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Wang Y, Mbiza NIT, Liu T, Wang Y, Zhang Y, Luo X, Chu L, Li J, Yang Y, Wang X, Zhang J, Yu Y. SfREPAT38, a pathogen response gene (REPAT), is involved in immune response of Spodoptera frugiperda larvae through mediating Toll signalling pathway. INSECT MOLECULAR BIOLOGY 2024; 33:417-426. [PMID: 38549231 DOI: 10.1111/imb.12909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 03/06/2024] [Indexed: 07/10/2024]
Abstract
REPAT (response to pathogen) is an immune-associated gene family that plays important roles in insect immune response to pathogens. Although nine REPAT genes have been identified in Spodoptera frugiperda (Lepidoptera: Noctuidae) currently, their functions and mechanisms in the immune response to pathogens still remain unclear. Therefore, SfREPAT38, a pathogen response gene (REPAT) of S. frugiperda, was characterised and its function was analysed. The results showed that SfREPAT38 contains a signal peptide and a transcription activator MBF2 (multi-protein bridging factor 2) domain. Quantitative real-time polymerase chain reaction analysis showed that SfREPAT38 was highly expressed in the sixth-instar larvae (L6) and was the highest in expression in the midgut of L6. We found that the expression of SfREPAT38 could be activated by challenge with four microbial pathogens (Bacillus thuringiensis, Metarhizium anisopliae, Spodoptera exigua nuclearpolyhedrosis and Escherichia coli), except 12 h after E. coli infection. Furthermore, the SfREPAT38 expression levels significantly decreased at 24, 48 and 72 h after SfREPAT38 dsRNA injection or feeding. Feeding with SfREPAT38 dsRNA significantly decreased the weight gain of S. frugiperda, and continuous feeding led to the death of S. frugiperda larvae from the fourth day. Moreover, SfREPAT38 dsRNA injection resulted in a significant decrease of weight gain on the fifth day. Silencing SfREPAT38 gene down-regulated the expression levels of immune genes belonging to the Toll pathway, including SPZ, Myd88, DIF, Cactus, Pell and Toll18W. After treatment with SfREPAT38 dsRNA, S. frugiperda became extremely sensitive to the B. thuringiensis infection, and the survival rate dramatically increased, with 100% mortality by the eighth day. The weight of S. frugiperda larvae was also significantly lower than that of the control groups from the second day onwards. In addition, the genes involved in the Toll signalling pathway and a few antibacterial peptide related genes were down-regulated after treatment. These results showed that SfREPAT38 is involved in the immune response of S. frugiperda larvae through mediating Toll signalling pathway.
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Affiliation(s)
- Yuxue Wang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Natasha Isabel Tanatsiwa Mbiza
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Ting Liu
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Yi Wang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Yi Zhang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Xincheng Luo
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Longyan Chu
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Jianping Li
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Yazhen Yang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Xiangping Wang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Jianmin Zhang
- Hubei Engineering Technology Center for Forewarning and Management of Agricultural and Forestry Pests, College of Agriculture, College of Life Sciences, Yangtze University, Jingzhou, Hubei Province, China
| | - Yonghao Yu
- Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi Province, China
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Afzal MBS, Ijaz M, Abbas N, Shad SA, Serrão JE. Resistance of Lepidopteran Pests to Bacillus thuringiensis Toxins: Evidence of Field and Laboratory Evolved Resistance and Cross-Resistance, Mode of Resistance Inheritance, Fitness Costs, Mechanisms Involved and Management Options. Toxins (Basel) 2024; 16:315. [PMID: 39057955 PMCID: PMC11281168 DOI: 10.3390/toxins16070315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/07/2024] [Accepted: 07/09/2024] [Indexed: 07/28/2024] Open
Abstract
Bacillus thuringiensis (Bt) toxins are potential alternatives to synthetic insecticides for the control of lepidopteran pests. However, the evolution of resistance in some insect pest populations is a threat and can reduce the effectiveness of Bt toxins. In this review, we summarize the results of 161 studies from 20 countries reporting field and laboratory-evolved resistance, cross-resistance, and inheritance, mechanisms, and fitness costs of resistance to different Bt toxins. The studies refer mainly to insects from the United States of America (70), followed by China (31), Brazil (19), India (12), Malaysia (9), Spain (3), and Australia (3). The majority of the studies revealed that most of the pest populations showed susceptibility and a lack of cross-resistance to Bt toxins. Factors that delay resistance include recessive inheritance of resistance, the low initial frequency of resistant alleles, increased fitness costs, abundant refuges of non-Bt, and pyramided Bt crops. The results of field and laboratory resistance, cross-resistance, and inheritance, mechanisms, and fitness cost of resistance are advantageous for predicting the threat of future resistance and making effective strategies to sustain the effectiveness of Bt crops.
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Affiliation(s)
- Muhammad Babar Shahzad Afzal
- Beekeeping & Hill Fruit Pests Research Station, Rawalpindi 46000, Pakistan;
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Mamuna Ijaz
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Naeem Abbas
- Pesticides and Environmental Toxicology Laboratory, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia
| | - Sarfraz Ali Shad
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - José Eduardo Serrão
- Department of General Biology, Federal University of Vicosa, Vicosa 36570-900, MG, Brazil;
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3
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Xu YJ, Zhang YN, Xue-Yang, Hao SP, Wang YJ, Yang XX, Shen YQ, Su Q, Xiao YD, Liu JQ, Li WS, He QH, Chen Y, Wang LL, Guo HZ, Xia QY, Mita K. Proteotranscriptomic analyses of the midgut and Malpighian tubules after a sublethal concentration of Cry1Ab exposure on Spodoptera litura. PEST MANAGEMENT SCIENCE 2024; 80:2587-2595. [PMID: 38265118 DOI: 10.1002/ps.7965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 12/12/2023] [Accepted: 01/04/2024] [Indexed: 01/25/2024]
Abstract
BACKGROUND Cry1Ab has emerged as a bio-insecticide to control Spodoptera litura (Lepidoptera: Noctuidae). However, the sublethal effects of Cry1Ab on the physiological changes and molecular level of S. litura have not been well documented. Our aims in this study were to assess the sublethal effect of Cry1Ab on S. litura, including midgut and Malpighian tubules as targets. RESULTS After sublethal Cry1Ab exposure, distinct histological alterations were mainly observed in the midgut. Furthermore, the results of comparative RNA sequencing and tandem mass tag-based proteomics showed that, in the midgut, most differential expression genes (DEGs) were up-regulated and significantly enriched in the serine protease activity pathway, and up-regulated differential expression proteins (DEPs) were mainly associated with the oxidative phosphorylation pathway, whereas the down-regulated involved in the ribosome pathways. In the Malpighian tubules, DEGs and DEPs were significantly enriched in the ribosome pathway. We proposed that ribosome may act as a universal target in energy metabolism with other pathways via the results of protein-protein interaction analysis. Further, by verification of the mRNA expression of some Cry protein receptor and detoxification genes after Cry1Ab treatment, it was suggested that the ribosomal proteins (RPs) possibly participate in influencing the Bt-resistance of S. litura larvae under sublethal Cry1Ab exposure. CONCLUSION Under sublethal Cry1Ab exposure, the midgut of S. litura was damaged, and the proteotranscriptomic analysis elucidated that Cry1Ab disrupted the energy homeostasis of larvae. Furthermore, we emphasized the potential role of ribosomes in sublethal Cry1Ab exposure. © 2024 Society of Chemical Industry.
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Affiliation(s)
- Ya-Jing Xu
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Yu-Ning Zhang
- Weste College, Southwest University, Chongqing, China
| | - Xue-Yang
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Shao-Peng Hao
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Yan-Jue Wang
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Xiao-Xue Yang
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Ya-Qin Shen
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Qing Su
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Ying Dan Xiao
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Jian-Qiu Liu
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Wan-Shun Li
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Qi-Hua He
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Yue Chen
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Li-Ling Wang
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Hui-Zhen Guo
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Qing-You Xia
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
| | - Kazuei Mita
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
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Liu L, He W, Xu P, Wei W, Wang J, Liu K. Contribution of the transcription factor SfGATAe to Bt Cry toxin resistance in Spodoptera frugiperda through reduction of ABCC2 expression. Int J Biol Macromol 2024; 267:131459. [PMID: 38593893 DOI: 10.1016/j.ijbiomac.2024.131459] [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: 02/01/2024] [Revised: 03/27/2024] [Accepted: 04/06/2024] [Indexed: 04/11/2024]
Abstract
Insect resistance evolution poses a significant threat to the advantages of biopesticides and transgenic crops utilizing insecticidal Cry-toxins from Bacillus thuringiensis (Bt). However, there is limited research on the relationship between transcriptional regulation of specific toxin receptors in lepidopteran insects and their resistance to Bt toxins. Here, we report the positive regulatory role of the SfGATAe transcription factor on the expression of the ABCC2 gene in Spodoptera frugiperda. DNA regions in the SfABCC2 promoter that are vital for regulation by SfGATAe, utilizing DAP-seq technology and promoter deletion mapping. Through yeast one-hybrid assays, DNA pull-down experiments, and site-directed mutagenesis, we confirmed that the transcription factor SfGATAe regulates the core control site PBS2 in the ABCC2 target gene. Tissue-specific expression analysis has revealed that SfGATAe is involved in the regulation and expression of midgut cells in the fall armyworm. Silencing SfGATAe in fall armyworm larvae resulted in reduced expression of SfABCC2 and decreased sensitivity to Cry1Ac toxin. Overall, this study elucidated the regulatory mechanism of the transcription factor SfGATAe on the expression of the toxin receptor gene SfABCC2 and this transcriptional control mechanism impacts the resistance of the fall armyworm to Bt toxins.
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Affiliation(s)
- Leilei Liu
- Center of Applied Biotechnology, School of Life Sciences and Technology, Wuhan University of Bioengineering, Wuhan, Hubei, China.
| | - Wenfeng He
- Center of Applied Biotechnology, School of Life Sciences and Technology, Wuhan University of Bioengineering, Wuhan, Hubei, China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Peiwen Xu
- Center of Applied Biotechnology, School of Life Sciences and Technology, Wuhan University of Bioengineering, Wuhan, Hubei, China; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Wei Wei
- Center of Applied Biotechnology, School of Life Sciences and Technology, Wuhan University of Bioengineering, Wuhan, Hubei, China
| | - Jintao Wang
- Center of Applied Biotechnology, School of Life Sciences and Technology, Wuhan University of Bioengineering, Wuhan, Hubei, China
| | - Kaiyu Liu
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
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Zwack PJ, Wu Y, Leininger C, Williams J, Richards EE, Wood C, Wong S, Bramlett M. Characterization of the mode of action of eCry1Gb.1Ig, a fall armyworm (Spodoptera frugiperda) active protein, with a novel site of action. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 201:105881. [PMID: 38685247 DOI: 10.1016/j.pestbp.2024.105881] [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: 02/21/2024] [Revised: 03/14/2024] [Accepted: 03/17/2024] [Indexed: 05/02/2024]
Abstract
Insect pests cause immense agronomic losses worldwide. One of the most destructive of major crops is the Fall Armyworm (Spodoptera frugiperda, FAW). The ability to migrate long distances, a prodigious appetite, and a demonstrated ability to develop resistance to insecticides, make it a difficult target to control. Insecticidal proteins, for example those produced by the bacterium Bacillus thuringiensis, are among the safest and most effective insect control agents. Genetically modified (GM) crops expressing such proteins are a key part of a successful integrated pest management (IPM) program for FAW. However, due to the development of populations resistant to commercialized GM products, new GM traits are desperately needed. Herein, we describe a further characterization of the newly engineered trait protein eCry1Gb.1Ig. Similar to other well characterized Cry proteins, eCry1Gb.1Ig is shown to bind FAW midgut cells and induce cell-death. Binding competition assays using trait proteins from other FAW-active events show a lack of competition when binding FAW brush border membrane vesicles (BBMVs) and when utilizing non-pore-forming versions as competitors in in vivo bioassays. Similarly, insect cell lines expressing SfABCC2 and SfABCC3 (well characterized receptors of existing commercial Cry proteins) are insensitive to eCry1Gb.1Ig. These findings are consistent with results from our previous work showing that eCry1Gb.1Ig is effective in controlling insects with resistance to existing traits. This underscores the value of eCry1Gb.1Ig as a new GM trait protein with a unique site-of-action and its potential positive impact to global food production.
