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De Bortoli CP, Polanczyk RA, Crickmore N. Throwing Brazilian strains into the melting pot of P. xylostella resistance to Bacillus thuringiensis. J Invertebr Pathol 2024; 204:108101. [PMID: 38574951 DOI: 10.1016/j.jip.2024.108101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 03/25/2024] [Accepted: 04/01/2024] [Indexed: 04/06/2024]
Abstract
The resistance of pest insects to biopesticides based on the bacterium Bacillus thuringiensis (Bt) is normally associated with changes to the receptors involved in the mechanism of action of the pesticidal proteins produced by Bt. In some strains of Plutella xylostella (the diamondback moth) resistance has evolved through a signalling mechanism in which the genes encoding the receptor proteins are downregulated whereas in others it has been linked to structural changes in the receptors themselves. One such well characterized mutation is in the ABCC2 gene indicating that changes to this protein can result in resistance. However other studies have found that knocking out this protein does not result in a significant level of resistance. In this study we wanted to test the hypothesis that constitutive receptor downregulation is the major cause of Bt resistance in P. xylostella and that mutations in the now poorly expressed receptor genes may not contribute significantly to the phenotype. To that end we investigated the expression of a receptor (ABCC2) and the major regulator of the signalling pathway (MAP4K4) in two resistant and four susceptible strains. No correlation was found between expression levels and susceptibility; however, a frameshift mutation was identified in the ABCC2 receptor in a newly characterized resistant strain.
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Affiliation(s)
- Caroline Placidi De Bortoli
- School of Life Sciences, University of Sussex, Brighton, UK; Faculty of Agricultural and Veterinary Sciences, Paulista State University "Júlio de Mesquita Filho", Jaboticabal Campus, SP, Brazil
| | - Ricardo Antonio Polanczyk
- Faculty of Agricultural and Veterinary Sciences, Paulista State University "Júlio de Mesquita Filho", Jaboticabal Campus, SP, Brazil
| | - Neil Crickmore
- School of Life Sciences, University of Sussex, Brighton, UK.
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2
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Amezian D, Nauen R, Van Leeuwen T. The role of ATP-binding cassette transporters in arthropod pesticide toxicity and resistance. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101200. [PMID: 38641174 DOI: 10.1016/j.cois.2024.101200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/10/2024] [Accepted: 04/07/2024] [Indexed: 04/21/2024]
Abstract
Pesticide resistance in arthropods threatens agricultural productivity and the control of vector-borne diseases. The ATP-binding cassette (ABC) transporters have emerged as important factors in the toxicity of synthetic pesticides, as well as for Bacillus thuringiensis insecticidal Cry protein binding. Depending on the localization of expression, both higher and lower expression of ABCs have been linked with pesticide resistance. The recent development of genetic-based approaches such as RNAi and CRISPR/Cas9 gene editing in nonmodel species, has greatly contributed to unveil their functional importance in pesticide toxicity and resistance. Using these tools, we are now poised to further unravel the molecular genetic mechanisms of gene regulation uncovering more elusive regulatory resistance genes.
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Affiliation(s)
- Dries Amezian
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Ralf Nauen
- Bayer AG, Crop Science Division, R&D, Alfred Nobel-Strasse 50, 40789 Monheim, Germany
| | - Thomas Van Leeuwen
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium.
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3
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Sato R. Utilization of Diverse Molecules as Receptors by Cry Toxin and the Promiscuous Nature of Receptor-Binding Sites Which Accounts for the Diversity. Biomolecules 2024; 14:425. [PMID: 38672442 PMCID: PMC11048593 DOI: 10.3390/biom14040425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
By 2013, it had been shown that the genes cadherin-like receptor (Cad) and ATP-binding cassette transporter subfamily C2 (ABCC2) were responsible for insect resistance to several Cry1A toxins, acting as susceptibility-determining receptors, and many review articles have been published. Therefore, this review focuses on information about receptors and receptor-binding sites that have been revealed since 2014. Since 2014, studies have revealed that the receptors involved in determining susceptibility vary depending on the Cry toxin subfamily, and that binding affinity between Cry toxins and receptors plays a crucial role. Consequently, models have demonstrated that ABCC2, ABCC3, and Cad interact with Cry1Aa; ABCC2 and Cad with Cry1Ab and Cry1Ac; ABCC2 and ABCC3 with Cry1Fa; ABCB1 with Cry1Ba, Cry1Ia, Cry9Da, and Cry3Aa; and ABCA2 with Cry2Aa and Cry2Ba, primarily in the silkworm, Bombyx mori. Furthermore, since 2017, it has been suggested that the binding sites of BmCad and BmABCC2 on Cry1Aa toxin overlap in the loop region of domain II, indicating that Cry toxins use various molecules as receptors due to their ability to bind promiscuously in this region. Additionally, since 2017, several ABC transporters have been identified as low-efficiency receptors that poorly induce cell swelling in heterologously expressing cultured cells. In 2024, research suggested that multiple molecules from the ABC transporter subfamily, including ABCC1, ABCC2, ABCC3, ABCC4, ABCC10, and ABCC11, act as low-efficiency receptors for a single Cry toxin in the midgut of silkworm larvae. This observation led to the hypothesis that the presence of such low-efficiency receptors contributes to the evolution of Cry toxins towards the generation of highly functional receptors that determine the susceptibility of individual insects. Moreover, this evolutionary process is considered to offer valuable insights for the engineering of Cry toxins to overcome resistance and develop countermeasures against resistance.
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Affiliation(s)
- Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei 184-8588, Tokyo, Japan
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Pinos D, Millán-Leiva A, Ferré J, Hernández-Martínez P. New Paralogs of the Heliothis virescens ABCC2 Transporter as Potential Receptors for Bt Cry1A Proteins. Biomolecules 2024; 14:397. [PMID: 38672415 PMCID: PMC11047971 DOI: 10.3390/biom14040397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024] Open
Abstract
The ATP-binding cassette (ABC) transporters are a superfamily of membrane proteins. These active transporters are involved in the export of different substances such as xenobiotics. ABC transporters from subfamily C (ABCC) have also been described as functional receptors for different insecticidal proteins from Bacillus thuringiensis (Bt) in several lepidopteran species. Numerous studies have characterized the relationship between the ABCC2 transporter and Bt Cry1 proteins. Although other ABCC transporters sharing structural and functional similarities have been described, little is known of their role in the mode of action of Bt proteins. For Heliothis virescens, only the ABCC2 transporter and its interaction with Cry1A proteins have been studied to date. Here, we have searched for paralogs to the ABCC2 gene in H. virescens, and identified two new ABC transporter genes: HvABCC3 and HvABCC4. Furthermore, we have characterized their gene expression in the midgut and their protein topology, and compared them with that of ABCC2. Finally, we discuss their possible interaction with Bt proteins by performing protein docking analysis.
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Affiliation(s)
- Daniel Pinos
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
| | - Anabel Millán-Leiva
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113 Valencia, Spain
| | - Juan Ferré
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
| | - Patricia Hernández-Martínez
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
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5
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Zhong J, Dos Santos RF, Abdelgaffar H, de Bortoli CP, Raza A, Jurat-Fuentes JL. Individual transmembrane domains of SfABCC2 from Spodoptera frugiperda do not serve as functional Cry1F receptors. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 199:105777. [PMID: 38458684 DOI: 10.1016/j.pestbp.2024.105777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/29/2023] [Accepted: 01/09/2024] [Indexed: 03/10/2024]
Abstract
The fall armyworm (Spodoptera frugiperda) is a major global pest causing severe damage to various crops, especially corn. Transgenic corn producing the Cry1F pesticidal protein from the bacterium Bacillus thuringiensis (Cry1F corn) showed effectiveness in controlling this pest until S. frugiperda populations at locations in North and South America evolved practical resistance. The mechanism for practical resistance involved disruptive mutations in an ATP binding cassette transporter subfamily C2 gene (SfABCC2), which serves as a functional Cry1F receptor in the midgut cells of susceptible S. frugiperda. The SfABCC2 protein contains two transmembrane domains (TMD1 and TMD2), each with a cytosolic nucleotide (ATP) binding domain (NBD1 and NBD2, respectively). Previous reports have demonstrated that disruptive mutations in TMD2 were linked with resistance to Cry1F, yet whether the complete SfABCC2 structure is needed for receptor functionality or if a single TMD-NBD protein can serve as functional Cry1F receptor remains unknown. In the present study, we separately expressed TMD1 and TMD2 with their corresponding NBDs in cultured insect cells and tested their Cry1F receptor functionality. Our results show that the complete SfABCC2 structure is required for Cry1F receptor functionality. Moreover, binding competition assays revealed that Cry1F specifically bound to SfABCC2, whereas neither SfTMD1-NBD1 nor SfTMD2-NBD2 exhibited any significant binding. These results provide insights into the molecular mechanism of Cry1F recognition by SfABCC2 in S. frugiperda, which could facilitate the development of more effective insecticidal proteins.
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Affiliation(s)
- Jianfeng Zhong
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA
| | | | - Heba Abdelgaffar
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA
| | | | - Ahmad Raza
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA.
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6
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Rezende TMT, Menezes HSG, Rezende AM, Cavalcanti MP, Silva YMG, de-Melo-Neto OP, Romão TP, Silva-Filha MHNL. Culex quinquefasciatus Resistant to the Binary Toxin from Lysinibacillus sphaericus Displays a Consistent Downregulation of Pantetheinase Transcripts. Biomolecules 2023; 14:33. [PMID: 38254633 PMCID: PMC10813629 DOI: 10.3390/biom14010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/07/2023] [Accepted: 12/11/2023] [Indexed: 01/24/2024] Open
Abstract
Culex quinquefasciatus resistance to the binary (Bin) toxin, the major larvicidal component from Lysinibacillus sphaericus, is associated with mutations in the cqm1 gene, encoding the Bin-toxin receptor. Downregulation of the cqm1 transcript was found in the transcriptome of larvae resistant to the L. sphaericus IAB59 strain, which produces both the Bin toxin and a second binary toxin, Cry48Aa/Cry49Aa. Here, we investigated the transcription profiles of two other mosquito colonies having Bin resistance only. These confirmed the cqm1 downregulation and identified transcripts encoding the enzyme pantetheinase as the most downregulated mRNAs in both resistant colonies. Further quantification of these transcripts reinforced their strong downregulation in Bin-resistant larvae. Multiple genes were found encoding this enzyme in Cx. quinquefasciatus and a recombinant pantetheinase was then expressed in Escherichia coli and Sf9 cells, with its presence assessed in the midgut brush border membrane of susceptible larvae. The pantetheinase was expressed as a ~70 kDa protein, potentially membrane-bound, which does not seem to be significantly targeted by glycosylation. This is the first pantetheinase characterization in mosquitoes, and its remarkable downregulation might reflect features impacted by co-selection with the Bin-resistant phenotype or potential roles in the Bin-toxin mode of action that deserve to be investigated.
