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Zheng Y, Li Y, Zhou K, Li T, VanDusen NJ, Hua Y. Precise genome-editing in human diseases: mechanisms, strategies and applications. Signal Transduct Target Ther 2024; 9:47. [PMID: 38409199 PMCID: PMC10897424 DOI: 10.1038/s41392-024-01750-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 02/28/2024] Open
Abstract
Precise genome-editing platforms are versatile tools for generating specific, site-directed DNA insertions, deletions, and substitutions. The continuous enhancement of these tools has led to a revolution in the life sciences, which promises to deliver novel therapies for genetic disease. Precise genome-editing can be traced back to the 1950s with the discovery of DNA's double-helix and, after 70 years of development, has evolved from crude in vitro applications to a wide range of sophisticated capabilities, including in vivo applications. Nonetheless, precise genome-editing faces constraints such as modest efficiency, delivery challenges, and off-target effects. In this review, we explore precise genome-editing, with a focus on introduction of the landmark events in its history, various platforms, delivery systems, and applications. First, we discuss the landmark events in the history of precise genome-editing. Second, we describe the current state of precise genome-editing strategies and explain how these techniques offer unprecedented precision and versatility for modifying the human genome. Third, we introduce the current delivery systems used to deploy precise genome-editing components through DNA, RNA, and RNPs. Finally, we summarize the current applications of precise genome-editing in labeling endogenous genes, screening genetic variants, molecular recording, generating disease models, and gene therapy, including ex vivo therapy and in vivo therapy, and discuss potential future advances.
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Affiliation(s)
- Yanjiang Zheng
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Yifei Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Kaiyu Zhou
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Tiange Li
- Department of Cardiovascular Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Nathan J VanDusen
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Yimin Hua
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
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Yuan G, Zeng C, Shi H, Yang Y, Du J, Zou C, Ma L, Pan G, Shen Y. Engineered Expression of Vip3A in Green Tissues as a Feasible Approach for the Control of Insect Pests in Maize. INSECTS 2023; 14:803. [PMID: 37887815 PMCID: PMC10607264 DOI: 10.3390/insects14100803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 09/26/2023] [Accepted: 10/01/2023] [Indexed: 10/28/2023]
Abstract
Genetic engineering technology offers opportunities to improve many important agronomic traits in crops, including insect-resistance. However, genetically modified (GM) exogenous proteins in edible tissues of transgenic crops has become an issue of intense public concern. To advance the application of GM techniques in maize, a Cre/loxP-based strategy was developed for manipulating the transgenes in green tissues while locking them in non-green tissues. In the strategy, the site-specific excision can be used to switch on or off the expression of transgenes at specific tissues. In this work, two basic transgenic maize, named KEY, carrying the Cre gene, and LOCK, containing the Vip3A gene with a blocked element, were obtained based on their separate fusion gene cassettes. The expression level and concentration of Vip3A were observed with a high specific accumulation in the green tissues (leaf and stem), and only a small amount was observed in the root and kernel tissues in the KEY × LOCK hybrids. The insect resistance of transgenic maize against two common lepidopteran pests, Ostrinia furnacalis and Spodoptera frugiperda, was assessed in the laboratory and field. The results indicate that the hybrids possessed high resistance levels against the two pests, with mortality rates above 73.6% and damage scales below 2.4 compared with the control group. Our results suggest that the Cre/loxP-mediated genetic engineering approach has a competitive advantage in GM maize. Overall, the findings from this study are significant for providing a feasible strategy for transgenes avoiding expression in edible parts and exploring novel techniques toward the biosafety of GM plants.
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Affiliation(s)
- Guangsheng Yuan
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region of Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China
| | | | | | | | | | | | | | | | - Yaou Shen
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region of Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China
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3
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Kim HY, Sakane S, Eguileor A, Carvalho Gontijo Weber R, Lee W, Liu X, Lam K, Ishizuka K, Rosenthal SB, Diggle K, Brenner DA, Kisseleva T. The Origin and Fate of Liver Myofibroblasts. Cell Mol Gastroenterol Hepatol 2023; 17:93-106. [PMID: 37743012 PMCID: PMC10665929 DOI: 10.1016/j.jcmgh.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/14/2023] [Accepted: 09/14/2023] [Indexed: 09/26/2023]
Abstract
Liver fibrosis of different etiologies is a serious health problem worldwide. There is no effective therapy available for liver fibrosis except the removal of the underlying cause of injury or liver transplantation. Development of liver fibrosis is caused by fibrogenic myofibroblasts that are not present in the normal liver, but rather activate from liver resident mesenchymal cells in response to chronic toxic or cholestatic injury. Many studies indicate that liver fibrosis is reversible when the causative agent is removed. Regression of liver fibrosis is associated with the disappearance of activated myofibroblasts and resorption of the fibrous scar. In this review, we discuss the results of genetic tracing and cell fate mapping of hepatic stellate cells and portal fibroblasts, their specific characteristics, and potential phenotypes. We summarize research progress in the understanding of the molecular mechanisms underlying the development and reversibility of liver fibrosis, including activation, apoptosis, and inactivation of myofibroblasts.
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Affiliation(s)
- Hyun Young Kim
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Sadatsugu Sakane
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Alvaro Eguileor
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Raquel Carvalho Gontijo Weber
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California; Department of Surgery, University of California San Diego School of Medicine, La Jolla, California
| | - Wonseok Lee
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Xiao Liu
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California; Department of Surgery, University of California San Diego School of Medicine, La Jolla, California
| | - Kevin Lam
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Kei Ishizuka
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California
| | - Sara Brin Rosenthal
- Center for Computational Biology and Bioinformatics, University of California San Diego, La Jolla, California
| | - Karin Diggle
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California; Department of Surgery, University of California San Diego School of Medicine, La Jolla, California
| | - David A Brenner
- Department of Medicine, University of California San Diego School of Medicine, La Jolla, California; Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California.
| | - Tatiana Kisseleva
- Department of Surgery, University of California San Diego School of Medicine, La Jolla, California.
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Effendi SSW, Ng IS. Prospective and challenges of live bacterial therapeutics from a superhero Escherichia coli Nissle 1917. Crit Rev Microbiol 2023; 49:611-627. [PMID: 35947523 DOI: 10.1080/1040841x.2022.2109405] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/02/2022] [Accepted: 08/01/2022] [Indexed: 11/03/2022]
Abstract
Escherichia coli Nissle 1917 (EcN), the active component of Mutaflor(R), is a notable probiotic from Gram-negative to treat Crohn's disease and irritable bowel syndrome. Therefore, a comprehensive genomic database maximizes the systemic probiotic assessment to discover EcN's role in human health. Recently, advanced synthetic and genetic tools have opened up a rich area to execute EcN as "living medicines" with controllable functions. Incorporating unique biomarkers allows the engineered EcN to switch genes on and off in response to environmental cues. Since EcN holds promise as a safe nature vehicle, more studies are desired to fully realize a wide range of probiotic potential for disease treatment. This review aims to deliver a historical origin of EcN, discuss the recent promising genetic toolbox in the rational design of probiotics, and pinpoint the clinical translation and evaluation of engineered EcN in vitro and in vivo. The summary of safety concerns, strategies of biotherapeutics development, and the challenges and prospects of engineered EcN is also concluded.
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Affiliation(s)
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
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Ye X, Vaghchhipawala Z, Williams EJ, Fu C, Liu J, Lu F, Hall EL, Guo SX, Frank L, Gilbertson LA. Cre-mediated autoexcision of selectable marker genes in soybean, cotton, canola and maize transgenic plants. PLANT CELL REPORTS 2023; 42:45-55. [PMID: 36316413 DOI: 10.1007/s00299-022-02935-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Efficient selectable marker gene autoexcision in transgenic plants of soybean, cotton, canola, and maize is achieved by effective Cre recombinase expression. Selectable marker genes are often required for efficient generation of transgenic plants in plant transformation but are not desired once the transgenic events are obtained. We have developed Cre/loxP autoexcision systems to remove selectable marker genes in soybean, cotton, canola and maize. We tested a set of vectors with diverse promoters and identified promising promoters to drive cre expression for each of the four crops. We evaluated both the efficiency of generating primary transgenic events with low transgene copy numbers, and the frequency of marker-free progeny in the next generation. The best performing vectors gave no obvious decrease in the transformation frequency in each crop and generated homozygous marker-free progeny in the next generation. We found that effective expression of Cre recombinase for marker gene autoexcision can be species dependent. Among the vectors tested, the best autoexcision frequency (41%) in soybean transformation came from using the soybean RSP1 promoter for cre expression. The cre gene expressed by soybean RSP1 promoter with an Arabidopsis AtpE intron delivered the best autoexcision frequency (69%) in cotton transformation. The cre gene expressed by the embryo-specific eUSP88 promoter from Vicia faba conferred the best marker excision frequency (32%) in canola transformation. Finally, the cre gene expressed by the rice CDC45-1 promoter resulted in 44% autoexcision in maize transformation. The Cre/loxP recombinase system enables the generation of selectable marker-free transgenic plants for commercial product development in four agriculturally important crops and provides further improvement opportunities for more specific and better marker excision efficiency.