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Affiliation(s)
- Paul J Zwack
- Syngenta Crop Protection LLC, Research Triangle Park, NC, USA.
| | - Yuexuan Wu
- Syngenta Crop Protection LLC, Research Triangle Park, NC, USA
| | - Chris Leininger
- Syngenta Crop Protection LLC, Research Triangle Park, NC, USA
| | | | | | - Chase Wood
- Syngenta Crop Protection LLC, Research Triangle Park, NC, USA
| | - Sarah Wong
- Syngenta Crop Protection LLC, Research Triangle Park, NC, USA
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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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De Bortoli CP, Santos RF, Assirati GJ, Sun X, Hietala L, Jurat-Fuentes JL. Exposure to Cry1 Toxins Increases Long Flight Tendency in Susceptible but Not in Cry1F-Resistant Female Spodoptera frugiperda (Lepidoptera: Noctuidae). INSECTS 2023; 15:7. [PMID: 38249013 PMCID: PMC10815942 DOI: 10.3390/insects15010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/23/2024]
Abstract
The fall armyworm (JE Smith) (Spodoptera frugiperda) is a polyphagous pest targeted by selected Cry and Vip3A insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) that are produced in transgenic Bt corn and cotton. Available evidence suggests that sublethal larval exposure to Cry1Ac increases flight activity in adult Spodoptera spp. However, it is not known whether this effect is also observed in survivors from generally lethal exposure to Cry1Ac. Moreover, while multiple cases of field-evolved resistance to Bt proteins have been described in the native range of S. frugiperda, the effect of resistance on flight behavior has not been examined. Long-distance migratory flight capacity of S. frugiperda is of concern given its ongoing global spread and the possibility that migrants may be carrying resistance alleles against pesticides and Bt crops. In this study, we used rotational flight mills to test the effects of generally lethal exposure to Cry1Ac in susceptible and sublethal exposure in Cry1F-resistant S. frugiperda strains. The results detected altered pupal weight after larval feeding on diet containing Cry proteins, which only translated in significantly increased tendency for longer flights in female moths from the susceptible strain. This information has relevant implications when considering current models and assumptions for resistance management of Bt crops.
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Affiliation(s)
- Caroline P. De Bortoli
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (C.P.D.B.); (R.F.S.); (G.J.A.); (L.H.)
| | - Rafael F. Santos
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (C.P.D.B.); (R.F.S.); (G.J.A.); (L.H.)
| | - Giordano J. Assirati
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (C.P.D.B.); (R.F.S.); (G.J.A.); (L.H.)
| | - Xiaocun Sun
- Research Computing Support, Office of Information Technology, University of Tennessee, Knoxville, TN 37996, USA;
| | - Lucas Hietala
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (C.P.D.B.); (R.F.S.); (G.J.A.); (L.H.)
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (C.P.D.B.); (R.F.S.); (G.J.A.); (L.H.)
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8
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Kerns DD, Yang F, Kerns DL, Stewart SD, Jurat-Fuentes JL. Reduced toxin binding associated with resistance to Vip3Aa in the corn earworm ( Helicoverpa zea). Appl Environ Microbiol 2023; 89:e0164423. [PMID: 38014960 PMCID: PMC10734485 DOI: 10.1128/aem.01644-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/17/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Helicoverpa zea is a major crop pest in the United States that is managed with transgenic corn and cotton that produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). However, H. zea has evolved widespread resistance to the Cry proteins produced in Bt corn and cotton, leaving Vip3Aa as the only plant-incorporated protectant in Bt crops that consistently provides excellent control of H. zea. The benefits provided by Bt crops will be substantially reduced if widespread Vip3Aa resistance develops in H. zea field populations. Therefore, it is important to identify resistance alleles and mechanisms that contribute to Vip3Aa resistance to ensure that informed resistance management strategies are implemented. This study is the first report of reduced binding of Vip3Aa to midgut receptors associated with resistance.
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Affiliation(s)
- Dawson D. Kerns
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Fei Yang
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - David L. Kerns
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Scott D. Stewart
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
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9
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Jin M, Shan Y, Li Q, Peng Y, Xiao Y. A novel Cry1A resistance allele of fall armyworm in the new invaded region. Int J Biol Macromol 2023; 244:125392. [PMID: 37321433 DOI: 10.1016/j.ijbiomac.2023.125392] [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: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023]
Abstract
The fall armyworm, Spodoptera frugiperda, is a devastating pest in its native range Western Hemisphere and has become a major invasive pest around the globe. Transgenic crops producing Bt toxins have been widely used to control S. frugiperda. However, the evolution of resistance threatens the sustainability of Bt crops. Field-evolved S. frugiperda resistance to Bt crops was observed in America, whereas, no case of field-resistance was reported in its newly invaded East Hemisphere. Here we investigated the molecular mechanism of a Cry1Ab-resistant LZ-R strain of S. frugiperda, which selected 27-generations using Cry1Ab after being collected in corn fields from China. Complementation tests between LZ-R strain and SfABCC2-KO strain, which have been knockout SfABCC2 gene and confer 174-fold resistance to Cry1Ab, showed a similar level of resistance in the F1-progeny as their parent stains, indicating that a common locus of SfABCC2 mutation in LZ-R stain. Sequencing of the full length of SfABCC2 cDNA from LZ-R strain, we characterize a novel mutation allele of SfABCC2. Cross-resistance results showed that Cry1Ab-resistance strain also confers >260-fold resistance to Cry1F, with no cross-resistance to Vip3A. These results provided evidence of a novel SfABCC2 mutation allele in the newly invaded East Hemisphere of S. frugiperda.
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Affiliation(s)
- Minghui Jin
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Yinxue Shan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Qi Li
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Yan Peng
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Yutao Xiao
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Gene Editing Technologies (Hainan), Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
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10
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Tandy P, Lamour K, Placidi de Bortoli C, Nagoshi R, Emrich SJ, Jurat-Fuentes JL. Screening for resistance alleles to Cry1 proteins through targeted sequencing in the native and invasive range of Spodoptera frugiperda (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:935-944. [PMID: 37311017 DOI: 10.1093/jee/toad061] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/02/2023] [Accepted: 03/30/2023] [Indexed: 06/15/2023]
Abstract
The fall armyworm, Spodoptera frugiperda (J. E. Smith), is a highly polyphagous pest native to the tropical Americas that has recently spread to become a global super-pest threatening food and fiber production. Transgenic crops producing insecticidal Cry and Vip3Aa proteins from Bacillus thuringiensis (Bt) are used for control of this pest in its native range. The evolution of practical resistance represents the greatest threat to sustainability of this technology and its potential efficacy in the S. frugiperda invasive range. Monitoring for resistance is vital to management approaches delaying S. frugiperda resistance to Bt crops. DNA-based resistance screening provides higher sensitivity and cost-effectiveness than currently used bioassay-based monitoring. So far, practical S. frugiperda resistance to Bt corn-producing Cry1F has been genetically linked to mutations in the SfABCC2 gene, providing a model to develop and test monitoring tools. In this study, we performed targeted SfABCC2 sequencing followed by Sanger sequencing to confirm the detection of known and candidate resistance alleles to Cry1F corn in field-collected S. frugiperda from continental USA, Puerto Rico, Africa (Ghana, Togo, and South Africa), and Southeast Asia (Myanmar). Results confirm that the distribution of a previously characterized resistance allele (SfABCC2mut) is limited to Puerto Rico and identify 2 new candidate SfABCC2 alleles for resistance to Cry1F, one of them potentially spreading along the S. frugiperda migratory route in North America. No candidate resistance alleles were found in samples from the invasive S. frugiperda range. These results provide support for the potential use of targeted sequencing in Bt resistance monitoring programs.
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Affiliation(s)
- Peter Tandy
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA
| | - Kurt Lamour
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA
| | | | - Rodney Nagoshi
- Center for Medical, Agricultural and Veterinary Entomology (CMAVE), United States Department of Agriculture-Agricultural Research Service, Gainesville, FL 32608, USA
| | - Scott J Emrich
- Department of Electrical Engineering and Computer Science, 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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11
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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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12
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Liao C, Zhang D, Cheng Y, Yang Y, Liu K, Wu K, Xiao Y. Down-regulation of HaABCC3, potentially mediated by a cis-regulatory mechanism, is involved in resistance to Cry1Ac in the cotton bollworm, Helicoverpa armigera. INSECT SCIENCE 2023; 30:135-145. [PMID: 35603737 DOI: 10.1111/1744-7917.13080] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/28/2022] [Accepted: 05/06/2022] [Indexed: 05/29/2023]
Abstract
Evolution of resistance to Cry proteins in multiple pest insects has been threatening the sustainable use of Bacillus thuringiensis (Bt)-transgenic crops. Better understanding about the mechanism of resistance to Cry proteins in insects is needed. Our preliminary study reported that the transcription of HaABCC3 was significantly decreased in a near-isogenic line (LFC2) of a Cry1Ac-resistant strain (LF60) of the global pest Helicoverpa armigera. However, the causality between HaABCC3 downregulation and resistance to Cry1Ac remains to be verified, and the regulatory mechanism underlying the HaABCC3 downregulation is still unclear. In this study, our data showed that both HaABCC3 and HaABCC3 downregulation were genetically linked to resistance to Cry1Ac in LF60. However, no InDels were observed in the coding sequence of HaABCC3 from LF60. Furthermore, F1 offspring from the cross of LF60 and a HaABCC2/3-knockout mutant exhibited moderate resistance to Cry1Ac toxin; this indicated that the high resistance to Cry1Ac toxin in LF60 may have resulted from multiple genetic factors, including HaABCC2 mis-splicing and HaABCC3 downregulation. Results from luciferase reporter assays showed that promoter activity of HaABCC3 in LF60 was significantly lower than that in the susceptible strain, which indicated that HaABCC3 downregulation was likely mediated by promoter variation. Consistently, multiple variations of the GATA- or FoxA-binding sites in the promoter region of HaABCC3 were identified. Collectively, all results in this study suggested that the downregulation of HaABCC3 observed in the H. armigera LF60 strain, which is resistant to Cry1Ac, may be mediated by a cis-regulatory mechanism.
