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Mathis JP, Clark C, Sethi A, Ortegon B, Rauscher G, Booth R, Coder S, Nelson ME. Utility of Cry1Ja for Transgenic Insect Control. Toxins (Basel) 2024; 16:384. [PMID: 39330842 PMCID: PMC11435796 DOI: 10.3390/toxins16090384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2024] [Revised: 08/26/2024] [Accepted: 08/30/2024] [Indexed: 09/28/2024] Open
Abstract
Insect control traits are a key component of improving the efficacy of insect pest management and maximizing crop yields for growers. Insect traits based on proteins expressed by the bacteria Bacillus thuringiensis (Bt) have proven to be very effective tools in achieving this goal. Unfortunately, the adaptability of insects has led to resistance to certain proteins in current commercial products. Therefore, new insecticidal traits representing a different mode of action (MoA) than those currently in use are needed. Cry1Ja has good insecticidal activity against various lepidopteran species, and it provides robust protection against insect feeding with in planta expression. For Bt proteins, different MoAs are determined by their binding sites in the insect midgut. In this study, competitive binding assays are performed using brush border membrane vesicles (BBMVs) from Helicoverpa zea, Spodoptera frugiperda, and Chrysodeixis includens to evaluate the MoA of Cry1Ja relative to representatives of the various Bt proteins that are expressed in current commercial products for lepidopteran insect protection. This study highlights differences in the shared Cry protein binding sites in three insect species, Cry1Ja bioactivity against Cry1Fa resistant FAW, and in planta efficacy against target pests. These data illustrate the potential of Cry1Ja for new insect trait development.
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Affiliation(s)
- John P. Mathis
- Corteva Agriscience, Indianapolis, IN 46268, USA; (C.C.); (A.S.); (B.O.); (G.R.); (R.B.); (S.C.)
| | | | | | | | | | | | | | - Mark E. Nelson
- Corteva Agriscience, Indianapolis, IN 46268, USA; (C.C.); (A.S.); (B.O.); (G.R.); (R.B.); (S.C.)
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Afzal MBS, Ijaz M, Abbas N, Shad SA, Serrão JE. Resistance of Lepidopteran Pests to Bacillus thuringiensis Toxins: Evidence of Field and Laboratory Evolved Resistance and Cross-Resistance, Mode of Resistance Inheritance, Fitness Costs, Mechanisms Involved and Management Options. Toxins (Basel) 2024; 16:315. [PMID: 39057955 PMCID: PMC11281168 DOI: 10.3390/toxins16070315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/07/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024] Open
Abstract
Bacillus thuringiensis (Bt) toxins are potential alternatives to synthetic insecticides for the control of lepidopteran pests. However, the evolution of resistance in some insect pest populations is a threat and can reduce the effectiveness of Bt toxins. In this review, we summarize the results of 161 studies from 20 countries reporting field and laboratory-evolved resistance, cross-resistance, and inheritance, mechanisms, and fitness costs of resistance to different Bt toxins. The studies refer mainly to insects from the United States of America (70), followed by China (31), Brazil (19), India (12), Malaysia (9), Spain (3), and Australia (3). The majority of the studies revealed that most of the pest populations showed susceptibility and a lack of cross-resistance to Bt toxins. Factors that delay resistance include recessive inheritance of resistance, the low initial frequency of resistant alleles, increased fitness costs, abundant refuges of non-Bt, and pyramided Bt crops. The results of field and laboratory resistance, cross-resistance, and inheritance, mechanisms, and fitness cost of resistance are advantageous for predicting the threat of future resistance and making effective strategies to sustain the effectiveness of Bt crops.
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Affiliation(s)
- Muhammad Babar Shahzad Afzal
- Beekeeping & Hill Fruit Pests Research Station, Rawalpindi 46000, Pakistan;
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Mamuna Ijaz
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Naeem Abbas
- Pesticides and Environmental Toxicology Laboratory, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
| | - Sarfraz Ali Shad
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - José Eduardo Serrão
- Department of General Biology, Federal University of Vicosa, Vicosa 36570-900, MG, Brazil;
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Fabrick JA, Li X, Carrière Y, Tabashnik BE. Molecular Genetic Basis of Lab- and Field-Selected Bt Resistance in Pink Bollworm. INSECTS 2023; 14:insects14020201. [PMID: 36835770 PMCID: PMC9959750 DOI: 10.3390/insects14020201] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/03/2023] [Accepted: 02/14/2023] [Indexed: 05/17/2023]
Abstract
Transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) control some important insect pests. However, evolution of resistance by pests reduces the efficacy of Bt crops. Here we review resistance to Bt cotton in the pink bollworm, Pectinophora gossypiella, one of the world's most damaging pests of cotton. Field outcomes with Bt cotton and pink bollworm during the past quarter century differ markedly among the world's top three cotton-producing countries: practical resistance in India, sustained susceptibility in China, and eradication of this invasive lepidopteran pest from the United States achieved with Bt cotton and other tactics. We compared the molecular genetic basis of pink bollworm resistance between lab-selected strains from the U.S. and China and field-selected populations from India for two Bt proteins (Cry1Ac and Cry2Ab) produced in widely adopted Bt cotton. Both lab- and field-selected resistance are associated with mutations affecting the cadherin protein PgCad1 for Cry1Ac and the ATP-binding cassette transporter protein PgABCA2 for Cry2Ab. The results imply lab selection is useful for identifying genes important in field-evolved resistance to Bt crops, but not necessarily the specific mutations in those genes. The results also suggest that differences in management practices, rather than genetic constraints, caused the strikingly different outcomes among countries.
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Affiliation(s)
- Jeffrey A. Fabrick
- USDA ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ 85138, USA
- Correspondence:
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
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Tabashnik BE, Unnithan GC, Yelich AJ, Fabrick JA, Dennehy TJ, Carrière Y. Responses to Bt toxin Vip3Aa by pink bollworm larvae resistant or susceptible to Cry toxins. PEST MANAGEMENT SCIENCE 2022; 78:3973-3979. [PMID: 35633103 DOI: 10.1002/ps.7016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/17/2022] [Accepted: 05/28/2022] [Indexed: 05/29/2023]
Abstract
BACKGROUND Transgenic crops that make insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, evolution of resistance to Bt toxins by pests diminishes the efficacy of Bt crops. Resistance to crystalline (Cry) Bt toxins has spurred adoption of crops genetically engineered to produce the Bt vegetative insecticidal protein Vip3Aa. Here we used laboratory diet bioassays to evaluate responses to Vip3Aa by pink bollworm (Pectinophora gossypiella), one of the world's most damaging pests of cotton. RESULTS Against pink bollworm larvae susceptible to Cry toxins, Vip3Aa was less potent than Cry1Ac or Cry2Ab. Conversely, Vip3Aa was more potent than Cry1Ac or Cry2Ab against laboratory strains highly resistant to those Cry toxins. Five Cry-susceptible field populations were less susceptible to Vip3Aa than a Cry-susceptible laboratory strain (APHIS-S). Relative to APHIS-S, significant resistance to Vip3Aa did not occur in strains selected in the laboratory for > 700-fold resistance to Cry1Ac or both Cry1Ac and Cry2Ab. CONCLUSIONS Resistance to Cry1Ac and Cry2Ab did not cause strong cross-resistance to Vip3Aa in pink bollworm, which is consistent with predictions based on the lack of shared midgut receptors between these toxins and previous results from other lepidopterans. Comparison of the Bt toxin concentration in plants relative to the median lethal concentration (LC50 ) from bioassays may be useful for estimating efficacy. The moderate potency of Vip3Aa against Cry1Ac- and Cry2Ab-resistant and susceptible pink bollworm larvae suggests that Bt cotton producing this toxin together with novel Cry toxins might be useful as one component of integrated pest management. © 2022 Society of Chemical Industry.
