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Pinos D, Wang Y, Hernández-Martínez P, He K, Ferré J. Alteration of a Cry1A Shared Binding Site in a Cry1Ab-Selected Colony of Ostrinia furnacalis. Toxins (Basel) 2022; 14:toxins14010032. [PMID: 35051009 PMCID: PMC8779817 DOI: 10.3390/toxins14010032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/15/2021] [Accepted: 12/24/2021] [Indexed: 12/10/2022] Open
Abstract
The Asian corn borer, Ostrinia furnacalis (Guenée, 1854), is a highly damaging pest in Asia and the Pacific islands, and larvae feed mainly from corn crops. To determine the suitability of Bt-corn technology for the future control of this pest, understanding the potential to develop resistance to Cry1Ab and the basis of cross-resistance to other Cry1 proteins is of great interest. Here, we have explored the binding of Cry1A proteins to brush border membrane vesicles from two O. furnacalis colonies, one susceptible (ACB-BtS) and one laboratory-selected with Cry1Ab (ACB-AbR). The insects developed resistance to Cry1Ab and showed cross-resistance to Cry1Aa, Cry1Ac, and Cry1F. Binding assays with radiolabeled Cry1Ab and brush border membrane vesicles from susceptible insects showed that Cry1A proteins shared binding sites, though the results were not conclusive for Cry1F. The results were confirmed using radiolabeled Cry1Aa. The resistant insects showed a reduction of the specific binding of both Cry1Ab and Cry1Aa, suggesting that part of the binding sites were lost or altered. Competition binding assays showed full competition between Cry1Ab and Cry1Aa proteins in the susceptible colony but only partial competition in resistant insects, confirming the alteration of some, but not all, binding sites for these two proteins. The binding site model for Cry1A proteins in O. furnacalis is in agreement with the occurrence of multiple membrane receptors for these proteins.
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Affiliation(s)
- Daniel Pinos
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Deparment of Genetics, Universitat de València, 46100 Burjassot, Spain; (D.P.); (P.H.-M.)
| | - Yueqin Wang
- The State Key Laboratory for Biology of Plant Diseas and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Y.W.); (K.H.)
| | - Patricia Hernández-Martínez
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Deparment of Genetics, Universitat de València, 46100 Burjassot, Spain; (D.P.); (P.H.-M.)
| | - Kanglai He
- The State Key Laboratory for Biology of Plant Diseas and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Y.W.); (K.H.)
| | - Juan Ferré
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Deparment of Genetics, Universitat de València, 46100 Burjassot, Spain; (D.P.); (P.H.-M.)
- Correspondence:
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Critical domains in the specific binding of radiolabelled Vip3Af insecticidal protein to brush border membrane vesicles from Spodoptera spp. and cultured insect cells. Appl Environ Microbiol 2021; 87:e0178721. [PMID: 34586902 DOI: 10.1128/aem.01787-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis have been used, in combination with Cry proteins, to better control insect pests and as a strategy to delay the evolution of resistance to Cry proteins in Bt crops (crops protected from insect attack by the expression of proteins from B. thuringiensis). In this study, we have set up the conditions to analyze the specific binding of 125I-Vip3Af to Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). Heterologous competition binding experiments revealed that Vip3Aa shares the same binding sites with Vip3Af, but that Vip3Ca does not recognize all of them. As expected, Cry1Ac and Cry1F did not compete for Vip3Af binding sites. By trypsin treatment of selected alanine-mutants, we were able to generate truncated versions of Vip3Af. Their use as competitors with 125I-Vip3Af indicated that only those molecules containing domains I to III (DI-III and DI-IV) were able to compete with the trypsin-activated Vip3Af protein for binding, and that molecules only containing either domain IV or domains IV and V (DIV and DIV-V) were unable to compete with Vip3Af. These results were further confirmed with competition binding experiments using 125I-DI-III. In addition, the truncated protein 125I-DI-III also bound specifically to Sf21 cells. Cell viability assays showed that the truncated proteins DI-III and DI-IV were as toxic to Sf21 cells as the activated Vip3Af, suggesting that domains IV and V are not necessary for the toxicity to Sf21 cells, in contrast to their requirement in vivo. IMPORTANCE This study shows that Vip3Af binding sites are fully shared with Vip3Aa, only partially shared with Vip3Ca, and not shared with Cry1Ac and Cry1F in two Spodoptera spp. Truncated versions of Vip3Af revealed that only domains I to III were necessary for the specific binding, most likely because they can form the functional tetrameric oligomer and because domain III is supposed to contain the binding epitopes. In contrast to results obtained in vivo (bioassays against larvae), domains IV and V are not necessary for the ex vivo toxicity to Sf21 cells.
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Chen D, Moar WJ, Jerga A, Gowda A, Milligan JS, Bretsynder EC, Rydel TJ, Baum JA, Semeao A, Fu X, Guzov V, Gabbert K, Head GP, Haas JA. Bacillus thuringiensis chimeric proteins Cry1A.2 and Cry1B.2 to control soybean lepidopteran pests: New domain combinations enhance insecticidal spectrum of activity and novel receptor contributions. PLoS One 2021; 16:e0249150. [PMID: 34138865 PMCID: PMC8211277 DOI: 10.1371/journal.pone.0249150] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/07/2021] [Indexed: 01/08/2023] Open
Abstract
Two new chimeric Bacillus thuringiensis (Bt) proteins, Cry1A.2 and Cry1B.2, were constructed using specific domains, which provide insecticidal activity against key lepidopteran soybean pests while minimizing receptor overlaps between themselves, current, and soon to be commercialized plant incorporated protectants (PIP's) in soybean. Results from insect diet bioassays demonstrate that the recombinant Cry1A.2 and Cry1B.2 are toxic to soybean looper (SBL) Chrysodeixis includens Walker, velvetbean caterpillar (VBC) Anticarsia gemmatalis Hubner, southern armyworm (SAW) Spodoptera eridania, and black armyworm (BLAW) Spodoptera cosmioides with LC50 values < 3,448 ng/cm2. Cry1B.2 is of moderate activity with significant mortality and stunting at > 3,448 ng/cm2, while Cry1A.2 lacks toxicity against old-world bollworm (OWB) Helicoverpa armigera. Results from disabled insecticidal protein (DIP) bioassays suggest that receptor utilization of Cry1A.2 and Cry1B.2 proteins are distinct from each other and from current, and yet to be commercially available, Bt proteins in soy such as Cry1Ac, Cry1A.105, Cry1F.842, Cry2Ab2 and Vip3A. However, as Cry1A.2 contains a domain common to at least one commercial soybean Bt protein, resistance to this common domain in a current commercial soybean Bt protein could possibly confer at least partial cross resistance to Cry1A2. Therefore, Cry1A.2 and Cry1B.2 should provide two new tools for controlling many of the major soybean insect pests described above.
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Affiliation(s)
- Danqi Chen
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - William J. Moar
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Agoston Jerga
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Anilkumar Gowda
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jason S. Milligan
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | | | - Timothy J. Rydel
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - James A. Baum
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Altair Semeao
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Xiaoran Fu
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Victor Guzov
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Karen Gabbert
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Graham P. Head
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey A. Haas
- Bayer Crop Science, Chesterfield, Missouri, United States of America
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Hetero-oligomerization of Bacillus thuringiensis Cry1A proteins enhance binding to the ABCC2 transporter of Spodoptera exigua. Biochem J 2021; 478:2589-2600. [PMID: 34129679 DOI: 10.1042/bcj20210137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 11/17/2022]
Abstract
The ATP binding cassette (ABC) transporters are membrane proteins that can act as putative receptors for Cry proteins from Bacillus thuringiensis (Bt) in the midgut of different insects. For the beet armyworm, Spodoptera exigua, ABCC2 and ABCC3 have been found to interact with Cry1A proteins, the main insecticidal proteins used in Bt crops, as well as Bt-based pesticides. The ABCC2 has shown to have specific binding towards Cry1Ac and is involved in the toxic process of Cry1A proteins, but the role of this transporter and how it relates with the Cry1A proteins is still unknown. Here, we have characterized the interactions between the SeABCC2 and the main proteins that bind to the receptor. By labeling the Cry1Aa protein, we have found that virtually all of the binding is in an oligomeric state, a conformation that allowed higher levels of specific binding that could not be achieved by the monomeric protein on its own. Furthermore, we have observed that Cry1A proteins can hetero-oligomerize in the presence of the transporter, which is reflected in an increase in binding and toxicity to SeABCC2-expressing cells. This synergism can be one of the reasons why B. thuringiensis co-expresses different Cry1 proteins that can apparently have similar binding preferences. The results from in vitro competition and ex vivo competition showed that Cry1Aa, Cry1Ab and Cry1Ac share functional binding sites. By using Cry1Ab-Cry1Ac chimeras, the presence of domain I from Cry1A proteins was revealed to be critical for oligomer formation.