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Affiliation(s)
- Chongyu Liao
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Dandan Zhang
- The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ying Cheng
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Yongbo Yang
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Kaiyu Liu
- College of Life Sciences, Central China Normal University, Wuhan, China
| | - Kongming Wu
- The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yutao Xiao
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
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13
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Oliveira NC, Phelan L, Labate CA, Cônsoli FL. Non-targeted metabolomics reveals differences in the gut metabolic profile of the fall armyworm strains when feeding different food sources. JOURNAL OF INSECT PHYSIOLOGY 2022; 139:104400. [PMID: 35598778 DOI: 10.1016/j.jinsphys.2022.104400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Spodoptera frugiperda (fall armyworm - FAW) is an important polyphagous agricultural pest feeding on nearly 350 host plants. FAW is undergoing incipient speciation with two well-characterized host-adapted strains, the "corn" (CS) and "rice" (RS) strains, which are morphologically identical but carry several genes under positive selection for host adaptation. We used non-targeted metabolomics based on gas chromatography/mass spectrometry to identify differences in metabolite profiles of the larval gut of CS and RS feeding on different host plants. Larvae were fed on artificial diet, maize, rice, or cotton leaves from eclosion to the sixth instar, when they had their midgut dissected for analysis. This study revealed that the midgut metabolome of FAW varied due to larval diet and differed between the FAW host-adapted strains. Additionally, we identified several candidate metabolites that may be involved in the adaptation of CS and RS to their host plants. Our findings provide clues toward the gut metabolic activities of the FAW strains.
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Affiliation(s)
- Nathalia C Oliveira
- Insect Interactions Laboratory, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
| | - Larry Phelan
- Department of Entomology, OARDC, The Ohio State University, Wooster, OH, United States
| | - Carlos A Labate
- Multi-User Proteomics, Metabolomics and Lipidomics Laboratory, Department of Genetics, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
| | - Fernando L Cônsoli
- Insect Interactions Laboratory, Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil.
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14
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Hernández-Martínez P, Bretsnyder EC, Baum JA, Haas JA, Head GP, Jerga A, Ferré J. Comparison of in vitro and in vivo binding site competition of Bacillus thuringiensis Cry1 proteins in two important maize pests. PEST MANAGEMENT SCIENCE 2022; 78:1457-1466. [PMID: 34951106 DOI: 10.1002/ps.6763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Binding site models, derived from in vitro competition binding studies, have been widely used for predicting potential cross-resistance among insecticidal proteins from Bacillus thuringiensis. However, because discrepancies have been found between binding data and observed cross-resistance patterns in some insect species, new tools are required to study the functional relevance of the shared binding sites. RESULTS Here, an in vivo approach has been applied to the competition studies to establish the functional relevance of shared binding sites as determined by in vitro competition assays. Using Cry disabled proteins as competitors in mixed protein overlay assays, we assessed the preference of Cry1Ab, Cry1Fa, and Cry1A.105 proteins for shared binding sites in vivo in two important corn pests, Ostrinia nubilalis and Spodoptera frugiperda. CONCLUSION This study shows that in vivo and in vitro binding site competition assays can provide useful information to better ascertain whether different Cry proteins share binding sites and, consequently, whether cross-resistance due to binding site alteration can occur. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Patricia Hernández-Martínez
- Department of Genetics, University Institute of Biotechnology and Biomedicine, University of Valencia, Burjassot, Spain
| | - Eric C Bretsnyder
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - James A Baum
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Jeff A Haas
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Graham P Head
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Agoston Jerga
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Juan Ferré
- Department of Genetics, University Institute of Biotechnology and Biomedicine, University of Valencia, Burjassot, Spain
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15
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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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16
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Chen D, Moar WJ, Jerga A, Gowda A, Milligan JS, Bretsynder EC, Rydel TJ, Baum JA, Semeao A, Fu X, Guzov V, Gabbert K, Head GP, Haas JA. Bacillus thuringiensis chimeric proteins Cry1A.2 and Cry1B.2 to control soybean lepidopteran pests: New domain combinations enhance insecticidal spectrum of activity and novel receptor contributions. PLoS One 2021; 16:e0249150. [PMID: 34138865 PMCID: PMC8211277 DOI: 10.1371/journal.pone.0249150] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/07/2021] [Indexed: 01/08/2023] Open
Abstract
Two new chimeric Bacillus thuringiensis (Bt) proteins, Cry1A.2 and Cry1B.2, were constructed using specific domains, which provide insecticidal activity against key lepidopteran soybean pests while minimizing receptor overlaps between themselves, current, and soon to be commercialized plant incorporated protectants (PIP's) in soybean. Results from insect diet bioassays demonstrate that the recombinant Cry1A.2 and Cry1B.2 are toxic to soybean looper (SBL) Chrysodeixis includens Walker, velvetbean caterpillar (VBC) Anticarsia gemmatalis Hubner, southern armyworm (SAW) Spodoptera eridania, and black armyworm (BLAW) Spodoptera cosmioides with LC50 values < 3,448 ng/cm2. Cry1B.2 is of moderate activity with significant mortality and stunting at > 3,448 ng/cm2, while Cry1A.2 lacks toxicity against old-world bollworm (OWB) Helicoverpa armigera. Results from disabled insecticidal protein (DIP) bioassays suggest that receptor utilization of Cry1A.2 and Cry1B.2 proteins are distinct from each other and from current, and yet to be commercially available, Bt proteins in soy such as Cry1Ac, Cry1A.105, Cry1F.842, Cry2Ab2 and Vip3A. However, as Cry1A.2 contains a domain common to at least one commercial soybean Bt protein, resistance to this common domain in a current commercial soybean Bt protein could possibly confer at least partial cross resistance to Cry1A2. Therefore, Cry1A.2 and Cry1B.2 should provide two new tools for controlling many of the major soybean insect pests described above.
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Affiliation(s)
- Danqi Chen
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - William J. Moar
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Agoston Jerga
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Anilkumar Gowda
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jason S. Milligan
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | | | - Timothy J. Rydel
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - James A. Baum
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Altair Semeao
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Xiaoran Fu
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Victor Guzov
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Karen Gabbert
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Graham P. Head
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey A. Haas
- Bayer Crop Science, Chesterfield, Missouri, United States of America
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17
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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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18
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Geographic Monitoring of Insecticide Resistance Mutations in Native and Invasive Populations of the Fall Armyworm. INSECTS 2021; 12:insects12050468. [PMID: 34070167 PMCID: PMC8158505 DOI: 10.3390/insects12050468] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/18/2022]
Abstract
Simple Summary The moth fall armyworm (Spodoptera frugiperda) is a major agricultural pest insect damaging a wide range of crops, especially corn. Field evolved resistance against Bacillus thuringiensis (Bt) toxins and synthetic insecticides has been repeatedly reported. While the fall armyworm is native to the Americas, its biological invasion was first reported from West Africa in 2016. Since then, this pest has been detected across sub-Saharan and North Africa, Asia, and Oceania. Here, we examine the geographical distribution of mutations causing resistance against Bt or synthetic insecticides to test if the invasion was accompanied by the spread of resistance mutations using 177 individuals collected from 12 geographic populations including North and South America, West and East Africa, India, and China. We observed that Bt resistance mutations generated in Puerto Rico or Brazil were found only from their native populations, while invasive populations had higher copy numbers of cytochrome P450 genes and higher proportions of resistance mutations at AChE, which are known to cause resistance against synthetic insecticides. This result explains the susceptibility to Bt insecticides and the resistance against synthetic insecticides in invasive Chinese populations. This information will be helpful in investigating the cause and consequence associated with insecticide resistance. Abstract Field evolved resistance to insecticides is one of the main challenges in pest control. The fall armyworm (FAW) is a lepidopteran pest species causing severe crop losses, especially corn. While native to the Americas, the presence of FAW was confirmed in West Africa in 2016. Since then, the FAW has been detected in over 70 countries covering sub-Saharan Africa, the Middle East, North Africa, South Asia, Southeast Asia, and Oceania. In this study, we tested whether this invasion was accompanied by the spread of resistance mutations from native to invasive areas. We observed that mutations causing Bt resistance at ABCC2 genes were observed only in native populations where the mutations were initially reported. Invasive populations were found to have higher gene numbers of cytochrome P450 genes than native populations and a higher proportion of multiple resistance mutations at acetylcholinesterase genes, supporting strong selective pressure for resistance against synthetic insecticides. This result explains the susceptibility to Bt insecticides and resistance to various synthetic insecticides in Chinese populations. These results highlight the necessity of regular and standardized monitoring of insecticide resistance in invasive populations using both genomic approaches and bioassay experiments.
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19
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Abdelgaffar H, Perera OP, Jurat-Fuentes JL. ABC transporter mutations in Cry1F-resistant fall armyworm (Spodoptera frugiperda) do not result in altered susceptibility to selected small molecule pesticides. PEST MANAGEMENT SCIENCE 2021; 77:949-955. [PMID: 32985759 DOI: 10.1002/ps.6106] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/31/2020] [Accepted: 09/28/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Transgenic crops producing Cry and Vip3 insecticidal proteins from the bacterium Bacillus thuringiensis provide effective control of the fall armyworm, Spodoptera frugiperda J. E. Smith. However, cases of practical S. frugiperda resistance to transgenic corn producing Cry1F, Cry1Ab and Cry1A.105 proteins have been reported in the Western hemisphere. Importantly, S. frugiperda resistance to Cry1F corn in Puerto Rico was previously associated with lower susceptibility to synthetic pesticides. When characterized, resistance to transgenic corn in S. frugiperda involved alterations in an ABC transporter subfamily C2 (SfABCC2) gene. The main goal of this work was to test the role of mutations in SfABCC2 that result in resistance to Cry1F in susceptibility to synthetic and semisynthetic small molecule pesticides. RESULTS Marginal but significantly reduced susceptibility to bifenthrin and increased susceptibility to spinetoram was detected in a Cry1F-resitant S. frugiperda strain from Puerto Rico carrying a frameshift mutation in the SfABCC2 gene. Gene editing by CRISPR/Cas9 created a SfABCC2 knockout in a laboratory reference S. frugiperda strain. When compared to the parental reference, the knockout strain displayed 25-fold resistance to Cry1F but no alteration in susceptibility to small molecule pesticides. CONCLUSION These results support that resistance to Cry1F due to mutations in the SfABCC2 gene do not affect susceptibility to the tested small molecule pesticides.
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Affiliation(s)
- Heba Abdelgaffar
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, USA
| | - Omaththage P Perera
- Southern Insect Management Research Unit, USDA, Agricultural Research Service, Stoneville, MS, USA
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20
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Jurat-Fuentes JL, Heckel DG, Ferré J. Mechanisms of Resistance to Insecticidal Proteins from Bacillus thuringiensis. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:121-140. [PMID: 33417820 DOI: 10.1146/annurev-ento-052620-073348] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are used in sprayable formulations or produced in transgenic crops as the most successful alternatives to synthetic pesticides. The most relevant threat to sustainability of Bt insecticidal proteins (toxins) is the evolution of resistance in target pests. To date, high-level resistance to Bt sprays has been limited to one species in the field and another in commercial greenhouses. In contrast, there are currently seven lepidopteran and one coleopteran species that have evolved practical resistance to transgenic plants producing insecticidal Bt proteins. In this article, we present a review of the current knowledge on mechanisms of resistance to Bt toxins, with emphasis on key resistance genes and field-evolved resistance, to support improvement of Bt technology and its sustainability.
