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Soil pathogen, Fusarium oxysporum induced wilt disease in chickpea: a review on its dynamicity and possible control strategies. PROCEEDINGS OF THE INDIAN NATIONAL SCIENCE ACADEMY 2021. [DOI: 10.1007/s43538-021-00030-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Lohn AF, Trtikova M, Chapela I, Van den Berg J, du Plessis H, Hilbeck A. Transgene behavior in Zea mays L. crosses across different genetic backgrounds: Segregation patterns, cry1Ab transgene expression, insecticidal protein concentration and bioactivity against insect pests. PLoS One 2020; 15:e0238523. [PMID: 32911522 PMCID: PMC7482933 DOI: 10.1371/journal.pone.0238523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/18/2020] [Indexed: 11/19/2022] Open
Abstract
Brazil and South Africa, countries with economies in transition, are characterized by a dual agrarian structure co-occurring, sometimes, alongside in the same region. Large-scale commercial farming produces crops for export to global markets on the one hand, and small-scale farming, on the other hand, provides for subsistence and local markets. In both systems, maize (Zea mays) is a key crop for these two countries. For the commercial system, maize is a commodity crop while for the small-scale system it is the prime staple crop. In commercial systems, farmers predominantly grow genetically modified (GM) hybrid maize. In small-scale systems, farmers rely on open pollinated varieties (OPVs) and/or landraces and are largely dependent on seed saving systems. The aim of this study was to understand the relationship between transgene expression rates, the resulting concentrations of the transgene product (Bt protein) and its bioactivity in insect pests following transgene flow from GM hybrid maize into non-genetically modified, non-GM near-isogenic maize hybrid (ISO) and OPVs. We modeled segregation patterns and measured cry1Ab transgene expression (mRNA quantification), Cry1Ab protein concentration and pest survival. Two groups of F1, F2 crosses and backcrosses with GM, ISO and OPV maize varieties from Brazil and South Africa were used. Bioassays with the larvae of two lepidopteran maize pest species, Helicoverpa armigera and Spodoptera littoralis, were carried out. Overall, the cry1Ab transgene outcrossed effectively into the genetic backgrounds tested. The cry1Ab transgene was stably expressed in both ISO and OPV genetic backgrounds. Transgene introgression led to consistent, though highly variable, concentrations of Cry1Ab toxins that were similar to those observed in GM parental maize. Most crosses, but not all, suggested the expected Mendelian segregation pattern. Transgene expression rates were significantly higher than expected from purely Mendelian segregation in the South African crosses. In South African materials, ISO and OPV crosses produced significantly lower Cry1Ab concentrations compared to the GM parental maize. The Cry1Ab toxins from crosses were bioactive and induced mortality rates of ≥92.19% in H. armigera and ≥40.63% in S. littoralis after a period of only 4 days. However, no correlations were observed between the quantitation of mRNA for cry1Ab and the corresponding Cry1Ab protein concentrations, nor between the Cry1Ab concentrations and insect mortality rates across different genetic backgrounds. We therefore suggest that while transcription of the cry1Ab transgene reliably determines the presence of Cry1Ab protein, mRNA levels do not reflect, by themselves, the end Cry1Ab protein concentrations found in the plant. Because predictably high Cry1Ab concentrations are a key prerequisite for effective insect resistance management (IRM) programs, this observation raises questions about the effectiveness of such programs in scenarios with complex crop genetic backgrounds. On the other hand, confirmed bioactivity in all crosses should be expected to impact small farmer's selection behavior, unknowingly favoring the insecticidal trait. This may lead to a fixation of the trait in the wider population, and may influence the genetic diversity of varieties maintained by small-scale farmers.
