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Yan Y, Guo YT, Chang CY, Li XM, Zhang MQ, Ding CH, Cui D, Sun C, Ren Y, Wang ML, Xie C, Ni Z, Sun Q, Chen F, Gou 缑金营 JY. HSP90.2 modulates 2Q2-mediated wheat resistance against powdery mildew. PLANT, CELL & ENVIRONMENT 2023; 46:1935-1945. [PMID: 36890722 DOI: 10.1111/pce.14579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/30/2023] [Accepted: 03/06/2023] [Indexed: 05/04/2023]
Abstract
Wheat (Triticum aestivum L.) is a critical food crop feeding the world, but pathogens threaten its production. Wheat Heat Shock Protein 90.2 (HSP90.2) is a pathogen-inducible molecular chaperone folding nascent preproteins. Here, we used wheat HSP90.2 to isolate clients regulated at the posttranslational level. Tetraploid wheat hsp90.2 knockout mutant was susceptible to powdery mildew, while the HSP90.2 overexpression line was resistant, suggesting that HSP90.2 was essential for wheat resistance against powdery mildew. We next isolated 1500 clients of HSP90.2, which contained a wide variety of clients with different biological classifications. We utilized 2Q2, a nucleotide-binding leucine repeat-rich protein, as a model to investigate the potential of HSP90.2 interactome in fungal resistance. The transgenic line co-suppressing 2Q2 was more susceptible to powdery mildew, suggesting 2Q2 as a novel Pm-resistant gene. The 2Q2 protein resided in chloroplasts, and HSP90.2 played a critical role in the accumulation of 2Q2 in thylakoids. Our data provided over 1500 HSP90.2 clients with a potential regulation at the protein folding process and contributed a nontypical approach to isolate pathogenesis-related proteins.
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Affiliation(s)
- Yan Yan
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
- School of Life Sciences, Fudan University, Shanghai, China
| | - Yue-Ting Guo
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Chao-Yan Chang
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Xiao-Ming Li
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Mei-Qi Zhang
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Ci-Hang Ding
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Dangqun Cui
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Congwei Sun
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Yan Ren
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Meng-Lu Wang
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Chaojie Xie
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Zhongfu Ni
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Qixin Sun
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Feng Chen
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Jin-Ying Gou 缑金营
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
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Vaucheret H. Epigenetic management of self and non-self: lessons from 40 years of transgenic plants. C R Biol 2023; 345:149-174. [PMID: 36847123 DOI: 10.5802/crbiol.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 12/02/2022]
Abstract
Plant varieties exhibiting unstable or variegated phenotypes, or showing virus recovery have long remained a mystery. It is only with the development of transgenic plants 40 years ago that the epigenetic features underlying these phenomena were elucidated. Indeed, the study of transgenic plants that did not express the introduced sequences revealed that transgene loci sometimes undergo transcriptional gene silencing (TGS) or post-transcriptional gene silencing (PTGS) by activating epigenetic defenses that naturally control transposable elements, duplicated genes or viruses. Even when they do not trigger TGS or PTGS spontaneously, stably expressed transgenes driven by viral promoters set apart from endogenous genes in their epigenetic regulation. As a result, transgenes driven by viral promoters are capable of undergoing systemic PTGS throughout the plant, whereas endogenous genes can only undergo local PTGS in cells where RNA quality control is impaired. Together, these results indicate that the host genome distinguishes self from non-self at the epigenetic level, allowing PTGS to eliminate non-self, and preventing PTGS to become systemic and kill the plant when it is locally activated against deregulated self.
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Alotaibi SS. Developing specific leaf promoters tools for genetic use in transgenic plants towards food security. Saudi J Biol Sci 2021; 28:5187-5192. [PMID: 34466096 PMCID: PMC8380998 DOI: 10.1016/j.sjbs.2021.05.046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/16/2021] [Accepted: 05/18/2021] [Indexed: 11/28/2022] Open
Abstract
Significant yields enrichments are necessitated for meeting the rapid global growth population together with the expected demanding for food, particularly major crops. Photosynthesis improvement is an unexploited opportunity in research on improving crop yields. However, the lack of sufficient molecular promoters tools leads to the need to explore and analyze native leaf-specified promoters for manipulating photosynthesis activities in plants. Two B. distachyon promoters, sedoheptulose-1, 7-bisphosphatase (SBPase) and fructose-1, 6-bisphosphate aldolase (FBPA), were isolated and cloned into an expression vector upstream of the eYFP reporter gene. The results demonstrate that both promoters actively function in N. benthamiana leaves in both agro-transiently assays, successfully regulating expression specifically to leaf-tissues. Exploring these active promoters could potentially provide new well genetic tools for any transgene expression in plants or leaves to genetically manipulate photosynthesis for yield improvement.
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Affiliation(s)
- Saqer S Alotaibi
- Biotechnology Department, College of Science, Taif University, P.O. BOX 11099, Taif 21944, Saudi Arabia
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4
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Woo JY, Kim YJ, Paek KH. CaLecRK-S.5, a pepper L-type lectin receptor kinase gene, accelerates Phytophthora elicitin-mediated defense response. Biochem Biophys Res Commun 2020; 524:951-956. [PMID: 32059849 DOI: 10.1016/j.bbrc.2020.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 02/03/2020] [Indexed: 02/03/2023]
Abstract
Innate immunity in plants relies on the recognition of pathogen-associated molecular patterns (PAMPs) by pattern-recognition receptors (PRRs) located on the plant cell surface. CaLecRK-S.5, a pepper L-type lectin receptor kinase, has been shown to confer broad-spectrum resistance through priming activation. To further elucidate the molecular mechanism of CaLecRK-S.5, transgenic tobacco plants were generated in this study. Interestingly, hemizygous transgenic plants exhibited a high accumulation of CaLecRK-S.5, but this accumulation was completely abolished in homozygous transgenic plants by a cosuppression mechanism. Gain-of-function and loss-of-function analyses revealed that CaLecRK-S.5 plays a positive role in Phytophthora elicitin-mediated defense responses.
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Affiliation(s)
- Joo Yong Woo
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Young Jin Kim
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Kyung-Hee Paek
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea.
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Alotaibi SS, Sparks CA, Parry MAJ, Simkin AJ, Raines CA. Identification of Leaf Promoters for Use in Transgenic Wheat. PLANTS 2018; 7:plants7020027. [PMID: 29597282 PMCID: PMC6027260 DOI: 10.3390/plants7020027] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 03/06/2018] [Accepted: 03/23/2018] [Indexed: 12/26/2022]
Abstract
Wheat yields have plateaued in recent years and given the growing global population there is a pressing need to develop higher yielding varieties to meet future demand. Genetic manipulation of photosynthesis in elite wheat varieties offers the opportunity to significantly increase yields. However, the absence of a well-defined molecular tool-box of promoters to manipulate leaf processes in wheat hinders advancements in this area. Two promoters, one driving the expression of sedoheptulose-1,7-bisphosphatase (SBPase) and the other fructose-1,6-bisphosphate aldolase (FBPA) from Brachypodium distachyon were identified and cloned into a vector in front of the GUS reporter gene. Both promoters were shown to be functionally active in wheat in both transient assays and in stably transformed wheat plants. Analysis of the stable transformants of wheat (cv. Cadenza) showed that both promoters controlled gus expression throughout leaf development as well as in other green tissues. The availability of these promoters provides new tools for the expression of genes in transgenic wheat leaves and also paves the way for multigene manipulation of photosynthesis to improve yields.