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Bacillus thuringiensis Cry1Ab Domain III β-16 Is Involved in Binding to Prohibitin, Which Correlates with Toxicity against Helicoverpa armigera (Lepidoptera: Noctuidae). Appl Environ Microbiol 2021; 87:AEM.01930-20. [PMID: 33127814 DOI: 10.1128/aem.01930-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/24/2020] [Indexed: 01/09/2023] Open
Abstract
Helicoverpa armigera is a major insect pest of several crops worldwide. This insect is susceptible to some Bacillus thuringiensis (Bt) Cry insecticidal proteins expressed in transgenic crops or used in biopesticides. Previously, we identified H. armigera prohibitin (HaPHB) as a Cry1Ac-binding protein. Here, we further analyzed the potential role of PHB as a Cry toxin receptor in comparison to cadherin (CAD), well recognized as a Cry1Ac receptor. HaPHB-2 midgut protein and HaCAD toxin-binding region (TBR) fragment from H. armigera were expressed in Escherichia coli cells, and binding assays with different Cry1 toxins were performed. We demonstrated that Cry1Ab, Cry1Ac, and Cry1Fa toxins bound to HaPHB-2 in a manner similar to that seen with HaCAD-TBR. Different Cry1Ab mutant toxins located in domain II (Cry1AbF371A and Cry1AbG439D) or domain III (Cry1AbL511A and Cry1AbN514A), which were previously characterized and found to be affected in receptor binding, were analyzed regarding their binding interaction with HaPHB-2 and toxicity against H. armigera One β-16 mutant (Cry1AbN514A) showed increased binding to HaPHB-2 that correlated with 6-fold-higher toxicity against H. armigera, whereas the other β-16 mutant (Cry1AbL511A) was affected in binding to HaPHB-2 and lost toxicity against H. armigera Our data indicate that β-16 from domain III of Cry1Ab is involved in interactions with HaPHB-2 and in toxicity. This report identifies a region of Cry1Ab involved in binding to HaPHB-2 from a Lepidoptera insect, suggesting that this protein may participate as a novel receptor in the mechanism of action of the Cry1 toxins in H. armigera IMPORTANCE Helicoverpa armigera is a polyphagous pest that feeds on important crops worldwide. This insect pest is sensitive to different Cry1 toxins from Bacillus thuringiensis In this study, we analyzed the potential role of PHB-2 as a Cry1 toxin receptor in comparison to CAD. We show that different Cry1 toxins bound to HaPHB-2 and HaCAD-TBR similarly and identify β-16 from domain III of Cry1Ab as a binding region involved in the interaction with HaPHB-2 and in toxicity. This report characterized HaPHB-Cry1 binding interaction, providing novel insights into potential target sites for improving Cry1 toxicity against H. armigera.
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Khan MH, Jander G, Mukhtar Z, Arshad M, Sarwar M, Asad S. Comparison of in Vitro and in Planta Toxicity of Vip3A for Lepidopteran Herbivores. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2959-2971. [PMID: 33080004 DOI: 10.1093/jee/toaa211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Indexed: 06/11/2023]
Abstract
Agricultural pest infestation is as old as domestication of food crops and contributes a major share to the cost of crop production. In a transgenic pest control approach, plant production of Vip3A, an insecticidal protein from Bacillus thuringiensis, is effective against lepidopteran pests. A synthetic Vip3A gene was evaluated for efficacy against Spodoptera litura Fabricius (Lepidoptera: Noctuidae; cotton leafworm), Spodoptera exigua Hübner (Lepidoptera: Noctuidae; beet armyworm), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae; fall armyworm), Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; cotton bollworm), Helicoverpa zea Boddie (Lepidoptera: Noctuidae; corn earworm), Heliothis virescens Fabricius (Lepidoptera: Noctuidae; tobacco budworm), and Manduca sexta L. (Lepidoptera: Sphingidae; tobacco hornworm) in tobacco. In artificial diet assays, the concentration required to achieve 50% mortality was highest for H. zea followed by H. virescens > S. exigua > H. armigera > M. sexta > S. frugiperda > S. litura. By contrast, in bioassays with detached leaves from Vip3A transgenic tobacco, the time until 50% lethality was M. sexta > H. virescens > S. litura > H. zea > H. armigera > S. exigua. There was no significant correlation between the artificial diet and transgenic plant bioassay results. Notably, the two insect species that are best-adapted for growth on tobacco, M. sexta and H. virescens, showed the greatest time to 50% mortality on Vip3A-transgenic tobacco. Together, our results suggest that artificial diet assays may be a poor predictor of Vip3A efficacy in transgenic plants, lepidopteran species vary in their sensitivity to Vip3A in diet-dependent manner, and host plant adaptation of the targeted herbivores should be considered when designing transgenic plants for pest control.
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Affiliation(s)
- Muhammad Hassaan Khan
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | | | - Zahid Mukhtar
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Muhammad Arshad
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Muhammad Sarwar
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
| | - Shaheen Asad
- Agricultural Biotechnology Division, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Pakistan Institute for Engineering and Applied Sciences (PIEAS), Nilore Islamabad, Pakistan
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Genomics and Proteomics Analyses Revealed Novel Candidate Pesticidal Proteins in a Lepidopteran-Toxic Bacillus thuringiensis Strain. Toxins (Basel) 2020; 12:toxins12110673. [PMID: 33114565 PMCID: PMC7693509 DOI: 10.3390/toxins12110673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 11/17/2022] Open
Abstract
Discovery and identification of novel insecticidal proteins in Bacillus thuringiensis (Bt) strains are of crucial importance for efficient biological control of pests and better management of insect resistance. In this study, the Bt strain KhF, toxic for Plodia interpunctella and Grapholita molesta larvae, underwent genomics and proteomics analyses to achieve a better understanding of the bases of its pathogenicity. The whole-genome sequencing results revealed that the KhF strain contained nine coding sequences with homologies to Bt insecticidal genes. The lepidopteran toxic mixture of spores and crystals of this Bt strain was subjected to liquid chromatography and tandem mass spectrometry (LC-MS/MS) to assess the protein composition. The results of the proteomic analyses, combined with the toxin gene sequences, revealed that two of the main components of the crystals were two new candidate pesticidal proteins, named KhFA and KhFB. These proteins showed a similarity lower than 36% to the other known Bt toxins. The phylogenetic analysis showed that the KhFA and KhFB grouped with the newly denominated Xpp and Mpp (former ETX/Mtx) pesticidal protein groups, respectively. Altogether, this study has led to the discovery of two novel candidate pesticidal toxins in the lepidopteran toxic KhF strain.
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da Costa Inácio G, Alves JVB, Santos MFC, Vacari AM, Figueiredo GP, Bernardes WA, Veneziani RCS, Ambrósio SR. Feeding deterrence towards Helicoverpa armigera by Tithonia diversifolia tagitinin C-enriched extract. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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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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Pinos D, Martínez-Solís M, Herrero S, Ferré J, Hernández-Martínez P. The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II. Toxins (Basel) 2019; 11:toxins11030172. [PMID: 30909393 PMCID: PMC6468857 DOI: 10.3390/toxins11030172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 12/27/2022] Open
Abstract
ABC proteins are primary-active transporters that require the binding and hydrolysis of ATP to transport substrates across the membrane. Since the first report of an ABCC2 transporter as receptor of Cry1A toxins, the number of ABC transporters known to be involved in the mode of action of Cry toxins has increased. In Spodoptera exigua, a mutation in the SeABCC2 gene is described as genetically linked to resistance to the Bt-product XentariTM. This mutation affects an intracellular domain involved in ATP binding, but not the extracellular loops. We analyzed whether this mutation affects the role of the SeABCC2 as a functional receptor to Cry1A toxins. The results show that Sf21 cells expressing the truncated form of the transporter were susceptible to Cry1A toxins. Moreover, specific Cry1Ac binding was observed in those cells expressing the truncated SeABCC2. Additionally, no differences in the irreversible Cry1Ac binding component (associated with the toxin insertion into the membrane) were observed when tested in Sf21 cells expressing either the full-length or the truncated form of the SeABCC2 transporter. Therefore, our results point out that the partial lack of the nucleotide binding domain II in the truncated transporter does not affect its functionality as a Cry1A receptor.