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Affiliation(s)
- André Felipe Lohn
- Plant Ecological Genetics, Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
- * E-mail:
| | - Miluse Trtikova
- Plant Ecological Genetics, Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Ignacio Chapela
- Department of Environmental Science, Policy and Management, University of California Berkeley, Berkeley, California, United States of America
| | - Johnnie Van den Berg
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Hannalene du Plessis
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Angelika Hilbeck
- Plant Ecological Genetics, Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
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Konstantinova T, Parvanova D, Atanassov A, Djilianov D. Stable Integration of Transgenes in Tobacco. BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.2003.10817051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Weinhold A, Kallenbach M, Baldwin IT. Progressive 35S promoter methylation increases rapidly during vegetative development in transgenic Nicotiana attenuata plants. BMC PLANT BIOLOGY 2013; 13:99. [PMID: 23837904 PMCID: PMC3716894 DOI: 10.1186/1471-2229-13-99] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 07/06/2013] [Indexed: 05/23/2023]
Abstract
BACKGROUND Genetically modified plants are widely used in agriculture and increasingly in ecological research to enable the selective manipulation of plant traits in the field. Despite their broad usage, many aspects of unwanted transgene silencing throughout plant development are still poorly understood. A transgene can be epigenetically silenced by a process called RNA directed DNA methylation (RdDM), which can be seen as a heritable loss of gene expression. The spontaneous nature of transgene silencing has been widely reported, but patterns of acquirement remain still unclear. RESULTS Transgenic wild tobacco plants (Nicotiana attenuata) expressing heterologous genes coding for antimicrobial peptides displayed an erratic and variable occurrence of transgene silencing. We focused on three independently transformed lines (PNA 1.2, PNA 10.1 and ICE 4.4) as they rapidly lost the expression of the resistance marker and down-regulated transgene expression by more than 200 fold after only one plant generation. Bisulfite sequencing indicated hypermethylation within the 35S and NOS promoters of these lines. To shed light on the progress of methylation establishment, we successively sampled leaf tissues from different stages during plant development and found a rapid increase in 35S promoter methylation during vegetative growth (up to 77% absolute increase within 45 days of growth). The levels of de novo methylation were inherited by the offspring without any visible discontinuation. A secondary callus regeneration step could interfere with the establishment of gene silencing and we found successfully restored transgene expression in the offspring of several regenerants. CONCLUSIONS The unpredictability of the gene silencing process requires a thorough selection and early detection of unstable plant lines. De novo methylation of the transgenes was acquired solely during vegetative development and did not require a generational change for its establishment or enhancement. A secondary callus regeneration step provides a convenient way to rescue transgene expression without causing undesirable morphological effects, which is essential for experiments that use transformed plants in the analysis of ecologically important traits.
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Affiliation(s)
- Arne Weinhold
- Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena 07745, Germany
| | - Mario Kallenbach
- Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena 07745, Germany
| | - Ian Thomas Baldwin
- Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena 07745, Germany
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Smolka A, Li XY, Heikelt C, Welander M, Zhu LH. Effects of transgenic rootstocks on growth and development of non-transgenic scion cultivars in apple. Transgenic Res 2010; 19:933-48. [PMID: 20135223 DOI: 10.1007/s11248-010-9370-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Accepted: 01/18/2010] [Indexed: 11/25/2022]
Abstract
Although cultivation of genetic modified (GM) annual crops has been steadily increasing in the recent 10 years, the commercial cultivation of GM fruit tree is still very limited and reports of field trials on GM fruit trees are rare. This is probably because development and evaluation of GM fruit trees require a long period of time due to long life cycles of trees. In this study, we report results from a field trial on three rolB transgenic dwarfing apple rootstocks of M26 and M9 together with non-transgenic controls grafted with five non-transgenic scion cultivars. We intended to investigate the effects of transgenic rootstock on non-transgenic scion cultivars under natural conditions as well as to evaluate the potential value of using the rolB gene to modify difficult-to-root rootstocks of fruit trees. The results showed that all rolB transgenic rootstocks significantly reduced vegetative growth including tree height regardless of scion cultivar, compared with the non-transgenic rootstocks. Flowering and fruiting were also decreased for cultivars grown on the transgenic rootstocks in most cases, but the fruit quality was not clearly affected by the transgenic rootstocks. Cutting experiment and RT-PCR analysis showed that the rolB gene was stably expressed under field conditions. PCR and RT-PCR analyses displayed that the rolB gene or its mRNA were not detectable in the scion cultivars, indicating no translocation of the transgene or its mRNA from rootstock to scion. Our results suggest that rolB modified rootstocks should be used in combination with vigorous scion cultivars in order to obtain sufficient vegetative growth and good yield. Alternatively, the rolB gene could be used to dwarf vigorous rootstocks of fruit trees or produce bonzai plants as it can significantly reduce the vegetative growth of plants.