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Affiliation(s)
| | | | | | - Jeffrey A Fabrick
- USDA ARS, US Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | | | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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Endo H. Molecular and Kinetic Models for Pore Formation of Bacillus thuringiensis Cry Toxin. Toxins (Basel) 2022; 14:toxins14070433. [PMID: 35878171 PMCID: PMC9321905 DOI: 10.3390/toxins14070433] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/03/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Cry proteins from Bacillus thuringiensis (Bt) and other bacteria are pesticidal pore-forming toxins. Since 2010, when the ABC transporter C2 (ABCC2) was identified as a Cry1Ac protein resistant gene, our understanding of the mode of action of Cry protein has progressed substantially. ABCC2 mediates high Cry1A toxicity because of its high activity for helping pore formation. With the discovery of ABCC2, the classical killing model based on pore formation and osmotic lysis became nearly conclusive. Nevertheless, we are still far from a complete understanding of how Cry proteins form pores in the cell membrane through interactions with their host gut membrane proteins, known as receptors. Why does ABCC2 mediate pore formation with high efficiency unlike other Cry1A-binding proteins? Is the “prepore” formation indispensable for pore formation? What is the mechanism underlying the synergism between ABCC2 and the 12-cadherin domain protein? We examine potential mechanisms of pore formation via receptor interactions in this paper by merging findings from prior studies on the Cry mode of action before and after the discovery of ABC transporters as Cry protein receptors. We also attempt to explain Cry toxicity using Cry–receptor binding affinities, which successfully predicts actual Cry toxicity toward cultured cells coexpressing ABC transporters and cadherin.
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Affiliation(s)
- Haruka Endo
- Department of Integrated Bioscience, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan
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Baranek J, Banaszak M, Kaznowski A, Lorent D. A novel Bacillus thuringiensis Cry9Ea-like protein with high insecticidal activity towards Cydia pomonella larvae. PEST MANAGEMENT SCIENCE 2021; 77:1401-1408. [PMID: 33099864 DOI: 10.1002/ps.6157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/23/2020] [Accepted: 10/25/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The host specificity of known Bacillus thuringiensis Cry and Vip pesticidal proteins still needs extensive investigation and the proteins currently used in crop protection are not effective against many pest species. Cydia pomonella (L.) is a widespread and economically important pest of apples, very difficult to control, since the larvae spend most of their life inside a fruit. Currently, large amounts of broad-spectrum, detrimental synthetic agents are used to combat this herbivore and therefore biopesticides with high activity against C. pomonella are very much needed. RESULTS The toxicity of B. thuringiensis Cry9Ea along with five distinct pesticidal proteins (Cry1Aa, Cry1Ca, Cry1Ia, Cry2Ab and Vip3Aa) has been determined towards the first-instar larvae of C. pomonella. Cry9Ea has much higher activity than the remaining tested proteins (30-1200-fold lower LC50 ) and possibly is the most potent B. thuringiensis pesticidal protein bioassayed against C. pomonella so far. In contrast, Cry9Ea is not toxic towards Spodoptera exigua (Hübn.), indicating a potentially narrow spectrum of activity. Both insect species show high variability in susceptibility to the remaining Cry/Vip proteins. CONCLUSIONS The obtained results extend the existing knowledge regarding B. thuringiensis pesticidal protein host range and indicate Cry9Ea as a promising candidate for successful biological control of C. pomonella. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Jakub Baranek
- Department of Microbiology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Magdalena Banaszak
- Department of Microbiology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Adam Kaznowski
- Department of Microbiology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Dagny Lorent
- Department of Microbiology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
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A novel Bacillus thuringiensis isolate toxic to cotton pink bollworm (Pectinophora gossypiella Saunders). Microb Pathog 2020; 150:104671. [PMID: 33307119 DOI: 10.1016/j.micpath.2020.104671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 01/11/2023]
Abstract
In this study, we report a novel indigenous Bacillus thuringiensis (Bt) isolate, T26, which showed spores and crystals under scanning electron microscope and pathogenicity against the pink bollworm (Pectinophora gossypiella Saunders) in artificial diet based bioassay. SDS-PAGE analysis of the spore-crystal mixture of the Bt isolate, T26 revealed presence of three major protein bands of approximate molecular weights of 80, 55 and 40 kDa. The draft genome assembly consists of 56 scaffolds with an entire draft genome size of 5,054,095 bp. NCBI blast analysis revealed that assembled draft genome is spread over in a chromosome (4,818,543 bp) and one plasmid (235,552 bp). NCBI Prokaryotic Genome Annotation Pipeline (PGAP) showed presence of 5033 coding gene sequences and 159 RNAs genes. None of the known lepidopteran active genes (cry1, cry2 and cry9) could be detected with PCR or with whole genome sequence analysis using Bt toxin scanner tool or CryProcessor tool. Thus, presence of protein crystals and toxicity towards cotton pink bollworm and absence of any known cry/vip/cyt type of genes in draft genome indicates it is a novel type of Bt isolate. Further investigation of this genome sequence along with protein sequencing will lead to understand the novel factors responsible for its virulence and could be a useful tool for the insect resistance management in pink bollworm.
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Li X, Miyamoto K, Takasu Y, Wada S, Iizuka T, Adegawa S, Sato R, Watanabe K. ATP-Binding Cassette Subfamily A Member 2 is a Functional Receptor for Bacillus thuringiensis Cry2A Toxins in Bombyx mori, but not for Cry1A, Cry1C, Cry1D, Cry1F, or Cry9A Toxins. Toxins (Basel) 2020; 12:E104. [PMID: 32041133 PMCID: PMC7076765 DOI: 10.3390/toxins12020104] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 11/29/2022] Open
Abstract
: Cry toxins are insecticidal proteins produced by Bacillus thuringiensis (Bt). They are used commercially to control insect pests since they are very active in specific insects and are harmless to the environment and human health. The gene encoding ATP-binding cassette subfamily A member 2 (ABCA2) was identified in an analysis of Cry2A toxin resistance genes. However, we do not have direct evidence for the role of ABCA2 for Cry2A toxins or why Cry2A toxin resistance does not cross to other Cry toxins. Therefore, we performed two experiments. First, we edited the ABCA2 sequence in Bombyx mori using transcription activator-like effector-nucleases (TALENs) and confirmed the susceptibility-determining ability in a diet overlay bioassay. Strains with C-terminal half-deleted BmABCA2 showed strong and specific resistance to Cry2A toxins; even strains carrying a deletion of 1 to 3 amino acids showed resistance. However, the C-terminal half-deleted strains did not show cross-resistance to other toxins. Second, we conducted a cell swelling assay and confirmed the specific ability of BmABCA2 to Cry2A toxins in HEK239 cells. Those demonstrated that BmABCA2 is a functional receptor for Cry2A toxins and that BmABCA2 deficiency-dependent Cry2A resistance does not confer cross-resistance to Cry1A, Cry1F, Cry1Ca, Cry1Da, or Cry9Aa toxins.
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Affiliation(s)
- Xiaoyi Li
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Sanae Wada
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
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Tabashnik BE, Carrière Y. Global Patterns of Resistance to Bt Crops Highlighting Pink Bollworm in the United States, China, and India. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2513-2523. [PMID: 31254345 DOI: 10.1093/jee/toz173] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Indexed: 05/29/2023]
Abstract
Crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt) have advanced pest control, but their benefits have been reduced by evolution of resistance in pests. The global monitoring data reviewed here reveal 19 cases of practical resistance to Bt crops, which is field-evolved resistance that reduces Bt crop efficacy and has practical consequences for pest control. Each case represents the responses of one pest species in one country to one Bt toxin. The results with pink bollworm (Pectinophora gossypiella) and Bt cotton differ strikingly among the world's three leading cotton-producing nations. In the southwestern United States, farmers delayed resistance by planting non-Bt cotton refuges from 1996 to 2005, then cooperated in a program that used Bt cotton, mass releases of sterile moths, and other tactics to eradicate this pest from the region. In China, farmers reversed low levels of pink bollworm resistance to Bt cotton by planting second-generation hybrid seeds from crosses between Bt and non-Bt cotton. This approach yields a refuge of 25% non-Bt cotton plants randomly interspersed within fields of Bt cotton. Farmers adopted this tactic voluntarily and unknowingly, not to manage resistance, but apparently because of its perceived short-term agronomic and economic benefits. In India, where non-Bt cotton refuges have been scarce and pink bollworm resistance to pyramided Bt cotton producing Cry1Ac and Cry2Ab toxins is widespread, integrated pest management emphasizing shortening of the cotton season, destruction of crop residues, and other tactics is now essential.