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Affiliation(s)
- Xudong Ye
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA.
| | | | - Edward J Williams
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
- Wisconsin Crop Innovation Center, 8520 University Green, Middleton, WI, 53562, USA
| | - Changlin Fu
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
| | - Jinyuan Liu
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
| | - Fengming Lu
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
| | - Erin L Hall
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
| | - Shirley X Guo
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
| | - LaRee Frank
- Bayer Crop Science, 700 Chesterfield Pkwy, St. Louis, MO, 63017, USA
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Ren H, Yin A, Wu P, Zhou H, Zhou J, Yu Y, Lu H. Establishment of a Cre-loxP System Based on a Leaky LAC4 Promoter and an Unstable panARS Element in Kluyveromyces marxianus. Microorganisms 2022; 10:microorganisms10061240. [PMID: 35744758 PMCID: PMC9227491 DOI: 10.3390/microorganisms10061240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/12/2022] [Accepted: 06/15/2022] [Indexed: 02/01/2023] Open
Abstract
The Cre-loxP system produces structural variations, such as deletion, duplication, inversion and translocation, at specific loci and induces chromosomal rearrangements in the genome. To achieve chromosomal rearrangements in Kluyveromyces marxianus, the positions and sequences of centromeres were identified in this species for the first time. Next, a Cre-loxP system was established in K. marxianus. In this system, the Cre recombinase was expressed from a leaky LAC4 promoter in a plasmid to alleviate the cytotoxicity of Cre, and the unstable plasmid contained a panARS element to facilitate the clearance of the plasmid from the cells. By using LAC4 as a reporter gene, the recombination frequencies between loxP sites or loxPsym sites were 99% and 73%, respectively. A K. marxianus strain containing 16 loxPsym sites in the genome was constructed. The recombination frequency of large-scale chromosomal rearrangements between 16 loxPsym sites was up to 38.9%. Our study provides valuable information and tools for studying chromosomal structures and functions in K. marxianus.
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Affiliation(s)
- Haiyan Ren
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
| | - Anqi Yin
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
| | - Pingping Wu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
| | - Huanyu Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
| | - Jungang Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
| | - Yao Yu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
- Correspondence: (Y.Y.); (H.L.)
| | - Hong Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200438, China; (H.R.); (A.Y.); (P.W.); (H.Z.); (J.Z.)
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai 200438, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
- Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai 200237, China
- Correspondence: (Y.Y.); (H.L.)
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7
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Artificial nondirectional site-specific recombination systems. iScience 2022; 25:103716. [PMID: 35072008 PMCID: PMC8762395 DOI: 10.1016/j.isci.2021.103716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/23/2021] [Accepted: 12/29/2021] [Indexed: 11/22/2022] Open
Abstract
Site-specific recombination systems (SRSs) are widely used in studies on synthetic biology and related disciplines. Nondirectional SRSs can randomly trigger excision, integration, reversal, and translocation, which are effective tools to achieve large-scale genome recombination. In this study, we designed 6 new nondirectional SRSs named Vika/voxsym1-4 and Dre/roxsym1-2. All 6 artificial nondirectional SRSs were able to generate random deletion and inversion in Saccharomyces cerevisiae. Moreover, all six SRSs were orthogonal to Cre/loxPsym. The pairwise orthogonal nondirected SRSs can simultaneously initiate large-scale and independent gene recombination in two different regions of the genome, which could not be accomplished using previous orthogonal systems. These SRSs were found to be robust while working in the cells at different growth stages, as well as in the different spatial structure of the chromosome. These artificial pairwise orthogonal nondirected SRSs offer newfound potential for site-specific recombination in synthetic biology. Designed six new artificial nondirectional site-specific recombination systems Pairwise orthogonal nondirected recombination systems in yeast The deletion efficiency of systems is far greater than the inversion efficiency These nondirectional recombination systems were found to be robust
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Zhang Z, Guo Y, Marasigan KM, Conner JA, Ozias-Akins P. Gene activation via Cre/lox-mediated excision in cowpea (Vigna unguiculata). PLANT CELL REPORTS 2022; 41:119-138. [PMID: 34591155 PMCID: PMC8803690 DOI: 10.1007/s00299-021-02789-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/15/2021] [Indexed: 05/11/2023]
Abstract
Expression of Cre recombinase by AtRps5apro or AtDD45pro enabled Cre/lox-mediated recombination at an early embryonic developmental stage upon crossing, activating transgenes in the hybrid cowpea and tobacco. Genetic engineering ideally results in precise spatiotemporal control of transgene expression. To activate transgenes exclusively in a hybrid upon fertilization, we evaluated a Cre/lox-mediated gene activation system with the Cre recombinase expressed by either AtRps5a or AtDD45 promoters that showed activity in egg cells and young embryos. In crosses between Cre recombinase lines and transgenic lines harboring a lox-excision reporter cassette with ZsGreen driven by the AtUbq3 promoter after Cre/lox-mediated recombination, we observed complete excision of the lox-flanked intervening DNA sequence between the AtUbq3pro and the ZsGreen coding sequence in F1 progeny upon genotyping but no ZsGreen expression in F1 seeds or seedlings. The incapability to observe ZsGreen fluorescence was attributed to the activity of the AtUbq3pro. Strong ZsGreen expression in F1 seeds was observed after recombination when ZsGreen was driven by the AtUbq10 promoter. Using the AtDD45pro to express Cre resulted in more variation in recombination frequencies between transgenic lines and crosses. Regardless of the promoter used to regulate Cre, mosaic F1 progeny were rare, suggesting gene activation at an early embryo-developmental stage. Observation of ZsGreen-expressing tobacco embryos at the globular stage from crosses with the AtRps5aproCre lines pollinated by the AtUbq3prolox line supported the early activation mode.
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Affiliation(s)
- Zhifen Zhang
- Department of Horticulture and Institute of Plant Breeding, Genetics and Genomics, University of Georgia, 2356 Rainwater Rd, Tifton, GA, 31793, USA
| | - Yinping Guo
- Department of Horticulture and Institute of Plant Breeding, Genetics and Genomics, University of Georgia, 2356 Rainwater Rd, Tifton, GA, 31793, USA
| | - Kathleen Monfero Marasigan
- Department of Horticulture and Institute of Plant Breeding, Genetics and Genomics, University of Georgia, 2356 Rainwater Rd, Tifton, GA, 31793, USA
| | - Joann A Conner
- Department of Horticulture and Institute of Plant Breeding, Genetics and Genomics, University of Georgia, 2356 Rainwater Rd, Tifton, GA, 31793, USA
| | - Peggy Ozias-Akins
- Department of Horticulture and Institute of Plant Breeding, Genetics and Genomics, University of Georgia, 2356 Rainwater Rd, Tifton, GA, 31793, USA.
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9
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Yang C, Ge J, Fu X, Luo K, Xu C. Dual Reproductive Cell-Specific Promoter-Mediated Split-Cre/LoxP System Suitable for Exogenous Gene Deletion in Hybrid Progeny of Transgenic Arabidopsis. Int J Mol Sci 2021; 22:5080. [PMID: 34064885 PMCID: PMC8151399 DOI: 10.3390/ijms22105080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 01/02/2023] Open
Abstract
Genetically modified (GM) crops possess some superior characteristics, such as high yield and insect resistance, but their biosafety has aroused broad public concern. Some genetic engineering technologies have recently been proposed to remove exogenous genes from GM crops. Few approaches have been applied to maintain advantageous traits, but excising exogenous genes in seeds or fruits from these hybrid crops has led to the generation of harvested food without exogenous genes. In a previous study, split-Cre mediated by split intein could recombine its structure and restore recombination activity in hybrid plants. In the current study, the recombination efficiency of split-Cre under the control of ovule-specific or pollen-specific promoters was validated by hybridization of transgenic Arabidopsis containing the improved expression vectors. In these vectors, all exogenous genes were flanked by two loxP sites, including promoters, resistance genes, reporter genes, and split-Cre genes linked to the reporter genes via LP4/2A. A gene deletion system was designed in which NCre was driven by proDD45, and CCre was driven by proACA9 and proDLL. Transgenic lines containing NCre were used as paternal lines to hybridize with transgenic lines containing CCre. Because this hybridization method results in no co-expression of the NCre and CCre genes controlled by reproduction-specific promoters in the F1 progeny, the desirable characteristics could be retained. After self-crossing in F1 progeny, the expression level and protein activity of reporter genes were detected, and confirmed that recombination of split-Cre had occurred and the exogenous genes were partially deleted. The gene deletion efficiency represented by the quantitative measurements of GUS enzyme activity was over 59%, with the highest efficiency of 73% among variable hybrid combinations. Thus, in the present study a novel dual reproductive cell-specific promoter-mediated gene deletion system was developed that has the potential to take advantage of the merits of GM crops while alleviating biosafety concerns.
