1
|
Hassan MM, Tenazas F, Williams A, Chiu JW, Robin C, Russell DA, Golz JF. Minimizing IP issues associated with gene constructs encoding the Bt toxin - a case study. BMC Biotechnol 2024; 24:37. [PMID: 38825715 PMCID: PMC11145813 DOI: 10.1186/s12896-024-00864-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 05/27/2024] [Indexed: 06/04/2024] Open
Abstract
BACKGROUND As part of a publicly funded initiative to develop genetically engineered Brassicas (cabbage, cauliflower, and canola) expressing Bacillus thuringiensis Crystal (Cry)-encoded insecticidal (Bt) toxin for Indian and Australian farmers, we designed several constructs that drive high-level expression of modified Cry1B and Cry1C genes (referred to as Cry1BM and Cry1CM; with M indicating modified). The two main motivations for modifying the DNA sequences of these genes were to minimise any licensing cost associated with the commercial cultivation of transgenic crop plants expressing CryM genes, and to remove or alter sequences that might adversely affect their activity in plants. RESULTS To assess the insecticidal efficacy of the Cry1BM/Cry1CM genes, constructs were introduced into the model Brassica Arabidopsis thaliana in which Cry1BM/Cry1CM expression was directed from either single (S4/S7) or double (S4S4/S7S7) subterranean clover stunt virus (SCSV) promoters. The resulting transgenic plants displayed a high-level of Cry1BM/Cry1CM expression. Protein accumulation for Cry1CM ranged from 5.18 to 176.88 µg Cry1CM/g dry weight of leaves. Contrary to previous work on stunt promoters, we found no correlation between the use of either single or double stunt promoters and the expression levels of Cry1BM/Cry1CM genes, with a similar range of Cry1CM transcript abundance and protein content observed from both constructs. First instar Diamondback moth (Plutella xylostella) larvae fed on transgenic Arabidopsis leaves expressing the Cry1BM/Cry1CM genes showed 100% mortality, with a mean leaf damage score on a scale of zero to five of 0.125 for transgenic leaves and 4.2 for wild-type leaves. CONCLUSIONS Our work indicates that the modified Cry1 genes are suitable for the development of insect resistant GM crops. Except for the PAT gene in the USA, our assessment of the intellectual property landscape of components presents within the constructs described here suggest that they can be used without the need for further licensing. This has the capacity to significantly reduce the cost of developing and using these Cry1M genes in GM crop plants in the future.
Collapse
Affiliation(s)
- Md Mahmudul Hassan
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
- Department of Genetics and Plant Breeding, Patuakhali Science and Technology University, Dumki, Patuakhali, 8602, Bangladesh
| | - Francis Tenazas
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Adam Williams
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jing-Wen Chiu
- School of Agriculture, Food and Ecosystem Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Charles Robin
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Derek A Russell
- Melbourne Veterinary School, University of Melbourne, Parkville, VIC, 3010, Australia
| | - John F Golz
- School of Biosciences, University of Melbourne, Parkville, VIC, 3010, Australia.
| |
Collapse
|
2
|
Pandey SP, Singh AP, Srivastava S, Chandrashekar K, Sane AP. A strong early acting wound-inducible promoter, RbPCD1pro, activates cryIAc expression within minutes of wounding to impart efficient protection against insects. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:1458-1470. [PMID: 30623549 PMCID: PMC6576099 DOI: 10.1111/pbi.13071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
The expression of insecticidal proteins under constitutive promoters in transgenic plants is fraught with problems like developmental abnormalities, yield drag, expression in unwanted tissues, and seasonal changes in expression. RbPCD1pro, a rapid, early acting wound-inducible promoter from rose that is activated within 5 min of wounding, was isolated and characterized. Wounding increased transcript levels up to 150 and 500 folds within 5 and 20 min coupled with high translation as seen by histochemical GUS enzyme activity within 5-20 min. RbPCD1pro was activated by both sucking and chewing insects and showed wound-inducible expression in various aerial tissues of plants representing commercially important dicot and monocot families. The promoter showed no expression in any vegetative tissue except upon wounding. Functionality of RbPCD1pro was tested by its ability to drive expression of the insecticidal protein gene cryIAc in transgenic Arabidopsis and tomato. Strong wound-inducible CryIAc expression was observed in both plants that increased 100-350 fold (Arabidopsis) and 280-600 fold (tomato) over the unwounded background within 5 min and over 1000-1600 fold within 20 min. The unwounded background level was just 3-6% of the CaMV35S promoter while wound-induced expression was 5-27 folds higher than the best CaMV35S line in just 5 min and 80-fold higher in 20 min. Transgenic plants showed strong resistance even to larger fourth instar larvae of H. armigera and no abnormalities in development and general plant growth. This is one of the earliest acting promoters with wide biotechnological application across monocot and dicot plants.