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Affiliation(s)
- Daniel Pinos
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - María Martínez-Solís
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Salvador Herrero
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Patricia Hernández-Martínez
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
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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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Martínez-Solís M, Pinos D, Endo H, Portugal L, Sato R, Ferré J, Herrero S, Hernández-Martínez P. Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 101:47-56. [PMID: 30077769 DOI: 10.1016/j.ibmb.2018.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/24/2018] [Accepted: 07/29/2018] [Indexed: 06/08/2023]
Abstract
Cry proteins from Bacillus thuringiensis (Bt) have been used to control insect pests either as formulated sprays or as in Bt-crops. However, field-evolved resistance to Bt proteins is threatening the long-term use of Bt products. The SeABCC2 locus has been genetically linked to resistance to a Bt bioinsecticide (Xentari™) in Spodoptera exigua (a mutation producing a truncated form of the transporter lacking an ATP binding domain was found in the resistant insects). Here, we investigated the role of SeABCC2 in the mode of action of Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and two Cry1A-1Ca hybrids by expressing the receptor in Sf21 and HEK293T cell lines. Cell toxicity assays showed that Sf21 cells expressing SeABCC2 become susceptible to Cry1A proteins. HEK293T cells expressing the transporter were found susceptible to Cry1A proteins but not to Cry1Ca. The results with the Cry1A-1Ca hybrids suggest that domain II from Cry1Ab/c is crucial for the toxicity to Sf21 cells, whereas domain III from Cry1Aa/b is crucial for the toxicity to HEK293T cells. Binding assays showed that the Cry1Ac binding is of high affinity and specific to cells expressing the SeABCC2 transporter. Heterologous competition experiments support a model in which domain II of Cry1Ab/c has a common binding site in the SeABCC2 protein, whereas domain III of Cry1Aa/b binds to a different binding site in the SeABCC2 protein.
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Affiliation(s)
- María Martínez-Solís
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Daniel Pinos
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Haruka Endo
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Leivi Portugal
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Salvador Herrero
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Patricia Hernández-Martínez
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
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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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Bel Y, Sheets JJ, Tan SY, Narva KE, Escriche B. Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens. Appl Environ Microbiol 2017; 83:e00326-17. [PMID: 28363958 PMCID: PMC5440703 DOI: 10.1128/aem.00326-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/23/2017] [Indexed: 11/20/2022] Open
Abstract
Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125-iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.
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Affiliation(s)
- Yolanda Bel
- Department of Genetics, Universitat de València, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Universitat de València, Burjassot, Spain
| | | | - Sek Yee Tan
- Dow AgroSciences, Indianapolis, Indiana, USA
| | | | - Baltasar Escriche
- Department of Genetics, Universitat de València, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Universitat de València, Burjassot, Spain
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Zhao M, Yuan X, Wei J, Zhang W, Wang B, Myint Khaing M, Liang G. Functional roles of cadherin, aminopeptidase-N and alkaline phosphatase from Helicoverpa armigera (Hübner) in the action mechanism of Bacillus thuringiensis Cry2Aa. Sci Rep 2017; 7:46555. [PMID: 28488696 PMCID: PMC5424343 DOI: 10.1038/srep46555] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/17/2017] [Indexed: 11/08/2022] Open
Abstract
A pyramid strategy combining the Cry1A and Cry2A toxins in Bt crops has been widely used throughout the world to delay pest adaption to transgenic crops and broaden the insecticidal spectrum. Midgut membrane-bound cadherin (CAD), aminopeptidase-N (APN) and alkaline phosphatase (ALP) are important for Cry1A toxicity in some lepidopteran larvae, but the proteins that bind Cry2A in the midgut of target insects and their role in the Cry2A mechanism of action are still unclear. In this study, we found that heterologously expressed CAD, APN4 and ALP2 peptides from the midgut of Helicoverpa armigera could bind to the Cry2Aa toxin with a high affinity. Additionally, the efficiency of Cry2Aa insecticidal activity against H. armigera larvae was obviously reduced after the genes encoding these proteins were silenced with specific siRNAs: CAD- and ALP2-silenced larvae showed significantly similar reductions in mortality due to the Cry2Aa toxin (41.67% and 43.06%, respectively), whereas a larger reduction in mortality was observed in APN4-silenced larvae (61.11%) than in controls. These results suggest that CAD, APN4 and ALP2 are involved in the mechanism of action of Cry2Aa in H. armigera and may play important functional roles in the toxicity of the Cry2Aa toxin.
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Affiliation(s)
- Man Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiangdong Yuan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jizhen Wei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Wanna Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bingjie Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Myint Myint Khaing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Gemei Liang
- 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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Lemes ARN, Figueiredo CS, Sebastião I, Marques da Silva L, da Costa Alves R, de Siqueira HÁA, Lemos MVF, Fernandes OA, Desidério JA. Cry1Ac and Vip3Aa proteins from Bacillus thuringiensis targeting Cry toxin resistance in Diatraea flavipennella and Elasmopalpus lignosellus from sugarcane. PeerJ 2017; 5:e2866. [PMID: 28123906 PMCID: PMC5244881 DOI: 10.7717/peerj.2866] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 12/06/2016] [Indexed: 01/30/2023] Open
Abstract
The biological potential of Vip and Cry proteins from Bacillus is well known and widely established. Thus, it is important to look for new genes showing different modes of action, selecting those with differentiated entomotoxic activity against Diatraea flavipennella and Elasmopalpus lignosellus, which are secondary pests of sugarcane. Therefore, Cry1 and Vip3 proteins were expressed in Escherichia coli, and their toxicities were evaluated based on bioassays using neonate larvae. Of those, the most toxic were Cry1Ac and Vip3Aa considering the LC50 values. Toxins from E. coli were purified, solubilized, trypsinized, and biotinylated. Brush Border Membrane Vesicles (BBMVs) were prepared from intestines of the two species to perform homologous and heterologous competition assays. The binding assays demonstrated interactions between Cry1Aa, Cry1Ac, and Vip3Aa toxins and proteins from the BBMV of D. flavipennella and E. lignosellus. Homologous competition assays demonstrated that binding to one of the BBMV proteins was specific for each toxin. Heterologous competition assays indicated that Vip3Aa was unable to compete for Cry1Ac toxin binding. Our results suggest that Cry1Ac and Vip3Aa may have potential in future production of transgenic sugarcane for control of D. flavipennella and E. lignosellus, but more research is needed on the potential antagonism or synergism of the toxins in these pests.