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Affiliation(s)
| | | | | | - Keming Luo
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing 400715, China; (C.Y.); (J.G.); (X.F.)
| | - Changzheng Xu
- Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Key Laboratory of Eco-Environments of Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing 400715, China; (C.Y.); (J.G.); (X.F.)
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10
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Glowa D, Comelli P, Chandler JW, Werr W. Clonal sector analysis and cell ablation confirm a function for DORNROESCHEN-LIKE in founder cells and the vasculature in Arabidopsis. PLANTA 2021; 253:27. [PMID: 33420666 PMCID: PMC7794208 DOI: 10.1007/s00425-020-03545-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 12/20/2020] [Indexed: 06/02/2023]
Abstract
Inducible lineage analysis and cell ablation via conditional toxin expression in cells expressing the DORNRÖSCHEN-LIKE transcription factor represent an effective and complementary adjunct to conventional methods of functional gene analysis. Classical methods of functional gene analysis via mutational and expression studies possess inherent limitations, and therefore, the function of a large proportion of transcription factors remains unknown. We have employed two complementary, indirect methods to obtain functional information for the AP2/ERF transcription factor DORNRÖSCHEN-LIKE (DRNL), which is dynamically expressed in flowers and marks lateral organ founder cells. An inducible, two-component Cre-Lox system was used to express beta-glucuronidase GUS in cells expressing DRNL, to perform a sector analysis that reveals lineages of cells that transiently expressed DRNL throughout plant development. In a complementary approach, an inducible system was used to ablate cells expressing DRNL using diphtheria toxin A chain, to visualise the phenotypic consequences. These complementary analyses demonstrate that DRNL functionally marks founder cells of leaves and floral organs. Clonal sectors also included the vasculature of the leaves and petals, implicating a previously unidentified role for DRNL in provasculature development, which was confirmed in cotyledons by closer analysis of drnl mutants. Our findings demonstrate that inducible gene-specific lineage analysis and cell ablation via conditional toxin expression represent an effective and informative adjunct to conventional methods of functional gene analysis.
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Affiliation(s)
- Dorothea Glowa
- Developmental Biology, Institute of Zoology, Cologne Biocenter, Cologne University, Zülpicher Straße 47b, 50674, Cologne, Germany
| | - Petra Comelli
- Developmental Biology, Institute of Zoology, Cologne Biocenter, Cologne University, Zülpicher Straße 47b, 50674, Cologne, Germany
| | - John W Chandler
- Developmental Biology, Institute of Zoology, Cologne Biocenter, Cologne University, Zülpicher Straße 47b, 50674, Cologne, Germany
| | - Wolfgang Werr
- Developmental Biology, Institute of Zoology, Cologne Biocenter, Cologne University, Zülpicher Straße 47b, 50674, Cologne, Germany.
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11
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Site-Specific Recombination with Inverted Target Sites: A Cautionary Tale of Dicentric and Acentric Chromosomes. Genetics 2020; 215:923-930. [PMID: 32586890 DOI: 10.1534/genetics.120.303394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 06/22/2020] [Indexed: 11/18/2022] Open
Abstract
Site-specific recombinases are widely used tools for analysis of genetics, development, and cell biology, and many schemes have been devised to alter gene expression by recombinase-mediated DNA rearrangements. Because the FRT and lox target sites for the commonly used FLP and Cre recombinases are asymmetrical, and must pair in the same direction to recombine, construct design must take into account orientation of the target sites. Both direct and inverted configurations have been used. However, the outcome of recombination between target sites on sister chromatids is frequently overlooked. This is especially consequential with inverted target sites, where exchange between oppositely oriented target sites on sisters will produce dicentric and acentric chromosomes. By using constructs that have inverted target sites in Drosophila melanogaster and in mice, we show here that dicentric chromosomes are produced in the presence of recombinase, and that the frequency of this event is quite high. The negative effects on cell viability and behavior can be significant, and should be considered when using such constructs.
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12
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Srirangan K, Loignon M, Durocher Y. The use of site-specific recombination and cassette exchange technologies for monoclonal antibody production in Chinese Hamster ovary cells: retrospective analysis and future directions. Crit Rev Biotechnol 2020; 40:833-851. [DOI: 10.1080/07388551.2020.1768043] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kajan Srirangan
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Martin Loignon
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Yves Durocher
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, Québec, Canada
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13
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Jat SK, Bhattacharya J, Sharma MK. Nanomaterial based gene delivery: a promising method for plant genome engineering. J Mater Chem B 2020; 8:4165-4175. [PMID: 32285905 DOI: 10.1039/d0tb00217h] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nanomaterials have attracted considerable attention from researchers in recent years due to their unique architecture and small dimensions. Significant progress has been made in the therapeutics, diagnostics, and delivery of biomolecules in animal cells. However, nanotechnology is still in its infancy in plant science. Nanotechnology offers tremendous opportunities for crop improvement and would make significant contributions to increase agricultural productivity. There are several reports where nanomaterial-induced improvement of the agronomic traits has been successfully achieved. However, very little is known about the interactions of nanomaterials with plant cells and the mechanism of internalization and delivery of biomolecules using nanoparticles as a carrier. Due to the presence of the cell wall, the delivery of biomolecules such as nucleic acids is a major challenge, which limits the application of nanomaterials in genetic engineering-mediated crop improvement. However, in recent years, the use of various nanomaterials like carbon nanotubes, magnetic nanoparticles, mesoporous silica nanoparticles, etc. for nucleic acid delivery in plant cells has been reported as proof of concept. Here, we intend to update researchers about the use of various nanomaterials as a novel gene delivery tool for plant genetic engineering. This review also explores the progress made in nanoparticle-mediated nucleic acid delivery in plant cells and their role in plant genome engineering.
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Affiliation(s)
- Sanjeev K Jat
- Crop Genetics & Informatics Group, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
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14
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Ramkumar TR, Lenka SK, Arya SS, Bansal KC. A Short History and Perspectives on Plant Genetic Transformation. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2020; 2124:39-68. [PMID: 32277448 DOI: 10.1007/978-1-0716-0356-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plant genetic transformation is an important technological advancement in modern science, which has not only facilitated gaining fundamental insights into plant biology but also started a new era in crop improvement and commercial farming. However, for many crop plants, efficient transformation and regeneration still remain a challenge even after more than 30 years of technical developments in this field. Recently, FokI endonuclease-based genome editing applications in plants offered an exciting avenue for augmenting crop productivity but it is mainly dependent on efficient genetic transformation and regeneration, which is a major roadblock for implementing genome editing technology in plants. In this chapter, we have outlined the major historical developments in plant genetic transformation for developing biotech crops. Overall, this field needs innovations in plant tissue culture methods for simplification of operational steps for enhancing the transformation efficiency. Similarly, discovering genes controlling developmental reprogramming and homologous recombination need considerable attention, followed by understanding their role in enhancing genetic transformation efficiency in plants. Further, there is an urgent need for exploring new and low-cost universal delivery systems for DNA/RNA and protein into plants. The advancements in synthetic biology, novel vector systems for precision genome editing and gene integration could potentially bring revolution in crop-genetic potential enhancement for a sustainable future. Therefore, efficient plant transformation system standardization across species holds the key for translating advances in plant molecular biology to crop improvement.
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Affiliation(s)
- Thakku R Ramkumar
- Agronomy Department, IFAS, University of Florida, Gainesville, FL, USA
| | - Sangram K Lenka
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India
| | - Sagar S Arya
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India
| | - Kailash C Bansal
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India.