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Affiliation(s)
- Tatiana M. T. Rezende
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (T.M.T.R.); (H.S.G.M.); (Y.M.G.S.); (T.P.R.)
| | - Heverly S. G. Menezes
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (T.M.T.R.); (H.S.G.M.); (Y.M.G.S.); (T.P.R.)
| | - Antonio M. Rezende
- Department of Microbiology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (A.M.R.); (M.P.C.); (O.P.d.-M.-N.)
| | - Milena P. Cavalcanti
- Department of Microbiology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (A.M.R.); (M.P.C.); (O.P.d.-M.-N.)
| | - Yuri M. G. Silva
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (T.M.T.R.); (H.S.G.M.); (Y.M.G.S.); (T.P.R.)
| | - Osvaldo P. de-Melo-Neto
- Department of Microbiology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (A.M.R.); (M.P.C.); (O.P.d.-M.-N.)
| | - Tatiany P. Romão
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (T.M.T.R.); (H.S.G.M.); (Y.M.G.S.); (T.P.R.)
| | - Maria Helena N. L. Silva-Filha
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife 50740-465, PE, Brazil; (T.M.T.R.); (H.S.G.M.); (Y.M.G.S.); (T.P.R.)
- National Institute for Molecular Entomology, Rio de Janeiro 21941-902, RJ, Brazil
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Iwabuchi K, Miyamoto K, Jouraku A, Takasu Y, Iizuka T, Adegawa S, Li X, Sato R, Watanabe K. ABC transporter subfamily B1 as a susceptibility determinant of Bombyx mori larvae to Cry1Ba, Cry1Ia and Cry9Da toxins. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 163:104030. [PMID: 37952901 DOI: 10.1016/j.ibmb.2023.104030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/05/2023] [Accepted: 10/28/2023] [Indexed: 11/14/2023]
Abstract
ATP binding cassette (ABC) transporters are a diverse family of transmembrane proteins. Specific subfamily members expressed in the lepidopteran midgut can act as susceptibility determinants for several insecticidal Bt Cry proteins. However, the susceptibility determinants to many Cry toxins still remain unclear. Therefore, we knocked out a series of ABC transporters that are highly expressed in the midgut of Bombyx mori larvae by transcription activator-like effector nuclease (TALEN)-mediated gene editing, and the lineages that became resistant to Cry toxins were searched by toxin overlay bioassay. As a result, the B. mori ABC transporter subfamily B1 (BmABCB1) knockout lineage showed 19.17-fold resistance to Cry1Ba, 876.2-fold resistance to Cry1Ia, and 29.1-fold resistance to Cry9Da, suggesting that BmABCB1 is the determinant of susceptibility to these toxins. BmABCC2 and BmABCC3 have been shown to be susceptibility determinants based on their function as receptors. Therefore, we next heterologously expressed these ABC transporters in HEK293T cells and performed a cell swelling assay to examine whether these molecules could exert receptor functions. As a result, BmABCB1-expressing cells showed swelling response to Cry1Ia and Cry9Da, and cells expressing PxABCB1, which is the Plutella xylostella ortholog of BmABCB1, showed swelling for Cry1Ba, suggesting that ABCB1 is a susceptibility determinant by functioning as a receptor to these toxins. Furthermore, in order to clarify how high binding affinity is based on receptor function, we performed surface plasmon resonance analysis and found that each KD of Cry1Ba, Cry1Ia, and Cry9Da to BmABCB1 were 7.69 × 10-8 M, 2.19 × 10-9 M, and 4.17 × 10-6 M respectively.
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Affiliation(s)
- Kana Iwabuchi
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Akiya Jouraku
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Satomi Adegawa
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Xiaoyi Li
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan.
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan.
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Wang S, Guo Y, Sun Y, Weng M, Liao Q, Qiu R, Zou S, Wu S. Identification of two Bacillus thuringiensis Cry3Aa toxin-binding aminopeptidase N from Rhynchophorus ferrugineus (Coleoptera: Curculionidae). BULLETIN OF ENTOMOLOGICAL RESEARCH 2023; 113:615-625. [PMID: 37466033 DOI: 10.1017/s0007485323000299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Rhynchophorus ferrugineus is a quarantine pest that mainly damages plants in tropical regions, which are essential economic resources. Cry3Aa has been used to control coleopteran pests and is known to be toxic to R. ferrugineus. The binding of the Cry toxin to specific receptors on the target insect plays a crucial role in the toxicological mechanism of Cry toxins. However, in the case of R. ferrugineus, the nature and identity of the receptor proteins involved remain unknown. In the present study, pull-down assays and mass spectrometry were used to identify two proteins of aminopeptidase N proteins (RfAPN2a and RfAPN2b) in the larval midguts of R. ferrugineus. Cry3Aa was able to bind to RfAPN2a (Kd = 108.5 nM) and RfAPN2b (Kd = 68.2 nM), as well as midgut brush border membrane vesicles (Kd = 482.5 nM). In silico analysis of both RfAPN proteins included the signal peptide and anchored sites for glycosyl phosphatidyl inositol. In addition, RfAPN2a and RfAPN2b were expressed in the human embryonic kidney 293T cell line, and cytotoxicity assays showed that the transgenic cells were not susceptible to activated Cry3Aa. Our results show that RfAPN2a and RfAPN2b are Cry3Aa-binding proteins involved in the Cry3Aa toxicity of R. ferrugineus. This study deepens our understanding of the action mechanism of Cry3Aa in R. ferrugineus larvae.
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Affiliation(s)
- Shaozhen Wang
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yajie Guo
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- Key Laboratory of Integrated Pest Management in Ecological Forests, Fujian Province University, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- Asian Research Center for Bioresource and Environmental Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 188-0002, Japan
| | - Yunzhu Sun
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- Key Laboratory of Integrated Pest Management in Ecological Forests, Fujian Province University, Fujian Agriculture and Forestry University, Fuzhou 350000, China
| | - Mingqing Weng
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- Key Laboratory of Integrated Pest Management in Ecological Forests, Fujian Province University, Fujian Agriculture and Forestry University, Fuzhou 350000, China
| | - Qiliao Liao
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
| | - Ru Qiu
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
| | - Shuangquan Zou
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
| | - Songqing Wu
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- Key Laboratory of Integrated Pest Management in Ecological Forests, Fujian Province University, Fujian Agriculture and Forestry University, Fuzhou 350000, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China, 350002
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9
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Panteleri R, Anthousi A, Denecke S, Boaventura D, Nauen R, Vontas J. Transgenic Drosophila to Functionally Validate Fall Armyworm ABCC2 Mutations Conferring Bt Resistance. Toxins (Basel) 2023; 15:386. [PMID: 37368687 DOI: 10.3390/toxins15060386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/05/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith; Lepidoptera: Noctuidae) is an invasive agricultural pest with a global distribution, causing major crop losses annually. Its control strategies largely rely on chemical insecticides and transgenic crops expressing Bacillus thuringiensis insecticidal proteins (Cry and Vip toxins); however, the development of high resistance poses a significant issue. The ATP-binding cassette transporter C2 (ABCC2) has been linked to Cry toxin pore formation, acting as a receptor of some Cry toxins. Recently detected mutations in the SfABCC2 gene in extracellular loop 4 (ECL4) have been associated with Bt toxin resistance in FAW. In the present study, we expressed the SfABCC2 gene in Drosophila melanogaster, a species normally unaffected by the Bt toxins. We demonstrate that susceptibility can be introduced by the ectopic and tissue-specific expression of wildtype SfABCC2. Next, we introduced mutations into ECL4-both individually and in combination-that have been recently described in Brazilian FAW and functionally validated by toxicity bioassays against the foliar Bt product Xentari. Our results provide an efficient demonstration of the suitability of transgenic Drosophila for validating FAW ABCC2 resistance mutations in ECL4 against Bt toxins, and potential cross-resistance issues between closely related proteins that use ABCC2.
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Affiliation(s)
- Rafaela Panteleri
- Department of Biology, University of Crete, Vassilika Vouton, 71409 Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 71409 Heraklion, Greece
| | - Amalia Anthousi
- Department of Biology, University of Crete, Vassilika Vouton, 71409 Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 71409 Heraklion, Greece
| | - Shane Denecke
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 71409 Heraklion, Greece
- Department of Pathobiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Debora Boaventura
- Bayer AG, Crop Science Division, R&D, Pest Control, 40789 Monheim, Germany
| | - Ralf Nauen
- Bayer AG, Crop Science Division, R&D, Pest Control, 40789 Monheim, Germany
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 71409 Heraklion, Greece
- Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece
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10
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Farhan Y, Smith JL, Sovic MG, Michel AP. Genetic mutations linked to field-evolved Cry1Fa-resistance in the European corn borer, Ostrinia nubilalis. Sci Rep 2023; 13:8081. [PMID: 37202428 DOI: 10.1038/s41598-023-35252-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023] Open
Abstract
Transgenic corn, Zea mays (L.), expressing insecticidal toxins such as Cry1Fa, from Bacillus thuringiensis (Bt corn) targeting Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) resulted in over 20 years of management success. The first case of practical field-evolved resistance by O. nubilalis to a Bt corn toxin, Cry1Fa, was discovered in Nova Scotia, Canada, in 2018. Laboratory-derived Cry1Fa-resistance by O. nubilalis was linked to a genome region encoding the ATP Binding Cassette subfamily C2 (ABCC2) gene; however, the involvement of ABCC2 and specific mutations in the gene leading to resistance remain unknown. Using a classical candidate gene approach, we report on O. nubilalis ABCC2 gene mutations linked to laboratory-derived and field-evolved Cry1Fa-resistance. Using these mutations, a DNA-based genotyping assay was developed to test for the presence of the Cry1Fa-resistance alleles in O. nubilalis strains collected in Canada. Screening data provide strong evidence that field-evolved Cry1Fa-resistance in O. nubilalis maps to the ABCC2 gene and demonstrates the utility of this assay for detecting the Cry1Fa resistance allele in O. nubilalis. This study is the first to describe mutations linked to Bt resistance in O. nubilalis and provides a DNA-based detection method that can be used for monitoring.