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Affiliation(s)
- Saqer S Alotaibi
- School of Biological Sciences, Wivenhoe Park, University of Essex, Colchester CO4 3SQ, UK.
- Biotechnology Department, Biological Sciences College, Taif University, At Taif 26571, Saudi Arabia.
| | - Caroline A Sparks
- Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK.
| | - Martin A J Parry
- Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK.
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
| | - Andrew J Simkin
- School of Biological Sciences, Wivenhoe Park, University of Essex, Colchester CO4 3SQ, UK.
- Genetics, Genomics and Breeding, NIAB EMR, New Road, East Malling ME19 6BJ, UK.
| | - Christine A Raines
- School of Biological Sciences, Wivenhoe Park, University of Essex, Colchester CO4 3SQ, UK.
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Lowder LG, Zhou J, Zhang Y, Malzahn A, Zhong Z, Hsieh TF, Voytas DF, Zhang Y, Qi Y. Robust Transcriptional Activation in Plants Using Multiplexed CRISPR-Act2.0 and mTALE-Act Systems. MOLECULAR PLANT 2018; 11:245-256. [PMID: 29197638 DOI: 10.1016/j.molp.2017.11.010] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/23/2017] [Accepted: 11/24/2017] [Indexed: 05/22/2023]
Abstract
User-friendly tools for robust transcriptional activation of endogenous genes are highly demanded in plants. We previously showed that a dCas9-VP64 system consisting of the deactivated CRISPR-associated protein 9 (dCas9) fused with four tandem repeats of the transcriptional activator VP16 (VP64) could be used for transcriptional activation of endogenous genes in plants. In this study, we developed a second generation of vector systems for enhanced transcriptional activation in plants. We tested multiple strategies for dCas9-based transcriptional activation, and found that simultaneous recruitment of VP64 by dCas9 and a modified guide RNA scaffold gRNA2.0 (designated CRISPR-Act2.0) yielded stronger transcriptional activation than the dCas9-VP64 system. Moreover, we developed a multiplex transcription activator-like effector activation (mTALE-Act) system for simultaneous activation of up to four genes in plants. Our results suggest that mTALE-Act is even more effective than CRISPR-Act2.0 in most cases tested. In addition, we explored tissue-specific gene activation using positive feedback loops. Interestingly, our study revealed that certain endogenous genes are more amenable than others to transcriptional activation, and tightly regulated genes may cause target gene silencing when perturbed by activation probes. Hence, these new tools could be used to investigate gene regulatory networks and their control mechanisms. Assembly of multiplex CRISPR-Act2.0 and mTALE-Act systems are both based on streamlined and PCR-independent Golden Gate and Gateway cloning strategies, which will facilitate transcriptional activation applications in both dicots and monocots.
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Affiliation(s)
- Levi G Lowder
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Jianping Zhou
- Department of Biotechnology, School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yingxiao Zhang
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA
| | - Aimee Malzahn
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA
| | - Zhaohui Zhong
- Department of Biotechnology, School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Tzung-Fu Hsieh
- Department of Plant and Microbial Biology and Plants for Human Health Institute, North Carolina State University, North Carolina Research Campus, Kannapolis, NC 28081, USA
| | - Daniel F Voytas
- Department of Genetics, Cell Biology and Development, Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yong Zhang
- Department of Biotechnology, School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China.
| | - Yiping Qi
- Department of Biology, East Carolina University, Greenville, NC 27858, USA; Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA; Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA.
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7
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Mori A, Sato H, Kasai M, Yamada T, Kanazawa A. RNA silencing in the life cycle of soybean: multiple restriction systems and spatiotemporal variation associated with plant architecture. Transgenic Res 2017; 26:349-362. [PMID: 28417275 DOI: 10.1007/s11248-017-0011-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 02/21/2017] [Indexed: 01/12/2023]
Abstract
The expression of transgenes introduced into a plant genome is sometimes suppressed by RNA silencing. Although local and systemic spread of RNA silencing have been studied, little is known about the mechanisms underlying spatial and temporal variation in transgene silencing between individual plants or between plants of different generations, which occurs seemingly stochastically. Here, we analyzed the occurrence, spread, and transmission of RNA silencing of the green fluorescent protein (GFP) gene over multiple generations of the progeny of a single soybean transformant. Observation of GFP fluorescence in entire plants of the T3-T5 generations indicated that the initiation and subsequent spread of GFP silencing varied between individuals, although this GFP silencing most frequently began in the primary leaves. In addition, GFP silencing could spread into the outer layer of seed coat tissues but was hardly detectable in the embryos. These results are consistent with the notion that transgene silencing involves its reset during reproductive phase, initiation after germination, and systemic spread in each generation. GFP silencing was absent in the pulvinus, suggesting that its cortical cells inhibit cell-to-cell spread or induction of RNA silencing. The extent of GFP silencing could differ between the stem and a petiole or between petiolules, which have limited vascular bundles connecting them and thus deter long-distant movement of silencing. Taken together, these observations indicate that the initiation and/or spread of RNA silencing depend on specific features of the architecture of the plant in addition to the mechanisms that can be conserved in higher plants.
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Affiliation(s)
- Ayumi Mori
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan
| | - Hiroshi Sato
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan
| | - Megumi Kasai
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan
| | - Tetsuya Yamada
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan
| | - Akira Kanazawa
- Research Faculty of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, 060-8589, Japan.