Collapse
Affiliation(s)
- Saurabh Prakash Pandey
- Plant Gene Expression LabCSIR‐National Botanical Research InstituteLucknowIndia
- Academy of Scientific and Innovative Research (AcSIR)GhaziabadIndia
| | - Amar Pal Singh
- Plant Gene Expression LabCSIR‐National Botanical Research InstituteLucknowIndia
- Present address:
National Institute for Plant Genome ResearchNew Delhi110067India
| | - Shruti Srivastava
- Plant Gene Expression LabCSIR‐National Botanical Research InstituteLucknowIndia
| | - Krishnappa Chandrashekar
- Genomics and Molecular Biology DivisionCSIR‐National Botanical Research InstituteLucknowIndia
- Present address:
IARI Regional CentreAundh, Pune411067India
| | - Aniruddha P. Sane
- Plant Gene Expression LabCSIR‐National Botanical Research InstituteLucknowIndia
- Academy of Scientific and Innovative Research (AcSIR)GhaziabadIndia
| |
Collapse
|
3
|
Sidorenko LV, Lee TF, Woosley A, Moskal WA, Bevan SA, Merlo PAO, Walsh TA, Wang X, Weaver S, Glancy TP, Wang P, Yang X, Sriram S, Meyers BC. GC-rich coding sequences reduce transposon-like, small RNA-mediated transgene silencing. NATURE PLANTS 2017; 3:875-884. [PMID: 29085072 DOI: 10.1038/s41477-017-0040-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 09/29/2017] [Indexed: 05/04/2023]
Abstract
The molecular basis of transgene susceptibility to silencing is poorly characterized in plants; thus, we evaluated several transgene design parameters as means to reduce heritable transgene silencing. Analyses of Arabidopsis plants with transgenes encoding a microalgal polyunsaturated fatty acid (PUFA) synthase revealed that small RNA (sRNA)-mediated silencing, combined with the use of repetitive regulatory elements, led to aggressive transposon-like silencing of canola-biased PUFA synthase transgenes. Diversifying regulatory sequences and using native microalgal coding sequences (CDSs) with higher GC content improved transgene expression and resulted in a remarkable trans-generational stability via reduced accumulation of sRNAs and DNA methylation. Further experiments in maize with transgenes individually expressing three crystal (Cry) proteins from Bacillus thuringiensis (Bt) tested the impact of CDS recoding using different codon bias tables. Transgenes with higher GC content exhibited increased transcript and protein accumulation. These results demonstrate that the sequence composition of transgene CDSs can directly impact silencing, providing design strategies for increasing transgene expression levels and reducing risks of heritable loss of transgene expression.
Collapse
Affiliation(s)
| | - Tzuu-Fen Lee
- Delaware Biotechnology Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19716, USA
- Dupont Pioneer, Johnston, IA, 50131, USA
| | - Aaron Woosley
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - William A Moskal
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Scott A Bevan
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - P Ann Owens Merlo
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Terence A Walsh
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Xiujuan Wang
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Staci Weaver
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Todd P Glancy
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - PoHao Wang
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Xiaozeng Yang
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, 100097, Beijing, China
| | - Shreedharan Sriram
- Dow AgroSciences LLC., 9330 Zionsville Road, Indianapolis, IN, 46268, USA
| | - Blake C Meyers
- Delaware Biotechnology Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19716, USA.
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA.
| |
Collapse
|
4
|
Bell SA, Shen C, Brown A, Hunt AG. Experimental Genome-Wide Determination of RNA Polyadenylation in Chlamydomonas reinhardtii. PLoS One 2016; 11:e0146107. [PMID: 26730730 PMCID: PMC4701671 DOI: 10.1371/journal.pone.0146107] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/14/2015] [Indexed: 11/20/2022] Open
Abstract
The polyadenylation of RNA is a near-universal feature of RNA metabolism in eukaryotes. This process has been studied in the model alga Chlamydomonas reinhardtii using low-throughput (gene-by-gene) and high-throughput (transcriptome sequencing) approaches that recovered poly(A)-containing sequence tags which revealed interesting features of this critical process in Chlamydomonas. In this study, RNA polyadenylation has been studied using the so-called Poly(A) Tag Sequencing (PAT-Seq) approach. Specifically, PAT-Seq was used to study poly(A) site choice in cultures grown in four different media types—Tris-Phosphate (TP), Tris-Phosphate-Acetate (TAP), High-Salt (HS), and High-Salt-Acetate (HAS). The results indicate that: 1. As reported before, the motif UGUAA is the primary, and perhaps sole, cis-element that guides mRNA polyadenylation in the nucleus; 2. The scope of alternative polyadenylation events with the potential to change the coding sequences of mRNAs is limited; 3. Changes in poly(A) site choice in cultures grown in the different media types are very few in number and do not affect protein-coding potential; 4. Organellar polyadenylation is considerable and affects primarily ribosomal RNAs in the chloroplast and mitochondria; and 5. Organellar RNA polyadenylation is a dynamic process that is affected by the different media types used for cell growth.