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Affiliation(s)
- Yasmine Farhan
- Department of Plant Agriculture, University of Guelph, Ridgetown Campus, Ridgetown, ON, Canada.
| | - Jocelyn L Smith
- Department of Plant Agriculture, University of Guelph, Ridgetown Campus, Ridgetown, ON, Canada
| | - Michael G Sovic
- Infectious Diseases Institute, The Ohio State University, Pickerington, OH, USA
| | - Andrew P Michel
- Department of Entomology, The Ohio State University, Wooster, OH, USA
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11
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Yang Y, Lu K, Qian J, Guo J, Xu H, Lu Z. Identification and characterization of ABC proteins in an important rice insect pest, Cnaphalocrocis medinalis unveil their response to Cry1C toxin. Int J Biol Macromol 2023; 237:123949. [PMID: 36894061 DOI: 10.1016/j.ijbiomac.2023.123949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/09/2023]
Abstract
Rice leaffolder (Cnaphalocrocis medinalis) is an important insect pest in paddy fields. Due to their essential role in the physiology and insecticidal resistance, ATP-binding cassette (ABC) proteins were studied in many insects. In this study, we identified the ABC proteins in C. medinalis through genomic data and analyzed their molecular characteristics. A total of 37 sequences with nucleotide-binding domain (NBD) were identified as ABC proteins and belonged to eight families (ABCA-ABCH). Four structure styles of ABC proteins were found in C. medinalis, including full structure, half structure, single structure, and ABC2 structure. In addition to these structures, TMD-NBD-TMD, NBD-TMD-NBD, and NBD-TMD-NBD-NBD were found in C. medinalis ABC proteins. Docking studies suggested that in addition to the soluble ABC proteins, other ABC proteins including ABCC4, ABCH1, ABCG3, ABCB5, ABCG1, ABCC7, ABCB3, ABCA3, and ABCC5 binding with Cry1C had higher weighted scores. The upregulation of ABCB1 and downregulation of ABCB3, ABCC1, ABCC7, ABCG1, ABCG3, and ABCG6 were associated with the C. medinalis response to Cry1C toxin. Collectively, these results help elucidate the molecular characteristics of C. medinalis ABC proteins, pave the way for further functional studies of C. medinalis ABC proteins, including their interaction with Cry1C toxin, and provide potential insecticide targets.
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Affiliation(s)
- Yajun Yang
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China
| | - Ke Lu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China; Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jianing Qian
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China
| | - Jiawen Guo
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China
| | - Hongxing Xu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China.
| | - Zhongxian Lu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection, Ministry of Agriculture and Rural Affairs, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agriculture Sciences, Hangzhou 310021, China.
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12
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IPD072Aa from Pseudomonas chlororaphis Targets Midgut Epithelial Cells in Killing Western Corn Rootworm ( Diabrotica virgifera virgifera). Appl Environ Microbiol 2023; 89:e0162222. [PMID: 36847510 PMCID: PMC10057879 DOI: 10.1128/aem.01622-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023] Open
Abstract
IPD072Aa from Pseudomonas chlororaphis is a new insecticidal protein that has been shown to have high activity against western corn rootworm (WCR). IPD072 has no sequence signatures or predicted structural motifs with any known protein revealing little insight into its mode of action using bioinformatic tools. As many bacterially derived insecticidal proteins are known to act through mechanisms that lead to death of midgut cells, we evaluated whether IPD072Aa also acts by targeting the cells of WCR midgut. IPD072Aa exhibits specific binding to brush border membrane vesicles (BBMVs) prepared from WCR guts. The binding was found to occur at binding sites that are different than those recognized by Cry3A or Cry34Ab1/Cry35Ab1, proteins expressed by current maize traits that target WCR. Using fluorescence confocal microscopy, immuno-detection of IPD072Aa in longitudinal sections from whole WCR larvae that were fed IPD072Aa revealed the association of the protein with the cells that line the gut. High-resolution scanning electron microscopy of similar whole larval sections revealed the disruption of the gut lining resulting from cell death caused by IPD072Aa exposure. These data show that the insecticidal activity of IPD072Aa results from specific targeting and killing of rootworm midgut cells. IMPORTANCE Transgenic traits targeting WCR based on insecticidal proteins from Bacillus thuringiensis have proven effective in protecting maize yield in North America. High adoption has led to WCR populations that are resistant to the trait proteins. Four proteins have been developed into commercial traits, but they represent only two modes of action due to cross-resistance among three. New proteins suited for trait development are needed. IPD072Aa, identified from the bacterium Pseudomonas chlororaphis, was shown to be effective in protecting transgenic maize against WCR. To be useful, IPD072Aa must work through binding to different receptors than those utilized by current traits to reduce risk of cross-resistance and understanding its mechanism of toxicity could aid in countering resistance development. Our results show that IPD072Aa binds to receptors in WCR gut that are different than those utilized by current commercial traits and its targeted killing of midgut cells results in larval death.
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Wang C, Deng Z, Yuan J, Xu K, Sha L, Guan X, Huang Z, Shao E. Removal of an Aminopeptidase N From Midgut Brush Border Does Not Affect Susceptibility of Spodoptera litura (Lepidoptera: Noctuidae) Larvae to Four Insecticidal Proteins of Bacillus thuringiensis (Bacillales: Bacillaceae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:223-232. [PMID: 36421056 DOI: 10.1093/jee/toac184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Indexed: 06/16/2023]
Abstract
Spodoptera litura is one of the most destructive lepidopteran insects of cabbages and cauliflowers in the world. Cry1 and Vip3 toxins from Bacillus thuringiensis have been reported to show toxicity in multiple lepidopteran insects. Binding of toxic molecules to specific receptors on the midgut epithelial cells is known to be a key step in the action mode of Bt toxins. Aminopeptidase N (APN) -like proteins have been reported to be binding sites of multiple Cry toxins in the midgut of Cry susceptible insects. In the present study, we identified six midgut APNs by analysis of the genome and midgut transcriptome of S. litura. CRISPR/Cas9 mediated gene-knockout system was utilized to mutate the GPI-anchor signal peptide at the C terminus of SlAPN1. SlAPN1 was verified to be removed from the midgut brush border membrane vesicles of a homozygous knockout strain of S. litura (SlAPN1-KO). Bioassay results indicated that susceptibility of the SlAPN1-KO strain to Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins was close to that of the wild-type strain of S. litura. RT-qPCR results showed that the transcriptional level of SlAPN2-6 was not up-regulated after knockout of the SlAPN1. Results in this study indicated that the SlAPN1 did not play a critical role in the pathway of toxicity of Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins in S. litura.
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Affiliation(s)
- Can Wang
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zhimin Deng
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Jin Yuan
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Kexin Xu
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Li Sha
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zhipeng Huang
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Ensi Shao
- National Engineering Research Center of JUNCAO Technology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
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Dechkla M, Charoenjotivadhanakul S, Imtong C, Visitsattapongse S, Li HC, Angsuthanasombat C. Cry4Aa and Cry4Ba Mosquito-Active Toxins Utilize Different Domains in Binding to a Particular Culex ALP Isoform: A Functional Toxin Receptor Implicating Differential Actions on Target Larvae. Toxins (Basel) 2022; 14:toxins14100652. [PMID: 36287921 PMCID: PMC9607545 DOI: 10.3390/toxins14100652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/10/2022] [Accepted: 09/16/2022] [Indexed: 11/16/2022] Open
Abstract
The three-domain Cry4Aa toxin produced from Bacillus thuringiensis subsp. israelensis was previously shown to be much more toxic to Culex mosquito larvae than its closely related toxin—Cry4Ba. The interaction of these two individual toxins with target receptors on susceptible larval midgut cells is likely to be the critical determinant in their differential toxicity. Here, two full-length membrane-bound alkaline phosphatase (mALP) isoforms from Culex quinquefasciatus larvae, Cq-mALP1263and Cq-mALP1264, predicted to be GPI-linked was cloned and functionally expressed in Spodoptera frugiperda (Sf9) cells as 57- and 61-kDa membrane-bound proteins, respectively. Bioinformatics analysis disclosed that both Cq-mALP isoforms share significant sequence similarity to Aedes aegypti-mALP—a Cry4Ba toxin receptor. In cytotoxicity assays, Sf9 cells expressing Cq-mALP1264, but not Cq-mALP1263, showed remarkably greater susceptibility to Cry4Aa than Cry4Ba, while immunolocalization studies revealed that both toxins were capable of binding to each Cq-mALP expressed on the cell membrane surface. Molecular docking of the Cq-mALP1264-modeled structure with individual Cry4 toxins revealed that Cry4Aa could bind to Cq-mALP1264 primarily through particular residues on three surface-exposed loops in the receptor-binding domain—DII, including Thr512, Tyr513 and Lys514 in the β10-β11loop. Dissimilarly, Cry4Ba appeared to utilize only certain residues in its C-terminal domain—DIII to interact with such a Culex counterpart receptor. Ala-substitutions of selected β10-β11loop residues (T512A, Y513A and K514A) revealed that only the K514A mutant displayed a drastic decrease in biotoxicity against C. quinquefasciatus larvae. Further substitution of Lys514 with Asp (K514D) revealed a further decrease in larval toxicity. Furthermore, in silico calculation of the binding affinity change (ΔΔGbind) in Cry4Aa-Cq-mALP1264 interactions upon these single-substitutions revealed that the K514D mutation displayed the largest ΔΔGbind value as compared to three other mutations, signifying an adverse impact of a negative charge at this critical receptor-binding position. Altogether, our present study has disclosed that these two related-Cry4 mosquito-active toxins conceivably exploited different domains in functional binding to the same Culex membrane-bound ALP isoform—Cq-mALP1264 for mediating differential toxicity against Culex target larvae.
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Affiliation(s)
- Manussawee Dechkla
- Department of Environmental Biology, Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok 10300, Thailand
- Correspondence: (M.D.); (C.A.)
| | - Sathapat Charoenjotivadhanakul
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand
| | - Chompounoot Imtong
- Laboratory of Structural Biochemistry and Cell Chemical Biology, Biophysics Institute for Research and Development (BIRD), Fang, Chiang Mai 50110, Thailand
| | - Sarinporn Visitsattapongse
- Department of Biomedical Engineering, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand
| | - Hui-Chun Li
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Chanan Angsuthanasombat
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand
- Laboratory of Structural Biochemistry and Cell Chemical Biology, Biophysics Institute for Research and Development (BIRD), Fang, Chiang Mai 50110, Thailand
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
- Correspondence: (M.D.); (C.A.)
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15
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Shwe SM, Prabu S, Jing D, He K, Wang Z. Synergistic interaction of Cry1Ah and Vip3Aa19 proteins combination with midgut ATP-binding cassette subfamily C receptors of Conogethes punctiferalis (Guenée) (Lepidoptera: Crambidae). Int J Biol Macromol 2022; 213:871-879. [PMID: 35690160 DOI: 10.1016/j.ijbiomac.2022.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/01/2022] [Accepted: 06/05/2022] [Indexed: 11/30/2022]
Abstract
Bacillus thuringiensis Cry and Vip proteins are highly effective at controlling agricultural pests and could be used in pyramided transgenic crops. However, the molecular mechanism underlying the Cry1Ah and Vip3Aa19 synergistic interaction has never been investigated at the molecular level in Yellow peach moth (YPM) Conogethes punctiferalis. Binding affinity and synergism of Cry1Ah and Vip3Aa19 proteins with ABC transporter subfamily C receptors ABCC1, ABCC2 and ABCC3 proteins from the midgut of YPM larva by using surface plasmon resonance (SPR) and pull-down assays. Both assays revealed that Cry1Ah could interact with ABCC1, ABCC2, and ABCC3, whereas Vip3Aa19 only interacts with ABCC1 and ABCC3, but not with ABCC2. Hence, when compared to the Vip3Aa19 protein, Cry1Ah had a higher binding affinity for ABCC1, ABCC2, and ABCC3. Furthermore, competitive binding assay between Cry1Ah and Vip3Aa19 protein with ABC transporter subfamily C receptors resulted in the final eluted protein samples displaying vibrant blue bands of Cry1Ah and very faint bands of Vip3Aa19. Suggesting that Cry and Vip proteins could deliver a synergistic effect after cleaving the midgut proteases. Therefore, this finding indicated that the Cry1Ah and Vip3Aa19 do not compete for interacting with midgut receptors and thus provide strong synergism against YPM.
