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Nihranz CT, Guzchenko IA, Casteel CL. Silencing ZmPP2C-A10 with a foxtail mosaic virus (FoMV) derived vector benefits maize growth and development following water limitation. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:956-964. [PMID: 37658795 DOI: 10.1111/plb.13568] [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: 06/21/2023] [Accepted: 07/23/2023] [Indexed: 09/05/2023]
Abstract
Global climate change is causing more frequent and severe droughts, which can have negative impacts on plant growth and crop productivity. Under drought conditions, plants produce the hormone ABA (abscisic acid), which regulates adaptive responses, such as stomatal closure and root elongation. Plant viruses have been used in the lab to convey new traits to plants and could also be used to increase production of ABA or to enhance downstream plant drought resistance responses. In this study, foxtail mosaic virus (FoMV) was used to silence ZmPP2C-A10, a negative regulator of ABA signalling, in maize (Zea mays L.). Both silenced and control plants were exposed to an 8-day drought treatment, followed by a 30-day period of rewatering, after which indicators of drought resistance were measured. After drought treatment, we observed a nearly twofold increase in expression of a stress-mitigation gene, ZmRAB17, reduced chlorophyll fluorescence changes (indicator of stress), and increased plant biomass and development in the ZmPP2C-A10-silenced maize compared to controls. These results demonstrate that the FoMV system can be used to silence endogenous expression of ZmPP2C-A10 and increase maize tolerance to drought. This could offer a useful tool to improve crop traits and reduce yield loss during the growing season.
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Affiliation(s)
- C T Nihranz
- Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, NY, USA
| | - I A Guzchenko
- Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, NY, USA
| | - C L Casteel
- Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, NY, USA
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Beernink BM, Whitham SA. Foxtail mosaic virus: A tool for gene function analysis in maize and other monocots. MOLECULAR PLANT PATHOLOGY 2023; 24:811-822. [PMID: 37036421 PMCID: PMC10257046 DOI: 10.1111/mpp.13330] [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: 10/31/2022] [Revised: 02/20/2023] [Accepted: 03/08/2023] [Indexed: 06/11/2023]
Abstract
Many plant viruses have been engineered into vectors for use in functional genomics studies, expression of heterologous proteins, and, most recently, gene editing applications. The use of viral vectors overcomes bottlenecks associated with mutagenesis and transgenesis approaches often implemented for analysis of gene function. There are several engineered viruses that are demonstrated or suggested to be useful in maize through proof-of-concept studies. However, foxtail mosaic virus (FoMV), which has a relatively broad host range, is emerging as a particularly useful virus for gene function studies in maize and other monocot crop or weed species. A few clones of FoMV have been independently engineered, and they have different features and capabilities for virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) of proteins. In addition, FoMV can be used to deliver functional guide RNAs in maize and other plants expressing the Cas9 protein, demonstrating its potential utility in virus-induced gene editing applications. There is a growing number of studies in which FoMV vectors are being applied for VIGS or VOX in maize and the vast majority of these are related to maize-microbe interactions. In this review, we highlight the biology and engineering of FoMV as well as its applications in maize-microbe interactions and more broadly in the context of the monocot functional genomics toolbox.
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Affiliation(s)
- Bliss M. Beernink
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
- Department of BiologyUniversity of ManitobaWinnipegManitobaCanada
| | - Steven A. Whitham
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
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Bredow M, Natukunda MI, Beernink BM, Chicowski AS, Salas‐Fernandez MG, Whitham SA. Characterization of a foxtail mosaic virus vector for gene silencing and analysis of innate immune responses in Sorghum bicolor. MOLECULAR PLANT PATHOLOGY 2023; 24:71-79. [PMID: 36088637 PMCID: PMC9742499 DOI: 10.1111/mpp.13270] [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: 07/12/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 05/08/2023]
Abstract
Sorghum is vulnerable to many biotic and abiotic stresses, which cause considerable yield losses globally. Efforts to genetically characterize beneficial sorghum traits, including disease resistance, plant architecture, and tolerance to abiotic stresses, are ongoing. One challenge faced by sorghum researchers is its recalcitrance to transformation, which has slowed gene validation efforts and utilization for cultivar development. Here, we characterize the use of a foxtail mosaic virus (FoMV) vector for virus-induced gene silencing (VIGS) by targeting two previously tested marker genes: phytoene desaturase (PDS) and ubiquitin (Ub). We additionally demonstrate VIGS of a subgroup of receptor-like cytoplasmic kinases (RLCKs) and report the role of these genes as positive regulators of early defence signalling. Silencing of subgroup 8 RLCKs also resulted in higher susceptibility to the bacterial pathogens Pseudomonas syringae pv. syringae (B728a) and Xanthomonas vasicola pv. holcicola, demonstrating the role of these genes in host defence against bacterial pathogens. Together, this work highlights the utility of FoMV-induced gene silencing in the characterization of genes mediating defence responses in sorghum. Moreover, FoMV was able to systemically infect six diverse sorghum genotypes with high efficiency at optimal temperatures for sorghum growth and therefore could be extrapolated to study additional traits of economic importance.