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Affiliation(s)
- Ana Rita Nunes Lemes
- Department of Biologia Aplicada á Agropecuária, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
| | - Camila Soares Figueiredo
- Department of Biologia Aplicada á Agropecuária, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
| | - Isis Sebastião
- Department of Biologia Aplicada á Agropecuária, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
| | | | - Rebeka da Costa Alves
- Department of Agronomia, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil
| | | | - Manoel Victor Franco Lemos
- Department of Biologia Aplicada á Agropecuária, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
| | - Odair Aparecido Fernandes
- Departamento de Fitossanidade/FCAV/UNESP, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
| | - Janete Apparecida Desidério
- Department of Biologia Aplicada á Agropecuária, Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
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17
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Cross-resistance to toxins used in pyramided Bt crops and resistance to Bt sprays in Helicoverpa zea. J Invertebr Pathol 2015; 132:149-156. [DOI: 10.1016/j.jip.2015.10.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 09/28/2015] [Accepted: 10/08/2015] [Indexed: 12/29/2022]
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18
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Wei J, Guo Y, Liang G, Wu K, Zhang J, Tabashnik BE, Li X. Cross-resistance and interactions between Bt toxins Cry1Ac and Cry2Ab against the cotton bollworm. Sci Rep 2015; 5:7714. [PMID: 25586723 PMCID: PMC4293620 DOI: 10.1038/srep07714] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 12/08/2014] [Indexed: 11/09/2022] Open
Abstract
To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the "pyramid" strategy uses plants that produce two or more toxins that kill the same pest. We conducted laboratory diet experiments with the cotton bollworm, Helicoverpa armigera, to evaluate cross-resistance and interactions between two toxins in pyramided Bt cotton (Cry1Ac and Cry2Ab). Selection with Cry1Ac for 125 generations produced 1000-fold resistance to Cry1Ac and 6.8-fold cross-resistance to Cry2Ab. Selection with Cry2Ab for 29 generations caused 5.6-fold resistance to Cry2Ab and 61-fold cross-resistance to Cry1Ac. Without exposure to Bt toxins, resistance to both toxins decreased. For each of the four resistant strains examined, 67 to 100% of the combinations of Cry1Ac and Cry2Ab tested yielded higher than expected mortality, reflecting synergism between these two toxins. Results showing minor cross-resistance to Cry2Ab caused by selection with Cry1Ac and synergism between these two toxins against resistant insects suggest that plants producing both toxins could prolong the efficacy of Bt cotton against this pest in China. Including toxins against which no cross-resistance occurs and integrating Bt cotton with other control tactics could also increase the sustainability of management strategies.
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Affiliation(s)
- Jizhen Wei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Yuyuan Guo
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Kongming Wu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
| | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA
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Li H, Bouwer G. Evaluation of the synergistic activities of Bacillus thuringiensis Cry proteins against Helicoverpa armigera (Lepidoptera: Noctuidae). J Invertebr Pathol 2014; 121:7-13. [DOI: 10.1016/j.jip.2014.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/09/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
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20
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Koul B, Srivastava S, Sanyal I, Tripathi B, Sharma V, Amla DV. Transgenic tomato line expressing modified Bacillus thuringiensis cry1Ab gene showing complete resistance to two lepidopteran pests. SPRINGERPLUS 2014; 3:84. [PMID: 24600542 PMCID: PMC3937457 DOI: 10.1186/2193-1801-3-84] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/05/2014] [Indexed: 11/24/2022]
Abstract
The modified truncated Bt-cry1Ab gene of Bacillus thuringiensis has been used for the development and selection of over expressing transgenic events in a commercially important variety of tomato (Solanum lycopersicum L.) by Agrobacterium-mediated leaf-disc transformation procedure. The integration and inheritance of cry1Ab gene in T0 transgenic plants and their progenies were determined by PCR, RT-PCR and Southern blot hybridization analysis. The toxin expression was monitored by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The transgenic line Ab25 E, expressing 0.47 ± 0.01% Cry1Ab toxin of total soluble protein (TSP) was finally selected in the T4 generation from the segregating population, showing 100% mortality to the second instar larvae of H. armigera and S. litura and minimal damages to leaves and fruits. Southern blot analysis data revealed single copy introgression of cry1Ab gene in highly-expressing Ab25 E transgenic line and expression of Cry1Ab toxin of molecular mass ~65 kDa was evident in Western blot analyses in transgenic plants of T4, T5 and T6 generation. Receptor binding assay performed with partially purified Cry1Ab protein from Ab25 E transgenic tomato line, confirmed efficient protein-protein interaction of Cry1Ab toxin with receptor(s) of both the insects. The higher level of Cry1Ab toxin (≈ 0.47 ± 0.01% TSP) did not affect the normal in vitro regeneration, plant development and fruit yield in this transgenic line. This high expressing Cry1Ab homozygous transgenic line can be a useful candidate in tomato breeding programmes for introgression of important agronomical traits.
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Affiliation(s)
- Bhupendra Koul
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
| | - Sugandha Srivastava
- Department of Microbiology, King George's Medical University (KGMU), Lucknow, 226 003 India
| | - Indraneel Sanyal
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
| | - Bhuminath Tripathi
- Department of Botany, Guru Ghasidas Vishwavidyalaya, Bilaspur, 495 009 Chhattisgarh India
| | - Vinay Sharma
- Department of Biosciences & Biotechnology, Banasthali Vidyapith, P.O. Banasthali, Tonk Road, Rajasthan, 304 022 India
| | - Devindra Vijay Amla
- Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 India
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Ai B, Li J, Feng D, Li F, Guo S. The elimination of DNA from the Cry toxin-DNA complex is a necessary step in the mode of action of the Cry8 toxin. PLoS One 2013; 8:e81335. [PMID: 24324685 PMCID: PMC3852532 DOI: 10.1371/journal.pone.0081335] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/17/2013] [Indexed: 11/30/2022] Open
Abstract
Several crystal (Cry) proteins are known to occur as DNA-protein complexes. However, the role of the DNA associated with the activated toxin in the mechanism of action of the Cry toxin has long been ignored. Here, we focused on the DNA-activated Cry toxin complex. Both forms of the Cry8Ca2 and Cry8Ea1 toxins, i.e., with or without bound DNA, were separately obtained. Size-exclusion chromatography analysis indicated that the Cry8Ca2 toxin-DNA complex has a tight or compact structure. The Cry8Ca2 toxin-DNA complex is more likely to move toward the air/water interface and is more hydrophobic than the toxin without DNA. Competitive binding assays indicated that the Cry8Ca2 and Cry8Ea1 toxins without DNA specifically bind to the midgut of Anomala corpulenta and Holotrichia parallela larvae, respectively. In contrast, the association of DNA with each toxin might result in the nonspecific recognition of the Cry toxin and its target receptor in the insect midgut. The association of the DNA fragment with the Cry8 toxin was shown to protect the Cry protein from digestion by proteases. Based on our results, we propose an additional step in the mechanism of action of the Cry8 toxin and elucidate the function of the associated DNA as well as the importance of the removal of this DNA for the insecticidal activity of the toxin.
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Affiliation(s)
- Bingjie Ai
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Jie Li
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Dongmei Feng
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Feng Li
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Shuyuan Guo
- School of Life Science, Beijing Institute of Technology, Beijing, China
- * E-mail:
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Sohail MN, Karimi SM, Asad S, Mansoor S, Zafar Y, Mukhtar Z. Development of broad-spectrum insect-resistant tobacco by expression of synthetic cry1Ac and cry2Ab genes. Biotechnol Lett 2012; 34:1553-60. [PMID: 22488439 DOI: 10.1007/s10529-012-0923-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 03/23/2012] [Indexed: 10/28/2022]
Abstract
Efficacy of two newly synthesized cry1Ac and cry2Ab genes was checked in tobacco before their expression in cotton. Both genes were artificially synthesized and codon optimized with respect to cotton-preferred codon usage. These genes were cloned in a plant expression vector and then transformed into tobacco. Fifty-eight putative transgenic plants were recovered from the selected explants. Successful integration of both genes in plant genome was confirmed by PCR amplification. Expression of transgenes was confirmed by PCR amplification from total plant RNA. Detached leaf insect bioassays were conducted with Helicoverpa armigera and Spodoptera exigua larvae. About 12 % of the transgenic plants showed significantly high resistance to S. exigua. Significant mortality (62 %) of H. armigera was recorded within 24 h of bioassays. Both toxins showed synergistic effect in tobacco and broadened the spectrum of plant activity against insects.