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Affiliation(s)
- Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee 37996, USA;
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany;
| | - Juan Ferré
- ERI of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot 46100, Spain;
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Tessnow AE, Behmer ST, Sword GA. Protein-carbohydrate regulation and nutritionally mediated responses to Bt are affected by caterpillar population history. PEST MANAGEMENT SCIENCE 2021; 77:335-342. [PMID: 32729162 DOI: 10.1002/ps.6022] [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: 04/14/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The widespread adoption of genetically modified crops, including Bacillius thuringensis (Bt) crops that target chewing insects, has transformed agricultural pest management. This increased use of Bt has raised concerns about the onset of resistance amongst target pests. Recent studies have shown that for some caterpillars, nutritional foraging (e.g. the ratio of proteins and carbohydrates consumed) can affect the insect susceptibility to the Bt toxin Cry1Ac. However, studies on both nutritional foraging and Bt susceptibility tend to rely on laboratory colonies without specifically addressing physiological differences that may occur between populations of the same species. Here, we used choice assays, no choice assays and dose response assays to address two overarching questions: Do populations of Spodoptera frugiperda (J.E. Smith) vary in their protein-carbohydrate foraging behavior? and Does protein-carbohydrate intake impact S. frugiperda's susceptibility to the Bt toxin Cry1F? RESULTS All three of our S. frugiperda populations actively regulated their protein-carbohydrate intake, but we observed significant differences between populations with respect to their self-selected protein-carbohydrate intake. We also found that feeding at the protein-carbohydrate intake target slightly increased Cry1F susceptibility for one S. frugiperda population, but had no effect on the other two populations. CONCLUSIONS Our findings indicate that inherent differences exist in the nutritional physiology of three S. frugiperda populations, possibly related to the time spent in culture. This suggests that population-level differences are an important consideration when drawing parallels between field-collected and laboratory-reared insects.
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Affiliation(s)
- Ashley E Tessnow
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Spencer T Behmer
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Ecology and Evolutionary Biology Interdisciplinary Program, Texas A&M University, College Station, TX, USA
| | - Gregory A Sword
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Ecology and Evolutionary Biology Interdisciplinary Program, Texas A&M University, College Station, TX, USA
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22
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Raeman R, Hua G, Zhang Q, Adang MJ. Fluorescent analyses of Bacillus thuringiensis Cry1Fa and Cry1Ab toxin binding sites on brush border membrane vesicles of Ostrinia nubilalis (Hübner), Diatraea grandiosella (Dyar), and Helicoverpa zea (Boddie) larvae. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 167:104592. [PMID: 32527425 DOI: 10.1016/j.pestbp.2020.104592] [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: 10/15/2019] [Revised: 04/01/2020] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
Bacillus thuringiensis (Bt) Cry1Fa and Cry1Ab proteins are important Cry toxins due to their high, selective toxicity against a number of lepidopteran species, including important pests of corn and cotton. Competition binding assays are a classical tool for investigating Cry toxin interactions with target pest insects. We developed a fluorescence-based binding assay and assessed Cry1Fa and Cry1Ab toxin binding to brush border membrane preparations from lepidopteran corn pests including Ostrinia nubilalis (European corn borer, ECB), Diatraea grandiosella (south western corn borer, SWCB), and Helicoverpa zea (corn earworm, CEW). Homologous and heterologous competition binding assays with fluorophore-(Alexa488)-labeled Cry1Fa toxin showed that Cry1Fa shares binding site(s) with Cry1Ab toxin in ECB, and SWCB for which Cry1Ab has higher affinity than Cry1Fa. Apart from the shared binding sites, Cry1Ab and Cry1Fa bind an additional site(s) in ECB and SWCB. In CEW, Cry1Fa and Cry1Ab each, has a high affinity binding site(s), which binds the heterologous toxin with low affinity. The Cry1Ab-Cry1Fa toxin binding models for ECB, SWCB and CEW based on our results are considered in the context of what is known about acquired cross-resistance against Cry1Ab and Cry1Fa toxins.
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Affiliation(s)
- Reben Raeman
- Departments of Entomology, University of Georgia, Athens, GA 30602-2603, United States of America
| | - Gang Hua
- Departments of Entomology, University of Georgia, Athens, GA 30602-2603, United States of America
| | - Qi Zhang
- Departments of Entomology, University of Georgia, Athens, GA 30602-2603, United States of America
| | - Michael J Adang
- Departments of Entomology, University of Georgia, Athens, GA 30602-2603, United States of America; Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602-2603, United States of America.
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Analysis of Cry1Ah Toxin-Binding Reliability to Midgut Membrane Proteins of the Asian Corn Borer. Toxins (Basel) 2020; 12:toxins12060418. [PMID: 32599715 PMCID: PMC7354594 DOI: 10.3390/toxins12060418] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/26/2020] [Accepted: 06/15/2020] [Indexed: 12/02/2022] Open
Abstract
Evolution of insect resistance to Bt toxins challenges the use of Cry toxins to control agricultural pests. In lepidopterans, Cry toxin affinity towards multiple midgut epithelial receptors has become a matter of dispute. Cry1Ah toxin-binding proteins were identified in the larval midgut of susceptible (ACB-BtS) and resistant (ACB-AhR) strains of the Asian corn borer (ACB). A pull-down assay was performed using biotinylated Cry1Ah toxin, and the binding proteins were identified by employing liquid chromatography–tandem mass spectrometry (LC-MS/MS). This study aimed to find the binding consistency of the midgut epithelial protein to the Cry1Ah toxin. The binding proteins from different fractions of SDS-PAGE showed a different pattern. We observed an isoform of prophenoloxidase PPO1b (UniProt Acc No. A0A1Q1MKI0), which was found only in the ACB-AhR fractions. Prophenoloxidase (proPO) is an extraordinary defense molecule activated in insect species during pathogen invasion and the wound healing process. Importantly, this prophenoloxidase might have direct/indirect interaction with the Cry1Ah toxin. Our data also suggest that factors like techniques, enrichment of binding proteins in the sample and the reversible and irreversible nature of the brush border membrane vesicles (BBMVs) to Cry toxins could cause the inconsistency in the protein–protein interactions. Moreover, inside the larva midgut, the influence of the Cry toxins under physiological conditions might be different from the laboratory procedures.
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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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25
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Xiao H, Ye X, Xu H, Mei Y, Yang Y, Chen X, Yang Y, Liu T, Yu Y, Yang W, Lu Z, Li F. The genetic adaptations of fall armyworm Spodoptera frugiperda facilitated its rapid global dispersal and invasion. Mol Ecol Resour 2020; 20:1050-1068. [PMID: 32359007 DOI: 10.1111/1755-0998.13182] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/31/2022]
Abstract
The fall armyworm (Spodoptera frugiperda) is a lepidopteran insect pest that causes huge economic losses. This notorious insect pest has rapidly spread over the world in the past few years. However, the mechanisms of rapid dispersal are not well understood. Here, we report a chromosome-level assembled genome of the fall armyworm, named the ZJ-version, using PacBio and Hi-C technology. The sequenced individual was a female collected from the Zhejiang province of China and had high heterozygosity. The assembled genome size of ZJ-version was 486 Mb, containing 361 contigs with an N50 of 1.13 Mb. Hi-C scaffolding further assembled the genome into 31 chromosomes and a portion of W chromosome, representing 97.4% of all contigs and resulted in a chromosome-level genome with scaffold N50 of 16.3 Mb. The sex chromosomes were identified by genome resequencing of a single male pupa and a single female pupa. About 28% of the genome was annotated as repeat sequences, and 22,623 protein-coding genes were identified. Comparative genomics revealed the expansion of the detoxification-associated gene families, chemoreception-associated gene families, nutrition metabolism and transport system gene families in the fall armyworm. Transcriptomic and phylogenetic analyses focused on these gene families revealed the potential roles of the genes in polyphagia and invasion of fall armyworm. The high-quality of the fall armyworm genome provides an important genomic resource for further explorations of the mechanisms of polyphagia and insecticide resistance, as well as for pest management of fall armyworm.
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Affiliation(s)
- Huamei Xiao
- Key Laboratory of Crop Growth and Development Regulation of Jiangxi Province, College of Life Sciences and Resource Environment, Yichun University, Yichun, China.,State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Xinhai Ye
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Hongxing Xu
- Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yang Mei
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Yi Yang
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Xi Chen
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Yajun Yang
- Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Tao Liu
- Annoroad Gene Technology (Beijing) Co Ltd, Beijing, China
| | - Yongyi Yu
- Annoroad Gene Technology (Beijing) Co Ltd, Beijing, China
| | - Weifei Yang
- Annoroad Gene Technology (Beijing) Co Ltd, Beijing, China
| | - Zhongxian Lu
- Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Fei Li
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
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26
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Oliveira CT, Machado SW, Bezerra CDS, Cardoso MH, Franco OL, Silva CP, Alves DG, Rios C, Macedo MLR. Effects of a Reserve Protein on Spodoptera frugiperda Development: A Biochemical and Molecular Approach to the Entomotoxic Mechanism. Molecules 2020; 25:E2195. [PMID: 32397098 PMCID: PMC7249069 DOI: 10.3390/molecules25092195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 11/25/2022] Open
Abstract
Talisin is a storage protein from Talisia esculenta seeds that presents lectin-like and peptidase inhibitor properties. These characteristics suggest that talisin plays a role in the plant defense process, making it a multifunctional protein. This work aimed to investigate the effects of chronic intake of talisin on fifth instar larvae of Spodoptera frugiperda, considered the main insect pest of maize and the cause of substantial economic losses in several other crops. The chronic intake of talisin presented antinutritional effects on the larvae, reducing their weight and prolonging the total development time of the insects. In addition, talisin-fed larvae also showed a significant reduction in the activity of trypsin-like enzymes. Midgut histology analysis of talisin-fed larvae showed alterations in the intestinal epithelium and rupture of the peritrophic membrane, possibly causing an increase of aminopeptidase activity in the midgut lumen. Talisin also proved to be resistant to degradation by the digestive enzymes of S. frugiperda. The transcription profile of trypsin, chymotrypsin and aminopeptidase genes was also analyzed through qPCR technique. Talisin intake resulted in differential expression of at least two genes from each of these classes of enzymes. Molecular docking studies indicated a higher affinity of talisin for the less expressed enzymes.
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Affiliation(s)
- Carolina Turatti Oliveira
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil; (C.T.O.); (S.W.M.)
- Programa multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Instituto de Biologia, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil;
| | - Suzy Wider Machado
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil; (C.T.O.); (S.W.M.)
| | - Cézar da Silva Bezerra
- Programa multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Instituto de Biologia, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil;
| | - Marlon Henrique Cardoso
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicase Biotecnologia, Universidade Católica de Brasília, Brasília, Distrito Federal 70790-160, Brazil; (M.H.C.); (O.L.F.)
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Mato Grosso do Sul 79117-900, Brazil
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicase Biotecnologia, Universidade Católica de Brasília, Brasília, Distrito Federal 70790-160, Brazil; (M.H.C.); (O.L.F.)
- S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Mato Grosso do Sul 79117-900, Brazil
| | - Carlos Peres Silva
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catariana, Florianópolis, Santa Catarina 88040-900, Brazil; (C.P.S.); (D.G.A.); (C.R.)
| | - Demetrio Gomes Alves
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catariana, Florianópolis, Santa Catarina 88040-900, Brazil; (C.P.S.); (D.G.A.); (C.R.)
| | - Cristina Rios
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catariana, Florianópolis, Santa Catarina 88040-900, Brazil; (C.P.S.); (D.G.A.); (C.R.)
| | - Maria Lígia R. Macedo
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil; (C.T.O.); (S.W.M.)