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8
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Maessen G. Genomic stability and stability of expression in genetically modified plants. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/plb.1997.46.1.3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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9
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Velten J, Cakir C, Youn E, Chen J, Cazzonelli CI. Transgene silencing and transgene-derived siRNA production in tobacco plants homozygous for an introduced AtMYB90 construct. PLoS One 2012; 7:e30141. [PMID: 22363419 PMCID: PMC3281821 DOI: 10.1371/journal.pone.0030141] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/10/2011] [Indexed: 12/15/2022] Open
Abstract
Transgenic tobacco (Nicotiana tabacum) lines were engineered to ectopically over-express AtMYB90 (PAP2), an R2-R3 Myb gene associated with regulation of anthocyanin production in Arabidopsis thaliana. Independently transformed transgenic lines, Myb27 and Myb237, accumulated large quantities of anthocyanin, generating a dark purple phenotype in nearly all tissues. After self-fertilization, some progeny of the Myb27 line displayed an unexpected pigmentation pattern, with most leaves displaying large sectors of dramatically reduced anthocyanin production. The green-sectored 27Hmo plants were all found to be homozygous for the transgene and, despite a doubled transgene dosage, to have reduced levels of AtMYB90 mRNA. The observed reduction in anthocyanin pigmentation and AtMYB90 mRNA was phenotypically identical to the patterns seen in leaves systemically silenced for the AtMYB90 transgene, and was associated with the presence of AtMYB90-derived siRNA homologous to both strands of a portion of the AtMYB90 transcribed region. Activation of transgene silencing in the Myb27 line was triggered when the 35S::AtMYB90 transgene dosage was doubled, in both Myb27 homozygotes, and in plants containing one copy of each of the independently segregating Myb27 and Myb237 transgene loci. Mapping of sequenced siRNA molecules to the Myb27 TDNA (including flanking tobacco sequences) indicated that the 3' half of the AtMYB90 transcript is the primary target for siRNA associated silencing in both homozygous Myb27 plants and in systemically silenced tissues. The transgene within the Myb27 line was found to consist of a single, fully intact, copy of the AtMYB90 construct. Silencing appears to initiate in response to elevated levels of transgene mRNA (or an aberrant product thereof) present within a subset of leaf cells, followed by spread of the resulting small RNA to adjacent leaf tissues and subsequent amplification of siRNA production.
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MESH Headings
- Anthocyanins/metabolism
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Base Sequence
- DNA, Bacterial/genetics
- DNA, Plant/genetics
- Gene Expression Regulation, Plant
- Gene Silencing
- Genetic Loci/genetics
- Genome, Plant/genetics
- Hemizygote
- Homozygote
- MicroRNAs/genetics
- MicroRNAs/metabolism
- Molecular Sequence Data
- Mutagenesis, Insertional/genetics
- Phenotype
- Pigmentation/genetics
- Plants, Genetically Modified
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Small Interfering/metabolism
- Nicotiana/genetics
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic
- Transgenes/genetics
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Affiliation(s)
- Jeff Velten
- United States Department of Agriculture-Agricultural Research Service, Lubbock, Texas, United States of America.
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La Paz JL, Pla M, Papazova N, Puigdomènech P, Vicient CM. Stability of the MON 810 transgene in maize. PLANT MOLECULAR BIOLOGY 2010; 74:563-571. [PMID: 20936423 DOI: 10.1007/s11103-010-9696-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 09/21/2010] [Indexed: 05/30/2023]
Abstract
We analysed the DNA variability of the transgene insert and its flanking regions in maize MON 810 commercial varieties. Southern analysis demonstrates that breeding, since the initial transformation event more than 10 years ago, has not resulted in any rearrangements. A detailed analysis on the DNA variability at the nucleotide level, using DNA mismatch endonuclease assays, showed the lack of polymorphisms in the transgene insert. We conclude that the mutation rate of the transgene is not significantly different from that observed in the maize endogenous genes. Six SNPs were observed in the 5'flanking region, corresponding to a Zeon1 retrotransposon long terminal repeat. All six SNPs are more than 500 bp upstream of the point of insertion of the transgene and do not affect the reliability of the established PCR-based transgene detection and quantification methods. The mutation rate of the flanking region is similar to that expected for a maize repetitive sequence. We detected low levels of cytosine methylation in leaves of different transgenic varieties, with no significant differences on comparing different transgenic varieties, and minor differences in cytosine methylation when comparing leaves at different developmental stages. There was also a reduction in cryIAb mRNA accumulation during leaf development.
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Affiliation(s)
- Jose Luis La Paz
- Molecular Genetics Department, Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB), Jordi Girona 18-24, 08034, Barcelona, Spain
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Hanke GT, Endo T, Satoh F, Hase T. Altered photosynthetic electron channelling into cyclic electron flow and nitrite assimilation in a mutant of ferredoxin:NADP(H) reductase. PLANT, CELL & ENVIRONMENT 2008; 31:1017-28. [PMID: 18410491 DOI: 10.1111/j.1365-3040.2008.01814.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The mechanism by which plants regulate channelling of photosynthetically derived electrons into different areas of chloroplast metabolism remains obscure. Possible fates of such electrons include use in carbon assimilation, nitrogen assimilation and redox signalling pathways, or return to the plastoquinone pool through cyclic electron flow. In higher plants, these electrons are made accessible to stromal enzymes, or for cyclic electron flow, as reduced ferredoxin (Fd), or NADPH. We investigated how knockout of an Arabidopsis (Arabidopsis thaliana) ferredoxin:NADPH reductase (FNR) isoprotein and the loss of strong thylakoid binding by the remaining FNR in this mutant affected the channelling of photosynthetic electrons into NADPH- and Fd-dependent metabolism. Chlorophyll fluorescence data show that these mutants have complex variation in cyclic electron flow, dependent on light conditions. Measurements of electron transport in isolated thylakoid and chloroplast systems demonstrated perturbed channelling to NADPH-dependent carbon and Fd-dependent nitrogen assimilating metabolism, with greater competition in the mutant. Moreover, mutants accumulate greater biomass than the wild type under low nitrate growth conditions, indicating that such altered chloroplast electron channelling has profound physiological effects. Taken together, our results demonstrate the integral role played by FNR isoform and location in the partitioning of photosynthetic reducing power.
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Affiliation(s)
- Guy Thomas Hanke
- Laboratory of Regulation of Biological Reactions and Laboratory of Protein Profiling Function Proteomics, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, Japan.
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12
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Eamens A, Wang MB, Smith NA, Waterhouse PM. RNA silencing in plants: yesterday, today, and tomorrow. PLANT PHYSIOLOGY 2008; 147:456-68. [PMID: 18524877 PMCID: PMC2409047 DOI: 10.1104/pp.108.117275] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Accepted: 02/26/2008] [Indexed: 05/17/2023]
Affiliation(s)
- Andrew Eamens
- Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, Australian Capital Territory 2601, Australia.
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13
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Chen R, Zhao X, Shao Z, Wei Z, Wang Y, Zhu L, Zhao J, Sun M, He R, He G. Rice UDP-glucose pyrophosphorylase1 is essential for pollen callose deposition and its cosuppression results in a new type of thermosensitive genic male sterility. THE PLANT CELL 2007; 19:847-61. [PMID: 17400897 PMCID: PMC1867369 DOI: 10.1105/tpc.106.044123] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
UDP-glucose pyrophosphorylase (UGPase) catalyzes the reversible production of glucose-1-phosphate and UTP to UDP-glucose and pyrophosphate. The rice (Oryza sativa) genome contains two homologous UGPase genes, Ugp1 and Ugp2. We report a functional characterization of rice Ugp1, which is expressed throughout the plant, with highest expression in florets, especially in pollen during anther development. Ugp1 silencing by RNA interference or cosuppression results in male sterility. Expressing a double-stranded RNA interference construct in Ugp1-RI plants resulted in complete suppression of both Ugp1 and Ugp2, together with various pleiotropic developmental abnormalities, suggesting that UGPase plays critical roles in plant growth and development. More importantly, Ugp1-cosuppressing plants contained unprocessed intron-containing primary transcripts derived from transcription of the overexpression construct. These aberrant transcripts undergo temperature-sensitive splicing in florets, leading to a novel thermosensitive genic male sterility. Pollen mother cells (PMCs) of Ugp1-silenced plants appeared normal before meiosis, but during meiosis, normal callose deposition was disrupted. Consequently, the PMCs began to degenerate at the early meiosis stage, eventually resulting in complete pollen collapse. In addition, the degeneration of the tapetum and middle layer was inhibited. These results demonstrate that rice Ugp1 is required for callose deposition during PMC meiosis and bridges the apoplastic unloading pathway and pollen development.