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Affiliation(s)
- Muhammad Nouman Sohail
- Plant Molecular Biology and Transformation Laboratory, Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, P.O. Box 577, Faisalabad, Pakistan
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23
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Determination of Cry toxin activity and identification of an aminopeptidase N receptor-like gene in Asymmathetes vulcanorum (Coleoptera: Curculionidae). J Invertebr Pathol 2012; 111:94-8. [PMID: 22721915 DOI: 10.1016/j.jip.2012.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/02/2012] [Accepted: 06/11/2012] [Indexed: 11/21/2022]
Abstract
An emergent pest is the weevil Asymmathetes vulcanorum, an insect that attacks Colombian potato areas. Here, some Cry proteins from the entomopathogenic bacteria Bacillus thuringiensis were evaluated as biological control strategy. It was found that Cry1B protoxin caused a mortality of 40% with a dose of 8000 ng/cm(2). Also in this research, it was identified a full length cDNA of an aminopeptidase N, a possible Cry protein receptor located in the insect midgut. This is the first report about B. thuringiensis as an alternative method for control of A. vulcanorum in Colombia.
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George DM, Rind FC, Bendall MW, Taylor MA, Gatehouse AMR. Developmental studies of transgenic maize expressing Cry1Ab on the African stem borer, Busseola fusca; effects on midgut cellular structure. PEST MANAGEMENT SCIENCE 2012; 68:330-339. [PMID: 21842526 DOI: 10.1002/ps.2260] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 06/23/2011] [Accepted: 06/23/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND Busseola fusca is a major pest of maize in Africa but unfortunately is difficult to control using chemical insecticides. Insect-resistant transgenic crops may provide an alternative viable strategy to control this pest. RESULTS Recombinant Cry1Ab (1%) reduced larval weight by 60% over the trial period, while larval weight in the control group increased by 25%; no effects on mortality were observed. Insect survival, developmental rate and pupal and adult weight were significantly reduced (P < 0.05) on maize expressing Cry1Ab (MON810) compared with the non-transformed parental line. These differences were more pronounced with second-instar larvae than with third-instar larvae. Leaf area consumed by Bacillus thuringiensis (Bt)-fed larvae was significantly lower (0.5 cm(2) larva(-1) day(-1)) compared with the area consumed by control-fed insects (3.3 cm(2) larva(-1) day(-1)). EM studies revealed that consumption of Bt maize deleteriously affected gut integrity. Effects were observed in columnar cells of the midgut epithelium, with the cytoplasm becoming highly vacuolated; the microvilli were disorganised, the mitochondria were abnormal and there was an increase in the number of lysosomal bodies. The rough endoplasmic reticulum had also become dilated. CONCLUSION This study confirms the potential for Bt maize, when used as part of an IPM programme, for control of B. fusca.
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Affiliation(s)
- Derick M George
- School of Biology, Newcastle University, Newcastle upon Tyne, UK
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Li H, Bouwer G. Toxicity of Bacillus thuringiensis Cry proteins to Helicoverpa armigera (Lepidoptera: Noctuidae) in South Africa. J Invertebr Pathol 2012; 109:110-6. [DOI: 10.1016/j.jip.2011.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/08/2011] [Accepted: 10/10/2011] [Indexed: 11/30/2022]
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Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding. Appl Microbiol Biotechnol 2011; 93:2365-75. [DOI: 10.1007/s00253-011-3547-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 08/01/2011] [Accepted: 08/13/2011] [Indexed: 02/08/2023]
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da Cunha FM, Caetano FH, Wanderley-Teixeira V, Torres JB, Teixeira AAC, Alves LC. Ultra-structure and histochemistry of digestive cells of Podisus nigrispinus (Hemiptera: Pentatomidae) fed with prey reared on bt-cotton. Micron 2011; 43:245-50. [PMID: 21900014 DOI: 10.1016/j.micron.2011.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 08/04/2011] [Accepted: 08/11/2011] [Indexed: 11/26/2022]
Abstract
The toxic effects of Bt proteins from the body of the prey/host to predators and parasitoids have been investigated as a route of impact on non-target insects of Bt crops. This research aimed to analyze ultrastructural changes and histochemistry in digestive cells of the middle region of the midgut of Podisus nigrispinus fed, since its second instar, with Spodoptera frugiperda reared on Bt cotton variety Acala90 B, which expresses the toxin Cry 1Ac, and its non-Bt isoline Acala 90. Fragments of the midgut of P. nigrispinus were analyzed by electron microscopy. For the histochemical analysis, Bromophenol Blue, Periodic Acid Schiff von Kossa, Alcian Blue pH 2.5 and Sudan Black were used. The Cry1Ac toxin of Bt cotton ingested by S. frugiperda promotes a disorganization in the perimicrovillar matrix of P. nigrispinus (third trophic level), thus generating ultrastructural changes in the digestive cells, as elongation of microvilli, presence of spherocrystals and granules of different electron densities, in addition to altering the distribution pattern of glycogen, lipids and calcium of these cells in the median region of the midgut. Thus, we conclude that species moderately susceptible to Cry1Ac toxin, such as S. frugiperda, can acquire this toxin and expose it to P. nigrispinus, which can interfere with your ability to predation.
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Affiliation(s)
- Franklin M da Cunha
- Department of Agronomy-Entomology, Rural Federal University of Pernambuco, Av. Dom Manoel de Medeiros s/n, Dois Irmãos, 52171-900, Recife, PE, Brazil.
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Crespo AL, Rodrigo-Simón A, Siqueira HA, Pereira EJ, Ferré J, Siegfried BD. Cross-resistance and mechanism of resistance to Cry1Ab toxin from Bacillus thuringiensis in a field-derived strain of European corn borer, Ostrinia nubilalis. J Invertebr Pathol 2011; 107:185-92. [DOI: 10.1016/j.jip.2011.04.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 03/27/2011] [Accepted: 04/15/2011] [Indexed: 12/24/2022]
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Binding sites for Bacillus thuringiensis Cry2Ae toxin on heliothine brush border membrane vesicles are not shared with Cry1A, Cry1F, or Vip3A toxin. Appl Environ Microbiol 2011; 77:3182-8. [PMID: 21441333 DOI: 10.1128/aem.02791-10] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The use of combinations of Bacillus thuringiensis (Bt) toxins with diverse modes of action for insect pest control has been proposed as the most efficient strategy to increase target range and delay the onset of insect resistance. Considering that most cases of cross-resistance to Bt toxins in laboratory-selected insect colonies are due to alteration of common toxin binding sites, independent modes of action can be defined as toxins sharing limited or no binding sites in brush border membrane vesicles (BBMV) prepared from the target insect larvae. In this paper, we report on the specific binding of Cry2Ae toxin to binding sites on BBMV from larvae of the three most commercially relevant heliothine species, Heliothis virescens, Helicoverpa zea, and Helicoverpa armigera. Using chromatographic purification under reducing conditions before labeling, we detected specific binding of radiolabeled Cry2Ae, which allowed us to perform competition assays using Cry1Ab, Cry1Ac, Cry1Fa, Vip3A, Cry2Ae, and Cry2Ab toxins as competitors. In these assays, Cry2Ae binding sites were shared with Cry2Ab but not with the tested Cry1 or Vip3A toxins. Our data support the use of Cry2Ae toxin in combination with Cry1 or Vip3A toxins in strategies to increase target range and delay the onset of heliothine resistance.
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Binding of Bacillus thuringiensis Cry1A toxins with brush border membrane vesicles of maize stem borer (Chilo partellus Swinhoe). J Invertebr Pathol 2011; 106:333-5. [DOI: 10.1016/j.jip.2010.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Revised: 08/27/2010] [Accepted: 09/02/2010] [Indexed: 11/23/2022]
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Sousa MEC, Santos FAB, Wanderley-Teixeira V, Teixeira AAC, de Siqueira HÁA, Alves LC, Torres JB. Histopathology and ultrastructure of midgut of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) fed Bt-cotton. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:1913-1919. [PMID: 20804764 DOI: 10.1016/j.jinsphys.2010.08.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 08/07/2010] [Accepted: 08/13/2010] [Indexed: 05/29/2023]
Abstract
The interaction of Cry toxins from Bacillus thuringiensis in the midgut of some insect larvae determines their efficacies as insecticides, due to the expression and availability of sites of action of the toxin in the midgut. Researches point out cases of resistance to Cry toxin due to alterations in the binding sites in columnar cell membrane. We analyzed the effects of Cry1Ac toxin expressed by Bt-cotton plants on Alabama argillacea midgut morphophysiology clarifying in levels of morphological and ultrastructural. Larvae in the 4th instar of A. argillacea after 20 min from ingesting Bt-cotton leaves expressing 0.183 ng of Cry1Ac exhibited ultrastructural and morphological modifications in the columnar cells with significant changes in the mitochondrial polymorphism, cytoplasmic vacuolization, microvillus and basal labyrinth. Expressive morphological alterations were also observed in the goblet cells indicating that the columnar cells are not the only target of the Cry1Ac toxin. The regenerative cells did not modify their structures and exhibited decrease in regeneration capacity. In conclusion, the ingestion of 0.183 ± 0.077 ng of Cry1Ac was enough to promote alterations in the columnar and goblet cells, besides reducing significantly the number of regenerative cells, which may have contributed to larval death. Nevertheless, further studies are necessary to determine the true cause of death.