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Affiliation(s)
- Melissa Bredow
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
| | - Martha Ibore Natukunda
- Department of AgronomyIowa State UniversityAmesIowaUSA
- Present address:
Department of BiologyAugustana UniversitySioux FallsSouth DakotaUSA.
| | - Bliss M. Beernink
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
- Present address:
Department of Biological SciencesUniversity of ManitobaWinnipegManitobaCanada.
| | - Aline Sartor Chicowski
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
| | | | - Steven A. Whitham
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
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Beernink BM, Lappe RR, Bredow M, Whitham SA. Impacts of RNA Mobility Signals on Virus Induced Somatic and Germline Gene Editing. Front Genome Ed 2022; 4:925088. [PMID: 35755451 PMCID: PMC9219249 DOI: 10.3389/fgeed.2022.925088] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Viral vectors are being engineered to deliver CRISPR/Cas9 components systemically in plants to induce somatic or heritable site-specific mutations. It is hypothesized that RNA mobility signals facilitate entry of viruses or single guide RNAs (sgRNAs) into the shoot apical meristem where germline mutations can occur. Our objective was to understand the impact of RNA mobility signals on virus-induced somatic and germline gene editing in Nicotiana benthamiana and Zea mays. Previously, we showed that foxtail mosaic virus (FoMV) expressing sgRNA induced somatic mutations in N. benthamiana and Z. mays expressing Cas9. Here, we fused RNA mobility signals to sgRNAs targeting the genes encoding either N. benthamiana phytoene desaturase (PDS) or Z. mays high affinity potassium transporter 1 (HKT1). Addition of Arabidopsis thaliana Flowering Locus T (AtFT) and A. thaliana tRNA-Isoleucine (AttRNAIle) did not improve FoMV-induced somatic editing, and neither were sufficient to facilitate germline mutations in N. benthamiana. Maize FT homologs, Centroradialus 16 (ZCN16) and ZCN19, as well as AttRNAIle were found to aid somatic editing in maize but did not enable sgRNAs delivered by FoMV to induce germline mutations. Additional viral guide RNA delivery systems were assessed for somatic and germline mutations in N. benthamiana with the intention of gaining a better understanding of the specificity of mobile signal-facilitated germline editing. Potato virus X (PVX), barley stripe mosaic virus (BSMV), and tobacco rattle virus (TRV) were included in this comparative study, and all three of these viruses delivering sgRNA were able to induce somatic and germline mutations. Unexpectedly, PVX, a potexvirus closely related to FoMV, expressing sgRNA alone induced biallelic edited progeny, indicating that mobility signals are dispensable in virus-induced germline editing. These results show that PVX, BSMV, and TRV expressing sgRNA all have an innate ability to induce mutations in the germline. Our results indicate that mobility signals alone may not be sufficient to enable virus-based delivery of sgRNAs using the viruses, FoMV, PVX, BSMV, and TRV into cell types that result in germline mutations.
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Yuan C, Li H, Qin C, Zhang X, Chen Q, Zhang P, Xu X, He M, Zhang X, Tör M, Xue D, Wang H, Jackson S, He Y, Liu Y, Shi N, Hong Y. Foxtail mosaic virus-induced flowering assays in monocot crops. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3012-3023. [PMID: 32061090 DOI: 10.1093/jxb/eraa080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 02/11/2020] [Indexed: 05/04/2023]
Abstract
Virus-induced flowering (VIF) exploits RNA or DNA viruses to express flowering time genes to induce flowering in plants. Such plant virus-based tools have recently attracted widespread attention for their fundamental and applied uses in flowering physiology and in accelerating breeding in dicotyledonous crops and woody fruit-trees. We now extend this technology to a monocot grass and a cereal crop. Using a Foxtail mosaic virus (FoMV)-based VIF system, dubbed FoMViF, we showed that expression of florigenic Flowering Locus T (FT) genes can promote early flowering and spikelet development in proso millet, a C4 grass species with potential as a nutritional food and biofuel resource, and in non-vernalized C3 wheat, a major food crop worldwide. Floral and spikelet/grain induction in the two monocot plants was caused by the virally expressed untagged or FLAG-tagged FT orthologs, and the florigenic activity of rice Hd3a was more pronounced than its dicotyledonous counterparts in proso millet. The FoMViF system is easy to use and its efficacy to induce flowering and early spikelet/grain production is high. In addition to proso millet and wheat, we envisage that FoMViF will be also applicable to many economically important monocotyledonous food and biofuel crops.
