flanked by insulators was created as landing pad for transgene stacking in sugarcane. These events displayed superior transgene expression compared to single-copy transgenic lines lacking insulators. Excision of the selectable marker gene from transgenic sugarcane lines was supported by FLPe/FRT site-specific recombination. Sugarcane, a tropical C4 grass in the genus Saccharum (Poaceae), accounts for nearly 80% of sugar produced worldwide and is also an important feedstock for biofuel production. Generating transgenic sugarcane with predictable and stable transgene expression is critical for crop improvement. In this study, we generated a highly expressed single copy locus as landing pad for transgene stacking. Transgenic sugarcane lines with stable integration of a single copy nptII expression cassette flanked by insulators supported higher transgene expression along with reduced line to line variation when compared to single copy events without insulators by NPTII ELISA analysis. Subsequently, the nptII selectable marker gene was efficiently excised from the sugarcane genome by the FLPe/FRT site-specific recombination system to create selectable marker free plants. This study provides valuable resources for future gene stacking using site-specific recombination or genome editing tools.
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Affiliation(s)
- Yang Zhao
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Jae Y Kim
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
- Department of Plant Resources, College of Industrial Science, Kongju National University, Yesan, 32439, Republic of Korea
| | - Ratna Karan
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Je H Jung
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
- Smart Farm Research Center, Institute of Natural Products, Korea Institute of Science and Technology (KIST), Gangwon-do, 25451, Republic of Korea
| | - Bhuvan Pathak
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Bruce Williamson
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Baskaran Kannan
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Duoduo Wang
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Florida - IFAS, Gainesville, FL, 32611, USA
| | - Chunyang Fan
- Syngenta Crop Protection, LLC, Research Triangle Park, NC, 27709, USA
| | - Wenjin Yu
- Syngenta Crop Protection, LLC, Research Triangle Park, NC, 27709, USA
| | - Shujie Dong
- Syngenta Crop Protection, LLC, Research Triangle Park, NC, 27709, USA
| | - Vibha Srivastava
- Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Fredy Altpeter
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida - IFAS, Gainesville, FL, 32611, USA.
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Florida - IFAS, Gainesville, FL, 32611, USA.
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Davies JP, Kumar S, Sastry-Dent L. Use of Zinc-Finger Nucleases for Crop Improvement. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 149:47-63. [PMID: 28712500 DOI: 10.1016/bs.pmbts.2017.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Over the past two decades, new technologies enabling targeted modification of plant genomes have been developed. Among these are zinc-finger nucleases (ZFNs) which are composed of engineered zinc-finger DNA-binding domains fused with a nuclease, generally the FokI nuclease. The zinc-finger domains are composed of a series of four to six 30 amino acid domains that can bind to trinucleotide sequences giving the entire DNA-binding domain specificity to 12-18 nucleotides. Since the FokI nuclease functions as a dimer, pairs of zinc-finger domains are designed to bind upstream and downstream of the cut site which increases the specificity of the complete ZFN to 24-36 nucleotides. The ability of these engineered nucleases to create targeted double-stranded breaks at designated locations throughout the genome has enabled precise deletion, addition, and editing of genes. These techniques are being used to create new genetic variation by deleting or editing endogenous gene sequences and enhancing the efficiency of transgenic product development through targeted insertion of transgenes to specific genomic locations and to sequentially add and/or delete transgenes from existing transgenic events.
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Orbegozo J, Solorzano D, Cuellar WJ, Bartolini I, Roman ML, Ghislain M, Kreuze J. Marker-free PLRV resistant potato mediated by Cre-loxP excision and RNAi. Transgenic Res 2016; 25:813-828. [PMID: 27544267 PMCID: PMC5104775 DOI: 10.1007/s11248-016-9976-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/05/2016] [Indexed: 11/17/2022]
Abstract
An inverted repeat construct corresponding to a segment of the potato leaf roll virus coat protein gene was created under control of a constitutive promoter and transferred into a transformation vector with a heat inducible Cre-loxP system to excise the nptII antibiotic resistance marker gene. Fifty-eight transgenic events were evaluated for resistance to PLRV by greenhouse inoculations, which lead to the identification of 7 highly resistant events, of which 4 were extremely resistant. This resistance was also highly effective against accumulation in subsequent tuber generations from inoculated plants, which has not been reported before. Northern blot analysis showed correlation of PLRV specific siRNA accumulation with the level of PLRV resistance. Heat mediated excision of the nptII antibiotic resistance gene in PLRV resistant events was highly efficient in one event with full excision in 71 % of treated explants. On the other hand 8 out of 10 analyzed events showed truncated T-DNA insertions lacking one of the two loxP sites as determined by PCR and confirmed by sequencing flanking regions in 2 events, suggesting cryptic LB sites in the non-coding region between the nptII gene and the flanking loxP site. Accordingly, it is proposed to modify the Cre-loxP vector by reducing the 1 kb size of the region between nptII, loxP, and the LB.