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Affiliation(s)
- Anders Smolka
- Department of Plant Breeding and Biotechnology, Swedish University of Agricultural Sciences, Box 101, 230 53, Alnarp, Sweden
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Sheppard AE, Timmis JN. Instability of plastid DNA in the nuclear genome. PLoS Genet 2009; 5:e1000323. [PMID: 19119415 PMCID: PMC2602989 DOI: 10.1371/journal.pgen.1000323] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 12/02/2008] [Indexed: 11/29/2022] Open
Abstract
Functional gene transfer from the plastid (chloroplast) and mitochondrial genomes to the nucleus has been an important driving force in eukaryotic evolution. Non-functional DNA transfer is far more frequent, and the frequency of such transfers from the plastid to the nucleus has been determined experimentally in tobacco using transplastomic lines containing, in their plastid genome, a kanamycin resistance gene (neo) readymade for nuclear expression. Contrary to expectations, non-Mendelian segregation of the kanamycin resistance phenotype is seen in progeny of some lines in which neo has been transferred to the nuclear genome. Here, we provide a detailed analysis of the instability of kanamycin resistance in nine of these lines, and we show that it is due to deletion of neo. Four lines showed instability with variation between progeny derived from different areas of the same plant, suggesting a loss of neo during somatic cell division. One line showed a consistent reduction in the proportion of kanamycin-resistant progeny, suggesting a loss of neo during meiosis, and the remaining four lines were relatively stable. To avoid genomic enlargement, the high frequency of plastid DNA integration into the nuclear genome necessitates a counterbalancing removal process. This is the first demonstration of such loss involving a high proportion of recent nuclear integrants. We propose that insertion, deletion, and rearrangement of plastid sequences in the nuclear genome are important evolutionary processes in the generation of novel nuclear genes. This work is also relevant in the context of transgenic plant research and crop production, because similar processes to those described here may be involved in the loss of plant transgenes.
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Affiliation(s)
- Anna E Sheppard
- School of Molecular and Biomedical Science, The University of Adelaide, South Australia, Australia.
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Marenkova (Novoselia) TV, Deineko EV, Shumny VK. Mosaic expression pattern of the nptII gene in transgenic tobacco plants Nu 21. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407070101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Marenkova TV, Deineko EV. The effect of duplications in the T-DNA on the stability of manifestation of heterologous genes in transgenic tobacco plants. RUSS J GENET+ 2006. [DOI: 10.1134/s1022795406050097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Docheva P, Christov N, Batchvarova R, Atanassov A. Sexual Crossing Approach for Combining Multiple Transgenes. BIOTECHNOL BIOTEC EQ 2003. [DOI: 10.1080/13102818.2003.10819190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Novoselia V, Deineko E, Filipenko E, Shumnyi V. Expression Stability of Marker Gene npt II in Transgenic Plants Nicotiana TobacumL. with Single T-DNA Insertion. BIOTECHNOL BIOTEC EQ 2001. [DOI: 10.1080/13102818.2001.10819121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Halpin C, Cooke SE, Barakate A, El Amrani A, Ryan MD. Self-processing 2A-polyproteins--a system for co-ordinate expression of multiple proteins in transgenic plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 17:453-9. [PMID: 10205902 DOI: 10.1046/j.1365-313x.1999.00394.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Achieving co-ordinate, high-level and stable expression of multiple transgenes in plants is currently difficult. Expression levels are notoriously variable and influenced by factors that act independently on transgenes at different genetic loci. Instability of expression due to loss, re-arrangement or silencing of transgenes may occur, and is exacerbated by increasing numbers of transgenic loci and repeated use of homologous sequences. Even linking two or more genes within a T-DNA does not necessarily result in co-ordinate expression. Linking proteins in a single open reading frame--a polyprotein--is a strategy for co-ordinate expression used by many viruses. After translation, polyproteins are processed into constituent polypeptides, usually by proteinases encoded within the polyprotein itself. However, in foot-and-mouth disease virus (FMDV), a sequence (2A) of just 16-20 amino acids appears to have the unique capability to mediate cleavage at its own C-terminus by an apparently enzyme-independent, novel type of reaction. This sequence can also mediate cleavage in a heterologous protein context in a range of eukaryotic expression systems. We have constructed a plasmid in which the 2A sequence is inserted between the reporter genes chloramphenicol acetyltransferase (CAT) and beta-glucuronidase (GUS), maintaining a single open reading frame. Here we report that expression of this construct in wheatgerm lysate and transgenic plants results in efficient cleavage of the polyprotein and co-ordinate expression of active CAT and GUS. Self-processing polyproteins using the FMDV 2A sequence could therefore provide a system for ensuring co-ordinated, stable expression of multiple introduced proteins in plant cells.
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Affiliation(s)
- C Halpin
- Zeneca Seeds, Jealott's Hill Research Station, Berkshire, UK.