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Affiliation(s)
- Rongzhi Chen
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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14
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Petsch KA, Mylne J, Botella JR. Cosuppression of eukaryotic release factor 1-1 in Arabidopsis affects cell elongation and radial cell division. PLANT PHYSIOLOGY 2005; 139:115-26. [PMID: 16113224 PMCID: PMC1203362 DOI: 10.1104/pp.105.062695] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2005] [Revised: 05/30/2005] [Accepted: 05/30/2005] [Indexed: 05/04/2023]
Abstract
The role of the eukaryotic release factor 1 (eRF1) in translation termination has previously been established in yeast; however, only limited characterization has been performed on any plant homologs. Here, we demonstrate that cosuppression of eRF1-1 in Arabidopsis (Arabidopsis thaliana) has a profound effect on plant morphology, resulting in what we term the broomhead phenotype. These plants primarily exhibit a reduction in internode elongation causing the formation of a broomhead-like cluster of malformed siliques at the top of the inflorescence stem. Histological analysis of broomhead stems revealed that cells are reduced in height and display ectopic lignification of the phloem cap cells, some phloem sieve cells, and regions of the fascicular cambium, as well as enhanced lignification of the interfascicular fibers. We also show that cell division in the fascicular cambial regions is altered, with the majority of vascular bundles containing cambial cells that are disorganized and possess enlarged nuclei. This is the first attempt at functional characterization of a release factor in vivo in plants and demonstrates the importance of eRF1-1 function in Arabidopsis.
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Affiliation(s)
- Katherine Anne Petsch
- Plant Genetic Engineering Laboratory, Department of Botany, School of Integrative Biology, University of Queensland, Brisbane, Australia
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15
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Dubois V, Botton E, Meyer C, Rieu A, Bedu M, Maisonneuve B, Mazier M. Systematic silencing of a tobacco nitrate reductase transgene in lettuce (Lactuca sativa L.). JOURNAL OF EXPERIMENTAL BOTANY 2005; 56:2379-88. [PMID: 16014365 DOI: 10.1093/jxb/eri230] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A population of 50 independent transgenic lettuces transformed with a nitrate reductase coding sequence under the control of the 35S promoter was studied. None of them showed significantly lower nitrate levels when compared with the untransformed plants, despite the presence of nitrate reductase (NR) activity that derives from the transgene in at least four of the transformants. No repercussion on total NR activity (endogenous+transgenic) was detected in these plants. Nevertheless, 28% of the transformants showed phenotypes characteristic of a general silencing of the NR genes as already described in tobacco and potato, i.e. bleaching of the leaves leading to the death of the plant. By northern blots, it was shown that the transgene was silenced in these chlorotic plants and also in the plants that did not show symptoms of chlorosis. Thus a silencing process specifically directed against the NR mRNA derived from the transgene occurred very early in the development of all the plants studied, whatever homologous endogenous NR mRNA is present in the plant. In some cases this transgene-specific silencing was shown subsequently to extend to the homologous endogenous NR mRNA. These results suggest that, in lettuce, the level of nitrate reductase mRNA is under tight expression control and this is able specifically to target transgenic transcripts by a post-transcriptional gene silencing (PTGS) mechanism during the first stage of development of the plantlet.
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Affiliation(s)
- Vincent Dubois
- INRA, Unité de Génétique et Amélioration des Fruits et Légumes, UR 1052, domaine St Maurice BP 94, F-84143 Montfavet cedex, France
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16
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Groenenboom MAC, Marée AFM, Hogeweg P. The RNA silencing pathway: the bits and pieces that matter. PLoS Comput Biol 2005; 1:155-65. [PMID: 16110335 PMCID: PMC1185647 DOI: 10.1371/journal.pcbi.0010021] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Accepted: 06/29/2005] [Indexed: 12/24/2022] Open
Abstract
Cellular pathways are generally proposed on the basis of available experimental knowledge. The proposed pathways, however, may be inadequate to describe the phenomena they are supposed to explain. For instance, by means of concise mathematical models we are able to reveal shortcomings in the current description of the pathway of RNA silencing. The silencing pathway operates by cleaving siRNAs from dsRNA. siRNAs can associate with RISC, leading to the degradation of the target mRNA. We propose and analyze a few small extensions to the pathway: a siRNA degrading RNase, primed amplification of aberrant RNA pieces, and cooperation between aberrant RNA to trigger amplification. These extensions allow for a consistent explanation for various types of silencing phenomena, such as virus induced silencing, transgene and transposon induced silencing, and avoidance of self-reactivity, as well as for differences found between species groups.
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Affiliation(s)
- Marian A C Groenenboom
- Theoretical Biology and Bioinformatics, University of Utrecht, Utrecht, The Netherlands.
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17
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Sanders M, Maddelein W, Depicker A, Van Montagu M, Cornelissen M, Jacobs J. An active role for endogenous beta-1,3-glucanase genes in transgene-mediated co-suppression in tobacco. EMBO J 2002; 21:5824-32. [PMID: 12411500 PMCID: PMC131083 DOI: 10.1093/emboj/cdf586] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2002] [Revised: 09/06/2002] [Accepted: 09/16/2002] [Indexed: 11/14/2022] Open
Abstract
Post-transcriptional gene silencing (PTGS) is characterized by the accumulation of short interfering RNAs that are proposed to mediate sequence-specific degradation of cognate and secondary target mRNAs. In plants, it is unclear to what extent endogenous genes contribute to this process. Here, we address the role of the endogenous target genes in transgene-mediated PTGS of beta-1,3-glucanases in tobacco. We found that mRNA sequences of the endogenous glucanase glb gene with varying degrees of homology to the Nicotiana plumbaginifolia gn1 transgene are targeted by the silencing machinery, although less efficiently than corresponding transgene regions. Importantly, we show that endogene-specific nucleotides in the glb sequence provide specificity to the silencing process. Consistent with this finding, small sense and antisense 21- to 23-nucleotide RNAs homologous to the endogenous glb gene were detected. Combined, these data demonstrate that a co-suppressed endogenous glucan ase gene is involved in signal amplification and selection of homologous targets, and show that endogenous genes can actively participate in PTGS in plants. The findings are introduced as a further sophistication of the post-transciptional silencing model.