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Affiliation(s)
- Su Mon Shwe
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Sivaprasath Prabu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Dapeng Jing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, 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, No. 2, West Yuanmingyuan Road, 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, No. 2, West Yuanmingyuan Road, Beijing 100193, China.
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16
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Toxicometabolomic profiling of resistant and susceptible western corn rootworm larvae feeding on Bt maize seedlings. Sci Rep 2022; 12:11639. [PMID: 35804088 PMCID: PMC9270432 DOI: 10.1038/s41598-022-15895-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/30/2022] [Indexed: 11/10/2022] Open
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is the most serious pest of maize (Zea mays L.) in the U.S. Corn Belt and parts of Europe. Transgenic maize hybrids expressing at least one of the four currently available insecticidal toxins from Bacillus thuringiensis (Bt) Berliner, currently the most widely adopted control method in continuous maize, have faltered due to the emergence of resistance. The resistance mechanisms of WCR to Bt toxins are not fully understood. We identified metabolic profiles of susceptible and resistant WCR larvae fed on maize hybrids expressing each of three available Cry3 proteins (eCry3Ab1, mCry3A, and Cry3Bb1) targeting corn rootworms and a control non-Bt maize via an untargeted metabolomics approach. Over 580 unique metabolites found in WCR larvae were classified into different pathways (amino acids, carbohydrates, cofactors and vitamins, energy, lipid, nucleotide, peptide, and xenobiotics). By exploring shifts in WCR larval metabolome exclusively by Bt toxins, several candidate metabolites and metabolic pathways were identified in susceptible and resistant larvae that may be involved in defense against or recovery from Bt ingestion by these larvae. These findings would provide mechanistic insights into altered metabolic pathways associated with the resistance mechanisms of WCR to Bt toxins.
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17
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Endo H. Molecular and Kinetic Models for Pore Formation of Bacillus thuringiensis Cry Toxin. Toxins (Basel) 2022; 14:toxins14070433. [PMID: 35878171 PMCID: PMC9321905 DOI: 10.3390/toxins14070433] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/03/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Cry proteins from Bacillus thuringiensis (Bt) and other bacteria are pesticidal pore-forming toxins. Since 2010, when the ABC transporter C2 (ABCC2) was identified as a Cry1Ac protein resistant gene, our understanding of the mode of action of Cry protein has progressed substantially. ABCC2 mediates high Cry1A toxicity because of its high activity for helping pore formation. With the discovery of ABCC2, the classical killing model based on pore formation and osmotic lysis became nearly conclusive. Nevertheless, we are still far from a complete understanding of how Cry proteins form pores in the cell membrane through interactions with their host gut membrane proteins, known as receptors. Why does ABCC2 mediate pore formation with high efficiency unlike other Cry1A-binding proteins? Is the “prepore” formation indispensable for pore formation? What is the mechanism underlying the synergism between ABCC2 and the 12-cadherin domain protein? We examine potential mechanisms of pore formation via receptor interactions in this paper by merging findings from prior studies on the Cry mode of action before and after the discovery of ABC transporters as Cry protein receptors. We also attempt to explain Cry toxicity using Cry–receptor binding affinities, which successfully predicts actual Cry toxicity toward cultured cells coexpressing ABC transporters and cadherin.
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Affiliation(s)
- Haruka Endo
- Department of Integrated Bioscience, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan
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18
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Transcriptional Analysis of Cotton Bollworm Strains with Different Genetic Mechanisms of Resistance and Their Response to Bacillus thuringiensis Cry1Ac Toxin. Toxins (Basel) 2022; 14:toxins14060366. [PMID: 35737027 PMCID: PMC9228822 DOI: 10.3390/toxins14060366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 01/27/2023] Open
Abstract
Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins are grown widely for pest control, but the evolution of resistance in target pests could reduce their efficacy. Mutations in genes encoding cadherin, ABC transporter or tetraspanin were linked with resistance to Cry1Ac in several lepidopteran insects, including the cotton bollworm (Helicoverpa armigera), a worldwide agricultural pest. However, the detailed molecular mechanisms by which these mutations confer insect resistance to Cry1Ac remain largely unknown. In this study, we analyzed the midgut transcriptomes of a susceptible SCD strain and three SCD-derived Cry1Ac-resistant strains of H. armigera (SCD-r1, with a naturally occurring deletion mutation of cadherin; SCD-KI, with a knock-in T92C point mutation in tetraspanin; and C2/3-KO, with both ABCC2 and ABCC3 knocked out). Evaluation of midgut transcript profiles of the four strains without Cry1Ac exposure identified many constitutively differentially expressed genes (DEGs) in the resistant SCD-r1 (n = 1355), SCD-KI (n = 1254) and C2/3-KO (n = 2055) strains. Analysis of DEGs in the midguts of each strain after Cry1Ac exposure revealed similar patterns of response to Cry1Ac in the SCD and SCD-r1 strains, but unique responses in the SCD-KI and C2/3-KO strains. Expression of midgut epithelium healing and defense-related genes was strongly induced by Cry1Ac intoxication in the SCD and SCD-r1 strains, while immune-related pattern recognition receptor and effector genes were highly expressed in the SCD-KI strain after Cry1Ac exposure. This study advances our knowledge of the transcriptomic basis for insect resistance to Bt toxins and provides a valuable resource for further molecular characterization of insect response to Cry1Ac toxin in H. armigera and other pest species.
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Yamamoto T. Engineering of Bacillus thuringiensis insecticidal proteins. JOURNAL OF PESTICIDE SCIENCE 2022; 47:47-58. [PMID: 35800392 PMCID: PMC9184247 DOI: 10.1584/jpestics.d22-016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/21/2022] [Indexed: 05/12/2023]
Abstract
Bacillus thuringiensis (Bt) has been used as sprayable pesticides for many decades. Bt strains utilized in these products produce multiple insecticidal proteins to complement a narrow insect specificity of each protein. In the late 1990s, genes encoding Bt insecticidal proteins were expressed in crop plants such as cotton and corn to protect these crops from insect damage. The first Bt protein used in transgenic cotton was Cry1Ac to control Heliothis virescens (tobacco budworm). Cry1Ab was applied to corn to control Ostrinia nubilalis (European corn borer). Since these insects have developed resistance to Cry1Ac and Cry1Ab, new Bt proteins are required to overcome the resistance. In order to protect corn furthermore, it is desired to control Diabrotica virgifera (Western corn rootworm), Helicoverpa zea (corn earworm) and Spodoptera frugiperda (fall armyworm). Recently, many new Bt insecticidal proteins have been discovered, but most of them require protein engineering to meet the high activity standard for commercialization. The engineering process for higher activity necessary for Bt crops is called optimization. The seed industry has been optimizing Bt insecticidal proteins to improve their insecticidal activity. In this review, several optimization projects, which have led to substantial activity increases of Bt insecticidal proteins, are described.
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Affiliation(s)
- Takashi Yamamoto
- Bacillus Tech LLC, Dublin, California 94568, U.S.A
- To whom correspondence should be addressed. E-mail:
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20
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Liu L, Wilcox XE, Fisher AJ, Boyd SD, Zhi J, Winkler DD, Bulla LA. Functional and Structural Analysis of the Toxin-Binding Site of the Cadherin G-Protein-Coupled Receptor, BT-R 1, for Cry1A Toxins of Bacillus thuringiensis. Biochemistry 2022; 61:752-766. [PMID: 35438971 DOI: 10.1021/acs.biochem.2c00089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The G-protein-coupled receptor BT-R1 in the moth Manduca sexta represents a class of single-membrane-spanning α-helical proteins within the cadherin family that regulate intercellular adhesion and contribute to important signaling activities that control cellular homeostasis. The Cry1A toxins, Cry1Aa, Cry1Ab, and Cry1Ac, produced by Bacillus thuringiensis bind BT-R1 very tightly (Kd = 1.1 nM) and trigger a Mg2+-dependent signaling pathway that involves the stimulation of G-protein α-subunit, which subsequently launches a coordinated signaling cascade, resulting in insect death. The three Cry1A toxins compete for the same binding site on BT-R1, and the pattern of inhibition of insecticidal activity against M. sexta is strikingly similar for all three toxins. The binding domain is localized in the 12th cadherin repeat (EC12: Asp1349 to Arg1460, 1349DR1460) in BT-R1 and to various truncation fragments derived therefrom. Fine mapping of EC12 revealed that the smallest fragment capable of binding is a highly conserved 94-amino acid polypeptide bounded by Ile1363 and Ser1456 (1363IS1456), designated as the toxin-binding site (TBS). Logistical regression analysis revealed that binding of an EC12 truncation fragment containing the TBS is antagonistic to each of the Cry1A toxins and completely inhibits the insecticidal activity of all three. Elucidation of the EC12 motif of the TBS by X-ray crystallography at a 1.9 Å resolution combined with results of competitive binding analyses, live cell experiments, and whole insect bioassays substantiate the exclusive involvement of BT-R1 in initiating insect cell death and demonstrate that the natural receptor BT-R1 contains a single TBS.