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Affiliation(s)
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
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10
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Bel Y, Zack M, Narva K, Escriche B. Specific binding of Bacillus thuringiensis Cry1Ea toxin, and Cry1Ac and Cry1Fa competition analyses in Anticarsia gemmatalis and Chrysodeixis includens. Sci Rep 2019; 9:18201. [PMID: 31796830 PMCID: PMC6890801 DOI: 10.1038/s41598-019-54850-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 11/15/2019] [Indexed: 11/25/2022] Open
Abstract
Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper) are two important defoliation pests of soybeans. In the present study, we have investigated the susceptibility and brush border membrane-binding properties of both species to Bacillus thuringiensis Cry1Ea toxin. Bioassays performed in first-instar larvae demonstrated potent activity against both soybean pests in terms of mortality or practical mortality. Competition-binding studies carried out with 125Iodine-labelled Cry1Ea, demonstrated the presence of specific binding sites on the midgut brush border membrane vesicles (BBMV) of both insect species. Heterologous competition-binding experiments indicated that Cry1Ea does not share binding sites with Cry1Ac or Cry1Fa in either soybean pest. This study contributes to the knowledge of Cry1Ea toxicity and midgut binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ea with other Bt proteins aimed at controlling lepidopteran pests in soybeans.
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Affiliation(s)
- Yolanda Bel
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, , Universitat de València, 46100, Burjassot, Spain
| | - Marc Zack
- Dow AgroSciences, Indianapolis, Indiana, USA
| | - Ken Narva
- Dow AgroSciences, Indianapolis, Indiana, USA
| | - Baltasar Escriche
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, , Universitat de València, 46100, Burjassot, Spain.
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11
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Bacillus thuringiensis Cry1Da_7 and Cry1B.868 Protein Interactions with Novel Receptors Allow Control of Resistant Fall Armyworms, Spodoptera frugiperda (J.E. Smith). Appl Environ Microbiol 2019; 85:AEM.00579-19. [PMID: 31175187 PMCID: PMC6677855 DOI: 10.1128/aem.00579-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/30/2019] [Indexed: 01/07/2023] Open
Abstract
Two new modified Bacillus thuringiensis (Bt) proteins, Cry1Da_7 and Cry1B.868, with activity against fall armyworms (FAW), Spodoptera frugiperda (J.E. Smith), were evaluated for their potential to bind new insect receptors compared to proteins currently deployed as plant-incorporated protectants (PIPs) in row crops. Results from resistant insect bioassays, disabled insecticidal protein (DIP) bioassays, and cell-based assays using insect cells expressing individual receptors demonstrate that receptor utilizations of the newly modified Cry1Da_7 and Cry1B.868 proteins are distinct from each other and from those of commercially available Bt proteins such as Cry1F, Cry1A.105, Cry2Ab, and Vip3A. Accordingly, these two proteins target different insect proteins in FAW midgut cells and when pyramided together should provide durability in the field against this economically important pest.IMPORTANCE There is increased concern with the development of resistance to insecticidal proteins currently expressed in crop plants, especially against high-resistance-risk pests such as fall armyworm (FAW), Spodoptera frugiperda, a maize pest that already has developed resistance to Bacillus thuringiensis (Bt) proteins such as Cry1F. Lepidopteran-specific proteins that bind new insect receptors will be critical in managing current Cry1F-resistant FAW and delaying future resistance development. Results from resistant insect assays, disabled insecticidal protein (DIP) bioassays, and cell-based assays using insect cells expressing individual receptors demonstrate that target receptors of the Cry1Da_7 and Cry1B.868 proteins are different from each other and from those of commercially available Bt proteins such as Cry1F, Cry1A.105, Cry2Ab, and Vip3A. Therefore, pyramiding these two new proteins in maize will provide durable control of this economically important pest in production agriculture.
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12
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Jerga A, Evdokimov AG, Moshiri F, Haas JA, Chen M, Clinton W, Fu X, Halls C, Jimenez-Juarez N, Kretzler CN, Panosian TD, Pleau M, Roberts JK, Rydel TJ, Salvador S, Sequeira R, Wang Y, Zheng M, Baum JA. Disabled insecticidal proteins: A novel tool to understand differences in insect receptor utilization. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 105:79-88. [PMID: 30605769 DOI: 10.1016/j.ibmb.2018.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/08/2018] [Accepted: 12/14/2018] [Indexed: 06/09/2023]
Abstract
The development of insect resistance to pesticides via natural selection is an acknowledged agricultural issue. Likewise, resistance development in target insect populations is a significant challenge to the durability of crop traits conferring insect protection and has driven the need for novel insecticidal proteins (IPs) with alternative mechanism of action (MOA) mediated by different insect receptors. The combination or "stacking" of transgenes encoding different insecticidal proteins in a single crop plant can greatly delay the development of insect resistance, but requires sufficient knowledge of MOA to identify proteins with different receptor preferences. Accordingly, a rapid technique for differentiating the receptor binding preferences of insecticidal proteins is a critical need. This article introduces the Disabled Insecticidal Protein (DIP) method as applied to the well-known family of three-domain insecticidal proteins from Bacillus thuringiensis and related bacteria. These DIP's contain amino acid substitutions in domain 1 that render the proteins non-toxic but still capable of competing with active proteins in insect feeding assays, resulting in a suppression of the expected insecticidal activity. A set of insecticidal proteins with known differences in receptor binding (Cry1Ab3, Cry1Ac.107, Cry2Ab2, Cry1Ca, Cry1A.105, and Cry1A.1088) has been studied using the DIP method, yielding results that are consistent with previous MOA studies. When a native IP and an excess of DIP are co-administered to insects in a feeding assay, the outcome depends on the overlap between their MOAs: if receptors are shared, then the DIP saturates the receptors to which the native protein would ordinarily bind, and acts as an antidote whereas, if there is no shared receptor, the toxicity of the native insecticidal protein is not inhibited. These results suggest that the DIP methodology, employing standard insect feeding assays, is a robust and effective method for rapid MOA differentiation among insecticidal proteins.
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Affiliation(s)
- Agoston Jerga
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA.
| | - Artem G Evdokimov
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Farhad Moshiri
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Jeffrey A Haas
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Mao Chen
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - William Clinton
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Xiaoran Fu
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Coralie Halls
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | | | | | | | - Michael Pleau
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - James K Roberts
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Timothy J Rydel
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Sara Salvador
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Reuben Sequeira
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Yanfei Wang
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Meiying Zheng
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - James A Baum
- Plant Biotechnology, Bayer Crop Science, Chesterfield, MO, 63017, USA
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13
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Naik VC, Kumbhare S, Kranthi S, Satija U, Kranthi KR. Field-evolved resistance of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), to transgenic Bacillus thuringiensis (Bt) cotton expressing crystal 1Ac (Cry1Ac) and Cry2Ab in India. PEST MANAGEMENT SCIENCE 2018; 74:2544-2554. [PMID: 29697187 DOI: 10.1002/ps.5038] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 05/29/2023]
Abstract
BACKGROUND Pink bollworm (PBW) adaptation to transgenic Bacillus thuringiensis (Bt) cotton expressing crystal 1Ac (Cry1Ac) (Bt-I) and Cry1Ac + Cry2Ab (Bt-II) was assessed in India during 2010-2017 in 38 districts of the 10 major cotton-growing states. RESULTS PBW larval incidence on Bt cotton was nil in northern India, wherein the resistance ratios (RRs) to Cry1Ac were 26-262 and those to Cry2Ab were 1-108. In central and southern India, the annual average PBW larval recovery from Bt II cotton was high at 28.85-72.49% during 2014-2017. In central and southern India, the 50% lethal concentration (LC50 ) of Cry1Ac increased from a mean of 0.330 µg mL-1 (range 0.126-0.849 µg mL-1 ) in 2013 to a mean of 6.938 µg mL-1 (range 3.52 to 10.30 µg mL-1 ) in 2017 and the RR increased from a mean of 47.12 (range 18-121) in 2013 to a mean of 1387 (704-2060) in 2017, whereas the LC50 value for Cry2Ab increased from a mean of 0.014 µg mL-1 (range 0.004-0.094 µg mL-1 ) in 2013 to a mean of 12.51 µg mL-1 (range 3.92 to 28.10 µg mL-1 ) in 2017 and the RR increased from a mean of 5.4 (range 1-31) in 2013 to a mean of 4196 (1306-9366) in 2017. CONCLUSION High PBW larval recovery on Bt-II in conjunction with high LC50 values for Cry1Ac and Cry2Ab in major cotton-growing districts of central and southern India provides evidence of field-evolved resistance in PBW to Bt-I and Bt-II cotton. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Vakudavath Cb Naik