- Programa multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Instituto de Biologia, Universidade Federal de Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul 79070-900, Brazil;
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Wang B, Wei J, Wang Y, Chen L, Liang G. Polycalin is involved in the toxicity and resistance to Cry1Ac toxin in Helicoverpa armigera (Hübner). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 104:e21661. [PMID: 32011765 DOI: 10.1002/arch.21661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/02/2020] [Accepted: 01/19/2020] [Indexed: 06/10/2023]
Abstract
Polycalin has been confirmed as a binding protein of the Cry toxins in a few Lepidoptera insects, but its function in the action mechanism of Cry1Ac and whether it is involved in resistance evolution are still unclear. In this study, Ligand blot and enzyme-linked immunosorbent assays showed that Helicoverpa armigera polycalin could specifically interact with Cry1Ac with a high affinity (Kd = 118.80 nM). Importantly, antisera blocking polycalin in H. armigera larvae decreased the toxicity of Cry1Ac by 31.84%. Furthermore, the relative gene and protein expressions were lower in Cry1Ac-resistant strain (LF60) than that in Cry1Ac-susceptible strain (LF). These findings indicated that H. armigera polycalin was a possible receptor of Cry1Ac and may be contributed to the resistance to Cry1Ac.
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Affiliation(s)
- Bingjie Wang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Key Laboratory of Integrated Pest Management of Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jizhen Wei
- State Key Laboratory of Wheat and Maize Crop Science, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Yanan Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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28
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Gichuhi J, Sevgan S, Khamis F, Van den Berg J, du Plessis H, Ekesi S, Herren JK. Diversity of fall armyworm, Spodoptera frugiperda and their gut bacterial community in Kenya. PeerJ 2020; 8:e8701. [PMID: 32185109 PMCID: PMC7060952 DOI: 10.7717/peerj.8701] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 02/06/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) is a polyphagous pest that causes widespread damage particularly to maize and sorghum in Africa. The microbiome associated with S. frugiperda could play a role in the insects' success and adaptability. However, bacterial communities in S. frugiperda remain poorly studied. METHODS We investigated the composition, abundance and diversity of microbiomes associated with larval and adult specimens of S. frugiperda collected from four maize growing regions in Kenya through high throughput sequencing of the bacterial 16S rRNA gene. The population structure of S. frugiperda in Kenya was assessed through amplification of the mitochondrial cytochrome oxidase subunit I gene. RESULTS We identified Proteobacteria and Firmicutes as the most dominant bacterial phyla and lesser proportions of Bacteroidetes and Actinobacteria. We also observed differences in bacterial microbiome diversity between larvae and adults that are a likely indication that some prominent larval bacterial groups are lost during metamorphosis. However, several bacterial groups were found in both adults and larvae suggesting that they are transmitted across developmental stages. Reads corresponding to several known entomopathogenic bacterial clades as well as the fungal entomopathogen, Metarhizium rileyi, were observed. Mitochondrial DNA haplotyping of the S. frugiperda population in Kenya indicated the presence of both "Rice" and "Corn" strains, with a higher prevalence of the "Rice" strain.
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Affiliation(s)
- Joseph Gichuhi
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Subramanian Sevgan
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Fathiya Khamis
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Johnnie Van den Berg
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Hannalene du Plessis
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Sunday Ekesi
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
| | - Jeremy K. Herren
- International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya
- MRC-University of Glasgow Centre for Virus Research, Henry Wellcome Building, Glasgow, UK
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29
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Wei W, Pan S, Ma Y, Xiao Y, Yang Y, He S, Bravo A, Soberón M, Liu K. GATAe transcription factor is involved in Bacillus thuringiensis Cry1Ac toxin receptor gene expression inducing toxin susceptibility. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 118:103306. [PMID: 31843687 DOI: 10.1016/j.ibmb.2019.103306] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
The insecticidal Cry toxins produced by Bacillus thuringiensis (Bt) are powerful tools for insect control. Cry toxin receptors such as cadherin (CAD), ABCC2 transporter and alkaline phosphatase (ALP), located on insect midgut cells, are needed for Cry toxicity. Although insect cell lines are useful experimental models for elucidating toxin action mechanism, most of them show low expression of Cry-receptors genes. The GATA transcription factor family plays important roles in regulating development and differentiation of intestine stem cells. Here, we investigated whether GATAs transcription factors are involved in the expression of Cry1Ac-receptors genes, using multiple insect cell lines. Four GATA genes were identified in the transcriptome of the midgut tissue from the lepidopteran larvae Helicoverpa armigera. These HaGATA genes were transiently expressed in three lepidopteran cell lines, Spodoptera frugiperda Sf9, H. armigera QB-Ha-E5 and Trichoplusia ni Hi5. Analysis of transcription activity using transcriptional gene-fusions showed that only H. armigera GATAe (HaGATAe) significantly increased the transcription of CAD, ABCC2 and ALP receptors genes in all insect cell lines. Key DNA regions for HaGATAe regulation were identified in the promoter sequence of these Cry-receptors genes by using promoter deletion mapping. The transient expression of HaGATAe in these cell lines, conferred sensitivity to Cry1Ac toxin, although in Hi5 cells the susceptibility to Cry1Ac was lower than in other two cell lines. High sensitivity to Cry1Ac correlated with simultaneous transcription of ABCC2 and CAD genes in Sf9 and QB-Ha-E5 cells. Our results reveal that HaGATAe enhances transcription of several lepidopteran Cry1Ac receptor genes in cultured insect cells.
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Affiliation(s)
- Wei Wei
- School of Life Sciences, Central China Normal University, Wuhan, 430070, China
| | - Shuang Pan
- School of Life Sciences, Central China Normal University, Wuhan, 430070, China
| | - Yuemin Ma
- School of Life Sciences, Central China Normal University, Wuhan, 430070, China
| | - Yutao Xiao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Yongbo Yang
- School of Life Sciences, Central China Normal University, Wuhan, 430070, China
| | - Sijia He
- School of Life Sciences, Central China Normal University, Wuhan, 430070, 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.
| | - Kaiyu Liu
- School of Life Sciences, Central China Normal University, Wuhan, 430070, China.
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Shabbir MZ, Zhang T, Prabu S, Wang Y, Wang Z, Bravo A, Soberón M, He K. Identification of Cry1Ah-binding proteins through pull down and gene expression analysis in Cry1Ah-resistant and susceptible strains of Ostrinia furnacalis. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 163:200-208. [PMID: 31973858 DOI: 10.1016/j.pestbp.2019.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 10/31/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
Bacillus thuringiensis produces insecticidal Cry toxins used in the control of multiple insect pests. Evolution of insect resistance to Bt toxins endangers the use of Cry toxins for pest control. Analysis of the Cry1Ah-binding proteins from brush border membrane vesicles (BBMV) of Ostrinia furnacalis, Asian corn borer (ACB) from the Cry1Ah-resistant (ACB-AhR) and susceptible (ACB-BtS) strains was performed by an improved pull down assay that includes coupling Cry1Ah to NHS-activated Sepharose combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our data show that Cry1Ah bound to alkaline phosphatase (ALP), cadherin-like (CAD), actin, aminopeptidase-N (APN), prophenoloxidase (proPO), serine proteinase inhibitor (SPI), immulectin, and V-ATPase and to other proteins that were not previously characterized as Cry-binding proteins in ACB-BtS strain. Analysis of Cry1Ah-pulled down proteins of the BBMV from ACB-AhR revealed that Cry1Ah toxin did not bind to ALP in ACB-AhR strain, suggesting that this protein may correlate with the resistant phenotype of this strain. Additionally, we analyzed the expression of representative genes coding for Cry1Ah-binding proteins such as ALP, APN, CAD, proPO, SPI, and immulectin by qRT-PCR. ACB-AhR showed increased expression levels of proPO (7.5 fold), ALP (6.2 fold) and APN (1.4 fold) in comparison to ACB-BtS strain. In contrast, the cad gene showed slight decreased expression in ACB-AhR strain (0.7 fold) compared with ACB-BtS strain. Our data suggest that differences in the susceptibility to Cry1Ah toxin in the ACB-AhR strain may be associated with reduced ALP binding sites and with an increased immune response. This study also brings evidence of a possible binding interaction of Cry1Ah toxin to immune related proteins like proPO.
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Affiliation(s)
- Muhammad Zeeshan Shabbir
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China
| | - Tiantao Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China
| | - Sivaprasath Prabu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China
| | - Yueqin Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China
| | - Zhenying Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China
| | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Mario Soberón
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, People's Republic of China.
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Boaventura D, Ulrich J, Lueke B, Bolzan A, Okuma D, Gutbrod O, Geibel S, Zeng Q, Dourado PM, Martinelli S, Flagel L, Head G, Nauen R. Molecular characterization of Cry1F resistance in fall armyworm, Spodoptera frugiperda from Brazil. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 116:103280. [PMID: 31740346 DOI: 10.1016/j.ibmb.2019.103280] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/05/2019] [Accepted: 11/12/2019] [Indexed: 05/21/2023]
Abstract
Fall armyworm, Spodoptera frugiperda (J.E. Smith) is a major lepidopteran pest of maize in Brazil and its control particularly relies on the use of genetically engineered crops expressing Bacillus thuringiensis (Bt) toxins such as Cry1F. However, control failures compromising the efficacy of this technology have been reported in many regions in Brazil, but the mechanism of Cry1F resistance in Brazilian fall armyworm populations remained elusive. Here we investigated the molecular mechanism of Cry1F resistance in two field-collected strains of S. frugiperda from Brazil exhibiting high levels of Cry1F resistance. We first rigorously evaluated several candidate reference genes for normalization of gene expression data across strains, larval instars and gut tissues, and identified ribosomal proteins L10, L17 and RPS3A to be most suitable. We then investigated the expression pattern of ten potential Bt toxin receptors/enzymes in both neonates and 2nd instar gut tissue of Cry1F resistant fall armyworm strains compared to a susceptible strain. Next we sequenced the ATP-dependent Binding Cassette subfamily C2 gene (ABCC2) and identified three mutated sites present in ABCC2 of both Cry1F resistant strains: two of them, a GY deletion (positions 788-789) and a P799 K/R amino acid substitution, located in a conserved region of ABCC2 extracellular loop 4 (EC4) and another amino acid substitution, G1088D, but in a less conserved region. We further characterized the role of the novel mutations present in EC4 by functionally expressing both wild type and mutated ABCC2 transporters in insect cell lines, and confirmed a critical role of both sites for Cry1F binding by cell viability assays. Finally, we assessed the frequency of the mutant alleles by pooled population sequencing and pyrosequencing in 40 fall armyworm populations collected from maize fields in different regions in Brazil. We found that the GY deletion being present at high frequency. However we also observed many rare alleles which disrupt residues between sites 783-799, and their diversity and abundance in field collected populations lends further support to the importance of the EC4 domain for Cry1F toxicity.