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Affiliation(s)
- Li Liu
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | | | | | - Stefanie D Boyd
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Jiahe Zhi
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Duane D Winkler
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
| | - Lee A Bulla
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas 75083, United States
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Tavares CS, Mishra R, Ghobrial PN, Bonning BC. Composition and abundance of midgut surface proteins in the Asian citrus psyllid, Diaphorina citri. J Proteomics 2022; 261:104580. [DOI: 10.1016/j.jprot.2022.104580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/04/2022] [Accepted: 04/04/2022] [Indexed: 10/18/2022]
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Bacillus thuringiensis Cry1Ac Protoxin and Activated Toxin Exert Differential Toxicity Due to a Synergistic Interplay of Cadherin with ABCC Transporters in the Cotton Bollworm. Appl Environ Microbiol 2022; 88:e0250521. [PMID: 35262369 DOI: 10.1128/aem.02505-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacillus thuringiensis Cry proteins are used worldwide for insect control. It was proposed that Cry-protoxins must be converted into activated toxin by proteases to bind midgut cell proteins to kill insects. However, Cry-protoxins also bind to midgut proteins and kill insects that have evolved resistance to activated toxins suggesting an independent toxicity pathway. Cadherin (CAD) and ABCC transporters are recognized as important receptors for Cry proteins. Here we constructed different Helicoverpa armigera mutations in these receptors by CRISPR/Cas9. HaCAD-KO mutant showed much higher resistance to Cry1Ac activated toxin than to Cry1Ac protoxin. In contrast, the HaABCC2-M and HaABCC3-M mutants showed higher resistance to Cry1Ac-protoxin than to activated toxin. However, in the double HaABCC2/3-KO mutant, very high levels of resistance were observed to both Cry1Ac protoxin and activated toxin, supporting that both ABC transporters have redundant functions for these two proteins. In addition, Hi5 cells transfected with HaCAD were susceptible only to the activated toxin but not to protoxin. In contrast, both forms of Cry1Ac were similarly toxic to Hi5 cells expressing HaABCC2 or HaABCC3. Co-expression of HaCAD with HaABCC2 or HaABCC3 revealed a more important synergistic effect for activated toxin compared to protoxin. Overall, our results show that toxicity of Cry1Ac activated toxin involves synergistic interplay of HaCAD with ABCC transporters, while the Cry1Ac protoxin toxicity is mainly mediated by ABCC transporters with little participation of HaCAD. These data help to understand the mode of action of Cry proteins that will be relevant to enhance efficacy and durability of Bt-crops. IMPORTANCE Better understanding of the mode of action of Bacillus thuringiensis toxins is beneficial for the sustainable application of Bt crops. It is generally accepted that Cry-protoxins need to be activated by proteases to bind with midgut cell proteins and exert toxicity against insects. Here, we provide new insights into the toxic pathway of Cry proteins in the cotton bollworm. First, our results demonstrate that Cry1Ac protoxin is able to exert cytotoxicity against the insect cells expressing ABCC transporters. Second, we reveal that CAD plays a critical role in the different toxicity of protoxin and toxin by facilitating a synergistic interplay with ABCC transporters. Our results provide in vivo and in vitro experimental evidence supporting that Cry1Ac protoxin exerts toxicity against H. armigera via different steps from that of toxin. These new findings on the mode of action of Cry proteins could be beneficial for efficacy enhancement and durability of Bt-crops.
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Franz L, Raming K, Nauen R. Recombinant Expression of ABCC2 Variants Confirms the Importance of Mutations in Extracellular Loop 4 for Cry1F Resistance in Fall Armyworm. Toxins (Basel) 2022; 14:toxins14020157. [PMID: 35202184 PMCID: PMC8878193 DOI: 10.3390/toxins14020157] [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: 01/21/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 01/15/2023] Open
Abstract
Fall armyworm (FAW), Spodoptera frugiperda, is a highly destructive and invasive global noctuid pest. Its control is based on insecticide applications and Bacillus thuringiensis (Bt) insecticidal Cry toxins expressed in transgenic crops, such as Cry1F in Bt corn. Continuous selection pressure has resulted in populations that are resistant to Bt corn, particularly in Brazil. FAW resistance to Cry1F was recently shown to be conferred by mutations of ATP-binding cassette transporter C2 (ABCC2), but several mutations, particularly indels in extracellular loop 4 (ECL4), are not yet functionally validated. We addressed this knowledge gap by baculovirus-free insect cell expression of ABCC2 variants (and ABCC3) by electroporation technology and tested their response to Cry1F, Cry1A.105 and Cry1Ab. We employed a SYTOXTM orange cell viability test measuring ABCC2-mediated Bt toxin pore formation. In total, we tested seven different FAW ABCC2 variants mutated in ECL4, two mutants modified in nucleotide binding domain (NBD) 2, including a deletion mutant lacking NBD2, and S. frugiperda ABCC3. All tested ECL4 mutations conferred high resistance to Cry1F, but much less to Cry1A.105 and Cry1Ab, whereas mutations in NBD2 hardly affected Bt toxin activity. Our study confirms the importance of indels in ECL4 for Cry1F resistance in S. frugiperda ABCC2.
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Challenges and approaches to studying pore-forming proteins. Biochem Soc Trans 2021; 49:2749-2765. [PMID: 34747994 PMCID: PMC8892993 DOI: 10.1042/bst20210706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/19/2021] [Accepted: 10/06/2021] [Indexed: 02/07/2023]
Abstract
Pore-forming proteins (PFPs) are a broad class of molecules that comprise various families, structural folds, and assembly pathways. In nature, PFPs are most often deployed by their host organisms to defend against other organisms. In humans, this is apparent in the immune system, where several immune effectors possess pore-forming activity. Furthermore, applications of PFPs are found in next-generation low-cost DNA sequencing, agricultural crop protection, pest control, and biosensing. The advent of cryoEM has propelled the field forward. Nevertheless, significant challenges and knowledge-gaps remain. Overcoming these challenges is particularly important for the development of custom, purpose-engineered PFPs with novel or desired properties. Emerging single-molecule techniques and methods are helping to address these unanswered questions. Here we review the current challenges, problems, and approaches to studying PFPs.
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Adegawa S, Yamaguchi N, Sato R. The base and root of domain II loops of Cry toxins contribute to binding to Bombyx mori ABC transporter C2. FEBS J 2021; 289:965-984. [PMID: 34618400 DOI: 10.1111/febs.16224] [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: 07/03/2021] [Revised: 08/28/2021] [Accepted: 10/06/2021] [Indexed: 01/17/2023]
Abstract
Little information is available regarding the region of Cry toxins involved in binding to their major receptors, the ATP-binding cassette (ABC) transporters. We analyzed which Cry1Aa amino acid residues contribute to binding to Bombyx mori ABC transporter C2 (BmABCC2). Several two oxidized double-cysteine substitution mutant toxins were made. In these, two amino acids at distant positions on toxin loop α8 and loop 2 or loop 2 and loop 3 were substituted with cysteine residues and crosslinked. These mutants exhibited a marked reduction in binding affinity to BmABCC2, suggesting that the binding site comprises complex cavities formed by loops α8, 2, and 3. Loop swapping between Cry1Aa and other BmABCC2-incompatible toxins indicated that loop 2 acts as a binding affinity-generating part of Cry1Aa toxin. Using single amino acid substitution mutants, the results of surface plasmon resonance (SPR) analysis and response assays with BmABCC2-expressing Sf9 cells indicated that Y366, R367, R368, and L447 in the Cry1Aa root and base region of loops 2 and 3 play important roles in binding. Furthermore, SPR analyses of these mutants suggested that a two-state binding model fits best the data obtained. Moreover, complex cavities and the above-mentioned amino acid residues contribute to the generation of multiple binding points and high-affinity binding. Finally, we found that the binding site of B. mori cadherin-like protein consists of complex cavities comprising loops 1, 2, and 3, partially overlapping that of BmABCC2, suggesting that the loop region of Cry1Aa toxin acts as a promiscuous binding site.
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Affiliation(s)
- Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Japan.,Japan Society for the Promotion of Science Research Fellowship for Young Scientists, Chiyoda, Japan
| | - Naomi Yamaguchi
- Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Japan
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Güney G, Cedden D, Hänniger S, Heckel DG, Coutu C, Hegedus DD, Mutlu DA, Suludere Z, Sezen K, Güney E, Toprak U. Silencing of an ABC transporter, but not a cadherin, decreases the susceptibility of Colorado potato beetle larvae to Bacillus thuringiensis ssp. tenebrionis Cry3Aa toxin. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 108:e21834. [PMID: 34288075 DOI: 10.1002/arch.21834] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/24/2021] [Accepted: 07/02/2021] [Indexed: 06/13/2023]
Abstract
The Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), is a major pest of potato plants worldwide and is notorious for its ability to develop resistance to insecticides. Cry3 toxins synthesized by Bacillus thuringiensis ssp. tenebrionis have been used successfully to manage this pest. Resistance to Cry toxins is a concerning problem for many insect pests; therefore, it is important to determine the mechanisms by which insects acquire resistance to these toxins. Cadherin-like and ABC transporter proteins have been implicated in the mode of action of Cry toxins as mutations in these genes render lepidopterans resistant to them; however, clear consensus does not exist on whether these proteins also play a role in Cry3 toxin activity and/or development of resistance in coleopterans. In the current study, we identified the L. decemlineata orthologues of the cadherin (LdCAD) and the ABCB transporter (LdABCB1) that have been implicated in the mode of action of Cry toxins in other coleopterans. Suppression of LdABCB1 via RNA interference reduced toxin-related larval mortality, whereas partial silencing of LdCAD did not. Our results suggest that the ABCB is involved in the mode of action of Cry3Aa toxins; however, no evidence was found to support the role of cadherin as a receptor of Cry3Aa in L. decemlineata.
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Affiliation(s)
- Gözde Güney
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
- Max Planck Institute for Chemical Ecology, Jena, Germany
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
| | - Doğa Cedden
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | | | - David G Heckel
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | | | - Kazım Sezen
- Department of Biology, Karadeniz Technical University, Trabzon, Turkey
| | - Ebru Güney
- Department of Biology, Karadeniz Technical University, Trabzon, Turkey
| | - Umut Toprak
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
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Liu Y, Jin M, Wang L, Wang H, Xia Z, Yang Y, Bravo A, Soberón M, Xiao Y, Liu K. SfABCC2 transporter extracellular loops 2 and 4 are responsible for the Cry1Fa insecticidal specificity against Spodoptera frugiperda. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 135:103608. [PMID: 34119653 DOI: 10.1016/j.ibmb.2021.103608] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/28/2021] [Accepted: 06/06/2021] [Indexed: 06/12/2023]
Abstract
Bacillus thuringiensis (Bt) bacteria produce Cry toxins that kill insect pests. Insect specificity of Cry toxins relies on their binding to larval gut membrane proteins such as cadherin and ATP-binding cassette (ABC) transporter proteins. Mutations in ABC transporters have been implicated in high levels of resistance to Cry toxins in multiple pests. Spodoptera frugiperda is an insect pest susceptible to Cry1Fa and Cry1Ab toxins while Mythimna separata is tolerant to Cry1Fa and less susceptible to Cry1Ab. Here, we analyzed the potential role of ABCC2 in determining the susceptibility of S. frugiperda to Cry1Fa and Cry1Ab, by expressing SfABCC2 or MsABCC2 in Hi5 insect cell line and by the systematic replacements of extracellular loops (ECLs) between these two proteins. Expression of SfABCC2 in Hi5 conferred susceptibility to both Cry1Fa and Cry1Ab, in contrast to the expression of MsABCC2 that mediated low toxicity to Cry1Ab and no toxicity to Cry1Fa in agreement with their larvicidal toxicities. The SfABCC2 and MsABCC2 amino acid sequences showed differential residues among ECL1, ECL2, ECL4 and ECL6 loops, while ECL3 and ECL5 share the same primary sequence. The exchange of ECLs between SfABCC2 and MsABCC2 demonstrated that ECL4 and ECL2 contribute to Cry1Fa toxicity, where ECL4 plays a major role. The medium region (named M2) of ECL4 was identified as the most important region of SfABCC2 involved in Cry1Fa toxicity as shown by point mutations in this region. These findings will be helpful to understand the mechanisms of action of Bt toxins in S. frugiperda.