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15
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Lansing F, Paszkowski-Rogacz M, Schmitt LT, Schneider PM, Rojo Romanos T, Sonntag J, Buchholz F. A heterodimer of evolved designer-recombinases precisely excises a human genomic DNA locus. Nucleic Acids Res 2020; 48:472-485. [PMID: 31745551 PMCID: PMC7107906 DOI: 10.1093/nar/gkz1078] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 10/29/2019] [Accepted: 11/04/2019] [Indexed: 01/04/2023] Open
Abstract
Site-specific recombinases (SSRs) such as the Cre/loxP system are useful genome engineering tools that can be repurposed by altering their DNA-binding specificity. However, SSRs that delete a natural sequence from the human genome have not been reported thus far. Here, we describe the generation of an SSR system that precisely excises a 1.4 kb fragment from the human genome. Through a streamlined process of substrate-linked directed evolution we generated two separate recombinases that, when expressed together, act as a heterodimer to delete a human genomic sequence from chromosome 7. Our data indicates that designer-recombinases can be generated in a manageable timeframe for precision genome editing. A large-scale bioinformatics analysis suggests that around 13% of all human protein-coding genes could be targetable by dual designer-recombinase induced genomic deletion (dDRiGD). We propose that heterospecific designer-recombinases, which work independently of the host DNA repair machinery, represent an efficient and safe alternative to nuclease-based genome editing technologies.
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Affiliation(s)
- Felix Lansing
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Maciej Paszkowski-Rogacz
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Lukas Theo Schmitt
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Paul Martin Schneider
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Teresa Rojo Romanos
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Jan Sonntag
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
| | - Frank Buchholz
- Medical Faculty and University Hospital Carl Gustav Carus, UCC Section Medical Systems Biology, TU Dresden, 01307 Dresden, Germany
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16
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Nguyen BN, Portnoy DA. An Inducible Cre- lox System to Analyze the Role of LLO in Listeria monocytogenes Pathogenesis. Toxins (Basel) 2020; 12:E38. [PMID: 31936068 PMCID: PMC7020405 DOI: 10.3390/toxins12010038] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/14/2019] [Accepted: 12/31/2019] [Indexed: 11/16/2022] Open
Abstract
Listeriolysin O (LLO) is a pore-forming cytolysin that allows Listeria monocytogenes to escape from phagocytic vacuoles and enter the host cell cytosol. LLO is expressed continuously during infection, but it has been a challenge to evaluate the importance of LLO secreted in the host cell cytosol because deletion of the gene encoding LLO (hly) prevents localization of L. monocytogenes to the cytosol. Here, we describe a L. monocytogenes strain (hlyfl) in which hly is flanked by loxP sites and Cre recombinase is under the transcriptional control of the L. monocytogenesactA promoter, which is highly induced in the host cell cytosol. In less than 2 h after infection of bone marrow-derived macrophages (BMMs), bacteria were 100% non-hemolytic. hlyfl grew intracellularly to levels 10-fold greater than wildtype L. monocytogenes and was less cytotoxic. In an intravenous mouse model, 90% of bacteria were non-hemolytic within three hours in the spleen and eight hours in the liver. The loss of LLO led to a 2-log virulence defect in the spleen and a 4-log virulence defect in the liver compared to WT L. monocytogenes. Thus, the production of LLO in the cytosol has significant impact on the pathogenicity of L. monocytogenes.
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Affiliation(s)
- Brittney N. Nguyen
- Graduate Group in Microbiology, University of California, Berkeley, CA 94720, USA;
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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17
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Du D, Jin R, Guo J, Zhang F. Construction of Marker-Free Genetically Modified Maize Using a Heat-Inducible Auto-Excision Vector. Genes (Basel) 2019; 10:genes10050374. [PMID: 31108922 PMCID: PMC6562874 DOI: 10.3390/genes10050374] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 11/30/2022] Open
Abstract
Gene modification is a promising tool for plant breeding, and gradual application from the laboratory to the field. Selectable marker genes (SMG) are required in the transformation process to simplify the identification of transgenic plants; however, it is more desirable to obtain transgenic plants without selection markers. Transgene integration mediated by site-specific recombination (SSR) systems into the dedicated genomic sites has been demonstrated in a few different plant species. Here, we present an auto-elimination vector system that uses a heat-inducible Cre to eliminate the selectable marker from transgenic maize, without the need for repeated transformation or sexual crossing. The vector combines an inducible site-specific recombinase (hsp70::Cre) that allows for the precise elimination of the selectable marker gene egfp upon heating. This marker gene is used for the initial positive selection of transgenic tissue. The egfp also functions as a visual marker to demonstrate the effectiveness of the heat-inducible Cre. A second marker gene for anthocyanin pigmentation (Rsc) is located outside of the region eliminated by Cre and is used for the identification of transgenic offspring in future generations. Using the heat-inducible auto-excision vector, marker-free transgenic maize plants were obtained in a precisely controlled genetic modification process. Genetic and molecular analyses indicated that the inducible auto-excision system was tightly controlled, with highly efficient DNA excision, and provided a highly reliable method to generate marker-free transgenic maize.
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Affiliation(s)
- Dengxiang Du
- National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Ruchang Jin
- National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jinjie Guo
- National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Fangdong Zhang
- National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
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18
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Pathak BP, Pruett E, Guan H, Srivastava V. Utility of I-SceI and CCR5-ZFN nucleases in excising selectable marker genes from transgenic plants. BMC Res Notes 2019; 12:272. [PMID: 31088537 PMCID: PMC6518718 DOI: 10.1186/s13104-019-4304-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/04/2019] [Indexed: 11/21/2022] Open
Abstract
Objectives Removal of selection marker genes from transgenic plants is highly desirable for their regulatory approval and public acceptance. This study evaluated the use of two nucleases, the yeast homing endonuclease, I-SceI, and the designed zinc finger nuclease, CCR5-ZFN, in excising marker genes from plants using rice and Arabidopsis as the models. Results In an in vitro culture assay, both nucleases were effective in precisely excising the DNA fragments marked by the nuclease target sites. However, rice cultures were found to be refractory to transformation with the I-SceI and CCR5-ZFN overexpressing constructs. The inducible I-SceI expression was also problematic in rice as the progeny of the transgenic lines expressing the heat-inducible I-SceI did not inherit the functional gene. On the other hand, heat-inducible I-SceI expression in Arabidopsis was effective in creating somatic excisions in transgenic plants but ineffective in generating heritable excisions. The inducible expression of CCR5-ZFN in rice, although transmitted stably to the progeny, appeared ineffective in creating detectable excisions. Therefore, toxicity of these nucleases in plant cells poses major bottleneck in their application in plant biotechnology, which could be avoided by expressing them transiently in cultures in vitro. Electronic supplementary material The online version of this article (10.1186/s13104-019-4304-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bhuvan P Pathak
- Dept. of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA.,Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
| | - Eliott Pruett
- Dept. of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA.,Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
| | - Huazhong Guan
- Dept. of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA.,Fujian Provincial Key Laboratory of Crop Breeding, Fujian Agricultural & Forestry University, Fuzhou, China
| | - Vibha Srivastava
- Dept. of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA. .,Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA. .,Dept. of Horticulture, University of Arkansas, Fayetteville, AR, USA.
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19
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Furuhata Y, Sakai A, Murakami T, Morikawa M, Nakamura C, Yoshizumi T, Fujikura U, Nishida K, Kato Y. A method using electroporation for the protein delivery of Cre recombinase into cultured Arabidopsis cells with an intact cell wall. Sci Rep 2019; 9:2163. [PMID: 30770845 PMCID: PMC6377677 DOI: 10.1038/s41598-018-38119-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/13/2018] [Indexed: 11/09/2022] Open
Abstract
Genome engineering in plants is highly dependent on the availability of effective molecular techniques. Despite vast quantities of research, genome engineering in plants is still limited in terms of gene delivery, which requires the use of infectious bacteria or harsh conditions owing to the difficulty delivering biomaterial into plant cells through the cell wall. Here, we describe a method that uses electroporation-mediated protein delivery into cultured Arabidopsis thaliana cells possessing an intact cell wall, and demonstrate Cre-mediated site-specific recombination. By optimizing conditions for the electric pulse, protein concentration, and electroporation buffer, we were able to achieve efficient and less-toxic protein delivery into Arabidopsis thaliana cells with 83% efficiency despite the cell wall. To the best of our knowledge, this is the first report demonstrating the electroporation-mediated protein delivery of Cre recombinase to achieve nucleic acid-free genome engineering in plant cells possessing an intact cell wall.
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Affiliation(s)
- Yuichi Furuhata
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan
| | - Ayako Sakai
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan
| | - Tomi Murakami
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan
| | - Mone Morikawa
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan
- Department of Biotechnology and Life Science, Tokyo University Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Chikashi Nakamura
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan
- Department of Biotechnology and Life Science, Tokyo University Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Takeshi Yoshizumi
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Ushio Fujikura
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Keiji Nishida
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Yoshio Kato
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8566, Japan.