Collapse
Affiliation(s)
- Stephen A. Bell
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, United States of America
| | - Chi Shen
- Division of Computer Science, Kentucky State University, Frankfort, Kentucky, United States of America
| | - Alishea Brown
- Division of Computer Science, Kentucky State University, Frankfort, Kentucky, United States of America
| | - Arthur G. Hunt
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
| |
Collapse
|
5
|
Koul B, Srivastava S, Sanyal I, Tripathi B, Sharma V, Amla DV. Transgenic tomato line expressing modified Bacillus thuringiensis cry1Ab gene showing complete resistance to two lepidopteran pests. SPRINGERPLUS 2014; 3:84. [PMID: 24600542 PMCID: PMC3937457 DOI: 10.1186/2193-1801-3-84] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/05/2014] [Indexed: 11/24/2022]
Abstract
The modified truncated Bt-cry1Ab gene of Bacillus thuringiensis has been used for the development and selection of over expressing transgenic events in a commercially important variety of tomato (Solanum lycopersicum L.) by Agrobacterium-mediated leaf-disc transformation procedure. The integration and inheritance of cry1Ab gene in T0 transgenic plants and their progenies were determined by PCR, RT-PCR and Southern blot hybridization analysis. The toxin expression was monitored by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The transgenic line Ab25 E, expressing 0.47 ± 0.01% Cry1Ab toxin of total soluble protein (TSP) was finally selected in the T4 generation from the segregating population, showing 100% mortality to the second instar larvae of H. armigera and S. litura and minimal damages to leaves and fruits. Southern blot analysis data revealed single copy introgression of cry1Ab gene in highly-expressing Ab25 E transgenic line and expression of Cry1Ab toxin of molecular mass ~65 kDa was evident in Western blot analyses in transgenic plants of T4, T5 and T6 generation. Receptor binding assay performed with partially purified Cry1Ab protein from Ab25 E transgenic tomato line, confirmed efficient protein-protein interaction of Cry1Ab toxin with receptor(s) of both the insects. The higher level of Cry1Ab toxin (≈ 0.47 ± 0.01% TSP) did not affect the normal in vitro regeneration, plant development and fruit yield in this transgenic line. This high expressing Cry1Ab homozygous transgenic line can be a useful candidate in tomato breeding programmes for introgression of important agronomical traits.
Collapse
Affiliation(s)
- Bhupendra Koul
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
| | - Sugandha Srivastava
- Department of Microbiology, King George's Medical University (KGMU), Lucknow, 226 003 India
| | - Indraneel Sanyal
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
| | - Bhuminath Tripathi
- Department of Botany, Guru Ghasidas Vishwavidyalaya, Bilaspur, 495 009 Chhattisgarh India
| | - Vinay Sharma
- Department of Biosciences & Biotechnology, Banasthali Vidyapith, P.O. Banasthali, Tonk Road, Rajasthan, 304 022 India
| | - Devindra Vijay Amla
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
| |
Collapse
|
6
|
Rawat P, Singh AK, Ray K, Chaudhary B, Kumar S, Gautam T, Kanoria S, Kaur G, Kumar P, Pental D, Burma PK. Detrimental effect of expression of Bt endotoxin Cry1Ac on in vitro regeneration, in vivo growth and development of tobacco and cotton transgenics. J Biosci 2011; 36:363-76. [PMID: 21654089 DOI: 10.1007/s12038-011-9074-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
High levels of expression of the cry1Ac gene from Bacillus thuringiensis cannot be routinely achieved in transgenic plants despite modifications made in the gene to improve its expression. This has been attributed to the instability of the transcript in a few reports. In the present study, based on the genetic transformation of cotton and tobacco, we show that the expression of the Cry1Ac endotoxin has detrimental effects on both the in vitro and in vivo growth and development of transgenic plants. A number of experiments on developing transgenics in cotton with different versions of cry1Ac gene showed that the majority of the plants did not express any Cry1Ac protein. Based on Southern blot analysis, it was also observed that a substantial number of lines did not contain the cry1Ac gene cassette although they contained the marker gene nptII. More significantly, all the lines that showed appreciable levels of expression were found to be phenotypically abnormal. Experiments on transformation of tobacco with different constructs expressing the cry1Ac gene showed that in vitro regeneration was inhibited by the encoded protein. Further, out of a total of 145 independent events generated with the different cry1Ac gene constructs in tobacco, only 21 showed expression of the Cry1Ac protein, confirming observations made in cotton that regenerants that express high levels of the Cry1Ac protein are selected against during regeneration of transformed events. This problem was circumvented by targeting the Cry1Ac protein to the chloroplast, which also significantly improved the expression of the protein.