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Affiliation(s)
- Yuanyuan Liu
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Minghui Jin
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Ling Wang
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Hubei Key Laboratory of Crop Disease, Insect Pests and Weeds Control, Institute of Plant Protection and Soil Fertility, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Haixia Wang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Zhichao Xia
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Yongbo Yang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, Mexico
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, Mexico
| | - Yutao Xiao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
| | - Kaiyu Liu
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China.
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28
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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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Liu L, Li Z, Luo X, Zhang X, Chou SH, Wang J, He J. Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects. Front Microbiol 2021; 12:665101. [PMID: 34140940 PMCID: PMC8203666 DOI: 10.3389/fmicb.2021.665101] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
In this article, we review the latest works on the insecticidal mechanisms of Bacillus thuringiensis Cry toxins and the resistance mechanisms of insects against Cry toxins. Currently, there are two models of insecticidal mechanisms for Cry toxins, namely, the sequential binding model and the signaling pathway model. In the sequential binding model, Cry toxins are activated to bind to their cognate receptors in the mid-intestinal epithelial cell membrane, such as the glycophosphatidylinositol (GPI)-anchored aminopeptidases-N (APNs), alkaline phosphatases (ALPs), cadherins, and ABC transporters, to form pores that elicit cell lysis, while in the signaling pathway model, the activated Cry toxins first bind to the cadherin receptor, triggering an extensive cell signaling cascade to induce cell apoptosis. However, these two models cannot seem to fully describe the complexity of the insecticidal process of Cry toxins, and new models are required. Regarding the resistance mechanism against Cry toxins, the main method insects employed is to reduce the effective binding of Cry toxins to their cognate cell membrane receptors by gene mutations, or to reduce the expression levels of the corresponding receptors by trans-regulation. Moreover, the epigenetic mechanisms, host intestinal microbiota, and detoxification enzymes also play significant roles in the insects' resistance against Cry toxins. Today, high-throughput sequencing technologies like transcriptomics, proteomics, and metagenomics are powerful weapons for studying the insecticidal mechanisms of Cry toxins and the resistance mechanisms of insects. We believe that this review shall shed some light on the interactions between Cry toxins and insects, which can further facilitate the development and utilization of Cry toxins.
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Affiliation(s)
- Lu Liu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhou Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xing Luo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xia Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.,Department of Molecular Biology, Qingdao Vland Biotech Inc., Qingdao, China
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jieping Wang
- Agricultural Bioresources Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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The Essential and Enigmatic Role of ABC Transporters in Bt Resistance of Noctuids and Other Insect Pests of Agriculture. INSECTS 2021; 12:insects12050389. [PMID: 33924857 PMCID: PMC8145640 DOI: 10.3390/insects12050389] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 11/18/2022]
Abstract
Simple Summary The insect family, Noctuidae, contains some of the most damaging pests of agriculture, including bollworms, budworms, and armyworms. Transgenic cotton and maize expressing Cry-type insecticidal proteins from Bacillus thuringiensis (Bt) are protected from such pests and greatly reduce the need for chemical insecticides. However, evolution of Bt resistance in the insects threatens the sustainability of this environmentally beneficial pest control strategy. Understanding the interaction between Bt toxins and their targets in the insect midgut is necessary to evaluate the risk of resistance evolution. ABC transporters, which in eukaryotes typically expel small molecules from cells, have recently been proposed as a target for the pore-forming Cry toxins. Here we review the literature surrounding this hypothesis in noctuids and other insects. Appreciation of the critical role of ABC transporters will be useful in discovering counterstrategies to resistance, which is already evolving in some field populations of noctuids and other insects. Abstract In the last ten years, ABC transporters have emerged as unexpected yet significant contributors to pest resistance to insecticidal pore-forming proteins from Bacillus thuringiensis (Bt). Evidence includes the presence of mutations in resistant insects, heterologous expression to probe interactions with the three-domain Cry toxins, and CRISPR/Cas9 knockouts. Yet the mechanisms by which ABC transporters facilitate pore formation remain obscure. The three major classes of Cry toxins used in agriculture have been found to target the three major classes of ABC transporters, which requires a mechanistic explanation. Many other families of bacterial pore-forming toxins exhibit conformational changes in their mode of action, which are not yet described for the Cry toxins. Three-dimensional structures of the relevant ABC transporters, the multimeric pore in the membrane, and other proteins that assist in the process are required to test the hypothesis that the ATP-switch mechanism provides a motive force that drives Cry toxins into the membrane. Knowledge of the mechanism of pore insertion will be required to combat the resistance that is now evolving in field populations of insects, including noctuids.
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Pinos D, Andrés-Garrido A, Ferré J, Hernández-Martínez P. Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins. Microbiol Mol Biol Rev 2021; 85:e00007-20. [PMID: 33504654 PMCID: PMC8549848 DOI: 10.1128/mmbr.00007-20] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Extensive use of chemical insecticides adversely affects both environment and human health. One of the most popular biological pest control alternatives is bioinsecticides based on Bacillus thuringiensis This entomopathogenic bacterium produces different protein types which are toxic to several insect, mite, and nematode species. Currently, insecticidal proteins belonging to the Cry and Vip3 groups are widely used to control insect pests both in formulated sprays and in transgenic crops. However, the benefits of B. thuringiensis-based products are threatened by insect resistance evolution. Numerous studies have highlighted that mutations in genes coding for surrogate receptors are responsible for conferring resistance to B. thuringiensis Nevertheless, other mechanisms may also contribute to the reduction of the effectiveness of B. thuringiensis-based products for managing insect pests and even to the acquisition of resistance. Here, we review the relevant literature reporting how invertebrates (mainly insects and Caenorhabditis elegans) respond to exposure to B. thuringiensis as either whole bacteria, spores, and/or its pesticidal proteins.
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Affiliation(s)
- Daniel Pinos
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Ascensión Andrés-Garrido
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Juan Ferré
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
| | - Patricia Hernández-Martínez
- Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain
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32
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Use of RNAi as a preliminary tool for screening putative receptors of nematicidal toxins from Bacillus thuringiensis. Arch Microbiol 2021; 203:1649-1656. [PMID: 33432376 DOI: 10.1007/s00203-020-02179-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/13/2020] [Accepted: 12/27/2020] [Indexed: 10/22/2022]
Abstract
Bacillus thuringiensis is a potential control agent for plant-parasitic nematodes. Nematode intestinal receptors for Cry21-type toxins are poorly known. Therefore, a strategy was tested as a primary screening tool to find possible Cry toxin receptors, using a nematicidal Bt strain and the RNAi technique on Caenorhabditis elegans. Six genes encoding intestinal membrane proteins were selected (abt-4, bre-1, bre-2, bre-3, asps-1, abl-1) as possible targets for Cry proteins. Fractions of each selected gene were amplified by PCR. Amplicons were cloned into the L4440 vector to transform the E. coli HT155 (DE3) strain. Transformed bacteria were used to silence the selected genes using the RNAi feeding method. Nematodes with silenced genes were tested with the Bt strain LBIT-107, which harbors the nematicidal protein Cry21Aa3, among others. Results indicated that nematodes with the silenced abt-4 gene were 69.5% more resistant to the LBIT-107 strain, in general, and 79% to the Cry21Aa3 toxin, specifically.
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Mishra R, Guo Y, Kumar P, Cantón PE, Tavares CS, Banerjee R, Kuwar S, Bonning BC. Streamlined phage display library protocols for identification of insect gut binding peptides highlight peptide specificity. CURRENT RESEARCH IN INSECT SCIENCE 2021; 1:100012. [PMID: 36003592 PMCID: PMC9387513 DOI: 10.1016/j.cris.2021.100012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 02/09/2021] [Accepted: 02/14/2021] [Indexed: 05/10/2023]
Abstract
Phage display libraries have been used to isolate insect gut binding peptides for use as pathogen transmission blocking agents, and to provide artificial anchors for increased toxicity of bacteria-derived pesticidal proteins. Previously, phage clones displaying enriched peptides were sequenced by Sanger sequencing. Here we present a streamlined protocol for identification of insect gut binding peptides, using insect-appropriate feeding strategies, with next generation sequencing and tailored bioinformatics analyses. The bioinformatics pipeline is designed to eliminate poorly enriched and false positive peptides, and to identify peptides predicted to be stable and hydrophilic. In addition to developing streamlined protocols, we also sought to address whether candidate gut binding peptides can bind to insects from more than one order, which is an important consideration for safe, practical use of peptide-modified pesticidal proteins. To this end, we screened phage display libraries for peptides that bind to the gut epithelia of two pest insects, the Asian citrus psyllid, Diaphorina citri (Hemiptera) and beet armyworm, Spodoptera exigua (Lepidoptera), and one beneficial insect, the western honey bee, Apis mellifera (Hymenoptera). While unique peptide sequences totaling 13,427 for D. citri, 89,561 for S. exigua and 69,053 for A. mellifera were identified from phage eluted from the surface of the insect guts, final candidate pools were comprised of 53, 107 and 1423 peptides respectively. The benefits of multiple rounds of biopanning, along with peptide binding properties in relation to practical use of peptide-modified pesticidal proteins for insect pest control are discussed.
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Functional validation of DvABCB1 as a receptor of Cry3 toxins in western corn rootworm, Diabrotica virgifera virgifera. Sci Rep 2020; 10:15830. [PMID: 32985523 PMCID: PMC7522262 DOI: 10.1038/s41598-020-72572-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/03/2020] [Indexed: 02/03/2023] Open
Abstract
Western corn rootworm (WCR), Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), is a serious insect pest in the major corn growing areas of North America and in parts of Europe. WCR populations with resistance to Bacillus thuringiensis (Bt) toxins utilized in commercial transgenic traits have been reported, raising concerns over their continued efficacy in WCR management. Understanding the modes of action of Bt toxins is important for WCR control and resistance management. Although different classes of proteins have been identified as Bt receptors for lepidopteran insects, identification of receptors in WCR has been limited with no reports of functional validation. Our results demonstrate that heterologous expression of DvABCB1 in Sf9 and HEK293 cells conferred sensitivity to the cytotoxic effects of Cry3A toxins. The result was further validated using knockdown of DvABCB1 by RNAi which rendered WCR larvae insensitive to a Cry3A toxin. However, silencing of DvABCB2 which is highly homologous to DvABCB1 at the amino acid level, did not reduce the sensitivity of WCR larvae to a Cry3A toxin. Furthermore, our functional studies corroborate different mode-of-actions for other insecticidal proteins including Cry34Ab1/35Ab1, Cry6Aa1, and IPD072Aa against WCR. Finally, reduced expression and alternatively spliced transcripts of DvABCB1 were identified in a mCry3A-resistant strain of WCR. Our results provide the first clear demonstration of a functional receptor in the molecular mechanism of Cry3A toxicity in WCR and confirmed its role in the mechanism of resistance in a mCry3A resistant strain of WCR.