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Affiliation(s)
- Chen Yuan
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Hongmei Li
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Cheng Qin
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xian Zhang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Qianqian Chen
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Pengcheng Zhang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiaorui Xu
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Meiling He
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xinlian Zhang
- Department of Family Medicine and Public Health, Division of Biostatistics & Bioinformatics, University of California San Diego, La Jolla, CA, USA
| | - Mahmut Tör
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
| | - Dawei Xue
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Huizhong Wang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Stephen Jackson
- Warwick-Hangzhou RNA Signaling Joint Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
| | - Yuehui He
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yule Liu
- Centre for Plant Biology and MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China
| | - Nongnong Shi
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
- Warwick-Hangzhou RNA Signaling Joint Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
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Mei Y, Beernink BM, Ellison EE, Konečná E, Neelakandan AK, Voytas DF, Whitham SA. Protein expression and gene editing in monocots using foxtail mosaic virus vectors. PLANT DIRECT 2019; 3:e00181. [PMID: 31768497 PMCID: PMC6874699 DOI: 10.1002/pld3.181] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 10/08/2019] [Accepted: 10/24/2019] [Indexed: 05/03/2023]
Abstract
Plant viruses can be engineered to carry sequences that direct silencing of target host genes, expression of heterologous proteins, or editing of host genes. A set of foxtail mosaic virus (FoMV) vectors was developed that can be used for transient gene expression and single guide RNA delivery for Cas9-mediated gene editing in maize, Setaria viridis, and Nicotiana benthamiana. This was accomplished by duplicating the FoMV capsid protein subgenomic promoter, abolishing the unnecessary open reading frame 5A, and inserting a cloning site containing unique restriction endonuclease cleavage sites immediately after the duplicated promoter. The modified FoMV vectors transiently expressed green fluorescent protein (GFP) and bialaphos resistance (BAR) protein in leaves of systemically infected maize seedlings. GFP was detected in epidermal and mesophyll cells by epifluorescence microscopy, and expression was confirmed by Western blot analyses. Plants infected with FoMV carrying the bar gene were temporarily protected from a glufosinate herbicide, and expression was confirmed using a rapid antibody-based BAR strip test. Expression of these proteins was stabilized by nucleotide substitutions in the sequence of the duplicated promoter region. Single guide RNAs expressed from the duplicated promoter mediated edits in the N. benthamiana Phytoene desaturase gene, the S. viridis Carbonic anhydrase 2 gene, and the maize HKT1 gene encoding a potassium transporter. The efficiency of editing was enhanced in the presence of synergistic viruses and a viral silencing suppressor. This work expands the utility of FoMV for virus-induced gene silencing (VIGS), virus-mediated overexpression (VOX), and virus-enabled gene editing (VEdGE) in monocots.
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Affiliation(s)
- Yu Mei
- Department of Plant Pathology and MicrobiologyIowa State UniversityAmesIAUSA
| | - Bliss M. Beernink
- Department of Plant Pathology and MicrobiologyIowa State UniversityAmesIAUSA
| | - Evan E. Ellison
- Department of Genetics, Cell Biology and DevelopmentCenter for Genome EngineeringCenter for Precision Plant GenomicsUniversity of MinnesotaSt. PaulMNUSA
| | - Eva Konečná
- Department of Genetics, Cell Biology and DevelopmentCenter for Genome EngineeringCenter for Precision Plant GenomicsUniversity of MinnesotaSt. PaulMNUSA
| | | | - Daniel F. Voytas
- Department of Genetics, Cell Biology and DevelopmentCenter for Genome EngineeringCenter for Precision Plant GenomicsUniversity of MinnesotaSt. PaulMNUSA
| | - Steven A. Whitham
- Department of Plant Pathology and MicrobiologyIowa State UniversityAmesIAUSA
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Abstract
Virus-induced gene silencing (VIGS) is a powerful technology for rapidly and transiently knocking down the expression of plant genes to study their functions. A VIGS vector for maize derived from Foxtail mosaic virus (FoMV), a positive-sense single-stranded RNA virus, was recently developed. A cloning site created near the 3' end of the FoMV genome enables insertion of 200-400 nucleotide fragments of maize genes targeted for silencing. The recombinant FoMV clones are inoculated into leaves of maize seedlings by biolistic particle delivery, and silencing is typically observed within 2 weeks after inoculation. This chapter provides a protocol for constructing FoMV VIGS clones and inoculating them into maize seedlings.