Collapse
Affiliation(s)
- Preeti Rawat
- Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Mathew LG, Maloney B, Takeda N, Mason HS. Spurious polyadenylation of Norovirus Narita 104 capsid protein mRNA in transgenic plants. PLANT MOLECULAR BIOLOGY 2011; 75:263-75. [PMID: 21203799 DOI: 10.1007/s11103-010-9725-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Accepted: 12/22/2010] [Indexed: 05/30/2023]
Abstract
Noroviruses are members of the family Caliciviridae, and cause a highly communicable gastroenteritis in humans. We explored the potential to develop a plant-based vaccine against Narita 104 virus, a Genogroup II Norovirus. In stably transgenic potato, we obtained very poor expression of Narita 104 virus capsid protein (NaVCP) despite the use of a strong constitutive promoter (dual enhancer 35S) driving the native coding sequence. We identified potentially detrimental sequence motifs that could mediate aberrant mRNA processing via spurious polyadenylation signals. Northern blots and RT-PCR analysis of total RNA revealed truncated transcripts that suggested premature polyadenylation. Site-directed mutagenesis to remove one potential polyadenylation near-upstream element resulted in an increased expression of NaVCP when transiently expressed in leaves of Nicotiana benthamiana. Further, cloning of the truncated cDNAs from transgenic NaVCP potato plants and transiently transfected N. benthamiana allowed us to identify at least ten different truncated transcripts resulting from premature polyadenylation of full length NaVCP transcripts. Comparative studies using real time PCR analysis from cDNA samples revealed lower accumulation of full length transcripts of NaVCP as compared to those from a gene encoding Norwalk Virus capsid protein (a related Genogroup I Norovirus) in transiently transfected plants. These findings provide evidence for impaired expression of NaVCP in transgenic plants mediated by spurious polyadenylation signals, and demonstrate the need to scrupulously search for potential polyadenylation signals in order to improve transgene expression in plants.
Collapse
Affiliation(s)
- Lolita G Mathew
- Center for Infectious Diseases and Vaccinology (CIDV), The Biodesign Institute at Arizona State University, 1001 South McAllister Avenue, Tempe, AZ 85287-5401, USA
| | | | | | | |
Collapse
|
8
|
Translational control of recombinant human acetylcholinesterase accumulation in plants. BMC Biotechnol 2007; 7:27. [PMID: 17537261 PMCID: PMC1913049 DOI: 10.1186/1472-6750-7-27] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 05/30/2007] [Indexed: 11/10/2022] Open
Abstract
Background Codon usage differences are known to regulate the levels of gene expression in a species-specific manner, with the primary factors often cited to be mRNA processing and accumulation. We have challenged this conclusion by expressing the human acetylcholinesterase coding sequence in transgenic plants in its native GC-rich sequence and compared to a matched sequence with (dicotyledonous) plant-optimized codon usage and a lower GC content. Results We demonstrate a 5 to 10 fold increase in accumulation levels of the "synaptic" splice variant of human acetylcholinesterase in Nicotiana benthamiana plants expressing the optimized gene as compared to the native human sequence. Both transient expression assays and stable transformants demonstrated conspicuously increased accumulation levels. Importantly, we find that the increase is not a result of increased levels of acetylcholinesterase mRNA, but rather its facilitated translation, possibly due to the reduced energy required to unfold the sequence-optimized mRNA. Conclusion Our findings demonstrate that codon usage differences may regulate gene expression at different levels and anticipate translational control of acetylcholinesterase gene expression in its native mammalian host as well.