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Affiliation(s)
- Matthew Sanders
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
| | - Wendy Maddelein
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
| | - Anna Depicker
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
| | - Marc Van Montagu
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
| | - Marc Cornelissen
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
| | - John Jacobs
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent and Bayer Bioscience N.V., J. Plateaustraat 22, B-9000 Ghent, Belgium Present address: Devgen N.V., Technologiepark 9, B-9052 Zwijnaarde, Belgium Corresponding author e-mail:
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18
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Abstract
In the 'RNA world' hypothesis it is postulated that RNA was the first genetic molecule. Recent discoveries in gene silencing research on plants, fungi and animals show that RNA indeed plays a key role not only in controlling invading nucleic acids, like viruses and transposable elements, but also in regulating the expression of transgenes and endogenous genes. Double-stranded RNAs were identified to be the triggering structures for the induction of a specific and highly efficient RNA silencing system, in which enzyme complexes, like Dicer and RISC, facilitate as 'molecular machines' the processing of dsRNA into characteristic small RNA species. RNA silencing can be transmitted rapidly from silenced to non-silenced cells by short and long distance signaling. There is evidence that at least one component of the signal is a specific, degradation-resistant RNA.
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Affiliation(s)
- Michael Metzlaff
- Bayer BioScience NV, Jozef Plateaustraat 22, B-9000 Gent, Belgium
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19
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Mitsuhara I, Shirasawa-Seo N, Iwai T, Nakamura S, Honkura R, Ohashi Y. Release from post-transcriptional gene silencing by cell proliferation in transgenic tobacco plants: possible mechanism for noninheritance of the silencing. Genetics 2002; 160:343-52. [PMID: 11805069 PMCID: PMC1461942 DOI: 10.1093/genetics/160.1.343] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transgenic tobacco plants that overproduce luciferase (Luc) frequently exhibit post-transcriptional gene silencing (PTGS) of luc. The silencing was observed over five generations and found not to be inherited but acquired by the next generation at a certain frequency. Luc imaging analysis of silenced plants revealed Luc activity only in proliferating tissues such as shoot meristem and developing flower. The luc gene expression has been recovered from silencing before development of germ cells, excluding a possible recovery from the PTGS at meiosis. A systemic silencing signal transferred from older tissue likely induces gene silencing of younger tissues in which cell proliferation has been completed. Only seeds maintained Luc activity, probably because of isolation from the silencing signal by a possible partition from the parent placenta. Calli newly induced from the leaf pieces of silenced plants recovered from the silencing and exhibited strong Luc activity similar to nonsilenced leaves, further indicating that the silencing cannot be maintained in proliferating cells. Thus release from PTGS in proliferating cells is a possible mechanism for noninheritance of silencing.
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Affiliation(s)
- Ichiro Mitsuhara
- Department of Molecular Genetics, National Institute of Agrobiological Sciences, Tsukuba City, Ibaraki 305-8602, Japan
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20
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Meza TJ, Kamfjord D, Håkelien AM, Evans I, Godager LH, Mandal A, Jakobsen KS, Aalen RB. The frequency of silencing in Arabidopsis thaliana varies highly between progeny of siblings and can be influenced by environmental factors. Transgenic Res 2001; 10:53-67. [PMID: 11252383 DOI: 10.1023/a:1008903026579] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In a collection of 111 transgenic Arabidopsis thaliana lines, silencing of the nptII gene was observed in 62 (56%) of the lines and three distinct nptII-silencing phenotypes were identified. Two T-DNA constructs were used, which differed in distance and orientation of the marker gene relative to the border sequences. Comparison of the sets of lines generated with each vector, indicate that the T-DNA construct configuration influence the incidence of lines displaying silencing, as well as the distribution of silencing phenotypes. Twenty lines were investigated more thoroughly. The frequency of silencing varied between siblings in 19 lines, including three lines containing a single T-DNA copy. The last line showed 100% silencing. The gus gene present in both constructs could be expressed in the presence of a silenced nptII gene. Investigation of methylation at a single site in the pnos promoter revealed partial methylation in multi-copy lines, but no methylation in single-copy lines. For 16 lines, the overall frequencies of silencing differed significantly between control plants and plants exposed to temperature stress; in 11 of these lines at the 0.1% level. In several cases, the frequency of silencing in progeny of stress-treated plants was higher than for the control group, while other lines showed higher frequencies of kanamycin-resistant progeny for the stress-treated sibling plants.
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Affiliation(s)
- T J Meza
- Department of Biology, University of Oslo, Norway
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21
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Granger CL, Cyr RJ. Spatiotemporal relationships between growth and microtubule orientation as revealed in living root cells of Arabidopsis thaliana transformed with green-fluorescent-protein gene construct GFP-MBD. PROTOPLASMA 2001; 216:201-14. [PMID: 11732188 DOI: 10.1007/bf02673872] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Arabidopsis thaliana plants were transformed with GFP-MBD (J. Marc et al., Plant Cell 10: 1927-1939, 1998) under the control of a constitutive (35S) or copper-inducible promoter. GFP-specific fluorescence distributions, levels, and persistence were determined and found to vary with age, tissue type, transgenic line, and individual plant. With the exception of an increased frequency of abnormal roots of 35S GFP-MBD plants grown on kanamycin-containing media, expression of GFP-MBD does not appear to affect plant phenotype. The number of leaves, branches, bolts, and siliques as well as overall height, leaf size, and seed set are similar between wild-type and transgenic plants as is the rate of root growth. Thus, we conclude that the transgenic plants can serve as a living model system in which the dynamic behavior of microtubules can be visualized. Confocal microscopy was used to simultaneously monitor growth and microtubule behavior within individual cells as they passed through the elongation zone of the Arabidopsis root. Generally, microtubules reoriented from transverse to oblique or longitudinal orientations as growth declined. Microtubule reorientation initiated at the ends of the cell did not necessarily occur simultaneously in adjacent neighboring cells and did not involve complete disintegration and repolymerization of microtubule arrays. Although growth rates correlated with microtubule reorientation, the two processes were not tightly coupled in terms of their temporal relationships, suggesting that other factor(s) may be involved in regulating both events. Additionally, microtubule orientation was more defined in cells whose growth was accelerating and less stringent in cells whose growth was decelerating, indicating that microtubule-orienting factor(s) may be sensitive to growth acceleration, rather than growth per se.