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Affiliation(s)
- Maria Esmeralda C Sousa
- Departamento de Agronomia, Programa de Pós-Graduacão em Entomologia Agrícola, Universidade Federal Rural de Pernambuco, Av. Dom Manoel de Medeiros s/n, Dois Irmãos, CEP 52171-900 Recife, PE, Brazil
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Knaak N, Franz AR, Santos GF, Fiuza LM. Histopathology and the lethal effect of Cry proteins and strains of Bacillus thuringiensis Berliner in Spodoptera frugiperda J.E. Smith Caterpillars (Lepidoptera, Noctuidae). BRAZ J BIOL 2010; 70:677-84. [DOI: 10.1590/s1519-69842010000300028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 04/29/2009] [Indexed: 11/22/2022] Open
Abstract
Among the phytophagous insects which attack crops, the fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera, Noctuidae) is particularly harmful in the initial growth phase of rice plants. As a potential means of controlling this pest, and considering that the entomopathogen Bacillus thuringiensis Berliner demonstrates toxicity due to synthesis of the Cry protein, the present study was undertaken to evaluate this toxic effect of B. thuringiensis thuringiensis 407 (pH 408) and B. thuringiensis kurstaki HD-73 on S. frugiperda. The following method was used. Both bacterial strains were evaluated in vitro in 1st instar S. frugiperda caterpillars, by means of histopathological assays. The Cry1Ab and Cry1Ac proteins, codified by the respective strains of B. thuringiensis, were evaluated in vivo by bioassays of 1st instar S. frugiperda caterpillars in order to determine the Mean Lethal Concentration (LC50). The results of the histopathological analysis of the midget of S. frugiperda caterpillars demonstrate that treatment with the B. thuringiensis thuringiensis strain was more efficient, because the degradations of the microvilosities started 9 hours after treatment application (HAT), while in the B. thuringiensis kurstaki the same effect was noticed only after 12 HAT. Toxicity data of the Cry1Ab and Cry1Ac proteins presented for the target-species LC50 levels of 9.29 and 1.79 μg.cm-2 respectively. The strains and proteins synthesised by B. thuringiensis thuringiensis and B. thuringiensis kurstaki are effective in controlling S. frugiperda, and may be used to produce new biopesticides or the genes may be utilised in the genetic transformation of Oryza sativa L.
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Affiliation(s)
- N. Knaak
- Universidade do Vale do Rio dos Sinos, Brazil
| | | | - GF. Santos
- Universidade do Vale do Rio dos Sinos, Brazil
| | - LM. Fiuza
- Universidade do Vale do Rio dos Sinos, Brazil; Instituto Riograndese do Arroz Irrigado, Brazil
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Ning C, Wu K, Liu C, Gao Y, Jurat-Fuentes JL, Gao X. Characterization of a Cry1Ac toxin-binding alkaline phosphatase in the midgut from Helicoverpa armigera (Hübner) larvae. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:666-672. [PMID: 20170658 DOI: 10.1016/j.jinsphys.2010.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 02/05/2010] [Accepted: 02/08/2010] [Indexed: 05/28/2023]
Abstract
Midgut membrane-bound alkaline phosphatases (mALP) tethered to the brush border membrane surface by a glycosylphosphatidylinositol (GPI) anchor have been proposed as crucial for Cry1Ac intoxication. In the present work, two full-length cDNAs-encoding alkaline phosphatases in the midgut of Helicoverpa armigera larvae were cloned and named HaALP1 (GenBank accession no. EU729322) and HaALP2 (GenBank accession no. EU729323), respectively. These two clones displayed high identity (above 94%) at the amino acid sequence, indicating that they may represent allelic variants, and were predicted to contain a GPI anchor. Protein sequence alignment revealed that HaALPs were grouped with mALP from the Heliothis virescens midgut. The HaALP1 and HaALP2 ( approximately 68kDa) proteins were heterologously expressed in Sf9 cells using a baculovirus expression system and purified to homogeneity. Ligand blot and dot blot analysis revealed that the Cry1Ac bound to both denatured and native purified HaALPs. Data from lectin blots, competition assays with soybean agglutinin (SBA) lectin and GalNAc binding inhibition assays were indicative of the presence of GalNAc on HaALPs and binding of Cry1Ac toxin to this residue. This observation was further confirmed through N-glycosidase digestion of HaALPs, which resulted in reduced Cry1Ac binding. Our data represent the first report on HaALPs and their putative role as receptors for Cry1Ac toxin in H. armigera.
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Affiliation(s)
- Changming Ning
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Gulbitti-Onarici S, Zaidi MA, Taga I, Ozcan S, Altosaar I. Expression of Cry1Ac in transgenic tobacco plants under the control of a wound-inducible promoter (AoPR1) isolated from Asparagus officinalis to control Heliothis virescens and Manduca sexta. Mol Biotechnol 2009; 42:341-9. [PMID: 19353306 DOI: 10.1007/s12033-009-9168-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 03/16/2009] [Indexed: 10/20/2022]
Abstract
Expression of cry1Ac gene from Bacillus thuringiensis (Bt) was evaluated under the control of a wound-inducible AoPR1 promoter from Asparagus officinalis in transgenic tobacco plants. The leaves of transgenic plants were mechanically wounded to evaluate the activity of the AoPR1 promoter in driving the expression of Cry1Ac protein at the wound site. Our results indicate that mechanical wounding of transgenic plants was effective in inducing the expression of Cry1Ac protein. As a result of this induction, the accumulated levels of Cry1Ac protein increased during 6-72 h post-wounding period. The leaves of transgenic tobacco plants were evaluated for resistance against Heliothis virescens and Manduca sexta in insect bioassays in two different ways. The detached tobacco leaves were either fed directly to the insect larvae or they were first mechanically wounded followed by a 72 h post-wounding feeding period. Complete protection of mechanically wounded leaves of transgenic plants was observed within 24 h of the bioassay. The leaves of transgenic plants fed directly (without pre-wounding) to the larvae achieved the same level of protection between 24 and 72 h of the bioassay.
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Affiliation(s)
- Selma Gulbitti-Onarici
- Department of Biochemistry Microbiology & Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
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Hernández-Martínez P, Ferré J, Escriche B. Broad-spectrum cross-resistance in Spodoptera exigua from selection with a marginally toxic Cry protein. PEST MANAGEMENT SCIENCE 2009; 65:645-650. [PMID: 19253909 DOI: 10.1002/ps.1725] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
BACKGROUND Spodoptera exigua (Hübner) has developed resistance to a wide range of chemical insecticides. Products based on Bacillus thuringiensis Cry toxins are used in integrated pest management as an ecologically friendly alternative for pest control. Since there are few B. thuringiensis Cry proteins highly active against S. exigua, it is desirable to apply appropriate resistance management strategies to prevent the evolution of resistance to these proteins. RESULTS Spodoptera exigua larvae were selected with Cry1Ab, a protein with low activity against this pest. Selected larvae developed > 30-fold resistance to Cry1Ab in 13 generations, relative to an unselected strain. The estimated realised heritability (h(2)) for the first five generations of selection was 0.15. Cross-resistance was also observed to the more active proteins Cry1Ca, Cry1Da and Cry1Fa (>20, 26 and > 8 respectively). The activity of midgut proteases to degrade the ingested toxin was tested, although no differences in activity were found between selected and unselected larvae. CONCLUSION Spodoptera exigua is able to evolve cross-resistance to highly active Cry proteins when exposed to a protein with marginal toxicity to this species. It is important to take this into account in areas where S. exigua is a secondary pest and B. thuringiensis Cry1A toxins are used to control other pests.