Collapse
|
9
|
Kumar S, Birah A, Chaudhary B, Burma PK, Gupta GP, Pental D. Plant codon optimized cry genes of Bacillus thuringiensis can be expressed as soluble proteins in Escherichia coli BL21 Codon Plus strain as NusA-Cry protein fusions. J Invertebr Pathol 2005; 88:83-6. [PMID: 15707873 DOI: 10.1016/j.jip.2004.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 09/01/2004] [Indexed: 11/25/2022]
Abstract
For optimal expression of delta-endotoxins from Bacillus thuringiensis in plants, preferential changes in the codon sequences, and reduction in overall AT content in the nucleotide sequence of the genes is important. Reports suggest that sequences with such modifications cannot be overexpressed in bacteria. We report here that the modified genes can be overexpressed in a strain of Escherichia coli carrying extra tRNA genes for some of the codons occurring at high frequency in plant genes and less preferred in E. coli. We also demonstrate that proteins when expressed as fusion products with NusA protein, are obtained as soluble fraction rather than in inclusion bodies. This allows easy and accurate LC50 analysis on insect pests.
Collapse
Affiliation(s)
- S Kumar
- Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India
| | | | | | | | | | | |
Collapse
|
10
|
Liu D, Burton S, Glancy T, Li ZS, Hampton R, Meade T, Merlo DJ. Insect resistance conferred by 283-kDa Photorhabdus luminescens protein TcdA in Arabidopsis thaliana. Nat Biotechnol 2003; 21:1222-8. [PMID: 12949536 DOI: 10.1038/nbt866] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2003] [Accepted: 07/17/2003] [Indexed: 11/09/2022]
Abstract
The tcdA gene of Photorhabdus luminescens encodes a 283-kDa protein, toxin A, that is highly toxic to a variety of insects, including some agriculturally important pests. We tested the efficacy of transgenic toxin A in Arabidopsis thaliana for control of feeding insects. Plants with toxin A expression above about 700 ng/mg of extractable protein were highly toxic to tobacco hornworm (Manduca sexta). Toxin A isolated from transgenic plants also strongly inhibited growth of the southern corn rootworm (Diabrotica undecimpunctata howardi). Addition of 5' and 3' untranslated regions of a tobacco osmotin gene (osm) increased toxin A production 10-fold and recovery of insect-resistant lines 12-fold. In the best line, high toxin A expression and insect resistance were maintained for at least five generations in all progeny. The intact tcdA mRNA represents the largest effective transgenic transcript produced in plants to date. These results may open a new route to transgenic pest control in agriculture.
Collapse
Affiliation(s)
- Dong Liu
- Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, USA.
| | | | | | | | | | | | | |
Collapse
|
11
|
Affiliation(s)
- D McElroy
- Agricultural Business Operations at Maxygen, 515 Galveston Drive, Redwood City, CA 94063, USA.
| |
Collapse
|
12
|
Nayak P, Basu D, Das S, Basu A, Ghosh D, Ramakrishnan NA, Ghosh M, Sen SK. Transgenic elite indica rice plants expressing CryIAc delta-endotoxin of Bacillus thuringiensis are resistant against yellow stem borer (Scirpophaga incertulas). Proc Natl Acad Sci U S A 1997; 94:2111-6. [PMID: 9122157 PMCID: PMC20049 DOI: 10.1073/pnas.94.6.2111] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Generation of insect-resistant, transgenic crop plants by expression of the insecticidal crystal protein (ICP) gene of Bacillus thuringiensis (Bt) is a standard crop improvement approach. In such cases, adequate expression of the most appropriate ICP against the target insect pest of the crop species is desirable. It is also considered advantageous to generate Bt-transgenics with multiple toxin systems to control rapid development of pest resistance to the ICP. Larvae of yellow stem borer (YSB), Scirpophaga incertulas, a major lepidopteran insect pest of rice, cause massive losses of rice yield. Studies on insect feeding and on the binding properties of ICP to brush border membrane receptors in the midgut of YSB larvae revealed that cryIAb and cryIAc are two individually suitable candidate genes for developing YSB-resistant rice. Programs were undertaken to develop Bt-transgenic rice with these ICP genes independently in a single cultivar. A cryIAc gene was reconstructed and placed under control of the maize ubiquitin 1 promoter, along with the first intron of the maize ubiquitin 1 gene, and the nos terminator. The gene construct was delivered to embryogenic calli of IR64, an elite indica rice cultivar, using the particle bombardment method. Six highly expressive independent transgenic ICP lines were identified. Molecular analyses and insect-feeding assays of two such lines revealed that the transferred synthetic cryIAc gene was expressed stably in the T2 generation of these lines and that the transgenic rice plants were highly toxic to YSB larvae and lessened the damage caused by their feeding.
Collapse
Affiliation(s)
- P Nayak
- Plant Molecular and Cellular Genetics Section and Centre for Plant Molecular Biology, Bose Institute, Calcutta, India
| | | | | | | | | | | | | | | |
Collapse
|