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Affiliation(s)
- C L Granger
- Biology Department, Pennsylvania State University, University Park, PA 16802, USA
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22
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Belbahri L, Chevalier L, Bensaddek L, Gillet F, Fliniaux MA, Boerjan W, Inzé D, Thomas D, Thomasset B. Different expression of anS-adenosylmethionine synthetase gene in transgenic tobacco callus modifies alkaloid biosynthesis. Biotechnol Bioeng 2000. [DOI: 10.1002/(sici)1097-0290(20000705)69:1<11::aid-bit2>3.0.co;2-j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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De Wilde C, Van Houdt H, De Buck S, Angenon G, De Jaeger G, Depicker A. Plants as bioreactors for protein production: avoiding the problem of transgene silencing. PLANT MOLECULAR BIOLOGY 2000; 43:347-359. [PMID: 10999415 DOI: 10.1007/978-94-011-4183-3_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plants are particularly attractive as large-scale production systems for proteins intended for therapeutical or industrial applications: they can be grown easily and inexpensively in large quantities that can be harvested and processed with the available agronomic infrastructures. The effective use of plants as bioreactors depends on the possibility of obtaining high protein accumulation levels that are stable during the life cycle of the transgenic plant and in subsequent generations. Silencing of the introduced transgenes has frequently been observed in plants, constituting a major commercial risk and hampering the general economic exploitation of plants as protein factories. Until now, the most efficient strategy to avoid transgene silencing involves careful design of the transgene construct and thorough analysis of transformants at the molecular level. Here, we focus on different aspects of the generation of transgenic plants intended for protein production and on their influence on the stability of heterologous gene expression.
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Affiliation(s)
- C De Wilde
- Vakgroep Moleculaire Genetica en Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, Belgium
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24
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Haldrup A, Naver H, Scheller HV. The interaction between plastocyanin and photosystem I is inefficient in transgenic Arabidopsis plants lacking the PSI-N subunit of photosystem I. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 17:689-98. [PMID: 10230065 DOI: 10.1046/j.1365-313x.1999.00419.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The PSI-N subunit of photosystem I (PSI) is restricted to higher plants and is the only subunit located entirely in the thylakoid lumen. The role of the PSI-N subunit in the PSI complex was investigated in transgenic Arabidopsis plants which were generated using antisense and co-suppression strategies. Several lines without detectable levels of PSI-N were identified. The plants lacking PSI-N assembled a functional PSI complex and were capable of photoautotrophic growth. When grown on agar media for several weeks the plants became chlorotic and developed significantly more slowly. However, under optimal growth conditions, the plants without PSI-N were visually indistinguishable from the wild-type although several photosynthetic parameters were affected. In the transformants, the second-order rate constant for electron transfer from plastocyanin to P700+, the oxidized reaction centre of PSI, was only 55% of the wild-type value, and steady-state NADP+ reduction was decreased to a similar extent. Quantum yield of oxygen evolution and PSII photochemistry were about 10% lower than in the wild-type at leaf level. Photochemical fluorescence quenching was lowered to a similar extent. Thus, the 40-50% lower activity of PSI at the molecular level was much less significant at the whole-plant level. This was partly explained by a 17% increase in PSI content in the plants lacking PSI-N.
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Affiliation(s)
- A Haldrup
- Department of Plant Biology, Royal Veterinary and Agricultural University, Frederiksberg, Copenhagen, Denmark.
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25
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Abstract
BACKGROUND In plants, post-transcriptional gene silencing results in RNA degradation after transcription. Among tobacco transformants carrying a nitrate reductase (Nia) construct under the control of the cauliflower mosaic virus 35S promoter (35S-Nia2), one class of transformants spontaneously triggers Nia post-transcriptional gene silencing (class II) whereas another class does not (class I). Non-silenced plants of both classes become silenced when grafted onto silenced stocks, indicating the existence of a systemic silencing signal. Graft-transmitted silencing is maintained in class II but not in class I plants when removed from silenced stocks, indicating similar requirements for spontaneous triggering and maintenance. RESULTS Introduction of 35S-Nia2 DNA by the gene transfer method called biolistics led to localised acquired silencing (LAS) in bombarded leaves of wild-type, class I and class II plants, and to systemic acquired silencing (SAS) in class II plants. SAS occurred even if the targeted leaf was removed 2 days after bombardment, indicating that the systemic signal is produced, transmitted and amplified rapidly. SAS was activated by sense, antisense and promoterless Nia2 DNA constructs, indicating that transcription is not required although it does stimulate SAS. CONCLUSIONS SAS was activated by biolistic introduction of promoterless constructs, indicating that the DNA itself is a potent activator of post-transcriptional gene silencing. The systemic silencing signal invaded the whole plant by cell-to-cell and long-distance propagation, and reamplification of the signal.
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Affiliation(s)
- J C Palauqui
- Laboratoire de Biologie Cellulaire, INRA- Centre de Versailles F-78026,Versailles, Cedex, France.
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26
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Miki BLA, Mcttugh SG, Labbe H, Ouellet T, Tolman JH, Brandle JE. Transgenic Tobacco: Gene Expression and Applications. ACTA ACUST UNITED AC 1999. [DOI: 10.1007/978-3-642-58439-8_25] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Vaucheret H, Béclin C, Elmayan T, Feuerbach F, Godon C, Morel JB, Mourrain P, Palauqui JC, Vernhettes S. Transgene-induced gene silencing in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 16:651-659. [PMID: 10069073 DOI: 10.1046/j.1365-313x.1998.00337.x] [Citation(s) in RCA: 220] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- H Vaucheret
- Laboratoire de Biologie Cellulaire, INRA, Versailles, France.
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28
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Engineering of a single-chain variable-fragment (scFv) antibody specific for the stolbur phytoplasma (Mollicute) and its expression in escherichia coli and tobacco plants. Appl Environ Microbiol 1998; 64:4566-72. [PMID: 9797323 PMCID: PMC106685 DOI: 10.1128/aem.64.11.4566-4572.1998] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From a hybridoma cell line (2A10) producing an immunoglobulin G1 directed against the major membrane protein of the stolbur phytoplasma, we have engineered scFv (single-chain variable-fragment) antibodies from the variable heavy (VH) and light (VL) domains of the immunoglobulin. The scFv gene was cloned and expressed in Escherichia coli. The expressed protein of 30 kDa could be recovered from the periplasmic fraction of the bacterial cells and was shown to be fully functional toward its phytoplasmal antigen, since enzyme-linked immunosorbent assay or immunofluorescence (IF) detection of the stolbur phytoplasma antigen by the scFv was identical to that of the native immunoglobulin. The scFv gene was then cloned in plasmid pBG-dAb-BIN of Agrobacterium tumefaciens to transform tobacco plants. The transformed plants were screened by PCR and Northern blotting for the presence and expression of the transgene, respectively, and by IF for expression of the scFv. One transgenic tobacco line, 1A6, was selected for challenge inoculation with the stolbur phytoplasma. When grafted on a stolbur phytoplasma-infected tobacco rootstock, the transgenic tobacco shoots grew free of symptoms and flowered after 2 months, while normal tobacco shoots showed severe stolbur symptoms during the same period and eventually died.