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Sarkar A, Hess D, Mondal HA, Banerjee S, Sharma HC, Das S. Homodimeric Alkaline Phosphatase Located at Helicoverpa armigera Midgut, a Putative Receptor of Cry1Ac Contains α-GalNAc in Terminal Glycan Structure as Interactive Epitope. J Proteome Res 2009; 8:1838-48. [DOI: 10.1021/pr8006528] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anindya Sarkar
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
| | - Daniel Hess
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
| | - Hossain A. Mondal
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
| | - Santanu Banerjee
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
| | - Hari C. Sharma
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
| | - Sampa Das
- Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, C.I.T. Scheme, VII-M, Kolkata 700054, India, The Protein Analysis Facility, Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland, and GT Crop Improvement, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India
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Specific binding of Bacillus thuringiensis Cry2A insecticidal proteins to a common site in the midgut of Helicoverpa species. Appl Environ Microbiol 2008; 74:7654-9. [PMID: 18931285 DOI: 10.1128/aem.01373-08] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
For a long time, it has been assumed that the mode of action of Cry2A toxins was unique and different from that of other three-domain Cry toxins due to their apparent nonspecific and unsaturable binding to an unlimited number of receptors. However, based on the homology of the tertiary structure among three-domain Cry toxins, similar modes of action for all of them are expected. To confirm this hypothesis, binding assays were carried out with (125)I-labeled Cry2Ab. Saturation assays showed that Cry2Ab binds in a specific and saturable manner to brush border membrane vesicles (BBMVs) of Helicoverpa armigera. Homologous-competition assays with (125)I-Cry2Ab demonstrated that this toxin binds with high affinity to binding sites in H. armigera and Helicoverpa zea midgut. Heterologous-competition assays showed a common binding site for three toxins belonging to the Cry2A family (Cry2Aa, Cry2Ab, and Cry2Ae), which is not shared by Cry1Ac. Estimation of K(d) (dissociation constant) values revealed that Cry2Ab had around 35-fold less affinity than Cry1Ac for BBMV binding sites in both insect species. Only minor differences were found regarding R(t) (concentration of binding sites) values. This study questions previous interpretations from other authors performing binding assays with Cry2A toxins and establishes the basis for the mode of action of Cry2A toxins.
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Menegassi A, Wassermann GE, Olivera-Severo D, Becker-Ritt AB, Martinelli AHS, Feder V, Carlini CR. Urease from cotton (Gossypium hirsutum) seeds: isolation, physicochemical characterization, and antifungal properties of the protein. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:4399-405. [PMID: 18494485 DOI: 10.1021/jf0735275] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ureases (EC 3.5.1.5) are metalloenzymes that hydrolyze urea to produce ammonia and carbon dioxide These enzymes, which are found in fungi, bacteria, and plants, show very similar structures. Despite an abundance of urease in vegetal tissues, the physiological role of this enzyme in plants is still poorly understood. It has been previously described that ureases from the legumes jackbean ( Canavalia ensiformis) and soybean ( Glycine max) have insecticidal activity and antifungal properties. This work presents the physicochemical purification and characterization of a urease from cotton ( Gossypium hirsutum) seeds, the first description of this enzyme in Malvaceae. The urease content varied among different cotton cultivars. Cotton seed urease (98.3 kDa) displayed low ureolytic activity but exhibited potent antifungal properties at sub-micromolar concentrations against different phytopathogenic fungi. As described for other ureases, the antifungal effect of cotton urease persisted after treatment with an irreversible inhibitor of its enzyme activity. The data suggest an important role of these proteins in plant defense.
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Affiliation(s)
- Angela Menegassi
- Graduate Program in Molecular and Cellular Biology-Center of Biotechnology and Department of Biophysics, Universidade Federal do Rio Grande do Sul-UFRGS, Porto Alegre, RS CEP 91501-970, Brazil
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Susceptibility of Spodoptera exigua to 9 toxins from Bacillus thuringiensis. J Invertebr Pathol 2008; 97:245-50. [DOI: 10.1016/j.jip.2007.11.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 10/10/2007] [Accepted: 11/05/2007] [Indexed: 11/30/2022]
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Bacillus thuringiensis Cry1Ac toxin-binding and pore-forming activity in brush border membrane vesicles prepared from anterior and posterior midgut regions of lepidopteran larvae. Appl Environ Microbiol 2008; 74:1710-6. [PMID: 18223107 DOI: 10.1128/aem.02827-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
It is generally accepted that Bacillus thuringiensis Cry toxins insert into the apical membrane of the larval midgut after binding to specific receptors, and there is evidence that the distribution of binding molecules along the midgut is not uniform. By use of the voltage-sensitive dye DiSC(3)(5) and (125)I-labeled Cry1Ac, we have measured the effect of Cry1Ac in terms of permeabilization capacity and of binding parameters on brush border membrane vesicles (BBMV) prepared from the anterior and the posterior regions of the larval midgut from two insect species, Manduca sexta and Helicoverpa armigera. The permeabilizing activity was significantly higher with BBMV from the posterior region than with the one observed in the anterior region in both insect species. Instead, (125)I-Cry1Ac bound specifically to BBMV from the two midgut regions, with no significant differences in the binding parameters between the anterior and posterior regions within an insect species. N-acetylgalactosamine inhibition patterns on pore formation and binding differed between anterior and posterior midgut regions and between species, providing evidence of a multifaceted involvement of the sugar in the Cry1Ac mode of action. The analysis of binding and pore formation in different midgut regions could be an effective method to study differences in the mode of action of Cry1Ac toxin in different species.
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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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González-Zamora JE, Camúñez S, Avilla C. Effects of Bacillus thuringiensis Cry toxins on developmental and reproductive characteristics of the predator Orius albidipennis (Hemiptera: Anthocoridae) under laboratory conditions. ENVIRONMENTAL ENTOMOLOGY 2007; 36:1246-1253. [PMID: 18284750 DOI: 10.1603/0046-225x(2007)36[1246:eobtct]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The effects of Cry toxins from Bacillus thuringiensis (Berliner) (Bt) on the anthocorid Orius albidipennis Reuter were studied under laboratory conditions. Tritrophic experiments were performed, in which Orius nymphs were fed Helicoverpa armigera (Hübner) larvae reared on a diet with Cry1Ac, Cry1Ab, or Cry2Ab toxins at different concentrations (0, 1, and 10 microg/ml), when supplemented with Ephestia kuehniella Zeller eggs. In complementary experiments, the Bt Cry1Ac toxin was directly fed to Orius nymphs at a very high concentration (1 mg/ml). No effects on prey consumption, developmental time, nymph survival, fecundity, and egg hatching of O. albidipennis were found in either experiment. It can be concluded that the toxins tested do not seem to pose a risk for the anthocorid O. albidipennis, especially when it is exposed through the prey.
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Affiliation(s)
- J E González-Zamora
- Department of Ciencias Agroforestales, University of Seville, E-41013 Seville, Spain.