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De Neve M, Van Houdt H, Bruyns AM, Van Montagu M, Depicker A. Screening for Transgenic Lines with Stable and Suitable Accumulation Levels of a Heterologous Protein. RECOMBINANT PROTEINS FROM PLANTS 1998. [DOI: 10.1007/978-1-60327-260-5_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Cecchini E, Gong Z, Geri C, Covey SN, Milner JJ. Transgenic Arabidopsis lines expressing gene VI from cauliflower mosaic virus variants exhibit a range of symptom-like phenotypes and accumulate inclusion bodies. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1997; 10:1094-101. [PMID: 9390424 DOI: 10.1094/mpmi.1997.10.9.1094] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Gene VI of cauliflower mosaic virus (CaMV) is an important determinant of symptom expression during infection. We have constructed a series of transgenic Arabidopsis lines that express gene VI protein (P6) from two CaMV isolates (Bari-1 and Cabb B-JI) that cause mild and severe symptoms, respectively, in Arabidopsis, and from a recombinant virus (Baji-31) with a hybrid gene VI that causes very severe symptoms. From 41 transgenic lines analyzed, 17 showed symptom-like phenotypes that ranged from mild vein chlorosis to severe chlorosis and stunting. P6 levels in transgenic lines varied from undetectable in the lowest expressors to levels greater than those in CaMV-infected plants. There was a strong correlation between phenotype severity and the level of P6, and with the gene VI origin in the order, Baji-31 > B-JI > Bari-1. This was similar to symptom severity in Arabidopsis infected with the respective CaMV variant. We also found that transgenic P6 accumulated in inclusion bodies that were similar to those found in infected plants but lacking virions. We conclude that expression of P6, in the absence of virus replication, elicits a subset of the host symptom responses normally observed during infection and that the level, sequence, and possibly the form of P6 are important in potentiating the process.
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Affiliation(s)
- E Cecchini
- Division of Biochemistry & Molecular Biology, Glasgow University, Scotland, U.K
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Sarul P, Vlahova M, Todorovska E, Atanassov A. Inheritance of Kanamycin and Ethionine Resistance Introduced in Alfalfa (Medicago Sativa L.) by Gene Transfer and Cell Selection. BIOTECHNOL BIOTEC EQ 1995. [DOI: 10.1080/13102818.1995.10818821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Matzke MA, Moscone EA, Park YD, Papp I, Oberkofler H, Neuhuber F, Matzke AJ. Inheritance and expression of a transgene insert in an aneuploid tobacco line. MOLECULAR & GENERAL GENETICS : MGG 1994; 245:471-85. [PMID: 7808397 DOI: 10.1007/bf00302260] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A T-DNA locus comprising nptII, uidA and nos genes--all under the control of the nos promoter (this locus was designated K because it encodes resistance to Kanamycin)--was found to be inherited erratically in a transgenic tobacco line. This anomalous behavior was partially explained following a karyotype analysis of plants representing several generations: these plants were aneuploids, presumably for the K-containing chromosome. During four generations of sexual propagation, transgenic plants that were either trisomic or tetrasomic for the K-containing chromosome (i.e. 2n = 49 or 2n = 50, respectively) were obtained. The trisomic plants (2n = 48 + 1) were virtually indistinguishable phenotypically from normal euploids (2n = 4x = 48), whereas the tetrasomic plants (2n = 48 + 2) were smaller, had somewhat misshapen leaves and exhibited reduced fertility. Although the amount of NPTII protein in different trisomic (K--, KK-, KKK) and tetrasomic (KK--, KKK-) plants was generally consistent with a K dosage effect, the genetic behavior of each trisomic--with respect to segregation of KanR and marker gene activity in progeny--was unique and not completely explicable by invoking aneuploidy. Specifically, unexpected gains or losses of K could occur, suggesting the formation of double reductional gametes and/or frequent gene conversion at this locus. The susceptibility of K locus marker genes to trans-inactivation in the trisomic and tetrasomic lines was tested by crossing in partially homologous silencing loci. In all transgenotypes tested, the three K marker genes were sensitive to trans-silencing, which was accompanied by methylation in all copies of the nos promotor. In addition to this directed inactivation/methylation, the K locus could also undergo infrequent, spontaneous partial methylation, which produced stable epialleles. In most plants, however, the multiple copies of the nos promoter at this locus remained unmethylated and active through four generations in all transgenotypes examined. The significance of these results for irregular inheritance patterns, aneuploid syndromes and homology-dependent gene silencing is discussed.
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Affiliation(s)
- M A Matzke
- Institute of Molecular Biology, Austrian Academy of Sciences, Salzburg
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