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20
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Fraczek MG, Naseeb S, Delneri D. History of genome editing in yeast. Yeast 2018; 35:361-368. [PMID: 29345746 PMCID: PMC5969250 DOI: 10.1002/yea.3308] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 12/27/2022] Open
Abstract
For thousands of years humans have used the budding yeast Saccharomyces cerevisiae for the production of bread and alcohol; however, in the last 30-40 years our understanding of the yeast biology has dramatically increased, enabling us to modify its genome. Although S. cerevisiae has been the main focus of many research groups, other non-conventional yeasts have also been studied and exploited for biotechnological purposes. Our experiments and knowledge have evolved from recombination to high-throughput PCR-based transformations to highly accurate CRISPR methods in order to alter yeast traits for either research or industrial purposes. Since the release of the genome sequence of S. cerevisiae in 1996, the precise and targeted genome editing has increased significantly. In this 'Budding topic' we discuss the significant developments of genome editing in yeast, mainly focusing on Cre-loxP mediated recombination, delitto perfetto and CRISPR/Cas.
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Affiliation(s)
- Marcin G. Fraczek
- The University of Manchester, Faculty of Biology, Medicine and HealthManchester Institute of BiotechnologyManchesterM1 7DNUK
| | - Samina Naseeb
- The University of Manchester, Faculty of Biology, Medicine and HealthManchester Institute of BiotechnologyManchesterM1 7DNUK
| | - Daniela Delneri
- The University of Manchester, Faculty of Biology, Medicine and HealthManchester Institute of BiotechnologyManchesterM1 7DNUK
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21
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Lukan T, Machens F, Coll A, Baebler Š, Messerschmidt K, Gruden K. Plant X-tender: An extension of the AssemblX system for the assembly and expression of multigene constructs in plants. PLoS One 2018; 13:e0190526. [PMID: 29300787 PMCID: PMC5754074 DOI: 10.1371/journal.pone.0190526] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 12/15/2017] [Indexed: 11/24/2022] Open
Abstract
Cloning multiple DNA fragments for delivery of several genes of interest into the plant genome is one of the main technological challenges in plant synthetic biology. Despite several modular assembly methods developed in recent years, the plant biotechnology community has not widely adopted them yet, probably due to the lack of appropriate vectors and software tools. Here we present Plant X-tender, an extension of the highly efficient, scar-free and sequence-independent multigene assembly strategy AssemblX, based on overlap-depended cloning methods and rare-cutting restriction enzymes. Plant X-tender consists of a set of plant expression vectors and the protocols for most efficient cloning into the novel vector set needed for plant expression and thus introduces advantages of AssemblX into plant synthetic biology. The novel vector set covers different backbones and selection markers to allow full design flexibility. We have included ccdB counterselection, thereby allowing the transfer of multigene constructs into the novel vector set in a straightforward and highly efficient way. Vectors are available as empty backbones and are fully flexible regarding the orientation of expression cassettes and addition of linkers between them, if required. We optimised the assembly and subcloning protocol by testing different scar-less assembly approaches: the noncommercial SLiCE and TAR methods and the commercial Gibson assembly and NEBuilder HiFi DNA assembly kits. Plant X-tender was applicable even in combination with low efficient homemade chemically competent or electrocompetent Escherichia coli. We have further validated the developed procedure for plant protein expression by cloning two cassettes into the newly developed vectors and subsequently transferred them to Nicotiana benthamiana in a transient expression setup. Thereby we show that multigene constructs can be delivered into plant cells in a streamlined and highly efficient way. Our results will support faster introduction of synthetic biology into plant science.
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Affiliation(s)
- Tjaša Lukan
- National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana, Slovenia
- International Postgraduate School, Ljubljana, Slovenia
- * E-mail:
| | - Fabian Machens
- University of Potsdam, Cell2Fab Research Unit, Potsdam, Germany
| | - Anna Coll
- National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana, Slovenia
| | - Špela Baebler
- National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana, Slovenia
| | | | - Kristina Gruden
- National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana, Slovenia
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22
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Chen H, Luo J, Zheng P, Zhang X, Zhang C, Li X, Wang M, Huang Y, Liu X, Jan M, Liu Y, Hu P, Tu J. Application of Cre-lox gene switch to limit the Cry expression in rice green tissues. Sci Rep 2017; 7:14505. [PMID: 29109405 PMCID: PMC5673937 DOI: 10.1038/s41598-017-14679-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 10/17/2017] [Indexed: 11/09/2022] Open
Abstract
The presence of genetically modified (GM) protein in the endosperm is important information for the public when considering the biological safety of transgenic rice. To limit the expression of GM proteins to rice green tissues, we developed a modified Cre-lox gene switch using two cassettes named KEY and LOCK. KEY contains a nuclear-localized Cre recombinase driven by the green-tissue-specific promoter rbcS. LOCK contains a Nos terminator (NosT), which is used to block the expression of the gene of interest (GOI), bounded by two loxP sites. When KEY and LOCK are pyramided into hybrid rice, a complete gene switch system is formed. The Cre recombinase from KEY excises loxP-NosT in LOCK and unlocks the GOI in green tissues but keeps it locked in the endosperm. This regulatory effect was demonstrated by eYFP and Bt expression assays. The presence of eYFP and Cre were confirmed in the leaf, sheath, stem, and glume but not in the root, anther or seed of the gene-switch-controlled eYFP hybrids. Meanwhile, gene switch-controlled Bt hybrid rice not only confined the expression of Bt protein to the green tissues but also showed high resistance to striped stem borers and leaffolders.
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Affiliation(s)
- Hao Chen
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Ju Luo
- State Key Laboratory of Rice Biology, China National Rice Research Institute. Ti-Yu-Chang Road No 359, Hangzhou, 310006, China
| | - Peng Zheng
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Xiaobo Zhang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Cuicui Zhang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Xinyuan Li
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Mugui Wang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Yuqing Huang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Xuejiao Liu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Mehmood Jan
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Yujun Liu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China
| | - Peisong Hu
- State Key Laboratory of Rice Biology, China National Rice Research Institute. Ti-Yu-Chang Road No 359, Hangzhou, 310006, China.
| | - Jumin Tu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Yu-Hang-Tang Road No 866, Hangzhou, 310058, China.
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23
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Cold inducible promoter driven Cre-lox system proved to be highly efficient for marker gene excision in transgenic barley. J Biotechnol 2017; 265:15-24. [PMID: 29103986 DOI: 10.1016/j.jbiotec.2017.10.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 10/16/2017] [Accepted: 10/26/2017] [Indexed: 12/12/2022]
Abstract
A Cre-lox based auto-excision strategy has been adapted for barley, capable of cre and selectable marker gene (SMG) removal. The cold inducible wheat promoter called wcs120 was utilised for driving Cre expression. The binary vector was carrying the transgene (uidA) and a so called 'recombination cassette' flanked by the lox sequences. This part included both the recombinase gene and the SMG (bar) under the control of a constitutive promoter. T0, T1 and T2 transgenic plants were subjected to low temperature (at 4°C, 10°C and 12°C) at different developmental stages to induce recombination. The presence of uidA, cre, and bar genes and recombination footprints were studied by PCR and DNA sequencing, while cre transcription was followed by qRT-PCR. These analyses indicated that, cold treatment of the germinating seeds (4°C for 3days) followed by plant growing at higher temperature (24°C) has been the most efficient (90-100%), and this treatment lead to heritable changes in the genome. Thermal separation of Cre accumulation (at low temperature) from Cre enzyme activity (at higher temperature) could have prevented the premature excision of its own encoding gene, and lead to high expression level thereby increasing recombination frequency.
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24
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NEMATPOUR F, MAHBOUDI F, KHALAJ V, VAZIRI B, AHMADI S, AHMADI M, EBADAT S, DAVAMI F. Optimization of monoclonal antibody expression in CHOcells by employing epigenetic gene regulation tools. Turk J Biol 2017. [DOI: 10.3906/biy-1702-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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25
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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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Pradhan S, Chakraborty A, Sikdar N, Chakraborty S, Bhattacharyya J, Mitra J, Manna A, Dutta Gupta S, Sen SK. Marker-free transgenic rice expressing the vegetative insecticidal protein (Vip) of Bacillus thuringiensis shows broad insecticidal properties. PLANTA 2016; 244:789-804. [PMID: 27165311 DOI: 10.1007/s00425-016-2535-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/15/2016] [Indexed: 06/05/2023]
Abstract
Genetically engineered rice lines with broad insecticidal properties against major lepidopteran pests were generated using a synthetic, truncated form of vegetative insecticidal protein (Syn vip3BR) from Bacillus thuringiensis. The selectable marker gene and the redundant transgene(s) were eliminated through Cre/ lox mediated recombination and genetic segregation to make consumer friendly Bt -rice. For sustainable resistance against lepidopteran insect pests, chloroplast targeted synthetic version of bioactive core component of a vegetative insecticidal protein (Syn vip3BR) of Bacillus thuringiensis was expressed in rice under the control of green-tissue specific ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit gene promoter. The transgenic plants (in Oryza sativa indica Swarna cultivar) showed high insect mortality rate in vitro against major rice pests, yellow stem borer (Scirpophaga incertulas), rice leaf folder (Cnaphalocrocis medinalis) and rice horn caterpillar (Melanitis leda ismene) in T1 generation, indicating insecticidal potency of Syn vip3BR. Under field conditions, the T1 plants showed considerable resistance against leaf folders and stem borers. The expression cassette (vip-lox-hpt-lox) as well as another vector with chimeric cre recombinase gene under constitutive rice ubiquitin1 gene promoter was designed for the elimination of selectable marker hygromycin phosphotransferase (hptII) gene. Crossing experiments were performed between T1 plants with single insertion site of vip-lox-hpt-lox T-DNA and one T1 plant with moderate expression of cre recombinase with linked bialaphos resistance (syn bar) gene. Marker gene excision was achieved in hybrids with up to 41.18 % recombination efficiency. Insect resistant transgenic lines, devoid of selectable marker and redundant transgene(s) (hptII + cre-syn bar), were established in subsequent generation through genetic segregation.