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Affiliation(s)
- Yu Mei
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey, Ames, IA, 50011, USA
| | - Steven A Whitham
- Department of Plant Pathology and Microbiology, Iowa State University, 351 Bessey, Ames, IA, 50011, USA.
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Vaira AM, Lim HS, Bauchan GR, Owens RA, Natilla A, Dienelt MM, Reinsel MD, Hammond J. Lolium latent virus (Alphaflexiviridae) coat proteins: expression and functions in infected plant tissue. J Gen Virol 2012; 93:1814-1824. [PMID: 22573739 DOI: 10.1099/vir.0.042960-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The genome of Lolium latent virus (LoLV; genus Lolavirus, family Alphaflexiviridae) is encapsidated by two carboxy-coterminal coat protein (CP) variants (about 28 and 33 kDa), in equimolar proportions. The CP ORF contains two 5'-proximal AUGs encoding Met 1 and Met 49, respectively promoting translation of the 33 and 28 kDa CP variants. The 33 kDa CP N-terminal domain includes a 42 aa sequence encoding a putative chloroplast transit peptide, leading to protein cleavage and alternative derivation of the approximately 28 kDa CP. Mutational analysis of the two in-frame start codons and of the putative proteolytic-cleavage site showed that the N-terminal sequence is crucial for efficient cell-to-cell movement, functional systemic movement, homologous CP interactions and particle formation, but is not required for virus replication. Blocking production of the 28 kDa CP by internal initiation shows no major outcome, whereas additional mutation to prevent proteolytic cleavage at the chloroplast membrane has a dramatic effect on virus infection.
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Affiliation(s)
- Anna Maria Vaira
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
- Istituto di Virologia Vegetale CNR, Strada delle Cacce 73, 10135, Torino, Italy
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National University, Daejeon, 305-764, Republic of Korea
| | - Gary R Bauchan
- USDA-ARS, PSI, Electron and Confocal Microscopy Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Robert A Owens
- USDA-ARS, PSI, Molecular Plant Pathology Laboratory, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Angela Natilla
- USDA-ARS, PSI, Molecular Plant Pathology Laboratory, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Margaret M Dienelt
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - Michael D Reinsel
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
| | - John Hammond
- USDA-ARS, USNA, Floral and Nursery Plants Research Unit, 10300 Baltimore Avenue, Beltsville, MD, USA
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Liu Z, Kearney CM. An efficient Foxtail mosaic virus vector system with reduced environmental risk. BMC Biotechnol 2010; 10:88. [PMID: 21162736 PMCID: PMC3022558 DOI: 10.1186/1472-6750-10-88] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 12/16/2010] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Plant viral vectors offer high-yield expression of pharmaceutical and commercially important proteins with a minimum of cost and preparation time. The use of Agrobacterium tumefaciens has been introduced to deliver the viral vector as a transgene to each plant cell via a simple, nonsterile infiltration technique called "agroinoculation". With agroinoculation, a full length, systemically moving virus is no longer necessary for excellent protein yield, since the viral transgene is transcribed and replicates in every infiltrated cell. Viral genes may therefore be deleted to decrease the potential for accidental spread and persistence of the viral vector in the environment. RESULTS In this study, both the coat protein (CP) and triple gene block (TGB) genetic segments were eliminated from Foxtail mosaic virus to create the "FECT" vector series, comprising a deletion of 29% of the genome. This viral vector is highly crippled and expresses little or no marker gene within the inoculated leaf. However, when co-agroinoculated with a silencing suppressor (p19 or HcPro), FECT expressed GFP at 40% total soluble protein in the tobacco host, Nicotiana benthamiana. The modified FoMV vector retained the full-length replicase ORF, the TGB1 subgenomic RNA leader sequence and either 0, 22 or 40 bases of TGB1 ORF (in vectors FECT0, FECT22 and FECT40, respectively). As well as N. benthamiana, infection of legumes was demonstrated. Despite many attempts, expression of GFP via syringe agroinoculation of various grass species was very low, reflecting the low Agrobacterium-mediated transformation rate of monocots. CONCLUSIONS The FECT/40 vector expresses foreign genes at a very high level, and yet has a greatly reduced biohazard potential. It can form no virions and can effectively replicate only in a plant with suppressed silencing.
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Affiliation(s)
- Zun Liu
- Department of Biology, Baylor University, One Bear Place #7388, Waco, TX, 76798 USA
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 USA
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