- Crop Protection Division, Central Institute for Cotton Research, Nagpur, India
| | - Sujit Kumbhare
- Crop Protection Division, Central Institute for Cotton Research, Nagpur, India
| | - Sandhya Kranthi
- Crop Protection Division, Central Institute for Cotton Research, Nagpur, India
| | - Usha Satija
- Crop Protection Division, Central Institute for Cotton Research, Nagpur, India
| | - Keshav R Kranthi
- Crop Protection Division, Central Institute for Cotton Research, Nagpur, India
- Technical Information Section, International Cotton Advisory Committee, Washington, DC, USA
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14
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Huang T, Lin Q, Qian X, Zheng Y, Yao J, Wu H, Li M, Jin X, Pan X, Zhang L, Guan X. Nematicidal Activity of Cry1Ea11 from Bacillus thuringiensis BRC-XQ12 Against the Pine Wood Nematode (Bursaphelenchus xylophilus). PHYTOPATHOLOGY 2018; 108:44-51. [PMID: 28945518 DOI: 10.1094/phyto-05-17-0179-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The nematicidal activity of 92 Bacillus thuringiensis strains against the pine wood nematode Bursaphelenchus xylophilus, one of the world's top 10 plant-parasitic nematodes, was determined. The insecticidal crystal proteins (ICPs) from Bacillus thuringiensis BRC-XQ12 were the most toxic to Bursaphelenchus xylophilus, with a lethal concentration 50 (LC50) of 32.13 μg/ml. Because the ICPs expressed by Bacillus thuringiensis BRC-XQ12 were closest to Cry1Ea6 and B. thuringiensis BRC-XQ12 contained four kinds of cry1 subgenes (cry1Aa, cry1Cb, cry1Ea, and cry1Ia), Cry1Ea was most likely to be the key active component against the nematode. The 3,516-bp cry1Ea11 gene from BRC-XQ12, as designated by the B. thuringiensis δ-endotoxin nomenclature committee, was expressed in Escherichia coli. Purified Cry1Ea11 showed an LC50 of 32.53 and 23.23 μg/ml at 24 and 48 h, with corresponding virulence equations of Y = 32.15X + 1.38 (R2 = 0.9951) and Y = 34.29X + 3.16 (R2 = 0.9792), respectively. In order to detect the pathway of B. thuringiensis Cry1Ea11 into Bursaphelenchus xylophilus, the nematode was fed with NHS-rhodamine-labeled GST-Cry1Ea11. The results of confocal laser-scanning microscopy showed that the 159-kDa GST-Cry1Ea11 could be detected in the stylet and the esophageal lumen of the pine wood nematode, indicating that GST-Cry1Ea11 could enter into the nematode through the stylet. As far as we know, no Cry1 proteins have been shown to have activity against plant-parasitic nematodes before. These results demonstrate that Cry1Ea11 is a promising nematicidal protein for controlling pine wilt disease rendered by B. xylophilus, further dramatically broadening the spectrum of Bacillus thuringiensis ICPs.
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Affiliation(s)
- Tianpei Huang
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Qunxin Lin
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Xiaoli Qian
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Ying Zheng
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Junmin Yao
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Huachuan Wu
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Mengmeng Li
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Xin Jin
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Xiaohong Pan
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Lingling Zhang
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
| | - Xiong Guan
- All authors: State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology (Ministry of Education), College of Life Sciences, Fujian Agriculture and Forestry University, and first, fifth, sixth, seventh, eighth, ninth, tenth, and eleventh authors: Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian, People's Republic of China, 350002
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15
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Zhang T, Coates BS, Wang Y, Wang Y, Bai S, Wang Z, He K. Down-regulation of aminopeptidase N and ABC transporter subfamily G transcripts in Cry1Ab and Cry1Ac resistant Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae). Int J Biol Sci 2017; 13:835-851. [PMID: 28808417 PMCID: PMC5555102 DOI: 10.7150/ijbs.18868] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/16/2017] [Indexed: 12/20/2022] Open
Abstract
The Asian corn borer (ACB), Ostrinia furnacalis (Lepidoptera: Crambidae), is a highly destructive pest of cultivated maize throughout East Asia. Bacillus thuringiensis (Bt) crystalline protein (Cry) toxins cause mortality by a mechanism involving pore formation or signal transduction following toxin binding to receptors along the midgut lumen of susceptible insects, but this mechanism and mutations therein that lead to resistance are not fully understood. In the current study, quantitative comparisons were made among midgut expressed transcripts from O. furnacalis susceptible (ACB-BtS) and laboratory selected strains resistant to Cry1Ab (ACB-AbR) and Cry1Ac toxins (ACB-AcR) when feeding on non-Bt diet. From a combined de novo transcriptome assembly of 83,370 transcripts, ORFs of ≥ 100 amino acids were predicted and annotated for 28,940 unique isoforms derived from 12,288 transcripts. Transcriptome-wide expression estimated from RNA-seq read depths predicted significant down-regulation of transcripts for previously known Bt resistance genes, aminopeptidase N1 (apn1) and apn3, as well as a putative ATP binding cassette transporter group G (abcg) gene in both ACB-AbR and -AcR (log2[fold-change] ≥ 1.36; P < 0.0001). The transcripts that were most highly differentially regulated in both ACB-AbR and -AcR compared to ACB-BtS (log2[fold-change] ≥ 2.0; P < 0.0001) included up- and down-regulation of serine proteases, storage proteins and cytochrome P450 monooxygenases, as well as up-regulation of genes with predicted transport function. This study predicted the significant down-regulation of transcripts for previously known Bt resistance genes, aminopeptidase N1 (apn1) and apn3, as well as abccg gene in both ACB-AbR and -AcR. These data are important for the understanding of systemic differences between Bt resistant and susceptible genotypes.
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Affiliation(s)
- Tiantao Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Brad S. Coates
- United States Department of Agriculture, Agricultural Research Service, Corn Insects & Crop Genetics Research Unit, Iowa State University, Ames, IA, 50011, USA
| | - Yueqin Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Yidong Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Shuxiong Bai
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhenying Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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16
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Sánchez-Yáñez JM, García-Ortiz VR, Ulibarri G, Hernández-Escareño JJ. Existencia y supervivencia de esporas de variedades de Bacillus thuringiesis en granos de almacén. JOURNAL OF THE SELVA ANDINA RESEARCH SOCIETY 2016. [DOI: 10.36610/j.jsars.2016.070200034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Manikandan R, Balakrishnan N, Sudhakar D, Udayasuriyan V. Development of leaffolder resistant transgenic rice expressing cry2AX1 gene driven by green tissue-specific rbcS promoter. World J Microbiol Biotechnol 2016; 32:37. [PMID: 26867598 DOI: 10.1007/s11274-015-2006-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 12/28/2015] [Indexed: 12/01/2022]
Abstract
The insecticidal cry genes of Bacillus thuringiensis (Bt) have been successfully used for development of insect resistant transgenic rice plants. In this study, a novel cry2AX1 gene consisting a sequence of cry2Aa and cry2Ac gene driven by rice rbcS promoter was introduced into a rice cultivar, ASD16. Among 27 putative rice transformants, 20 plants were found to be positive for cry2AX1 gene. The expression of Cry2AX1 protein in transgenic rice plants ranged from 5.95 to 122.40 ng/g of fresh leaf tissue. Stable integration of the transgene was confirmed in putative transformants of rice by Southern blot hybridization analysis. Insect bioassay on T0 transgenic rice plants against rice leaffolder (Cnaphalocrosis medinalis) recorded larval mortality up to 83.33%. Stable inheritance and expression of cry2AX1 gene in T1 progenies was demonstrated using Southern and ELISA. The detached leaf bit bioassay with selected T1 plants showed 83.33-90.00% mortality against C. medinalis. The whole plant bioassay for T1 plants with rice leaffolder showed significant level of resistance even at a lower level of Cry2AX1 expression varying from 131 to 158 ng/g fresh leaf tissue during tillering stage.
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Affiliation(s)
- R Manikandan
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641 003, India
| | - N Balakrishnan
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641 003, India
| | - D Sudhakar
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641 003, India
| | - V Udayasuriyan
- Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641 003, India.
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18
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Xu C, Wang BC, Yu Z, Sun M. Structural insights into Bacillus thuringiensis Cry, Cyt and parasporin toxins. Toxins (Basel) 2014; 6:2732-70. [PMID: 25229189 PMCID: PMC4179158 DOI: 10.3390/toxins6092732] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 11/30/2022] Open
Abstract
Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type α-PFTs, Cyt toxin type β-PFTs and aerolysin type β-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively.