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Affiliation(s)
- Subrata Pradhan
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
| | - Anirban Chakraborty
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Narattam Sikdar
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Saikat Chakraborty
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Jagannath Bhattacharyya
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Joy Mitra
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Anulina Manna
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Snehasish Dutta Gupta
- Department of Agricultural and Food Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Soumitra Kumar Sen
- Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
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Abstract
The bacteriophage λ Red homologous recombination system has been studied over the past 50 years as a model system to define the mechanistic details of how organisms exchange DNA segments that share extended regions of homology. The λ Red system proved useful as a system to study because recombinants could be easily generated by co-infection of genetically marked phages. What emerged from these studies was the recognition that replication of phage DNA was required for substantial Red-promoted recombination in vivo, and the critical role that double-stranded DNA ends play in allowing the Red proteins access to the phage DNA chromosomes. In the past 16 years, however, the λ Red recombination system has gained a new notoriety. When expressed independently of other λ functions, the Red system is able to promote recombination of linear DNA containing limited regions of homology (∼50 bp) with the Escherichia coli chromosome, a process known as recombineering. This review explains how the Red system works during a phage infection, and how it is utilized to make chromosomal modifications of E. coli with such efficiency that it changed the nature and number of genetic manipulations possible, leading to advances in bacterial genomics, metabolic engineering, and eukaryotic genetics.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
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Abstract
The use of Cre recombinase to carry out conditional mutagenesis of transgenes and insert DNA cassettes into eukaryotic chromosomes is widespread. In addition to the numerous in vivo and in vitro applications that have been reported since Cre was first shown to function in yeast and mammalian cells nearly 30 years ago, the Cre-loxP system has also played an important role in understanding the mechanism of recombination by the tyrosine recombinase family of site-specific recombinases. The simplicity of this system, requiring only a single recombinase enzyme and short recombination sequences for robust activity in a variety of contexts, has been an important factor in both cases. This review discusses advances in the Cre recombinase field that have occurred over the past 12 years since the publication of Mobile DNA II. The focus is on those recent contributions that have provided new mechanistic insights into the reaction. Also discussed are modifications of Cre and/or the loxP sequence that have led to improvements in genome engineering applications.
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Hoenicka H, Lehnhardt D, Nunna S, Reinhardt R, Jeltsch A, Briones V, Fladung M. Level of tissue differentiation influences the activation of a heat-inducible flower-specific system for genetic containment in poplar (Populus tremula L.). PLANT CELL REPORTS 2016; 35:369-84. [PMID: 26521210 DOI: 10.1007/s00299-015-1890-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/04/2015] [Accepted: 10/16/2015] [Indexed: 05/20/2023]
Abstract
Differentiation level but not transgene copy number influenced activation of a gene containment system in poplar. Heat treatments promoted CRE gene body methylation. The flower-specific transgene deletion was confirmed. Gene flow between genetic modified trees and their wild relatives is still motive of concern. Therefore, approaches for gene containment are required. In this study, we designed a novel strategy for achieving an inducible and flower-specific transgene removal from poplar trees but still expressing the transgene in the plant body. Hence, pollen carrying transgenes could be used for breeding purposes under controlled conditions in a first phase, and in the second phase genetic modified poplars developing transgene-free pollen grains could be released. This approach is based on the recombination systems CRE/loxP and FLP/frt. Both gene constructs contained a heat-inducible CRE/loxP-based spacer sequence for in vivo assembling of the flower-specific FLP/frt system. This allowed inducible activation of gene containment. The FLP/frt system was under the regulation of a flower-specific promoter, either CGPDHC or PTD. Our results confirmed complete CRE/loxP-based in vivo assembling of the flower-specific transgene excision system after heat treatment in all cells for up to 30 % of regenerants derived from undifferentiated tissue cultures. Degradation of HSP::CRE/loxP spacer after recombination but also persistence as extrachromosomal DNA circles were detected in sub-lines obtained after heat treatments. Furthermore, heat treatment promoted methylation of the CRE gene body. A lower methylation level was detected at CpG sites in transgenic sub-lines showing complete CRE/loxP recombination and persistence of CRE/loxP spacer, compared to sub-lines with incomplete recombination. However, our results suggest that low methylation might be necessary but not sufficient for recombination. The flower-specific FLP/frt-based transgene deletion was confirmed in 6.3 % of flowers.
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Affiliation(s)
- Hans Hoenicka
- Thünen-Institute of Forest Genetics, 22927, Grosshansdorf, Germany.
| | - Denise Lehnhardt
- Thünen-Institute of Forest Genetics, 22927, Grosshansdorf, Germany
| | - Suneetha Nunna
- Institute of Biochemistry, University of Stuttgart, 70569, Stuttgart, Germany
| | | | - Albert Jeltsch
- Institute of Biochemistry, University of Stuttgart, 70569, Stuttgart, Germany
| | | | - Matthias Fladung
- Thünen-Institute of Forest Genetics, 22927, Grosshansdorf, Germany.
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Nandy S, Zhao S, Pathak BP, Manoharan M, Srivastava V. Gene stacking in plant cell using recombinases for gene integration and nucleases for marker gene deletion. BMC Biotechnol 2015; 15:93. [PMID: 26452472 PMCID: PMC4600305 DOI: 10.1186/s12896-015-0212-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/01/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Practical approaches for multigene transformation and gene stacking are extremely important for engineering complex traits and adding new traits in transgenic crops. Trait deployment by gene stacking would greatly simplify downstream plant breeding and trait introgression into cultivars. Gene stacking into pre-determined genomic sites depends on mechanisms of targeted DNA integration and recycling of selectable marker genes. Targeted integrations into chromosomal breaks, created by nucleases, require large transformation efforts. Recombinases such as Cre-lox, on the other hand, efficiently drive site-specific integrations in plants. However, the reversibility of Cre-lox recombination, due to the incorporation of two cis-positioned lox sites, presents a major bottleneck in its application in gene stacking. Here, we describe a strategy of resolving this bottleneck through excision of one of the cis-positioned lox, embedded in the marker gene, by nuclease activity. METHODS All transgenic lines were developed by particle bombardment of rice callus with plasmid constructs. Standard molecular approach was used for building the constructs. Transgene loci were analyzed by PCR, Southern hybridization, and DNA sequencing. RESULTS We developed a highly efficient gene stacking method by utilizing powerful recombinases such as Cre-lox and FLP-FRT, for site-specific gene integrations, and nucleases for marker gene excisions. We generated Cre-mediated site-specific integration locus in rice and showed excision of marker gene by I-SceI at ~20 % efficiency, seamlessly connecting genes in the locus. Next, we showed ZFN could be used for marker excision, and the locus can be targeted again by recombinases. Hence, we extended the power of recombinases to gene stacking application in plants. Finally, we show that heat-inducible I-SceI is also suitable for marker excision, and therefore could serve as an important tool in streamlining this gene stacking platform. CONCLUSIONS A practical approach for gene stacking in plant cell was developed that allows targeted gene insertions through rounds of transformation, a method needed for introducing new traits into transgenic lines for their rapid deployment in the field. By using Cre-lox, a powerful site-specific recombination system, this method greatly improves gene stacking efficiency, and through the application of nucleases develops marker-free, seamless stack of genes at pre-determined chromosomal sites.