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Grossi-De-Sa MF, De Magalhaes MQ, Silva MS, Silva SM, Dias SC, Nakasu EYT, Brunetta PSF, Oliveira GR, De Oliveira Neto OB, De Oliveira RS, Soares LHB, Ayub MAZ, Siqueira HAA, Figueira EL. Susceptibility of Anthonomus grandis (Cotton Boll Weevil) and Spodoptera frugiperda (Fall Armyworm) to a Cry1Ia-type Toxin from a Brazilian Bacillus thuringiensis Strain. BMB Rep 2007; 40:773-82. [DOI: 10.5483/bmbrep.2007.40.5.773] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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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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Budatha M, Meur G, Dutta-Gupta A. A novel aminopeptidase in the fat body of the moth Achaea janata as a receptor for Bacillus thuringiensis Cry toxins and its comparison with midgut aminopeptidase. Biochem J 2007; 405:287-97. [PMID: 17402938 PMCID: PMC1904524 DOI: 10.1042/bj20070054] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacillus thuringiensis insecticidal crystal proteins bind to cell-surface receptors which represent a family of aminopeptidases [APN (aminopeptidase N)] present on the brush border membrane of insect midgut cells of susceptible insects leading to pore formation and death of the insect. We report here for the first time the presence of a novel APN in the fat body of the moth Achaea janata. Northern blotting detected at least one APN-specific transcript in the fat body, whereas two transcripts of different sizes were detected in the midgut. We have cloned two full-length APN cDNAs of 3015 bp and 2850 bp from fat body and midgut respectively, which encode proteins of 1004 and 950 amino acids. These two APNs share only 33% amino acid sequence identity, but both display the typical APN features, such as the N-terminal signal peptide, several putative glycosylation sites, C-terminal glycosylphosphatidylinositol anchor signal, the APN-specific zinc-binding/gluzincin motif HEXXHX(18)E and gluzincin motif GAMENWG. The fat body APN manifested a variation in its expression with respect to tissue and developmental stage. In spite of the abundance of the APN transcript in the fat body, fairly low APN activity was detected in this tissue. The fat-body- and midgut-specific APNs showed differential interaction with various Cry1A toxins. Besides, the level of toxicity of different Cry subtypes varied enormously with mode/site of delivery, such as intrahaemocoelic injections and feeding bioassays. These data indicate that the fat body might be a potential alternative Cry toxin target site in the moth.
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Affiliation(s)
| | - Gargi Meur
- School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Aparna Dutta-Gupta
- School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
- To whom correspondence should be addressed (email )
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Leonardi MG, Caccia S, González-Cabrera J, Ferré J, Giordana B. Leucine Transport Is Affected by Bacillus thuringiensis Cry1 Toxins in Brush Border Membrane Vesicles from Ostrinia nubilalis Hb (Lepidoptera: Pyralidae) and Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae) Midgut. J Membr Biol 2007; 214:157-64. [PMID: 17558532 DOI: 10.1007/s00232-006-0042-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 12/18/2006] [Indexed: 01/25/2023]
Abstract
The pore-forming activity of Cry1Ab, Cry1Fa and Cry1Ca toxins and their interaction with leucine transport mediated by the K(+)/leucine cotransporter were studied in brush border membrane vesicles (BBMVs) isolated from the midgut of Ostrinia nubilalis and Sesamia nonagrioides. In both species, as in other Lepidoptera, leucine uptake by BBMVs can take place in the absence of cations, but it can also be driven by a K(+) gradient. Experiments with the voltage-sensitive fluorescent dye 3,3'-diethylthiacarbocyanine iodide proved that Cry1Ab, a Bacillus thuringiensis toxin active in vivo, enhanced the membrane permeability to potassium in O. nubilalis BBMVs. This result is in agreement with similar effects observed in S. nonagrioides BBMV incubated with various Cry1 toxins active in vivo. The effect of the above toxins was tested on the initial rate of 0.1 mM: leucine influx. Instead of an increase in leucine influx, a reduction was observed with the Cry1 toxins active in vivo. Cry1Ab and Cry1Fa, but not the inactive toxin Cry1Da, inhibited in a dose-dependent manner leucine uptake both in the absence and in the presence of a K(+) gradient, a clear indication that their effect is independent of the channel formed by the toxins and that this effect is exerted directly on the amino acid transport system.
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Affiliation(s)
- M Giovanna Leonardi
- Dipartimento di Biologia, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
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Wang P, Zhao JZ, Rodrigo-Simón A, Kain W, Janmaat AF, Shelton AM, Ferré J, Myers J. Mechanism of resistance to Bacillus thuringiensis toxin Cry1Ac in a greenhouse population of the cabbage looper, Trichoplusia ni. Appl Environ Microbiol 2006; 73:1199-207. [PMID: 17189446 PMCID: PMC1828666 DOI: 10.1128/aem.01834-06] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The cabbage looper, Trichoplusia ni, is one of only two insect species that have evolved resistance to Bacillus thuringiensis in agricultural situations. The trait of resistance to B. thuringiensis toxin Cry1Ac from a greenhouse-evolved resistant population of T. ni was introgressed into a highly inbred susceptible laboratory strain. The resulting introgression strain, GLEN-Cry1Ac-BCS, and its nearly isogenic susceptible strain were subjected to comparative genetic and biochemical studies to determine the mechanism of resistance. Results showed that midgut proteases, hemolymph melanization activity, and midgut esterase were not altered in the GLEN-Cry1Ac-BCS strain. The pattern of cross-resistance of the GLEN-Cry1Ac-BCS strain to 11 B. thuringiensis Cry toxins showed a correlation of the resistance with the Cry1Ab/Cry1Ac binding site in T. ni. This cross-resistance pattern is different from that found in a previously reported laboratory-selected Cry1Ab-resistant T. ni strain, evidently indicating that the greenhouse-evolved resistance involves a mechanism different from the laboratory-selected resistance. Determination of specific binding of B. thuringiensis toxins Cry1Ab and Cry1Ac to the midgut brush border membranes confirmed the loss of midgut binding to Cry1Ab and Cry1Ac in the resistant larvae. The loss of midgut binding to Cry1Ab/Cry1Ac is inherited as a recessive trait, which is consistent with the recessive inheritance of Cry1Ab/Cry1Ac resistance in this greenhouse-derived T. ni population. Therefore, it is concluded that the mechanism for the greenhouse-evolved Cry1Ac resistance in T. ni is an alteration affecting the binding of Cry1Ab and Cry1Ac to the Cry1Ab/Cry1Ac binding site in the midgut.
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Affiliation(s)
- Ping Wang
- Department of Entomology, Cornell University, Geneva, NY 14456, USA.
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de Barros Moreira Beltrão H, Silva-Filha MHNL. Interaction of Bacillus thuringiensis svar. israelensis Cry toxins with binding sites from Aedes aegypti (Diptera: Culicidae) larvae midgut. FEMS Microbiol Lett 2006; 266:163-9. [PMID: 17132151 DOI: 10.1111/j.1574-6968.2006.00527.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
This work shows in vitro processing of Bacillus thuringiensis svar. isralensis Cry toxins and the capacity of the active fragments to bind the midgut microvilli of Aedes aegypti larvae. Processing of Cry11Aa, Cry4Aa and Cry4Ba yielded double fragments of 38-30, 45-20 and 45-18 kDa, respectively. Competition assays showed that all active (125)I-Cry toxins are able to specifically bind to brush border membrane fractions and they might share a common class of binding sites. The values of IC(50) suggested that toxins do not display high affinity for the receptors from brush border membrane fractions, while dissociation assays showed that binding was irreversible, indicating the insertion of toxins in the cell membrane.
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Ruiz de Escudero I, Estela A, Escriche B, Caballero P. Potential of the Bacillus thuringiensis toxin reservoir for the control of Lobesia botrana (Lepidoptera: Tortricidae), a major pest of grape plants. Appl Environ Microbiol 2006; 73:337-40. [PMID: 17085712 PMCID: PMC1797137 DOI: 10.1128/aem.01511-06] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The potential of Bacillus thuringiensis Cry proteins to control the grape pest Lobesia botrana was explored by testing first-instar larvae with Cry proteins belonging to the Cry1, Cry2, and Cry9 groups selected for their documented activities against Lepidoptera. Cry9Ca, a toxin from B. thuringiensis, was the protein most toxic to L. botrana larvae, followed in decreasing order by Cry2Ab, Cry1Ab, Cry2Aa, and Cry1Ia7, with 50% lethal concentration values of 0.09, 0.1, 1.4, 3.2, and 8.5 microg/ml of diet, respectively. In contrast, Cry1Fa and Cry1JA were not active at the assayed concentration (100 microg/ml). In vitro binding and competition experiments showed that none of the toxins tested (Cry1Ia, Cry2Aa, Cry2Ab, and Cry9C) shared binding sites with Cry1Ab. We conclude that either Cry1Ia or Cry9C could be used in combination with Cry1Ab to control this pest, either as the active components of B. thuringiensis sprays or expressed together in transgenic plants.
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Affiliation(s)
- Iñigo Ruiz de Escudero
- Departamento de Producción Agraria, Universidad Pública de Navarra, 31006 Pamplona, Spain
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