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Affiliation(s)
- Chengchen Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Bi-Cheng Wang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
| | - Ziniu Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
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19
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Zhang T, He M, Gatehouse AMR, Wang Z, Edwards MG, Li Q, He K. Inheritance patterns, dominance and cross-resistance of Cry1Ab- and Cry1Ac-selected Ostrinia furnacalis (Guenée). Toxins (Basel) 2014; 6:2694-707. [PMID: 25216083 PMCID: PMC4179155 DOI: 10.3390/toxins6092694] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 08/13/2014] [Accepted: 08/18/2014] [Indexed: 01/18/2023] Open
Abstract
Two colonies of Asian corn borer, Ostrinia furnacalis (Guenée), artificially selected from a Bt-susceptible colony (ACB-BtS) for resistance to Cry1Ab (ACB-AbR) and Cry1Ac (ACB-AcR) toxins, were used to analyze inheritance patterns of resistance to Cry1 toxins. ACB-AbR and ACB-AcR evolved significant levels of resistance, with resistance ratios (RR) of 39-fold and 78.8-fold to Cry1Ab and Cry1Ac, respectively. The susceptibility of ACB-AbR larvae to Cry1Ac and Cry1F toxins, which had not previously been exposed, were significantly reduced, being >113-fold and 48-fold, respectively. Similarly, susceptibility of ACB-AcR larvae to Cry1Ab and Cry1F were also significantly reduced (RR > nine-fold, RR > 18-fold, respectively), indicating cross-resistance among Cry1Ab, Cry1Ac, and Cry1F toxins. However, ACB-AbR and ACB-AcR larvae were equally susceptible to Cry1Ie as were ACB-BtS larvae, indicating no cross-resistance between Cry1Ie and Cry1Ab or Cry1Ac toxins; this may provide considerable benefits in preventing or delaying the evolution of resistance in ACB to Cry1Ab and Cry1Ac toxins. Backcrossing studies indicated that resistance to Cry1Ab toxin was polygenic in ACB-AbR, but monogenic in ACB-AcR, whilst resistance to Cry1Ac toxin was primarily monogenic in both ACB-AbR and ACB-AcR, but polygenic as resistance increased.
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Affiliation(s)
- Tiantao Zhang
- The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Mingxia He
- The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Angharad M R Gatehouse
- Newcastle Institute for Research on Sustainability, School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.
| | - Zhenying Wang
- The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Martin G Edwards
- Newcastle Institute for Research on Sustainability, School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK.
| | - Qing Li
- Agronomy College, Sichuan Agricultural University, Chengdu 611130, China.
| | - Kanglai He
- The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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20
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Fabrick JA, Ponnuraj J, Singh A, Tanwar RK, Unnithan GC, Yelich AJ, Li X, Carrière Y, Tabashnik BE. Alternative splicing and highly variable cadherin transcripts associated with field-evolved resistance of pink bollworm to bt cotton in India. PLoS One 2014; 9:e97900. [PMID: 24840729 PMCID: PMC4026531 DOI: 10.1371/journal.pone.0097900] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 04/25/2014] [Indexed: 11/25/2022] Open
Abstract
Evolution of resistance by insect pests can reduce the benefits of insecticidal proteins from Bacillus thuringiensis (Bt) that are used extensively in sprays and transgenic crops. Despite considerable knowledge of the genes conferring insect resistance to Bt toxins in laboratory-selected strains and in field populations exposed to Bt sprays, understanding of the genetic basis of field-evolved resistance to Bt crops remains limited. In particular, previous work has not identified the genes conferring resistance in any cases where field-evolved resistance has reduced the efficacy of a Bt crop. Here we report that mutations in a gene encoding a cadherin protein that binds Bt toxin Cry1Ac are associated with field-evolved resistance of pink bollworm (Pectinophora gossypiella) in India to Cry1Ac produced by transgenic cotton. We conducted laboratory bioassays that confirmed previously reported resistance to Cry1Ac in pink bollworm from the state of Gujarat, where Bt cotton producing Cry1Ac has been grown extensively. Analysis of DNA from 436 pink bollworm from seven populations in India detected none of the four cadherin resistance alleles previously reported to be linked with resistance to Cry1Ac in laboratory-selected strains of pink bollworm from Arizona. However, DNA sequencing of pink bollworm derived from resistant and susceptible field populations in India revealed eight novel, severely disrupted cadherin alleles associated with resistance to Cry1Ac. For these eight alleles, analysis of complementary DNA (cDNA) revealed a total of 19 transcript isoforms, each containing a premature stop codon, a deletion of at least 99 base pairs, or both. Seven of the eight disrupted alleles each produced two or more different transcript isoforms, which implicates alternative splicing of messenger RNA (mRNA). This represents the first example of alternative splicing associated with field-evolved resistance that reduced the efficacy of a Bt crop.
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Affiliation(s)
- Jeffrey A. Fabrick
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Arid Land Agricultural Research Center, Maricopa, Arizona, United States of America
- * E-mail:
| | - Jeyakumar Ponnuraj
- National Institute of Plant Health Management, Rajendranagar, Hyderabad, Andhra Pradesh, India
| | - Amar Singh
- National Centre for Integrated Pest Management, Indian Agricultural Research Institute, New Delhi, Delhi, India
| | - Raj K. Tanwar
- National Centre for Integrated Pest Management, Indian Agricultural Research Institute, New Delhi, Delhi, India
| | - Gopalan C. Unnithan
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
| | - Alex J. Yelich
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
| | - Bruce E. Tabashnik
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
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Shu C, Su H, Zhang J, He K, Huang D, Song F. Characterization of cry9Da4, cry9Eb2, and cry9Ee1 genes from Bacillus thuringiensis strain T03B001. Appl Microbiol Biotechnol 2013; 97:9705-13. [PMID: 23455566 DOI: 10.1007/s00253-013-4781-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/11/2013] [Accepted: 02/15/2013] [Indexed: 10/27/2022]
Abstract
Three cry9 genes, cry9Da4, cry9Eb2, and cry9Ee1, were cloned from Bacillus thuringiensis strain T03B001 using a high-resolution melting analysis method. All three cry9 genes were overexpressed in Escherichia coli Rosetta (DE3), and the expressed products Cry9Eb2 and Cry9Ee1 were shown to be toxic to Plutella xylostella and Ostrinia furnacalis, but not to Helicoverpa armigera or Colaphellus bowringi. The bioassay of Cry9Eb2 and Cry9Ee1 against Cry1Ac-resistant P. xylostella strains indicated that both novel Cry9 toxins exhibited no cross-resistance with Cry1Ac. Cry9Eb2 and Cry9Ee1 can be applied not only for P. xylostella and O. furnacalis control, but also for the Cry1Ac-resistance management of pests.
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Affiliation(s)
- Changlong Shu
- Northeast Agricultural University, Harbin, 150030, People's Republic of China
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22
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Zhang L, Huang F, Rogers Leonard B, Chen M, Clark T, Zhu YC, Wangila DS, Yang F, Niu Y. Susceptibility of Cry1Ab maize-resistant and -susceptible strains of sugarcane borer (Lepidoptera: Crambidae) to four individual Cry proteins. J Invertebr Pathol 2013; 112:267-72. [DOI: 10.1016/j.jip.2012.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/03/2012] [Accepted: 12/15/2012] [Indexed: 10/27/2022]
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23
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Similar genetic basis of resistance to Bt toxin Cry1Ac in Boll-selected and diet-selected strains of pink bollworm. PLoS One 2012; 7:e35658. [PMID: 22530065 PMCID: PMC3329465 DOI: 10.1371/journal.pone.0035658] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 03/21/2012] [Indexed: 11/19/2022] Open
Abstract
Genetically engineered cotton and corn plants producing insecticidal Bacillus thuringiensis (Bt) toxins kill some key insect pests. Yet, evolution of resistance by pests threatens long-term insect control by these transgenic Bt crops. We compared the genetic basis of resistance to Bt toxin Cry1Ac in two independently derived, laboratory-selected strains of a major cotton pest, the pink bollworm (Pectinophora gossypiella [Saunders]). The Arizona pooled resistant strain (AZP-R) was started with pink bollworm from 10 field populations and selected with Cry1Ac in diet. The Bt4R resistant strain was started with a long-term susceptible laboratory strain and selected first with Bt cotton bolls and later with Cry1Ac in diet. Previous work showed that AZP-R had three recessive mutations (r1, r2, and r3) in the pink bollworm cadherin gene (PgCad1) linked with resistance to Cry1Ac and Bt cotton producing Cry1Ac. Here we report that inheritance of resistance to a diagnostic concentration of Cry1Ac was recessive in Bt4R. In interstrain complementation tests for allelism, F(1) progeny from crosses between AZP-R and Bt4R were resistant to Cry1Ac, indicating a shared resistance locus in the two strains. Molecular analysis of the Bt4R cadherin gene identified a novel 15-bp deletion (r4) predicted to cause the loss of five amino acids upstream of the Cry1Ac-binding region of the cadherin protein. Four recessive mutations in PgCad1 are now implicated in resistance in five different strains, showing that mutations in cadherin are the primary mechanism of resistance to Cry1Ac in laboratory-selected strains of pink bollworm from Arizona.