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Affiliation(s)
- Jeanette Orbegozo
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru
- West University Av. C/O Veterinary Service, El Paso, TX, 79968, USA
| | - Dennis Solorzano
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru
- Dirección de Salud (DISA) II, Ministerio de Salud, Lima 04, Peru
| | - Wilmer J Cuellar
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru
- International Center for Tropical Agriculture (CIAT), Palmira, Colombia
| | - Ida Bartolini
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru
- Servicio Nacional de Sanidad Agraria (SENASA), Lima, Peru
| | | | - Marc Ghislain
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru
- CIP, P.O. Box 25171, Nairobi, 00603, Kenya
| | - Jan Kreuze
- International Potato Center (CIP), P.O. Box 1558, Lima 12, Peru.
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Kumar S, AlAbed D, Worden A, Novak S, Wu H, Ausmus C, Beck M, Robinson H, Minnicks T, Hemingway D, Lee R, Skaggs N, Wang L, Marri P, Gupta M. A modular gene targeting system for sequential transgene stacking in plants. J Biotechnol 2015; 207:12-20. [PMID: 25913173 DOI: 10.1016/j.jbiotec.2015.04.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 03/14/2015] [Accepted: 04/03/2015] [Indexed: 11/16/2022]
Abstract
A modular, selection-based method was developed for site-specific integration of transgenes into a genomic locus to create multigene stacks. High-frequency gene targeting was obtained using zinc finger nuclease (ZFN)-mediated double-strand break (DSB) formation at a pre-defined target genomic location using a unique intron directly downstream of a promoter driving a selectable marker gene to facilitate homology between target and donor sequences. In this system, only insertion into the target locus leads to a functional selectable marker, and regeneration from random insertions of the promoterless donor construct are reduced on selection media. A new stack of transgenes can potentially be loaded with each successive cycle of gene targeting by exchanging the selectable marker gene using the intron homology. This system was tested in maize using the pat selectable marker gene, whereby up to 30% of the plants regenerated on Bialaphos-containing medium were observed to have the donor construct integrated into the target locus. Unlike previous gene targeting methods that utilize defective or partial genes for selecting targeted events, the present method exchanges fully functional genes with every cycle of targeting, thereby allowing the recycling of selectable marker genes, hypothetically for multiple generations of gene targeting.
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Affiliation(s)
- Sandeep Kumar
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
| | - Diaa AlAbed
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Andrew Worden
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Stephen Novak
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Huixia Wu
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Carla Ausmus
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Margaret Beck
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Heather Robinson
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Tatyana Minnicks
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Daren Hemingway
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Ryan Lee
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Nicole Skaggs
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Lizhen Wang
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Pradeep Marri
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
| | - Manju Gupta
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
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Nandy S, Srivastava V. Marker-free site-specific gene integration in rice based on the use of two recombination systems. PLANT BIOTECHNOLOGY JOURNAL 2012; 10:904-12. [PMID: 22686401 DOI: 10.1111/j.1467-7652.2012.00715.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Transgene integration mediated by heterologous site-specific recombination (SSR) systems into the dedicated genomic sites has been demonstrated in a few different plant species. This approach of plant transformation generates a precise site-specific integration (SSI) structure consisting of a single copy of the transgene construct. As a result, stable transgene expression correlated with promoter strength and gene copy number is observed among independent transgenic lines and faithfully transmitted through subsequent generations. Site-specific integration approaches use selectable marker genes, removal of which is necessary for the implementation of this approach as a biotechnology application. As SSR systems are also excellent tools for excising marker genes from transgene locus, a molecular strategy involving gene integration followed by marker excision, each mediated by a distinct recombination system, was earlier proposed. Experimental validation of this approach is the focus of this work. Using FLPe-FRT system for site-specific gene integration and heat-inducible Cre-lox for marker gene excision, marker-free SSI lines were developed in the first generation itself. More importantly, progeny derived from these lines inherited the marker-free locus, indicating efficient germinal transmission. Finally, as the transgene expression from SSI locus was not altered upon marker excision, this method is suitable for streamlining the production of marker-free SSI lines.
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Affiliation(s)
- Soumen Nandy
- Department of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA
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