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Bacterial Toxins, Current Perspectives. Toxins (Basel) 2020; 12:toxins12090570. [PMID: 32899816 PMCID: PMC7551839 DOI: 10.3390/toxins12090570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/03/2020] [Indexed: 12/28/2022] Open
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Noriega DD, Arraes FBM, Antonino JD, Macedo LLP, Fonseca FCA, Togawa RC, Grynberg P, Silva MCM, Negrisoli AS, Morgante CV, Grossi-de-Sa MF. Comparative gut transcriptome analysis of Diatraea saccharalis in response to the dietary source. PLoS One 2020; 15:e0235575. [PMID: 32745084 PMCID: PMC7398519 DOI: 10.1371/journal.pone.0235575] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/17/2020] [Indexed: 12/21/2022] Open
Abstract
The sugarcane borer (Diatraea saccharalis, Fabricius, 1794) is a devastating pest that causes millions of dollars of losses each year to sugarcane producers by reducing sugar and ethanol yields. The control of this pest is difficult due to its endophytic behavior and rapid development. Pest management through biotechnological approaches has emerged in recent years as an alternative to currently applied methods. Genetic information about the target pests is often required to perform biotechnology-based management. The genomic and transcriptomic data for D. saccharalis are very limited. Herein, we report a tissue-specific transcriptome of D. saccharalis larvae and a differential expression analysis highlighting the physiological characteristics of this pest in response to two different diets: sugarcane and an artificial diet. Sequencing was performed on the Illumina HiSeq 2000 platform, and a de novo assembly was generated. A total of 27,626 protein-coding unigenes were identified, among which 1,934 sequences were differentially expressed between treatments. Processes such as defence, digestion, detoxification, signaling, and transport were highly represented among the differentially expressed genes (DEGs). Furthermore, seven aminopeptidase genes were identified as candidates to encode receptors of Cry proteins, which are toxins of Bacillus thuringiensis used to control lepidopteran pests. Since plant-insect interactions have produced a considerable number of adaptive responses in hosts and herbivorous insects, the success of phytophagous insects relies on their ability to overcome challenges such as the response to plant defences and the intake of nutrients. In this study, we identified metabolic pathways and specific genes involved in these processes. Thus, our data strongly contribute to the knowledge advancement of insect transcripts, which can be a source of target genes for pest management.
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Affiliation(s)
- Daniel D. Noriega
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Department of Cellular Biology, University of Brasília, Brasília-DF, Brazil
- Catholic University of Brasília, Brasília-DF, Brazil
| | - Fabricio B. M. Arraes
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Biotechnology Center, UFRGS, Porto Alegre-RS, Brazil
| | - José Dijair Antonino
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Departamento de Agronomia/Entomologia, UFRPE, Recife-PE, Brazil
| | | | - Fernando C. A. Fonseca
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Department of Cellular Biology, University of Brasília, Brasília-DF, Brazil
| | | | | | | | | | - Carolina V. Morgante
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Embrapa Semi Arid, Petrolina-PE, Brazil
| | - Maria F. Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília-DF, Brazil
- Catholic University of Brasília, Brasília-DF, Brazil
- National Institute of Science and Technology–INCT PlantStress Biotech–EMBRAPA, Brasilia-DF, Brazil
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Pinos D, Chakroun M, Millán-Leiva A, Jurat-Fuentes JL, Wright DJ, Hernández-Martínez P, Ferré J. Reduced Membrane-Bound Alkaline Phosphatase Does Not Affect Binding of Vip3Aa in a Heliothis virescens Resistant Colony. Toxins (Basel) 2020; 12:toxins12060409. [PMID: 32575644 PMCID: PMC7354626 DOI: 10.3390/toxins12060409] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/29/2020] [Accepted: 06/17/2020] [Indexed: 11/16/2022] Open
Abstract
The Vip3Aa insecticidal protein from Bacillus thuringiensis (Bt) is produced by specific transgenic corn and cotton varieties for efficient control of target lepidopteran pests. The main threat to this technology is the evolution of resistance in targeted insect pests and understanding the mechanistic basis of resistance is crucial to deploy the most appropriate strategies for resistance management. In this work, we tested whether alteration of membrane receptors in the insect midgut might explain the >2000-fold Vip3Aa resistance phenotype in a laboratory-selected colony of Heliothis virescens (Vip-Sel). Binding of 125I-labeled Vip3Aa to brush border membrane vesicles (BBMV) from 3rd instar larvae from Vip-Sel was not significantly different from binding in the reference susceptible colony. Interestingly, BBMV from Vip-Sel larvae showed dramatically reduced levels of membrane-bound alkaline phosphatase (mALP) activity, which was further confirmed by a strong downregulation of the membrane-bound alkaline phosphatase 1 (HvmALP1) gene. However, the involvement of HvmALP1 as a receptor for the Vip3Aa protein was not supported by results from ligand blotting and viability assays with insect cells expressing HvmALP1.
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Affiliation(s)
- Daniel Pinos
- Department of Genetics, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (M.C.); (A.M.-L.); (P.H.-M.)
| | - Maissa Chakroun
- Department of Genetics, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (M.C.); (A.M.-L.); (P.H.-M.)
| | - Anabel Millán-Leiva
- Department of Genetics, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (M.C.); (A.M.-L.); (P.H.-M.)
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA;
| | - Denis J. Wright
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berks SL5 7PY, UK;
| | - Patricia Hernández-Martínez
- Department of Genetics, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (M.C.); (A.M.-L.); (P.H.-M.)
| | - Juan Ferré
- Department of Genetics, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (M.C.); (A.M.-L.); (P.H.-M.)
- Correspondence:
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Huang J, Xu Y, Zuo Y, Yang Y, Tabashnik BE, Wu Y. Evaluation of five candidate receptors for three Bt toxins in the beet armyworm using CRISPR-mediated gene knockouts. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 121:103361. [PMID: 32199887 DOI: 10.1016/j.ibmb.2020.103361] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/06/2020] [Accepted: 03/15/2020] [Indexed: 05/29/2023]
Abstract
Insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) can provide safe and effective control of some major pests, but evolution of resistance by pests diminishes these benefits. Better understanding of the genetics and mechanisms of resistance is urgently needed to improve methods for monitoring, managing, and countering pest resistance to Bt toxins. Here we used CRISPR-mediated knockouts to evaluate the role of five genes encoding candidate Bt toxin receptors in Spodoptera exigua (beet armyworm), a devastating pest of vegetable, field and flower crops. We compared susceptibility to Bt toxins Cry1Ac, Cry1Fa, and Cry1Ca between the parent susceptible strain and each of five strains homozygous for the knockout of one of the candidate genes (SeAPN1, SeCad1, SeABCC1, SeABCC2 or SeABCC3). The results from the 15 pairwise comparisons reveal that SeABCC2 has a major role and SeCad1 a minor role in mediating toxicity of Cry1Ac and Cry1Fa. SeABCC2 also has a minor role in toxicity of Cry1Ca. In addition, the results imply little or no role for the other three candidate receptors in toxicity of Cry1Ac or Cry1Fa; or for the four candidate receptors other than SeABCC2 in toxicity of Cry1Ca.
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Affiliation(s)
- Jianlei Huang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yanjun Xu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yayun Zuo
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA.
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
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Wang J, Ma H, Zhao S, Huang J, Yang Y, Tabashnik BE, Wu Y. Functional redundancy of two ABC transporter proteins in mediating toxicity of Bacillus thuringiensis to cotton bollworm. PLoS Pathog 2020; 16:e1008427. [PMID: 32191775 PMCID: PMC7108736 DOI: 10.1371/journal.ppat.1008427] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/31/2020] [Accepted: 02/21/2020] [Indexed: 01/20/2023] Open
Abstract
Evolution of pest resistance reduces the efficacy of insecticidal proteins from the gram-positive bacterium Bacillus thuringiensis (Bt) used widely in sprays and transgenic crops. Better understanding of the genetic basis of resistance is needed to more effectively monitor, manage, and counter pest resistance to Bt toxins. Here we used CRISPR/Cas9 gene editing to clarify the genetics of Bt resistance and the associated effects on susceptibility to other microbial insecticides in one of the world’s most damaging pests, the cotton bollworm (Helicoverpa armigera). We discovered that CRISPR-mediated knockouts of ATP-binding cassette (ABC) transporter genes HaABCC2 and HaABCC3 together caused >15,000-fold resistance to Bt toxin Cry1Ac, whereas knocking out either HaABCC2 or HaABCC3 alone had little or no effect. Inheritance of resistance was autosomal and recessive. Bioassays of progeny from interstrain crosses revealed that one wild type allele of either HaABCC2 or HaABCC3 is sufficient to sustain substantial susceptibility to Cry1Ac. In contrast with previous results, susceptibility to two insecticides derived from bacteria other than Bt (abamectin and spinetoram), was not affected by knocking out HaABCC2, HaABCC3, or both. The results here provide the first evidence that either HaABCC2 or HaABCC3 protein is sufficient to confer substantial susceptibility to Cry1Ac. The functional redundancy of these two proteins in toxicity of Cry1Ac to H. armigera is expected to reduce the likelihood of field-evolved resistance relative to disruption of a toxic process where mutations affecting a single protein can confer resistance. Insect-killing proteins from the soil bacterium Bacillus thuringiensis (Bt) are increasingly important as environmentally friendly alternatives to conventional insecticides. However, widespread planting for the past two decades of crops genetically engineered to produce Bt proteins has spurred rapid evolution of resistance in pests. Better understanding of the genetic basis of pest resistance to Bt toxins is urgently needed to address this problem. We used CRISPR gene editing to clarify the genetics of resistance to Bt toxins in the cotton bollworm, one of the world’s most damaging pests. We discovered that CRISPR-mediated inactivation of two larval midgut transporter proteins that act as receptors for Bt toxins caused a 15,000-fold increase in the concentration of Bt toxin needed to kill fifty per cent of larvae. By contrast, inactivating each of these transporter proteins alone had little or no effect. These results provide the first evidence that either of these two transporter proteins can confer susceptibility to Bt toxins. Because resistance to Bt toxins requires mutations in each of the two genes encoding these two proteins, pest resistance is less likely to evolve via this route relative to interference with toxic processes where a single mutation can confer resistance.