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Affiliation(s)
- Soumen Nandy
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Shan Zhao
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Bhuvan P Pathak
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Muthusamy Manoharan
- Department of Agriculture, 144 Woodard Hall, University of Arkansas at Pine Bluff, Pine Bluff, AR, 71601, USA.
| | - Vibha Srivastava
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
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Polóniová Z, Jopčík M, Matušíková I, Libantová J, Moravčíková J. The pollen- and embryo-specific Arabidopsis DLL promoter bears good potential for application in marker-free Cre/loxP self-excision strategy. PLANT CELL REPORTS 2015; 34:469-81. [PMID: 25504050 DOI: 10.1007/s00299-014-1726-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/10/2014] [Accepted: 12/03/2014] [Indexed: 06/04/2023]
Abstract
KEY MESSAGE Marker-free transgenic plants can be generated with high efficiency by using the Cre/ lox P self-excision system controlled by the pollen- and embryo-specific Arabidopsis DLL promoter. In this work, we aimed to study the feasibility of using the pollen- and embryo-specific DLL promoter of the At4g16160 gene from Arabidopsis thaliana in a Cre/loxP self-excision strategy. A Cre/loxP self-excision cassette controlled by the DLL promoter was introduced into the tobacco genome via Agrobacterium-mediated transformation. No evidence for premature activation of the Cre/loxP system was observed in primary transformants. The efficiency of nptII removal during pollen and embryo development was investigated in transgenic T1 progenies derived from eight self- and four cross-pollinated T0 lines, respectively. Segregation and rooting assays were performed to select recombined T1 plants. Molecular analyses of these plants confirmed the excision event in all analysed T0 lines and marker-free transgenic T1 plants were obtained with efficiency of up to 96.2%. The Arabidopsis DLL promoter appears to be a strong candidate to drive Cre-mediated recombination not only in tobacco as a model plant, but also in other plant species.
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Affiliation(s)
- Zuzana Polóniová
- Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademicka 2, P.O. Box 39A, 95 007, Nitra, Slovak Republic,
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Blundell JR, Levy SF. Beyond genome sequencing: Lineage tracking with barcodes to study the dynamics of evolution, infection, and cancer. Genomics 2014; 104:417-30. [DOI: 10.1016/j.ygeno.2014.09.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/03/2014] [Accepted: 09/16/2014] [Indexed: 12/19/2022]
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Xu J, Liu X, Gao B, Karin M, Tsukamoto H, Brenner D, Kisseleva T. New Approaches for Studying Alcoholic Liver Disease. CURRENT PATHOBIOLOGY REPORTS 2014; 2:171-183. [PMID: 26594598 DOI: 10.1007/s40139-014-0053-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alcoholic liver disease (ALD) is major cause of chronic liver injury which results in liver fibrosis and cirrhosis. According to the surveillance report published by the National Institute on Alcohol Abuse and Alcoholism, liver cirrhosis is the 12th leading cause of death in the United States with 48 % of these deaths being attributed to excessive alcohol consumption. ALD includes a spectrum of disorders from simple steatosis to steatohepatitis, fibrosis, and hepatocellular carcinoma. Several mechanisms play a critical role in the pathogenesis of ALD. These include ethanol-induced oxidative stress and depletion of glutathione, pathological methionine metabolism, increased gut permeability and release of endotoxins into the portal blood, recruitment and activation of inflammatory cells including bone marrow-derived and liver resident macrophages (Kupffer cells). Chronic alcohol consumption results in liver damage and activation of hepatic stellate cells (HSCs) and myofibroblasts, leading to liver fibrosis. Here we discuss the current view on factors that are specific for different stages of ALD and those that regulate its progression, including cytokines and chemokines, alcohol-responsive intracellular signaling pathways, and transcriptional factors. We also review recent studies demonstrating that alcohol-mediated changes can be regulated on an epigenetic level, including microRNAs. Finally, we discuss the reversibility of liver fibrosis and inactivation of HSCs as a potential strategy for treating alcohol-induced liver damage.
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Affiliation(s)
- Jun Xu
- Department of Medicine, UC San Diego, San Diego, CA, USA
| | - Xiao Liu
- Department of Medicine, UC San Diego, San Diego, CA, USA
| | - Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Michael Karin
- Department of Pharmacology, UC San Diego, San Diego, CA, USA
| | - Hidekazu Tsukamoto
- Southern California Research Center for ALPD & Cirrhosis Department of Pathology Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, USA
| | - David Brenner
- Department of Medicine, UC San Diego, San Diego, CA, USA
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Xu J, Liu X, Koyama Y, Wang P, Lan T, Kim IG, Kim IH, Ma HY, Kisseleva T. The types of hepatic myofibroblasts contributing to liver fibrosis of different etiologies. Front Pharmacol 2014; 5:167. [PMID: 25100997 PMCID: PMC4105921 DOI: 10.3389/fphar.2014.00167] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 06/25/2014] [Indexed: 01/18/2023] Open
Abstract
Liver fibrosis results from dysregulation of normal wound healing, inflammation, activation of myofibroblasts, and deposition of extracellular matrix (ECM). Chronic liver injury causes death of hepatocytes and formation of apoptotic bodies, which in turn, release factors that recruit inflammatory cells (neutrophils, monocytes, macrophages, and lymphocytes) to the injured liver. Hepatic macrophages (Kupffer cells) produce TGFβ1 and other inflammatory cytokines that activate Collagen Type I producing myofibroblasts, which are not present in the normal liver. Secretion of TGFβ1 and activation of myofibroblasts play a critical role in the pathogenesis of liver fibrosis of different etiologies. Although the composition of fibrogenic myofibroblasts varies dependent on etiology of liver injury, liver resident hepatic stellate cells and portal fibroblasts are the major source of myofibroblasts in fibrotic liver in both experimental models of liver fibrosis and in patients with liver disease. Several studies have demonstrated that hepatic fibrosis can reverse upon cessation of liver injury. Regression of liver fibrosis is accompanied by the disappearance of fibrogenic myofibroblasts followed by resorption of the fibrous scar. Myofibroblasts either apoptose or inactivate into a quiescent-like state (e.g., stop collagen production and partially restore expression of lipogenic genes). Resolution of liver fibrosis is associated with recruitment of macrophages that secrete matrix-degrading enzymes (matrix metalloproteinase, collagenases) and are responsible for fibrosis resolution. However, prolonged/repeated liver injury may cause irreversible crosslinking of ECM and formation of uncleavable collagen fibers. Advanced fibrosis progresses to cirrhosis and hepatocellular carcinoma. The current review will summarize the role and contribution of different cell types to populations of fibrogenic myofibroblasts in fibrotic liver.
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Affiliation(s)
- Jun Xu
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Xiao Liu
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Yukinori Koyama
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Ping Wang
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Tian Lan
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - In-Gyu Kim
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - In H Kim
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Hsiao-Yen Ma
- School of Medicine, University of California at San Diego La Jolla, CA, USA
| | - Tatiana Kisseleva
- School of Medicine, University of California at San Diego La Jolla, CA, USA
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Kratochwil CF, Rijli FM. The Cre/Lox system to assess the development of the mouse brain. Methods Mol Biol 2014; 1082:295-313. [PMID: 24048942 DOI: 10.1007/978-1-62703-655-9_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Cre-mediated recombination has become a powerful tool to confine gene deletions (conditional knockouts) or overexpression of genes (conditional knockin/overexpression). By spatiotemporal restriction of genetic manipulations, major problems of classical knockouts such as embryonic lethality can be circumvented. Furthermore Cre-mediated recombination has broad applicability in the analysis of the cellular behavior of subpopulations and cell types as well as for genetic fate mapping. This chapter will give an overview about applications for the Cre/LoxP system and their execution.
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Shcherbak N, Kishchenko O, Sakhno L, Komarnytsky I, Kuchuk M. Lox-dependent gene expression in transgenic plants obtained via Agrobacterium-mediated transformation. CYTOL GENET+ 2013. [DOI: 10.3103/s0095452713030079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kobelt D, Schleef M, Schmeer M, Aumann J, Schlag PM, Walther W. Performance of high quality minicircle DNA for in vitro and in vivo gene transfer. Mol Biotechnol 2013; 53:80-9. [PMID: 22467123 DOI: 10.1007/s12033-012-9535-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Plasmid DNA is frequently used particularly for nonviral gene therapy. Conventional plasmid DNA contains bacterial backbone and resistance gene sequences, as well as immunogenic CpG motifs. These components are not required for transgene expression. They represent a potential risk for safe clinical application and reduce gene transfer rates as well as transgene expression. To overcome these drawbacks, the minicircle technology is removing such sequences, to improve performance and also to reduce DNA size. Here, we show the effective production of luciferase, GFP, or lacZ-carrying minicircle DNA with high yield and reproducible high quality. They are used for lipofection or electroporation gene transfer into human melanoma and colon carcinoma cell lines. Comparison of respective parental plasmid and minicircle-mediated luciferase gene transfer shows improved luciferase expression by minicircle in all cell lines. This is not associated with increase in intracellular minicircle copy numbers after lipofection or electroporation. The minicircles rather mediate enhanced transgene mRNA transcription compared to their parental plasmids. In addition, FACS analysis revealed increase in counts of GFP positive cells after minicircle gene transfer, indicating higher gene transfer rates. Furthermore, minicircle showed also improved performance in vivo after jet-injection gene transfer. Therefore, availability of minicircles with reproducible high quality and sufficient amount makes them an applicable and effective alternative to conventional plasmid gene vectors.