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Asymmetrical cross-resistance between Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in pink bollworm. Proc Natl Acad Sci U S A 2009; 106:11889-94. [PMID: 19581574 DOI: 10.1073/pnas.0901351106] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some key insect pests and can reduce reliance on insecticide sprays. Sustainable use of such crops requires methods for delaying evolution of resistance by pests. To thwart pest resistance, some transgenic crops produce 2 different Bt toxins targeting the same pest. This "pyramid" strategy is expected to work best when selection for resistance to 1 toxin does not cause cross-resistance to the other toxin. The most widely used pyramid is transgenic cotton producing Bt toxins Cry1Ac and Cry2Ab. Cross-resistance between these toxins was presumed unlikely because they bind to different larval midgut target sites. Previous results showed that laboratory selection with Cry1Ac caused little or no cross-resistance to Cry2A toxins in pink bollworm (Pectinophora gossypiella), a major cotton pest. We show here, however, that laboratory selection of pink bollworm with Cry2Ab caused up to 420-fold cross-resistance to Cry1Ac as well as 240-fold resistance to Cry2Ab. Inheritance of resistance to high concentrations of Cry2Ab was recessive. Larvae from a laboratory strain resistant to Cry1Ac and Cry2Ab in diet bioassays survived on cotton bolls producing only Cry1Ac, but not on cotton bolls producing both toxins. Thus, the asymmetrical cross-resistance seen here does not threaten the efficacy of pyramided Bt cotton against pink bollworm. Nonetheless, the results here and previous evidence indicate that cross-resistance occurs between Cry1Ac and Cry2Ab in some key cotton pests. Incorporating the potential effects of such cross-resistance in resistance management plans may help to sustain the efficacy of pyramided Bt crops.
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Wu X, Rogers Leonard B, Zhu YC, Abel CA, Head GP, Huang F. Susceptibility of Cry1Ab-resistant and -susceptible sugarcane borer (Lepidoptera: Crambidae) to four Bacillus thuringiensis toxins. J Invertebr Pathol 2009; 100:29-34. [DOI: 10.1016/j.jip.2008.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 09/30/2008] [Accepted: 10/08/2008] [Indexed: 11/29/2022]
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Production and characterization of Bacillus thuringiensis Cry1Ac-resistant cotton bollworm Helicoverpa zea (Boddie). Appl Environ Microbiol 2007; 74:462-9. [PMID: 18024681 DOI: 10.1128/aem.01612-07] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Laboratory-selected Bacillus thuringiensis-resistant colonies are important tools for elucidating B. thuringiensis resistance mechanisms. However, cotton bollworm, Helicoverpa zea, a target pest of transgenic corn and cotton expressing B. thuringiensis Cry1Ac (Bt corn and cotton), has proven difficult to select for stable resistance. Two populations of H. zea (AR and MR), resistant to the B. thuringiensis protein found in all commercial Bt cotton varieties (Cry1Ac), were established by selection with Cry1Ac activated toxin (AR) or MVP II (MR). Cry1Ac toxin reflects the form ingested by H. zea when feeding on Bt cotton, whereas MVP II is a Cry1Ac formulation used for resistance selection and monitoring. The resistance ratio (RR) for AR exceeded 100-fold after 11 generations and has been maintained at this level for nine generations. This is the first report of stable Cry1Ac resistance in H. zea. MR crashed after 11 generations, reaching only an RR of 12. AR was only partially cross-resistant to MVP II, suggesting that MVP II does not have the same Cry1Ac selection pressure as Cry1Ac toxin against H. zea and that proteases may be involved with resistance. AR was highly cross-resistant to Cry1Ab toxin but only slightly cross-resistant to Cry1Ab expressing corn leaf powder. AR was not cross-resistant to Cry2Aa2, Cry2Ab2-expressing corn leaf powder, Vip3A, and cypermethrin. Toxin-binding assays showed no significant differences, indicating that resistance was not linked to a reduction in binding. These results aid in understanding why this pest has not evolved B. thuringiensis resistance, and highlight the need to choose carefully the form of B. thuringiensis protein used in experiments.
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Khasdan V, Sapojnik M, Zaritsky A, Horowitz AR, Boussiba S, Rippa M, Manasherob R, Ben-Dov E. Larvicidal activities against agricultural pests of transgenic Escherichia coli expressing combinations of four genes from Bacillus thuringiensis. Arch Microbiol 2007; 188:643-53. [PMID: 17665174 DOI: 10.1007/s00203-007-0285-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2007] [Revised: 06/19/2007] [Accepted: 07/11/2007] [Indexed: 10/23/2022]
Abstract
The genes cry1Ac and cry1Ca from Bacillus thuringiensis subsps. kurstaki HD-73 and aizawai 4J4, respectively, encoding delta-endotoxins against lepidopteran larvae were isolated, cloned and expressed in Escherichia coli, with and without cyt1Aa (encoding cytolytic protein) and p20 (accessory protein) from subsp. israelensis. Nine combinations of the genes under control of an early T7, P A1 inducible promoter, produced the encoding proteins. Toxicities were examined against larvae of three major agricultural pests: Pectinophora gossypiella, Helicoverpa armigera and Spodoptera littoralis. The clones expressing cyt1Aa, with or without p20, were not toxic. The clone expressing cry1Ac (pBt-1A) was the most toxic to P. gossypiella (LC50 of 0.27 x 10(8) cells g(-1)). Clone pBt-1CA expressing cry1Ca and cry1Ac displayed the highest toxicity (LC50 of 0.12 x 10(8) cells ml(-1)) against S. littoralis. Clone pBt-1CARCy expressing all four genes (cry1Ca, cry1Ac, p20, cyt1Aa) in tandem exhibited the highest toxicity to H. armigera (LC50 of 0.16 x 10(8) cells ml(-1)). Cyt1Aa failed to raise the toxicity of these Cry toxins against P. gossypiella and S. littoralis but significantly enhanced toxicity against H. armigera. Two additional clones expressing either cry1Ac or cry1Ca under tandem promoters, P A1 and P psbA (constitutive), displayed significantly higher toxicities (7.5- to 140-fold) than their counterparts with P A1 alone, reducing the LC50 values to below 10(7) cells ml(-1).
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Affiliation(s)
- Vadim Khasdan
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105, Israel
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Swiecicka I, Mahillon J. The clonal structure of Bacillus thuringiensis isolates from north-east Poland does not correlate with their cry gene diversity. Environ Microbiol 2005; 7:34-9. [PMID: 15643933 DOI: 10.1111/j.1462-2920.2004.00662.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The genetic relationship among 103 natural Bacillus thuringiensis isolates was investigated on the basis of polymerase chain reaction amplification of their specific crystal (cry) protein type genes and chromosomal DNA profiling by pulsed-field gel electrophoresis (PFGE). The strains were recovered from the intestines of small wild rodents and insectivores from the Biebrza National Park and the Lomza Landscape Park of the Narew River Valley in north-east Poland. The percentage of B. thuringiensis strains harbouring genes coding for toxins active against Lepidoptera (cry1, cry2, cry9) was very high (64%) compared with that of Diptera-specific strains (cry4, 14%). No strain with cry genes coding for proteins directed against coleopteran larvae and nematodes was found. After digestion with NotI and AscI, only nine PFGE pulsotypes were observed among all isolates, indicating a clonal structure for the B. thuringiensis population from NE Poland. Interestingly, no correlation was observed between the DNA pulsotype strains and their crystal gene content and diversity. These results therefore emphasize the importance of cry gene horizontal transfer occurring among natural isolates of B. thuringiensis.