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Affiliation(s)
- Jing Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Huanhuan Ma
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Shan Zhao
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Jianlei Huang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Bruce E. Tabashnik
- Department of Entomology, University of Arizona, Tucson, Arizona, United States of America
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- * E-mail:
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Ren X, Wang Y, Ma Y, Jiang W, Ma X, Hu H, Wang D, Ma Y. Midgut de novo transcriptome analysis and gene expression profiling of Spodoptera exigua larvae exposed with sublethal concentrations of Cry1Ca protein. 3 Biotech 2020; 10:138. [PMID: 32158634 DOI: 10.1007/s13205-020-2129-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 02/11/2020] [Indexed: 12/01/2022] Open
Abstract
Spodoptera exigua (Hübner) is a polyphagous pest on agricultural crops, whose control is based mainly on the application of chemical insecticides. Bacillus thuringiensis (Bt) is one of the most important biological agents that have been successfully applied as a biological control, and Cry1Ca protein is considered to be active against S. exigua. Therefore, to understand the response of S. exigua to Cry1Ca protein, high-throughput sequencing was used to analyse the S. exigua larval midgut after treatment with sublethal concentrations of Cry1Ca protein. Transcriptome data showed that a total of 98,571 unigenes with an N50 value of 1135 bp and a mean length of 653 bp were obtained. Furthermore, 2962 differentially expressed genes (DEGs) were identified after Cry1Ca challenge, including 1508 up-regulated and 1454 down-regulated unigenes. Among these DEGs, detoxification (CYP, CarE, and GST) and Bt resistance (ALP, APN, and ABC transporter)-related genes were differentially expressed in the midgut of S. exigua after Cry1Ca treatment. However, most DEGs of protective enzymes were down-regulated, while most DEGs related with serine protease and REPAT were up-regulated. Furthermore, almost all DEGs related to the immune signaling pathway, antimicrobial protein, and lysozyme were up-regulated by Cry1Ca treatment. These results indicated that the detoxification enzyme, protective enzymes, Bt resistance-related genes, serine protease, REPAT, and the immune response might have been involved in the response of S. exigua to Cry1Ca protein. In summary, analysis of the transcriptomal expression of genes involved in Cry1Ca protein against S. exigua provided potential clues for elucidating the host response processes and defensive mechanisms underlying Cry1Ca toxicity.
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Affiliation(s)
- Xiangliang Ren
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Yingying Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
- Honghu Agricultural Technology Extension Center, Jingzhou, 433200 Hubei China
| | - Yajie Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Weili Jiang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Xiaoyan Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Hongyan Hu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Dan Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Yan Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
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Li X, Miyamoto K, Takasu Y, Wada S, Iizuka T, Adegawa S, Sato R, Watanabe K. ATP-Binding Cassette Subfamily A Member 2 is a Functional Receptor for Bacillus thuringiensis Cry2A Toxins in Bombyx mori, but not for Cry1A, Cry1C, Cry1D, Cry1F, or Cry9A Toxins. Toxins (Basel) 2020; 12:E104. [PMID: 32041133 PMCID: PMC7076765 DOI: 10.3390/toxins12020104] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 11/29/2022] Open
Abstract
: Cry toxins are insecticidal proteins produced by Bacillus thuringiensis (Bt). They are used commercially to control insect pests since they are very active in specific insects and are harmless to the environment and human health. The gene encoding ATP-binding cassette subfamily A member 2 (ABCA2) was identified in an analysis of Cry2A toxin resistance genes. However, we do not have direct evidence for the role of ABCA2 for Cry2A toxins or why Cry2A toxin resistance does not cross to other Cry toxins. Therefore, we performed two experiments. First, we edited the ABCA2 sequence in Bombyx mori using transcription activator-like effector-nucleases (TALENs) and confirmed the susceptibility-determining ability in a diet overlay bioassay. Strains with C-terminal half-deleted BmABCA2 showed strong and specific resistance to Cry2A toxins; even strains carrying a deletion of 1 to 3 amino acids showed resistance. However, the C-terminal half-deleted strains did not show cross-resistance to other toxins. Second, we conducted a cell swelling assay and confirmed the specific ability of BmABCA2 to Cry2A toxins in HEK239 cells. Those demonstrated that BmABCA2 is a functional receptor for Cry2A toxins and that BmABCA2 deficiency-dependent Cry2A resistance does not confer cross-resistance to Cry1A, Cry1F, Cry1Ca, Cry1Da, or Cry9Aa toxins.
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Affiliation(s)
- Xiaoyi Li
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Sanae Wada
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
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Zhou J, Guo Z, Kang S, Qin J, Gong L, Sun D, Guo L, Zhu L, Bai Y, Zhang Z, Zhou X, Zhang Y. Reduced expression of the P-glycoprotein gene PxABCB1 is linked to resistance to Bacillus thuringiensis Cry1Ac toxin in Plutella xylostella (L.). PEST MANAGEMENT SCIENCE 2020; 76:712-720. [PMID: 31359575 DOI: 10.1002/ps.5569] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/12/2019] [Accepted: 07/23/2019] [Indexed: 05/15/2023]
Abstract
BACKGROUND Rapid evolution of pest resistance has seriously threatened the sustainable use of Bacillus thuringiensis (Bt). The diamondback moth, Plutella xylostella (L.), is the first pest to develop resistance to Bt biopesticides in the open field, which renders it an excellent model to explore the molecular basis of Bt resistance in insects. Our previous midgut transcriptome and RNA-Seq profiles showed that the P-glycoprotein gene PxABCB1 was down-regulated in two Cry1Ac-resistant P. xylostella strains, suggesting its potential involvement in Cry1Ac resistance in P. xylostella. RESULTS In this study, the bona fide full-length cDNA sequence of the PxABCB1 gene was cloned and analyzed, and the expression of the PxABCB1 gene was detected in all tissues and developmental stages, with the highest expression in midgut tissue and the female adult stage. Although no consistent non-synonymous mutations were identified between the susceptible and resistant strains, PxABCB1 gene expression was remarkably decreased in all resistant strains, and the association was further validated by Cry1Ac selection in the moderately resistant SZ-R strain. Moreover, knockdown of the PxABCB1 gene expression resulted in significantly reduced larval susceptibility to Cry1Ac toxin in the DBM1Ac-S strain, and decreased expression of the PxABCB1 gene was tightly linked to Cry1Ac resistance in P. xylostella. CONCLUSION Our results demonstrated that down-regulation of the PxABCB1 gene is associated with both laboratory-selected and field-evolved Cry1Ac resistance in P. xylostella. This knowledge will be conducive to further elucidating the complicated molecular basis of Bt resistance and developing new insect resistance management tactics. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Junlei Zhou
- Longping Branch, Graduate School of Hunan University, Changsha, China
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhaojiang Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shi Kang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jianying Qin
- Longping Branch, Graduate School of Hunan University, Changsha, China
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lijun Gong
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dan Sun
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Le Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Liuhong Zhu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yang Bai
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhuzhu Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaomao Zhou
- Longping Branch, Graduate School of Hunan University, Changsha, China
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
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Zhu B, Sun X, Nie X, Liang P, Gao X. MicroRNA-998-3p contributes to Cry1Ac-resistance by targeting ABCC2 in lepidopteran insects. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 117:103283. [PMID: 31759051 DOI: 10.1016/j.ibmb.2019.103283] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/30/2019] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
Cry protein toxins produced by Bacillus thuringiensis (Bt) are now widely used in sprays and transgenic crops to control insect pests. Most recently, ATP-binding cassette transporter proteins (ABC transporter), including ABCC2, ABCC3, ABCG1, ABCA2 and ABCB1, were reported as putative receptors for different Cry toxins. However, little is known about the regulatory mechanism involved in the expression of these ABC transporter genes. In the present study, a conserved target site of miR-998-3p was identified from the coding sequence (CDS) of ABCC2 in diverse lepidopteran insects. Luciferase reporter assays demonstrated that miR-998-3p could bind to the CDS of ABCC2 and down-regulate its expression through a conserved site and several non-conserved sites in three representative lepidopteran pests, including Helicoverpa armigera, Spodoptera exigua and Plutella xylostella. Injection of miR-998-3p agomir significantly reduced the abundance of ABCC2, accompanied by increased tolerance to Cry1Ac toxin in H. armigera, S. exigua and P. xylostella (Cry-S) larvae, while injection of miR-998-3p antagomir increased the abundance of ABCC2 dramatically, and thereby reduced the Cry1Ac resistance in a Cry1Ac resistant population of P. xylostella (GX-R). These results give a better understanding of the mechanisms of post-transcriptional regulation of ABCC2, and will be helpful for further studies on the role of miRNAs in the regulation of Cry1Ac resistance in lepidopteran pests.
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Affiliation(s)
- Bin Zhu
- Department of Entomology, China Agricultural University, Beijing, 100193, PR China
| | - Xi Sun
- Department of Entomology, China Agricultural University, Beijing, 100193, PR China
| | - Ximan Nie
- Department of Entomology, China Agricultural University, Beijing, 100193, PR China
| | - Pei Liang
- Department of Entomology, China Agricultural University, Beijing, 100193, PR China.
| | - Xiwu Gao
- Department of Entomology, China Agricultural University, Beijing, 100193, PR China
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Adedipe F, Grubbs N, Coates B, Wiegmman B, Lorenzen M. Structural and functional insights into the Diabrotica virgifera virgifera ATP-binding cassette transporter gene family. BMC Genomics 2019; 20:899. [PMID: 31775611 PMCID: PMC6882327 DOI: 10.1186/s12864-019-6218-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 10/22/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The western corn rootworm, Diabrotica virgifera virgifera, is a pervasive pest of maize in North America and Europe, which has adapted to current pest management strategies. In advance of an assembled and annotated D. v. virgifera genome, we developed transcriptomic resources to use in identifying candidate genes likely to be involved in the evolution of resistance, starting with members of the ATP-binding cassette (ABC) transporter family. RESULTS In this study, 65 putative D. v. virgifera ABC (DvvABC) transporters were identified within a combined transcriptome assembly generated from embryonic, larval, adult male, and adult female RNA-sequence libraries. Phylogenetic analysis placed the deduced amino-acid sequences of the DvvABC transporters into eight subfamilies (A to H). To supplement our sequence data with functional analysis, we identified orthologs of Tribolium castaneum ABC genes which had previously been shown to exhibit overt RNA interference (RNAi) phenotypes. We identified eight such D. v. virgifera genes, and found that they were functionally similar to their T. castaneum counterparts. Interestingly, depletion of DvvABCB_39715 and DvvABCG_3712 transcripts in adult females produced detrimental reproductive and developmental phenotypes, demonstrating the potential of these genes as targets for RNAi-mediated insect control tactics. CONCLUSIONS By combining sequence data from four libraries covering three distinct life stages, we have produced a relatively comprehensive de novo transcriptome assembly for D. v. virgifera. Moreover, we have identified 65 members of the ABC transporter family and provided the first insights into the developmental and physiological roles of ABC transporters in this pest species.
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Affiliation(s)
- Folukemi Adedipe
- Department of Entomology and Plant Pathology, North Carolina State University, Box 7613, 1566 Thomas Hall, Raleigh, NC, 27695-7613, USA
| | - Nathaniel Grubbs
- Department of Entomology and Plant Pathology, North Carolina State University, Box 7613, 1566 Thomas Hall, Raleigh, NC, 27695-7613, USA
| | - Brad Coates
- USDA-ARS, Corn Insects & Crop Genetics Research Unit, Ames, IA, 50011, USA
| | - Brian Wiegmman
- Department of Entomology and Plant Pathology, North Carolina State University, Box 7613, 1566 Thomas Hall, Raleigh, NC, 27695-7613, USA
| | - Marcé Lorenzen
- Department of Entomology and Plant Pathology, North Carolina State University, Box 7613, 1566 Thomas Hall, Raleigh, NC, 27695-7613, USA.
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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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