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Affiliation(s)
- Debora Boaventura
- Institute of Crop Science and Resource Conservation, University of Bonn, 53115, Bonn, Germany; Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany
| | - Julia Ulrich
- Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany
| | - Bettina Lueke
- Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany
| | - Anderson Bolzan
- Department of Entomology and Acarology, University of São Paulo, Piracicaba, São Paulo, Brazil
| | - Daniela Okuma
- Bayer S.A, Crop Science, Av. Dr. Roberto Moreira, 5005, Paulinia, SP, Brazil
| | - Oliver Gutbrod
- Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany
| | - Sven Geibel
- Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany
| | - Qin Zeng
- Bayer U.S, Crop Science, R&D, 700 Chesterfield Pkwy W, Chesterfield, MO, 63017, USA
| | - Patrick M Dourado
- Bayer S.A, Crop Science, R&D, Avenida Nacoes Unidas, São Paulo, Brazil
| | - Samuel Martinelli
- Bayer U.S, Crop Science, R&D, 700 Chesterfield Pkwy W, Chesterfield, MO, 63017, USA
| | - Lex Flagel
- Bayer U.S, Crop Science, R&D, 700 Chesterfield Pkwy W, Chesterfield, MO, 63017, USA
| | - Graham Head
- Bayer U.S, Crop Science, R&D, 700 Chesterfield Pkwy W, Chesterfield, MO, 63017, USA
| | - Ralf Nauen
- Bayer AG, Crop Science, R&D, Alfred Nobel Str. 50, 40789, Monheim, Germany.
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Peterson B, Sanko TJ, Bezuidenhout CC, van den Berg J. Transcriptome and differentially expressed genes of Busseola fusca (Lepidoptera: Noctuidae) larvae challenged with Cry1Ab toxin. Gene 2019; 710:387-398. [PMID: 31136783 DOI: 10.1016/j.gene.2019.05.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Busseola fusca (Fuller) (Lepidoptera: Noctuidae), a major insect pest of maize in sub-Saharan Africa, has developed high levels of non-recessive resistance to Cry1Ab toxin expressed in genetically modified Bt maize. Multiple resistance mechanisms to various Cry toxins have been identified in Lepidoptera, but no study has yet been done to determine the mechanism of Cry1Ab resistance in B. fusca. Therefore, the larval transcriptome of B. fusca was sequenced, de novo assembled and characterized. Differential expression analysis was performed to compare gene expression profiles of Cry toxin challenged and unchallenged neonate larvae to assess the molecular basis of the defence mechanism employed by this insect. Several genes associated with Cry toxin resistance in other lepidopteran pests were detected in B. fusca. Results suggest that differential expression of metabolic and immune-related genes might explain Cry1Ab toxin defence in this pest (supplemental file). Transcript expression profiles of neonates demonstrated that 33.59% and 60.31% of the 131 differentially expressed genes were upregulated and downregulated in the toxin-challenged neonate larvae, respectively. Transcripts were grouped into two subclusters according to the similarity of their expression patterns. Transcripts in subcluster 1 were moderately upregulated in the toxin-challenged neonate larvae, and, conversely, downregulated in the unchallenged neonate larvae. The solute carrier organic anion transporter, which is involved in insecticide detoxification, was upregulated in the toxin-challenged neonate larvae. Conversely, most of the transcripts in subcluster 2 were moderately downregulated in the toxin-challenged neonate larvae, and upregulated for neonates feeding on non-challenged maize. Four unidentified transcripts were extremely down-regulated in the toxin-challenged neonate larvae, and upregulated in the unchallenged neonate larvae. Further studies are recommended to establish if there is a direct correlation between these differentially expressed genes and the observed resistance. Elucidation of such defence mechanisms is crucial for developing insect resistance management strategies to ensure sustainable use of genetically modified maize in Africa. Nevertheless, this is the first study on gene expression profiles of B. fusca strains challenged with Cry toxin. The transcriptome characterized in this study provides a significant resource base for future studies on B. fusca and contributes to understanding some of the gene regulation and signalling networks involved in the defence of B. fusca against Cry1Ab toxin.
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Affiliation(s)
- Bianca Peterson
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Potchefstroom 2531, South Africa.
| | - Tomasz Janusz Sanko
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Potchefstroom 2531, South Africa
| | - Cornelius Carlos Bezuidenhout
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Potchefstroom 2531, South Africa.
| | - Johnnie van den Berg
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Potchefstroom 2531, South Africa.
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Dhania NK, Chauhan VK, Chaitanya R, Dutta-Gupta A. Midgut de novo transcriptome analysis and gene expression profiling of Achaea janata larvae exposed with Bacillus thuringiensis (Bt)-based biopesticide formulation. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2019; 30:81-90. [DOI: 10.1016/j.cbd.2019.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/19/2018] [Accepted: 02/14/2019] [Indexed: 11/24/2022]
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de Bortoli CP, Jurat-Fuentes JL. Mechanisms of resistance to commercially relevant entomopathogenic bacteria. CURRENT OPINION IN INSECT SCIENCE 2019; 33:56-62. [PMID: 31358196 DOI: 10.1016/j.cois.2019.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/21/2019] [Accepted: 03/27/2019] [Indexed: 05/29/2023]
Abstract
Bacteria represent the most commercially successful entomopathogenic microbial group, with most commercialized insecticides containing gram-positive bacteria in the Bacillaceae family. Resistance to entomopathogenic bacteria threatens sustainable agriculture, and information on the mechanisms and genes involved is vital to develop management practices aimed at reducing this risk. We provide an integrative summary on mechanisms responsible for resistance to commercialized entomopathogenic bacteria, including information on resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt crops). The available experimental evidence identifies alterations in binding of insecticidal proteins to receptors in the host as the main mechanism for high levels of resistance to entomopathogenic bacteria.
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Affiliation(s)
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, United States.
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Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Cameroon: Case study on its distribution, damage, pesticide use, genetic differentiation and host plants. PLoS One 2019; 14:e0215749. [PMID: 31034480 PMCID: PMC6488053 DOI: 10.1371/journal.pone.0215749] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/08/2019] [Indexed: 11/19/2022] Open
Abstract
Maize farmers in sub-Saharan Africa recently experienced unusual damage in their farms, attributed to the fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith). This pest was first recorded in Africa in 2016, but detailed information on its distribution and damage and farmer’s response in invaded areas are largely lacking. In this study, we determined FAW distribution, genetic diversity, host plants, crop damage, and farmers’ responses. S. frugiperda was recorded in the 10 regions of Cameroon. Average percentage of infested plants and damage severity (on a scale of 1 to 5) were lowest—20.7 ± 7.4% and 2.1 ± 0.1 respectively—in the Sahelian regions and greatest—69.0 ± 4.3% and 3.1 ± 0.1 respectively—in the Western Highlands. Altitude did not influence FAW incidence and severity and its larvae infrequently co-occurred with maize stemborers on the same plants, suggesting possible direct and/or indirect competition between the two groups of maize pests. In response to this new threat to maize production, farmers have opted for the application of synthetic pesticides. Although our experiments were not designed to determine pesticide efficacy, as parameters such as time since application were not considered, our observations suggest lack of a drastic effect on S. frugiperda infestations on maize. There were two haplotypes of FAW co-occurring in Cameroon corresponding to the rice and corn strains and separated by 1.7% sequence divergence, which does not support the existence of cryptic species. S. frugiperda larvae were also recorded on Sorghum bicolor (L.) Moench (10.6%), Solanum tuberosum L. (2.8%), Ipomoea batatas (L.) Lam. (1.9%), Saccharum officinarum L (0.8%), Phaseolus vulgaris L. (0.4%) and Gossypium hirsutum L. (1.9%). This study show that two strains are present in all agroecological zones in Cameroon, and probably in neighboring countries of central Africa sharing the same agroecologies. Management options should therefore consider the use of specific natural enemies and an informed decision of intervention based on strain capture and damage threshold, to avoid pesticide resistance that may arise from inadequate use of chemicals. Further studies should also be undertaken to assess the response of the two S. frugiperda strains to biopesticides and botanical insecticides.
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Xiao Y, Wu K. Recent progress on the interaction between insects and Bacillus thuringiensis crops. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180316. [PMID: 30967027 PMCID: PMC6367150 DOI: 10.1098/rstb.2018.0316] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2018] [Indexed: 11/13/2022] Open
Abstract
Extensive use of chemical pesticides poses a great threat to the environment and food safety. The discovery of Bacillus thuringiensis (Bt) toxins with effective insecticidal activity against pests and the development of transgenic technology of plants opened a new era of pest control. Transgenic Bt crops, including maize, cotton and soya bean, have now been produced and commercialized to protect against about 30 major coleopteran and lepidopteran pests, greatly benefiting the environment and the economy. However, with the long-term cultivation of Bt crops, some target pests have gradually developed resistance. Numerous studies have indicated that mutations in genes for toxins activation, toxin-binding and insect immunization are important sources in Bt resistance. An in-depth exploration of the corresponding Bt-resistance mechanisms will aid in the design of new strategies to prevent and control pests. Future research will focus on Bt crops expressing new genes and multiple genes to control a broader range of pests as part of an integrated pest management programme. This article is part of the theme issue 'Biotic signalling sheds light on smart pest management'.
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Affiliation(s)
- Yutao Xiao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, People's Republic of China
| | - Kongming Wu
- The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, People's Republic of China
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37
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Abdelgaffar H, Tague ED, Castro Gonzalez HF, Campagna SR, Jurat-Fuentes JL. Midgut metabolomic profiling of fall armyworm (Spodoptera frugiperda) with field-evolved resistance to Cry1F corn. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 106:1-9. [PMID: 30630033 DOI: 10.1016/j.ibmb.2019.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/21/2018] [Accepted: 01/05/2019] [Indexed: 06/09/2023]
Abstract
Populations of the fall armyworm (Spodoptera frugiperda) have developed resistance to transgenic corn producing the Cry1F insecticidal protein from the bacterium Bacillus thuringiensis (Bt). Resistance in S. frugiperda from Puerto Rico is genetically linked to a mutation in an ATP Binding Cassette subfamily C2 gene (SfABCC2) that results in a truncated, non-functional Cry1F toxin receptor protein. Since ABCC2 proteins are involved in active export of xenobiotics and other metabolites from the cell, we hypothesized that Cry1F-resistant fall armyworm with a non-functional SfABCC2 protein would display altered gut metabolome composition when compared to susceptible insects. Mass spectrometry and multivariate statistical analyses identified 126 unique metabolites from larval guts, of which 7 were found to display statistically significant altered levels between midguts from susceptible and Cry1F-resistant S. frugiperda larvae when feeding on meridic diet. Among these 7 differentially present metabolites, 6 were found to significantly accumulate (1.3-3.5-fold) in midguts from Cry1F-resistant larvae, including nucleosides, asparagine, and carbohydrates such as trehalose 6-phosphate and sedoheptulose 1/7-phosphate. In contrast, metabolomic comparisons of larvae fed on non-transgenic corn identified 5 metabolites with statistically significant altered levels and only 2 of them, 2-isopropylmalate and 3-phosphoserine, that significantly accumulated (2.3- and 3.5-fold, respectively) in midguts from Cry1F-resistant compared to susceptible larvae. These results identify a short list of candidate metabolites that may be transported by SfABCC2 and that may have the potential to be used as resistance markers.
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Affiliation(s)
- Heba Abdelgaffar
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, 37996, USA
| | - Eric D Tague
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA
| | - Hector F Castro Gonzalez
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA; Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, 37996, USA
| | - Shawn R Campagna
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA; Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, 37996, USA
| | - Juan L Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, 37996, USA.