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Affiliation(s)
- Dennis Kobelt
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany.
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Transgenic Approaches to Enhance Phytoremediation of Heavy Metal-Polluted Soils. SOIL BIOLOGY 2013. [DOI: 10.1007/978-3-642-35564-6_12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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TG1 integrase-based system for site-specific gene integration into bacterial genomes. Appl Microbiol Biotechnol 2012; 97:4039-48. [DOI: 10.1007/s00253-012-4491-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/30/2012] [Accepted: 10/02/2012] [Indexed: 10/27/2022]
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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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41
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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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Scientific opinion addressing the safety assessment of plants developed through cisgenesis and intragenesis. EFSA J 2012. [DOI: 10.2903/j.efsa.2012.2561] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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De Paepe A, De Buck S, Nolf J, Depicker A. High frequency of single-copy T-DNA transformants produced after floral dip in CRE-expressing Arabidopsis plants. Methods Mol Biol 2012; 847:317-333. [PMID: 22351019 DOI: 10.1007/978-1-61779-558-9_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Transgenic plants that harbor a single copy of the introduced transgene are preferable to those with multiple transgene copies because multiple T-DNA copies correlate with expression variability and susceptibility to silencing. Especially after the commonly used floral-dip Agrobacterium-mediated transformation method, the frequency of single-copy transformants is low. The CRE/loxP recombinase-based strategy to resolve complex T-DNA loci has proven to be successful to efficiently obtain single-copy T-DNA transformants by directly transforming loxP-containing T-DNA vectors in CRE-expressing Arabidopsis thaliana plants. This chapter describes in detail how to transform three available loxP-containing T-DNA vectors into CRE-producing Arabidopsis C24 plants and subsequently how to analyze the transgenic plants for the T-DNA locus structure.
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Affiliation(s)
- Annelies De Paepe
- Department of Plant Systems Biology, VIB, Department of Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
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Site-specific recombinases as tools for heterologous gene integration. Appl Microbiol Biotechnol 2011; 92:227-39. [DOI: 10.1007/s00253-011-3519-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 07/19/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022]
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Nandy S, Srivastava V. Site-specific gene integration in rice genome mediated by the FLP-FRT recombination system. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:713-21. [PMID: 21083801 DOI: 10.1111/j.1467-7652.2010.00577.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plant transformation based on random integration of foreign DNA often generates complex integration structures. Precision in the integration process is necessary to ensure the formation of full-length, single-copy integration. Site-specific recombination systems are versatile tools for precise genomic manipulations such as DNA excision, inversion or integration. The yeast FLP-FRT recombination system has been widely used for DNA excision in higher plants. Here, we report the use of FLP-FRT system for efficient targeting of foreign gene into the engineered genomic site in rice. The transgene vector containing a pair of directly oriented FRT sites was introduced by particle bombardment into the cells containing the target locus. FLP activity generated by the co-bombarded FLP gene efficiently separated the transgene construct from the vector-backbone and integrated the backbone-free construct into the target site. Strong FLP activity, derived from the enhanced FLP protein, FLPe, was important for the successful site-specific integration (SSI). The majority of the transgenic events contained a precise integration and expressed the transgene. Interestingly, each transgenic event lacked the co-bombarded FLPe gene, suggesting reversion of the integration structure in the presence of the constitutive FLPe expression. Progeny of the precise transgenic lines inherited the stable SSI locus and expressed the transgene. This work demonstrates the application of FLP-FRT system for site-specific gene integration in plants using rice as a model.
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Affiliation(s)
- Soumen Nandy
- Department of Crop, Soil & Environmental Sciences, University of Arkansas, Fayetteville, AR, USA
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Abstract
The present study assessed the efficacy of a heat-inducible cre gene for conditional removal of the marker gene from a rice genome via Cre-lox recombination. A cre gene controlled by the soybean heat-shock promoter was introduced into the rice genome along with the recombination target (lox) construct. Cre-mediated recombination was expected to remove the marker gene and activate the promoter-less GUS gene. Six transgenic lines displayed well-regulated heat-inducible Cre activity in the callus. However, only one line that contained a single copy of the cre gene maintained this property in the regenerated plants and their progeny. Marker-free progeny were obtained from the plant that was heat-treated at the seedling stage, indicating the inheritance of the recombination 'footprint'. The presence of the 'footprint' was verified by polymerase chain reaction and Southern analysis. Therefore, the cre gene controlled by the soybean heat-shock promoter is an effective tool for conditional removal of the marker gene in rice.
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Lu C, Napier JA, Clemente TE, Cahoon EB. New frontiers in oilseed biotechnology: meeting the global demand for vegetable oils for food, feed, biofuel, and industrial applications. Curr Opin Biotechnol 2010; 22:252-9. [PMID: 21144729 DOI: 10.1016/j.copbio.2010.11.006] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 11/07/2010] [Indexed: 11/25/2022]
Abstract
Vegetable oils have historically been a valued commodity for food use and to a lesser extent for non-edible applications such as detergents and lubricants. The increasing reliance on biodiesel as a transportation fuel has contributed to rising demand and higher prices for vegetable oils. Biotechnology offers a number of solutions to meet the growing need for affordable vegetable oils and vegetable oils with improved fatty acid compositions for food and industrial uses. New insights into oilseed metabolism and its transcriptional control are enabling biotechnological enhancement of oil content and quality. Alternative crop platforms and emerging technologies for metabolic engineering also hold promise for meeting global demand for vegetable oils and for enhancing nutritional, industrial, and biofuel properties of vegetable oils.
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Affiliation(s)
- Chaofu Lu
- Department of Plant Sciences, Plant Pathology, Montana State University, Bozeman, MT 59717, USA
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Meyers B, Zaltsman A, Lacroix B, Kozlovsky SV, Krichevsky A. Nuclear and plastid genetic engineering of plants: Comparison of opportunities and challenges. Biotechnol Adv 2010; 28:747-56. [DOI: 10.1016/j.biotechadv.2010.05.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 05/26/2010] [Accepted: 05/26/2010] [Indexed: 01/18/2023]
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Chromosome engineering: power tools for plant genetics. Trends Biotechnol 2010; 28:605-10. [PMID: 20933291 DOI: 10.1016/j.tibtech.2010.09.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Revised: 09/08/2010] [Accepted: 09/10/2010] [Indexed: 12/12/2022]
Abstract
The term "chromosome engineering" describes technologies in which chromosomes are manipulated to change their mode of genetic inheritance. This review examines recent innovations in chromosome engineering that promise to greatly increase the efficiency of plant breeding. Haploid Arabidopsis thaliana have been produced by altering the kinetochore protein CENH3, yielding instant homozygous lines. Haploid production will facilitate reverse breeding, a method that downregulates recombination to ensure progeny contain intact parental chromosomes. Another chromosome engineering success is the conversion of meiosis into mitosis, which produces diploid gametes that are clones of the parent plant. This is a key step in apomixis (asexual reproduction through seeds) and could help to preserve hybrid vigor in the future. New homologous recombination methods in plants will potentiate many chromosome engineering applications.
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Kempe K, Rubtsova M, Berger C, Kumlehn J, Schollmeier C, Gils M. Transgene excision from wheat chromosomes by phage phiC31 integrase. PLANT MOLECULAR BIOLOGY 2010; 72:673-687. [PMID: 20127141 DOI: 10.1007/s11103-010-9606-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 01/17/2010] [Indexed: 05/28/2023]
Abstract
The Streptomyces phage phiC31 integrase was tested for its ability to excise transgenic DNA from the wheat genome by site-specific recombination. Plants that stably express phiC31 integrase were crossed to plants carrying a target construct bearing the phiC31 recognition sites, attP and attB. In the progeny, phiC31 recombinase mediates recombination between the att sites of the target locus, which results in excision of the intervening DNA. Recombination events could be identified in 34 independent wheat lines by PCR and Southern blot analysis and by sequencing of the excision footprints. Recombinant loci were inherited to the subsequent generation. The results presented here establish the integrase-att system as a tool for catalysing the precise elimination of DNA sequences from wheat chromosomes.
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Affiliation(s)
- Katja Kempe
- Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstr. 3, 06466, Gatersleben, Germany
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