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29
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Palauqui JC, Vaucheret H. Transgenes are dispensable for the RNA degradation step of cosuppression. Proc Natl Acad Sci U S A 1998; 95:9675-80. [PMID: 9689140 PMCID: PMC21398 DOI: 10.1073/pnas.95.16.9675] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/1998] [Indexed: 02/08/2023] Open
Abstract
Cosuppression results in the degradation of RNA from host genes and homologous transgenes after transcription in the nucleus. By using grafting experiments, we have shown previously that a systemic signal mediates the propagation of cosuppression of Nia host genes and 35S-Nia2 transgenes from silenced 35S-Nia2 transgenic stocks to nonsilenced 35S-Nia2 transgenic scions but not to wild-type scions. Here, we examined the requirements for triggering and maintenance of cosuppression in various types of scions. Grafting-induced silencing occurred in 35S-Nia2 transgenic lines over-accumulating Nia mRNA whether they are able to spontaneously trigger cosuppression or not and in 35S-Nia2 transgene-free plants over-accumulating host Nia mRNA caused by metabolic derepression. When grafting-induced silenced scions were removed from the silenced stocks and regrafted onto wild-type plants, silencing was not maintained in the 35S-Nia2 transgene-free plants and in the 35S-Nia2 transgenic lines that are not able to trigger cosuppression spontaneously. Conversely, silencing was maintained in the 35S-Nia2 transgenic lines that are able to trigger cosuppression spontaneously. Our results indicate that the presence of a 35S-Nia2 transgene is dispensable for the RNA degradation step of posttranscriptional silencing when host Nia mRNA over-accumulate above the level of wild-type plants. They also suggest that grafting-induced RNA degradation does not result in the production of the systemic silencing signal required for spontaneous triggering and maintenance.
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Affiliation(s)
- J C Palauqui
- Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, 78026 Versailles Cedex, France
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30
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Abstract
In recent years the concept of pathogen-derived resistance (PDR) has been successfully exploited for conferring resistance against viruses in many crop plants. Starting with coat protein-mediated resistance, the range has been broadened to the use of other viral genes as a source of PDR. However, in the course of the efforts, often no clear correlation could be made between expression levels of the transgenes and observed virus resistance levels. Several reports mentioned high resistance levels using genes incapable of producing protein, but in these cases, even plants accumulating high amounts of transgene RNA were not most resistant. To accommodate these unexplained observations, a resistance mechanism involving specific breakdown of viral RNAs has been proposed. Recent progress towards understanding the RNA-mediated resistance mechanism and similarities with the co-suppression phenomenon will be discussed.
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Affiliation(s)
- M Prins
- Department of Virology, Wageningen Agricultural University, The Netherlands
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31
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Caplan A, Berger PH, Naderi M. Phenotypic Variation Between Transgenic Plants: What is Making Gene Expression Unpredictable? ACTA ACUST UNITED AC 1998. [DOI: 10.1007/978-94-015-9125-6_27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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32
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Palauqui JC, Elmayan T, Pollien JM, Vaucheret H. Systemic acquired silencing: transgene-specific post-transcriptional silencing is transmitted by grafting from silenced stocks to non-silenced scions. EMBO J 1997; 16:4738-45. [PMID: 9303318 PMCID: PMC1170100 DOI: 10.1093/emboj/16.15.4738] [Citation(s) in RCA: 499] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Using grafting procedures, we investigated the transmission of co-suppression of nitrate reductase and nitrite reductase host genes and transgenes and of post-transcriptional silencing of a uidA transgene encoding glucuronidase in tobacco. We demonstrate that silencing is transmitted with 100% efficiency from silenced stocks to non-silenced scions expressing the corresponding transgene. Transmission is unidirectional from stock to scion, transgene specific, locus independent and requires the presence of a transcriptionally active transgene in the target scion. The transmission of co-suppression occurs when silenced stocks and non-silenced target scions are physically separated by up to 30 cm of stem of a non-target wild-type plant. Taken together, these results suggest that a non-metabolic, transgene-specific, diffusable messenger mediates the propagation of de novo post-transcriptional silencing through the plant.
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MESH Headings
- DNA, Complementary/genetics
- DNA, Plant/genetics
- Gene Transfer Techniques
- Genes, Plant
- Glucuronidase/genetics
- Nitrate Reductase
- Nitrate Reductases/genetics
- Plants, Genetically Modified
- Plants, Toxic
- RNA Processing, Post-Transcriptional
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Suppression, Genetic
- Nicotiana/enzymology
- Nicotiana/genetics
- Nicotiana/metabolism
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Affiliation(s)
- J C Palauqui
- Laboratoire de Biologie Cellulaire, INRA, Versailles, France
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33
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Abstract
Overexpression of chimeric transgenes in plants can trigger post-transcriptional gene silencing that is dependent on epigenetic information and physiological conditions. The current view is that unproductive RNA serves as a crucial signal for gene silencing, although direct evidence is lacking for this theory. A signalling cascade then leads to strongly enhanced turnover of all RNAs that share a critical degree of sequence similarity. The molecular details of the mechanism are, however, insufficiently understood to explain the phenomenon completely and to comprehend its biological significance.
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Affiliation(s)
- A Depicker
- Laboratorium voor Genetica, Department of Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), Universiteit Gent, KL Ledeganckstraat 35, B-9000, Gent, Belgium
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34
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Baulcombe DC. RNA as a target and an initiator of post-transcriptional gene silencing in transgenic plants. PLANT MOLECULAR BIOLOGY 1996; 32:79-88. [PMID: 8980475 DOI: 10.1007/978-94-009-0353-1_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Post-transcriptional gene silencing in transgenic plants is the manifestation of a mechanism that suppresses RNA accumulation in a sequence-specific manner. The target RNA species may be the products of transgenes, endogenous plant genes or viral RNAs. For an RNA to be a target it is necessary only that it has sequence homology to the sense RNA product of the transgene. There are three current hypotheses to account for the mechanism of post transcriptional gene silencing. These models all require production of an antisense RNA of the RNA targets to account for the specificity of the mechanism. There could be either direct transcription of the antisense RNA from the transgene, antisense RNA produced in response to over expression of the transgene or antisense RNA produced in response to the production of an aberrant sense RNA product of the transgene. To determine which of these models is correct it will be necessary to find out whether transgene methylation, which is frequently associated with the potential of transgenes to confer post-transcriptional gene silencing, is a cause or a consequence of the process.
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Affiliation(s)
- D C Baulcombe
- Sainsbury Laboratory, John Innes Centre, Norwich, UK
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35
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Baulcombe DC. RNA as a target and an initiator of post-transcriptional gene silencing in transgenic plants. PLANT MOLECULAR BIOLOGY 1996; 32:79-88. [PMID: 8980475 DOI: 10.1007/bf00039378] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Post-transcriptional gene silencing in transgenic plants is the manifestation of a mechanism that suppresses RNA accumulation in a sequence-specific manner. The target RNA species may be the products of transgenes, endogenous plant genes or viral RNAs. For an RNA to be a target it is necessary only that it has sequence homology to the sense RNA product of the transgene. There are three current hypotheses to account for the mechanism of post transcriptional gene silencing. These models all require production of an antisense RNA of the RNA targets to account for the specificity of the mechanism. There could be either direct transcription of the antisense RNA from the transgene, antisense RNA produced in response to over expression of the transgene or antisense RNA produced in response to the production of an aberrant sense RNA product of the transgene. To determine which of these models is correct it will be necessary to find out whether transgene methylation, which is frequently associated with the potential of transgenes to confer post-transcriptional gene silencing, is a cause or a consequence of the process.