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Affiliation(s)
- Izabela Swiecicka
- Department of Microbiology, Institute of Biology, University of Białystok, 15-950 Białystok, Swierkowa 20B, Poland.
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Sayyed AH, Raymond B, Ibiza-Palacios MS, Escriche B, Wright DJ. Genetic and biochemical characterization of field-evolved resistance to Bacillus thuringiensis toxin Cry1Ac in the diamondback moth, Plutella xylostella. Appl Environ Microbiol 2005; 70:7010-7. [PMID: 15574894 PMCID: PMC535196 DOI: 10.1128/aem.70.12.7010-7017.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The long-term usefulness of Bacillus thuringiensis Cry toxins, either in sprays or in transgenic crops, may be compromised by the evolution of resistance in target insects. Managing the evolution of resistance to B. thuringiensis toxins requires extensive knowledge about the mechanisms, genetics, and ecology of resistance genes. To date, laboratory-selected populations have provided information on the diverse genetics and mechanisms of resistance to B. thuringiensis, highly resistant field populations being rare. However, the selection pressures on field and laboratory populations are very different and may produce resistance genes with distinct characteristics. In order to better understand the genetics, biochemical mechanisms, and ecology of field-evolved resistance, a diamondback moth (Plutella xylostella) field population (Karak) which had been exposed to intensive spraying with B. thuringiensis subsp. kurstaki was collected from Malaysia. We detected a very high level of resistance to Cry1Ac; high levels of resistance to B. thuringiensis subsp. kurstaki Cry1Aa, Cry1Ab, and Cry1Fa; and a moderate level of resistance to Cry1Ca. The toxicity of Cry1Ja to the Karak population was not significantly different from that to a standard laboratory population (LAB-UK). Notable features of the Karak population were that field-selected resistance to B. thuringiensis subsp. kurstaki did not decline at all in unselected populations over 11 generations in laboratory microcosm experiments and that resistance to Cry1Ac declined only threefold over the same period. This finding may be due to a lack of fitness costs expressed by resistance strains, since such costs can be environmentally dependent and may not occur under ordinary laboratory culture conditions. Alternatively, resistance in the Karak population may have been near fixation, leading to a very slow increase in heterozygosity. Reciprocal genetic crosses between Karak and LAB-UK populations indicated that resistance was autosomal and recessive. At the highest dose of Cry1Ac tested, resistance was completely recessive, while at the lowest dose, it was incompletely dominant. A direct test of monogenic inheritance based on a backcross of F1 progeny with the Karak population suggested that resistance to Cry1Ac was controlled by a single locus. Binding studies with 125I-labeled Cry1Ab and Cry1Ac revealed greatly reduced binding to brush border membrane vesicles prepared from this field population.
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Affiliation(s)
- Ali H Sayyed
- Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, United Kingdom.
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Abstract
The Cry family of Bacillus thuringiensis insecticidal and nematicidal proteins constitutes a valuable source of environmentally benign compounds for the control of insect pests and disease agents. An understanding of Cry toxin resistance at a molecular level will be critical to the long-term utility of this technology; it may also shed light on basic mechanisms used by other bacterial toxins that target specific organisms or cell types. Selection and cross-resistance studies have confirmed that genetic adaptation can elicit varying patterns of Cry toxin resistance, which has been associated with deficient protoxin activation by host proteases, and defective Cry toxin-binding cell surface molecules, such as cadherins, aminopeptidases and glycolipids. Recent work also suggests Cry toxin resistance may be induced in invertebrates as an active immune response. The use of model invertebrates, such as Caenorhabditis elegans and Drosophila melanogaster, as well as advances in insect genomics, are likely to accelerate efforts to clone Cry toxin resistance genes and come to a detailed and broad understanding of Cry toxin resistance.
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Affiliation(s)
- Joel S Griffitts
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093-0349, USA
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Jurat-Fuentes JL, Gould FL, Adang MJ. Dual resistance to Bacillus thuringiensis Cry1Ac and Cry2Aa toxins in Heliothis virescens suggests multiple mechanisms of resistance. Appl Environ Microbiol 2004; 69:5898-906. [PMID: 14532042 PMCID: PMC201244 DOI: 10.1128/aem.69.10.5898-5906.2003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One strategy for delaying evolution of resistance to Bacillus thuringiensis crystal (Cry) endotoxins is the production of multiple Cry toxins in each transgenic plant (gene stacking). This strategy relies upon the assumption that simultaneous evolution of resistance to toxins that have different modes of action will be difficult for insect pests. In B. thuringiensis-transgenic (Bt) cotton, production of both Cry1Ac and Cry2Ab has been proposed to delay resistance of Heliothis virescens (tobacco budworm). After previous laboratory selection with Cry1Ac, H. virescens strains CXC and KCBhyb developed high levels of cross-resistance not only to toxins similar to Cry1Ac but also to Cry2Aa. We studied the role of toxin binding alteration in resistance and cross-resistance with the CXC and KCBhyb strains. In toxin binding experiments, Cry1A and Cry2Aa toxins bound to brush border membrane vesicles from CXC, but binding of Cry1Aa was reduced for the KCBhyb strain compared to susceptible insects. Since Cry1Aa and Cry2Aa do not share binding proteins in H. virescens, our results suggest occurrence of at least two mechanisms of resistance in KCBhyb insects, one of them related to reduction of Cry1Aa toxin binding. Cry1Ac bound irreversibly to brush border membrane vesicles (BBMV) from YDK, CXC, and KCBhyb larvae, suggesting that Cry1Ac insertion was unaffected. These results highlight the genetic potential of H. virescens to become resistant to distinct Cry toxins simultaneously and may question the effectiveness of gene stacking in delaying evolution of resistance.
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González-Cabrera J, Escriche B, Tabashnik BE, Ferré J. Binding of Bacillus thuringiensis toxins in resistant and susceptible strains of pink bollworm (Pectinophora gossypiella). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2003; 33:929-935. [PMID: 12915184 DOI: 10.1016/s0965-1748(03)00099-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Evolution of resistance by pests could cut short the success of transgenic plants producing toxins from Bacillus thuringiensis, such as Bt cotton. The most common mechanism of insect resistance to B. thuringiensis is reduced binding of toxins to target sites in the brush border membrane of the larval midgut. We compared toxin binding in resistant and susceptible strains of Pectinophora gossypiella, a major pest of cotton worldwide. Using Cry1Ab and Cry1Ac labeled with (125)I and brush border membrane vesicles (BBMV), competition experiments were performed with unlabeled Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ca, Cry1Ja, Cry2Aa, and Cry9Ca. In the susceptible strain, Cry1Aa, Cry1Ab, Cry1Ac, and Cry1Ja bound to a common binding site that was not shared by the other toxins tested. Reciprocal competition experiments with Cry1Ab, Cry1Ac, and Cry1Ja showed that these toxins do not bind to any additional binding sites. In the resistant strain, binding of (125)I-Cry1Ac was not significantly affected; however, (125)I-Cry1Ab did not bind to the BBMV. This result, along with previous data from this strain, shows that the resistance fits the "mode 1" pattern of resistance described previously in Plutella xylostella, Plodia interpunctella, and Heliothis virescens.
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Affiliation(s)
- Joel González-Cabrera
- Departamento de Genética, Facultad de CC. Biológicas, Universidad de Valencia, , 46100-Burjassot, Valencia, Spain
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Tabashnik BE, Dennehy TJ, Sims MA, Larkin K, Head GP, Moar WJ, Carrière Y. Control of resistant pink bollworm (Pectinophora gossypiella) by transgenic cotton that produces Bacillus thuringiensis toxin Cry2Ab. Appl Environ Microbiol 2002; 68:3790-4. [PMID: 12147473 PMCID: PMC124036 DOI: 10.1128/aem.68.8.3790-3794.2002] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a major cotton pest. To counter potential problems with resistance, second-generation transgenic cotton that produces B. thuringiensis toxin Cry2Ab alone or in combination with Cry1Ac has been developed. In greenhouse bioassays, a pink bollworm strain selected in the laboratory for resistance to Cry1Ac survived equally well on transgenic cotton with Cry1Ac and on cotton without Cry1Ac. In contrast, Cry1Ac-resistant pink bollworm had little or no survival on second-generation transgenic cotton with Cry2Ab alone or with Cry1Ac plus Cry2Ab. Artificial diet bioassays showed that resistance to Cry1Ac did not confer strong cross-resistance to Cry2Aa. Strains with >90% larval survival on diet with 10 microg of Cry1Ac per ml showed 0% survival on diet with 3.2 or 10 microg of Cry2Aa per ml. However, the average survival of larvae fed a diet with 1 microg of Cry2Aa per ml was higher for Cry1Ac-resistant strains (2 to 10%) than for susceptible strains (0%). If plants with Cry1Ac plus Cry2Ab are deployed while genes that confer resistance to each of these toxins are rare, and if the inheritance of resistance to both toxins is recessive, the efficacy of transgenic cotton might be greatly extended.