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Kahn TW, Chakroun M, Williams J, Walsh T, James B, Monserrate J, Ferré J. Efficacy and Resistance Management Potential of a Modified Vip3C Protein for Control of Spodoptera frugiperda in Maize. Sci Rep 2018; 8:16204. [PMID: 30385802 PMCID: PMC6212501 DOI: 10.1038/s41598-018-34214-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 10/15/2018] [Indexed: 11/08/2022] Open
Abstract
A modified Vip3C protein has been developed that has a spectrum of activity that has the potential to be commercially useful for pest control, and shows good efficacy against Spodoptera frugiperda in insect bioassays and field trials. For the first time Vip3A and Vip3C proteins have been compared to Cry1 and Cry2 proteins in a complete set of experiments from insect bioassays to competition binding assays to field trials, and the results of these complementary experiments are in agreement with each other. Binding assays with radiolabelled toxins and brush border membrane vesicles from S. frugiperda and Helicoverpa armigera show that the modified Vip3C protein shares binding sites with Vip3A, and does not share sites with Cry1F or Cry2A. In agreement with the resulting binding site model, Vip3A-resistant insects were also cross-resistant to the modified Vip3C protein. Furthermore, maize plants expressing the modified Vip3C protein, but not those expressing Cry1F protein, were protected against Cry1F-resistant S. frugiperda in field trials.
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Affiliation(s)
- Theodore W Kahn
- BASF Agricultural Solutions Seed US LLC, 3500 Paramount Parkway, Morrisville, NC, 27560, USA
| | - Maissa Chakroun
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain
- Centre de Biotechnologie de Sfax (CBS), Sfax, Tunisia
| | - Jayme Williams
- BASF Agricultural Solutions Seed US LLC, 3500 Paramount Parkway, Morrisville, NC, 27560, USA
| | - Tom Walsh
- CSIRO, Black Mountain, Clunies Ross St., Acton, 2601, ACT, Australia
| | - Bill James
- CSIRO, Black Mountain, Clunies Ross St., Acton, 2601, ACT, Australia
| | - Jessica Monserrate
- BASF Agricultural Solutions Seed US LLC, 3500 Paramount Parkway, Morrisville, NC, 27560, USA
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain.
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Chen L, Wei J, Liu C, Zhang W, Wang B, Niu L, Liang G. Specific Binding Protein ABCC1 Is Associated With Cry2Ab Toxicity in Helicoverpa armigera. Front Physiol 2018; 9:745. [PMID: 29971014 PMCID: PMC6018205 DOI: 10.3389/fphys.2018.00745] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/28/2018] [Indexed: 01/10/2023] Open
Abstract
A pyramid strategy combining the crystal (Cry) 1A and 2A toxins in Bacillus thuringiensis (Bt) crops are active against many species of insects and nematode larvae. It has been widely used to delay pest adaption to genetically modified plants and broaden the insecticidal spectrum in many countries. Unfortunately, Cry2A can also bind with the specific receptor proteins of Cry1A. ATP-binding cassette (ABC) transporters can interact with Cry1A toxins as receptors in the insect midgut, and ABC transporter mutations result in resistance to Bt proteins. However, there is limited knowledge of the ABC transporters that specifically bind to Cry2Ab. Here, we cloned the ABCC1 gene in Helicoverpa armigera, which expressed at all larval stages and in nine different tissues. Expression levels were particularly high in fifth-instar larvae and Malpighian tubules. The two heterologously expressed HaABCC1 transmembrane domain peptides could specifically bind to Cry2Ab with high affinity levels. Moreover, transfecting HaABCC1 into the Spodoptera frugiperda nine insect cell significantly increased its mortality when exposed to Cry2Ab in vitro, and silencing HaABCC1 in H. armigera by RNA interference significantly reduced the mortality of larvae exposed to Cry2Ab in vivo. Altogether current results suggest that HaABCC1 serves as a functional receptor for Cry2Ab.
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Affiliation(s)
- Lin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jizhen Wei
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Chen Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wanna Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bingjie Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - LinLin Niu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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Yu T, Li X, Coates BS, Zhang Q, Siegfried BD, Zhou X. microRNA profiling between Bacillus thuringiensis Cry1Ab-susceptible and -resistant European corn borer, Ostrinia nubilalis (Hübner). INSECT MOLECULAR BIOLOGY 2018; 27:279-294. [PMID: 29451334 DOI: 10.1111/imb.12376] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Transgenic maize hybrids that express insecticidal Bacillus thuringiensis (Bt) crystalline (Cry) protein toxins effectively protect against the European corn borer, Ostrinia nubilalis, a devastating maize pest. Field monitoring and laboratory selections have detected varying levels of O. nubilalis resistance to Cry1Ab toxin. MicroRNAs (miRNAs) are short noncoding RNAs that are involved in post-transcriptional gene regulation. Their potential roles in the evolution of Bt resistance, however, remain largely unknown. Sequencing of small RNA libraries from the midgut of Cry1Ab-susceptible and resistant O. nubilalis larvae resulted in the discovery of 277 miRNAs, including 248 conserved and 29 novel. Comparative analyses of miRNA expression profiles between the laboratory strains predicted 26 and nine significantly up- and down-regulated transcripts, respectively, in the midgut of Cry1Ab resistant larvae. Amongst 15 differentially regulated miRNAs examined by quantitative real-time PCR, nine (60%) were validated as cosegregating with Cry1Ab resistance in a backcross progeny. Differentially expressed miRNAs were predicted to affect transcripts involved in cell membrane components with functions in metabolism and binding, and the putative Bt-resistance genes aminopeptidase N and cadherin. These results lay the foundation for future investigation of the potential role of miRNAs in the evolution of Bt resistance.
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Affiliation(s)
- T Yu
- Department of Entomology, University of Kentucky, Lexington, KY, USA
| | - X Li
- Department of Entomology, University of Kentucky, Lexington, KY, USA
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - B-S Coates
- Corn Insects & Crop Genetics Research Unit, USDA-ARS, Ames, IA, USA
| | - Q Zhang
- Department of Entomology, University of Kentucky, Lexington, KY, USA
- College of Plant Protection, Shenyang Agricultural University, Shenyang, China
| | - B-D Siegfried
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - X Zhou
- Department of Entomology, University of Kentucky, Lexington, KY, USA
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Rojas JC, Kolomiets MV, Bernal JS. Nonsensical choices? Fall armyworm moths choose seemingly best or worst hosts for their larvae, but neonate larvae make their own choices. PLoS One 2018; 13:e0197628. [PMID: 29795622 PMCID: PMC5967860 DOI: 10.1371/journal.pone.0197628] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/04/2018] [Indexed: 02/07/2023] Open
Abstract
Selecting optimal host plants is critical for herbivorous insects, such as fall armyworm (Spodoptera frugiperda), an important maize pest in the Americas and Africa. Fall armyworm larvae are presumed to have limited mobility, hence female moths are presumed to be largely responsible for selecting hosts. We addressed host selection by fall armyworm moths and neonate and older (3rd-instar) larvae, as mediated by resistance and herbivory in maize plants. Thus, we compared discrimination among three maize cultivars with varying degrees of resistance to fall armyworm, and between plants subjected or not to two types of herbivory. The cultivars were: (i) susceptible, and deficient in jasmonic acid (JA) production and green leaf volatiles (GLV) emissions (inbred line B73-lox10); (ii) modestly resistant (B73), and; (iii) highly resistant (Mp708). The herbivory types were: (i) ongoing (= fall armyworm larvae present), and; (ii) future (= fall armyworm eggs present). In choice tests, moths laid more eggs on the highly resistant cultivar, and least on the susceptible cultivar, though on those cultivars larvae performed poorest and best, respectively. In the context of herbivory, moths laid more eggs: (i) on plants subject to versus free of future herbivory, regardless of whether plants were deficient or not in JA and GLV production; (ii) on plants subject versus free of ongoing herbivory, and; (iii) on plants not deficient in compared to deficient in JA and GLV production. Neonate larvae dispersed aerially from host plants (i.e. ballooned), and most larvae colonized the modestly resistant cultivar, and fewest the highly resistant cultivar, suggesting quasi-directional, directed aerial descent. Finally, dispersing older larvae did not discriminate among the three maize cultivars, nor between maize plants and (plastic) model maize plants, suggesting random, visually-oriented dispersal. Our results were used to assemble a model of host selection by fall armyworm moths and larvae, including recommendations for future research.
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Affiliation(s)
- Julio C. Rojas
- Department of Entomology, Texas A&M University, College Station, TX, United States of America
| | - Michael V. Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, United States of America
| | - Julio S. Bernal
- Department of Entomology, Texas A&M University, College Station, TX, United States of America
- * E-mail:
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Domain III of Cry1Ac Is Critical to Binding and Toxicity against Soybean Looper (Chrysodeixis includens) but Not to Velvetbean Caterpillar (Anticarsia gemmatalis). Toxins (Basel) 2018; 10:toxins10030095. [PMID: 29495466 PMCID: PMC5869383 DOI: 10.3390/toxins10030095] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 02/13/2018] [Accepted: 02/22/2018] [Indexed: 01/10/2023] Open
Abstract
Insecticidal proteins Cry1Ac and Cry2Ac7 from the bacterium Bacillus thuringiensis (Bt) belong to the three-domain family of Bt toxins. Commercial transgenic soybean hybrids produce Cry1Ac to control the larvae of the soybean looper (Chrysodeixis includens) and the velvet bean caterpillar (Anticarsia gemmatalis). The specificity of Cry1Ac is determined by loops extending from domain II and regions of domain III in the three-dimensional structure of the toxin. In this study, we constructed a hybrid toxin (H1.2Ac) containing domains I and II of Cry1Ac and domain III of Cry2Ac7, in an attempt to obtain a protein with enhanced toxicity compared to parental toxins. Bioassays with H1.2Ac revealed toxicity against the larvae of A. gemmatalis but not against C. includens. Saturation binding assays with radiolabeled toxins and midgut brush border membrane vesicles demonstrated no specific H1.2Ac binding to C. includens, while binding in A. gemmatalis was specific and saturable. Results from competition binding assays supported the finding that Cry1Ac specificity against A. gemmatalis is mainly dictated by domain II. Taken together, these distinct interactions with binding sites may help explain the differential susceptibility to Cry1Ac in C. includens and A. gemmatalis, and guide the design of improved toxins against soybean pests.