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Affiliation(s)
- D C Baulcombe
- Sainsbury Laboratory, John Innes Centre, Norwich, UK
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36
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Abstract
Homology-dependent gene silencing phenomena in plants have received considerable attention, especially when it was discovered that the presence of homologous sequences not only affected the stability of transgene expression, but that the activity of endogenous genes could be altered after insertion of homologous transgenes into the genome. Homology-mediated inactivation most likely comprises at least two different molecular mechanisms that induce gene silencing at the transcriptional or posttranscriptional level, respectively. In this review we discuss different mechanistic models for plant-specific inactivation mechanisms and their relationship with repeat-specific silencing phenomena in other species.
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Affiliation(s)
- P. Meyer
- Max-Delbruck-Laboratorium in der MPG, Carl-von-Linne Weg 10, Koln, D-50829 Germany, Centre for Plant Biochemistry & Biotechnology and Department of Genetics, University of Leeds, Leeds LS2 9JT, United Kingdom, Max-Planck-Institut fur Zuchtungsforschung, Carl-von-Line Weg 10, Koln, D-50829 Germany
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37
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Baulcombe DC, English JJ. Ectopic pairing of homologous DNA and post-transcriptional gene silencing in transgenic plants. Curr Opin Biotechnol 1996. [DOI: 10.1016/s0958-1669(96)80009-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Henskens YM, Veerman EC, Nieuw Amerongen AV. Cystatins in health and disease. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1996; 377:71-86. [PMID: 8868064 DOI: 10.1515/bchm3.1996.377.2.71] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Proteolytic enzymes have many physiological functions in plants, bacteria, viruses, protozoa and mammals. They play a role in processes such as food digestion, complement activation or blood coagulation. The action of proteolytic enzymes is biologically controlled by proteinase inhibitors and increasing attention is being paid to the physiological significance of these natural inhibitors in pathological processes. The reason for this growing interest is that uncontrolled proteolysis can lead to irreversible damage e.g. in chronic inflammation or tumor metastasis. This review focusses on the possible role of the cystatins, natural and specific inhibitors of the cysteine proteinases, in pathological processes.
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Affiliation(s)
- Y M Henskens
- Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam (ACTA), Netherlands
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39
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Palauqui JC, Vaucheret H. Field trial analysis of nitrate reductase co-suppression: a comparative study of 38 combinations of transgene loci. PLANT MOLECULAR BIOLOGY 1995; 29:149-59. [PMID: 7579160 DOI: 10.1007/bf00019126] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Co-suppression of host genes and 35S transgenes encoding nitrate reductase was previously reported in transgenic tobacco plants (Nicotiana tabacum cv. Paraguay or Burley) using either a full-length cDNA or fragments devoid of the 3' and/or 5' UTR. Co-suppression was previously shown to affect a limited fraction of the progeny of one transgenic tobacco line homozygous for a single transgene locus, and the phenomenon occurred at each generation. In this work, 38 combinations of transgene loci derived from 13 independent transgenic lines homozygous for a single transgene locus were field-tested under two different conditions in an attempt to determine the corresponding frequencies of co-suppression, i.e. the percentage of plants showing co-suppression. Each of the 13 homozygous lines exhibited a different frequency of co-suppression, ranging from 0% to 57%. High frequencies were found to be associated with transgene loc carrying a high number of copy of the transgene, suggesting a transgene dose effect. Combinations carrying 2 non-allelic transgene loci in a hemizygous state exhibited frequencies of co-suppression between those of each of the 2 transgene loci in a homozygous state, while combinations carrying 2 non-allelic transgene loci in a homozygous state exhibited frequencies of co-suppression higher than the sum of those of the 2 transgene loci alone in a homozygous state, clearly confirming a transgene dose effect. Co-suppression frequencies were increased when the plants were grown initially in vitro, suggesting some environmental effect. The roles of transgene copy number, number of transgene loci and environmental factors are discussed in the light of a threshold hypothesis.
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Affiliation(s)
- J C Palauqui
- Laboratoire de Biologie Cellulaire, INRA, Versailles, France
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40
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Instability of Transgene Expression in Field Grown Tobacco Carrying the csr1-1 Gene for Sulfonylurea Herbicide Resistance. Nat Biotechnol 1995. [DOI: 10.1038/nbt0995-994] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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41
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Vaucheret H, Palauqui JC, Elmayan T, Moffatt B. Molecular and genetic analysis of nitrite reductase co-suppression in transgenic tobacco plants. MOLECULAR & GENERAL GENETICS : MGG 1995; 248:311-7. [PMID: 7565593 DOI: 10.1007/bf02191598] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Silencing of Nia host genes and transgenes (encoding nitrate reductase) was previously achieved by introducing into tobacco plants the tobacco Nia2 cDNA cloned downstream of the cauliflower mosaic virus (CaMV) 35S promoter. To check whether Nii host genes and transgenes (encoding nitrite reductase, the second enzyme of the nitrate assimilation pathway) were also susceptible to silencing, a transgene consisting of the tobacco Nii1 gene with two copies of the enhancer of the 35S promoter cloned 1 kb upstream of the Nii promoter region was introduced into tobacco plants. Among nine independent transformants analysed, two showed silencing of Nii host genes and transgenes in some descendants after selfing, but never after back-crossing with wild-type plants, suggesting that silencing depends on the number of transgene loci and/or on certain allelic or ectopic combinations of transgene loci. In one transformant carrying a single transgene locus in a homozygous state, silencing was triggered in all progeny plants of each generation, 20 to 50 days after germination. Field trial analysis confirmed that silencing was not triggered when the transgene locus of this latter line was present in a hemizygous state. In addition, it was revealed that silencing can be triggered, albeit at low frequency and later during the development, when this transgene locus is brought into the presence of a non-allelic transgene locus by crossing, suggesting that a homozygous state is not absolutely required.
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MESH Headings
- Cloning, Molecular
- Crosses, Genetic
- DNA/genetics
- Enhancer Elements, Genetic
- Gene Expression Regulation, Plant
- Genes, Plant
- Germination
- Homozygote
- Nitrite Reductases/genetics
- Plants, Genetically Modified
- Plants, Toxic
- Promoter Regions, Genetic
- RNA, Messenger/genetics
- Suppression, Genetic/genetics
- Time Factors
- Nicotiana/enzymology
- Nicotiana/genetics
- Nicotiana/physiology
- Transformation, Genetic
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Affiliation(s)
- H Vaucheret
- Laboratoire de Biologie Cellulaire, INRA, Versailles, France
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42
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Meins F, Kunz C. Gene silencing in transgenic plants: a heuristic autoregulation model. Curr Top Microbiol Immunol 1995; 197:105-20. [PMID: 7493487 DOI: 10.1007/978-3-642-79145-1_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- F Meins
- Friedrich Miescher Institute, Basel, Switzerland
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