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Affiliation(s)
- Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, Arizona 85721, USA.
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Liu YB, Tabashnik BE, Dennehy TJ, Carrière Y, Sims MA, Meyer SK. Oviposition on and mining in bolls of Bt and non-Bt cotton by resistant and susceptible pink bollworm (Lepidoptera: Gelechiidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2002; 95:143-148. [PMID: 11942750 DOI: 10.1603/0022-0493-95.1.143] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Transgenic cotton that produces insecticidal crystal protein Cry1Ac of Bacillus thuringiensis (Bt) has been effective in controlling pink bollworm, Pectinophora gossypiella (Saunders). We compared responses to bolls of Bt cotton and non-Bt cotton by adult females and neonates from susceptible and Cry1Ac-resistant strains of pink bollworm. In choice tests on caged cotton plants in the greenhouse, neither susceptible nor resistant females laid fewer eggs on Bt cotton bolls than on non-Bt cotton bolls, indicating that the Bt toxin did not deter oviposition. Multiple regression revealed that the number of eggs laid per boll was negatively associated with boll age and positively associated with boll diameter. Females also laid more eggs per boll on plants with more bolls. The distribution of eggs among bolls of Bt cotton and non-Bt cotton was clumped, indicating that boll quality rather than avoidance of previously laid eggs was a primary factor in oviposition preference. Parallel to the results from oviposition experiments, in laboratory no-choice tests with 10 neonates per boll, the number of entrance holes per boll did not differ between Bt cotton and non-Bt cotton for susceptible and resistant neonates. Also, like females, neonates preferred younger bolls and larger bolls. Thus, acceptance of bolls by females for oviposition and by neonates for mining was affected by boll age and diameter, but not by Bt toxin in bolls. The lack of discrimination between Bt and non-Bt cotton bolls by pink bollworm from susceptible and resistant strains indicates that oviposition and mining initiation are independent of susceptibility to Cry1Ac.
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Affiliation(s)
- Yong-Biao Liu
- Department of Entomology, University of Arizona, Tucson 85721, USA.
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Ferré J, Van Rie J. Biochemistry and genetics of insect resistance to Bacillus thuringiensis. ANNUAL REVIEW OF ENTOMOLOGY 2002; 47:501-33. [PMID: 11729083 DOI: 10.1146/annurev.ento.47.091201.145234] [Citation(s) in RCA: 481] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Bacillus thuringiensis (Bt) is a valuable source of insecticidal proteins for use in conventional sprayable formulations and in transgenic crops, and it is the most promising alternative to synthetic insecticides. However, evolution of resistance in insect populations is a serious threat to this technology. So far, only one insect species has evolved significant levels of resistance in the field, but laboratory selection experiments have shown the high potential of other species to evolve resistance against Bt. We have reviewed the current knowledge on the biochemical mechanisms and genetics of resistance to Bt products and insecticidal crystal proteins. The understanding of the biochemical and genetic basis of resistance to Bt can help design appropriate management tactics to delay or reduce the evolution of resistance in insect populations.
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Affiliation(s)
- Juan Ferré
- Department of Genetics, University of Valencia, 46110-Burjassot (Valencia), Spain.
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Herrero S, González-Cabrera J, Tabashnik BE, Ferré J. Shared binding sites in Lepidoptera for Bacillus thuringiensis Cry1Ja and Cry1A toxins. Appl Environ Microbiol 2001; 67:5729-34. [PMID: 11722929 PMCID: PMC93366 DOI: 10.1128/aem.67.12.5729-5734.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2001] [Accepted: 10/10/2001] [Indexed: 11/20/2022] Open
Abstract
Bacillus thuringiensis toxins act by binding to specific target sites in the insect midgut epithelial membrane. The best-known mechanism of resistance to B. thuringiensis toxins is reduced binding to target sites. Because alteration of a binding site shared by several toxins may cause resistance to all of them, knowledge of which toxins share binding sites is useful for predicting cross-resistance. Conversely, cross-resistance among toxins suggests that the toxins share a binding site. At least two strains of diamondback moth (Plutella xylostella) with resistance to Cry1A toxins and reduced binding of Cry1A toxins have strong cross-resistance to Cry1Ja. Thus, we hypothesized that Cry1Ja shares binding sites with Cry1A toxins. We tested this hypothesis in six moth and butterfly species, each from a different family: Cacyreus marshalli (Lycaenidae), Lobesia botrana (Tortricidae), Manduca sexta (Sphingidae), Pectinophora gossypiella (Gelechiidae), P. xylostella (Plutellidae), and Spodoptera exigua (Noctuidae). Although the extent of competition varied among species, experiments with biotinylated Cry1Ja and radiolabeled Cry1Ac showed that Cry1Ja and Cry1Ac competed for binding sites in all six species. A recent report also indicates shared binding sites for Cry1Ja and Cry1A toxins in Heliothis virescens (Noctuidae). Thus, shared binding sites for Cry1Ja and Cry1A occur in all lepidopteran species tested so far.
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Affiliation(s)
- S Herrero
- Department of Genetics, University of Valencia, 46100-Burjassot (Valencia), Spain
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Liu YB, Tabashnik BE, Dennehy TJ, Patin AL, Sims MA, Meyer SK, Carrière Y. Effects of Bt cotton and crylac toxin on survival and development of pink bollworm (Lepidoptera: Gelechiidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2001; 94:1237-1242. [PMID: 11681689 DOI: 10.1603/0022-0493-94.5.1237] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We evaluated the effects of Bacillus thuringiensis (Bt) toxin CrylAc on survival and development of a susceptible strain and laboratory-selected resistant strains of pink bollworm, Pectinophora gossypiella (Saunders). For susceptible and resistant strains tested on artificial diet, increases in CrylAc concentration reduced developmental rate and pupal weight. In greenhouse tests, survival of resistant larvae on transgenic cotton that produces CrylAc (Bt cotton) was 46% relative to their survival on non-Bt cotton. In contrast, Bt cotton killed all susceptible larvae tested. F1 hybrid progeny of resistant and susceptible adults did not survive on Bt cotton, which indicates recessive inheritance of resistance. Compared with resistant or susceptible larvae reared on non-Bt cotton, resistant larvae reared on Bt cotton had lower survival and slower development, and achieved lower pupal weight and fecundity. Recessive resistance to Bt cotton is consistent with one of the basic assumptions of the refuge strategy for delaying resistance to Bt cotton. Whereas slower development of resistant insects on Bt cotton could increase the probability of mating between resistant adults and accelerate resistance, negative effects of Bt cotton on the survival and development of resistant larvae could delay evolution of resistance.
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Affiliation(s)
- Y B Liu
- Department of Entomology, University of Arizona, Tucson 85721, USA
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Meyer SK, Tabashnik BE, Liu YB, Wirth MC, Federici BA. Cyt1A from Bacillus thuringiensis lacks toxicity to susceptible and resistant larvae of diamondback moth (Plutella xylostella) and pink bollworm (Pectinophora gossypiella). Appl Environ Microbiol 2001; 67:462-3. [PMID: 11133481 PMCID: PMC92601 DOI: 10.1128/aem.67.1.462-463.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We tested Cyt1Aa, a cytolytic endotoxin of Bacillus thuringiensis, against susceptible and Cry1A-resistant larvae of two lepidopteran pests, diamondback moth (Plutella xylostella) and pink bollworm (Pectinophora gossypiella). Unlike previous results obtained with mosquito and beetle larvae, Cyt1Aa alone or in combination with Cry toxins was not highly toxic to the lepidopteran larvae that we examined.
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Affiliation(s)
- S K Meyer
- Department of Entomology, University of Arizona, Tucson, Arizona 85721, USA
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