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Ren XL, Hu HY, Jiang WL, Ma XY, Ma YJ, Li GQ, Ma Y. Three GPI-anchored alkaline phosphatases are involved in the intoxication of Cry1Ca toxin to Spodoptera exigua larvae. J Invertebr Pathol 2018; 151:32-40. [DOI: 10.1016/j.jip.2017.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 10/22/2017] [Accepted: 10/26/2017] [Indexed: 02/08/2023]
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Burtet LM, Bernardi O, Melo AA, Pes MP, Strahl TT, Guedes JV. Managing fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), with Bt maize and insecticides in southern Brazil. PEST MANAGEMENT SCIENCE 2017; 73:2569-2577. [PMID: 28695664 DOI: 10.1002/ps.4660] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/27/2017] [Accepted: 07/04/2017] [Indexed: 05/28/2023]
Abstract
BACKGROUND Maize plants expressing insecticidal proteins of Bacillus thuringiensis are valuable options for managing fall armyworm (FAW), Spodoptera frugiperda, in Brazil. However, control failures were reported, and therefore insecticides have been used to control this species. Based on these, we evaluated the use of Bt maize and its integration with insecticides against FAW in southern Brazil. RESULTS Early-planted Agrisure TL, Herculex, Optimum Intrasect and non-Bt maize plants were severely damaged by FAW and required up to three insecticidal sprays. In contrast, YieldGard VT Pro, YieldGard VT Pro 3, PowerCore, Agrisure Viptera and Agrisure Viptera 3 showed little damage and did not require insecticides. Late-planted Bt maize plants showed significant damage by FAW and required up to four sprays, with the exceptions of Agrisure Viptera and Agrisure Viptera 3. Exalt (first and second sprays); Lannate + Premio (first spray) and Avatar (second spray); and Karate + Match (first spray) and Ampligo (second spray) were the most effective insecticides against FAW larvae in Bt and non-Bt maize. CONCLUSION Maize plants expressing Cry proteins exhibited FAW control failures in southern Brazil, necessitating insecticidal sprays. In contrast, Bt maize containing the Vip3Aa20 protein remained effective against FAW. However, regardless of the insecticide used against FAW surviving on Bt maize, grain yields were similar. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Leonardo M Burtet
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Oderlei Bernardi
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Adriano A Melo
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Maiquel P Pes
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Thiago T Strahl
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Jerson Vc Guedes
- Department of Plant Protection, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
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Banerjee R, Hasler J, Meagher R, Nagoshi R, Hietala L, Huang F, Narva K, Jurat-Fuentes JL. Mechanism and DNA-based detection of field-evolved resistance to transgenic Bt corn in fall armyworm (Spodoptera frugiperda). Sci Rep 2017; 7:10877. [PMID: 28883440 PMCID: PMC5589895 DOI: 10.1038/s41598-017-09866-y] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 07/31/2017] [Indexed: 01/28/2023] Open
Abstract
Evolution of resistance threatens sustainability of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). The fall armyworm (Spodoptera frugiperda) is a devastating pest of corn in the Western Hemisphere initially controlled by transgenic Bt corn producing the Cry1Fa insecticidal protein (event TC1507). However field-evolved resistance to TC1507 was observed in Puerto Rico in 2007 and has subsequently been reported in a number of locations in North and South America. Early studies on Puerto Rico fall armyworm populations found that the resistance phenotype was associated with reduced expression of alkaline phosphatase. However, in this work we show that field-evolved resistance to Cry1Fa Bt corn in Puerto Rico is closely linked to a mutation in an ATP Binding Cassette subfamily C2 (ABCC2) gene that functions as a Cry1Fa receptor in susceptible insects. Furthermore, we report a DNA-based genotyping test used to demonstrate the presence of the resistant (SfABCC2mut) allele in Puerto Rico populations in 2007, coincident with the first reports of damage to TC1507 corn. These DNA-based field screening data provide strong evidence that resistance to TC1507 in fall armyworm maps to the SfABCC2 gene and provides a useful molecular marker for detecting the SfABCC2mut allele in resistant fall armyworm.
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Affiliation(s)
- Rahul Banerjee
- Genome Science and Technology Graduate Program, University of Tennessee, Knoxville, TN, 37996, USA
| | | | - Robert Meagher
- Center for Medical, Agricultural and Veterinary Entomology, Insect Behavior and Biocontrol Research Unit, USDA-ARS, Gainesville, FL, 32608, USA
| | - Rodney Nagoshi
- Center for Medical, Agricultural and Veterinary Entomology, Insect Behavior and Biocontrol Research Unit, USDA-ARS, Gainesville, FL, 32608, USA
| | - Lucas Hietala
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Fangneng Huang
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
| | | | - Juan Luis Jurat-Fuentes
- Genome Science and Technology Graduate Program, University of Tennessee, Knoxville, TN, 37996, USA.
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996, USA.
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Chauhan VK, Dhania NK, Chaitanya RK, Senthilkumaran B, Dutta-Gupta A. Larval Mid-Gut Responses to Sub-Lethal Dose of Cry Toxin in Lepidopteran Pest Achaea janata. Front Physiol 2017; 8:662. [PMID: 28928675 PMCID: PMC5591868 DOI: 10.3389/fphys.2017.00662] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/21/2017] [Indexed: 01/07/2023] Open
Abstract
The lack of homogeneity in field application of Bacillus thuringiensis formulation often results in ingestion of sub-lethal doses of the biopesticide by a fraction of pest population and there by promotes the toxin tolerance and resistance in long term. Gut regeneration seems to be one of the possible mechanism by which this is accomplished. However, the existing information is primarily derived from in vitro studies using mid-gut cell cultures. Present study illustrates cellular and molecular changes in mid-gut epithelium of a Bt-susceptible polyphagous insect pest castor semilooper, Achaea janata in response to a Cry toxin formulation. The present report showed that prolonged exposure to sub-lethal doses of Cry toxin formulation has deleterious effect on larval growth and development. Histological analysis of mid-gut tissue exhibits epithelial cell degeneration, which is due to necrotic form of cell death followed by regeneration through enhanced proliferation of mid-gut stem cells. Cell death is demonstrated by confocal microscopy, flow-cytometry, and DNA fragmentation analysis. Cell proliferation in control vs. toxin-exposed larvae is evaluated by bromodeoxyuridine (BrdU) labeling and toluidine blue staining. Intriguingly, in situ mRNA analysis detected the presence of arylphorin transcripts in larval mid-gut epithelial cells. Quantitative PCR analysis further demonstrates altered expression of arylphorin gene in toxin-exposed larvae when compared with the control. The coincidence of enhanced mid-gut cell proliferation coincides with the elevated arylphorin expression upon Cry intoxication suggests that it might play a role in the regeneration of mid-gut epithelial cells.
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Affiliation(s)
- Vinod K Chauhan
- Department of Animal Biology, School of Life Sciences, University of HyderabadHyderabad, India
| | - Narender K Dhania
- Department of Animal Biology, School of Life Sciences, University of HyderabadHyderabad, India
| | - R K Chaitanya
- Centre for Animal Sciences, School of Basic and Applied Sciences, Central University of PunjabBathinda, India
| | | | - Aparna Dutta-Gupta
- Department of Animal Biology, School of Life Sciences, University of HyderabadHyderabad, India
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Li J, Ma Y, Yuan W, Xiao Y, Liu C, Wang J, Peng J, Peng R, Soberón M, Bravo A, Yang Y, Liu K. FOXA transcriptional factor modulates insect susceptibility to Bacillus thuringiensis Cry1Ac toxin by regulating the expression of toxin-receptor ABCC2 and ABCC3 genes. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 88:1-11. [PMID: 28736301 DOI: 10.1016/j.ibmb.2017.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/19/2017] [Indexed: 06/07/2023]
Abstract
Cry toxins produced by Bacillus thuringiensis (Bt) are insecticidal proteins widely used in insect control. Recently, it was shown that ATP-binding cassette transporter proteins (ABC) such as ABCC2, ABCC3, ABCG1 and ABCA2 are implicated in the insecticidal action of Cry toxins as putative receptors. However, the transcriptional regulators involved in the expression of ABC transporter genes remain unknown. Sequence analysis of promoter regions of ABCC2 gene from Helicoverpa armigera and ABCC3 gene from Spodoptera litura Sl-HP cultured cells, revealed the potential participation of Forkhead box protein A (FOXA), a transcription factor that regulates the expression of genes through remodeling chromatin. To determine if FOXA was involved in regulating expression of ABCC2 and ABCC3 genes, the expression of FOXA, ABCC2 and ABCC3 was compared in Sl-HP cells that are sensitive to Cry1Ac toxin with those in S. frugiperda Sf9 cells that are not sensitive to the toxin. Expression levels of those genes were significantly higher in Sl-HP than in Sf9 cells. Transient expression of FOXA in Sf9 cells activated ABCC2 and ABCC3 transcription, which directly correlated with enhanced Cry1Ac-susceptibility in these cells. Silencing of FOXA gene expression by RNAi in H. armigera larvae resulted in a decreased expression of ABCC2 and ABCC3 without affecting expression of other Cry toxin receptor genes such as alkaline phosphatase, aminopeptidase or cadherin. Silencing of FOXA gene expression also resulted in a Cry1Ac-tolerant phenotype since lower mortality and higher pupation rate were observed in diet containing Cry1Ac protoxin in comparison with the control group. These results demonstrate that FOXA up-regulates expression of the Cry1Ac-toxin receptor ABCC2 and ABCC3 genes, and that lower FOXA expression correlates with tolerance to Cry toxin in cell lines and in lepidopteran larvae.
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Affiliation(s)
- Jianghuai Li
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Yuemin Ma
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Wanli Yuan
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Yutao Xiao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Chenxi Liu
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China
| | - Jia Wang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Jianxin Peng
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Rong Peng
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
| | - Yongbo Yang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
| | - Kaiyu Liu
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan 430079, China.
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Bel Y, Sheets JJ, Tan SY, Narva KE, Escriche B. Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens. Appl Environ Microbiol 2017; 83:e00326-17. [PMID: 28363958 PMCID: PMC5440703 DOI: 10.1128/aem.00326-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/23/2017] [Indexed: 11/20/2022] Open
Abstract
Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125-iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.
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Affiliation(s)
- Yolanda Bel
- Department of Genetics, Universitat de València, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Universitat de València, Burjassot, Spain
| | | | - Sek Yee Tan
- Dow AgroSciences, Indianapolis, Indiana, USA
| | | | - Baltasar Escriche
- Department of Genetics, Universitat de València, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BioTecMed), Universitat de València, Burjassot, Spain
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Venugopal PD, Dively GP. Climate change, transgenic corn adoption and field-evolved resistance in corn earworm. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170210. [PMID: 28680673 PMCID: PMC5493915 DOI: 10.1098/rsos.170210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
Increased temperature anomaly during the twenty-first century coincides with the proliferation of transgenic crops containing the bacterium Bacillus thuringiensis (Berliner) (Bt) to express insecticidal Cry proteins. Increasing temperatures profoundly affect insect life histories and agricultural pest management. However, the implications of climate change on Bt crop-pest interactions and insect resistance to Bt crops remains unexamined. We analysed the relationship of temperature anomaly and Bt adoption with field-evolved resistance to Cry1Ab Bt sweet corn in a major pest, Helicoverpa zea (Boddie). Increased Bt adoption during 1996-2016 suppressed H. zea populations, but increased temperature anomaly buffers population reduction. Temperature anomaly and its interaction with elevated selection pressure from high Bt acreage probably accelerated the Bt-resistance development. Helicoverpa zea damage to corn ears, kernel area consumed, mean instars and proportion of late instars in Bt varieties increased with Bt adoption and temperature anomaly, through additive or interactive effects. Risk of Bt-resistant H. zea spreading is high given extensive Bt adoption, and the expected increase in overwintering and migration. Our study highlights the challenges posed by climate change for Bt biotechnology-based agricultural pest management, and the need to incorporate evolutionary processes affected by climate change into Bt-resistance management programmes.
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Affiliation(s)
- P. Dilip Venugopal
- Science and Technology Policy Fellow, American Association for the Advancement of Science, Hosted by Transportation and Climate Division, Office of Transportation and Air Quality, United States Environmental Protection Agency, 1200 Pennsylvania Avenue NW, Washington, DC 20004, USA
| | - Galen P. Dively
- Department of Entomology, University of Maryland, 4112 Plant Sciences Building, 4291 Fieldhouse Dr, College Park, MD 20742, USA
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50
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Zhao M, Yuan X, Wei J, Zhang W, Wang B, Myint Khaing M, Liang G. Functional roles of cadherin, aminopeptidase-N and alkaline phosphatase from Helicoverpa armigera (Hübner) in the action mechanism of Bacillus thuringiensis Cry2Aa. Sci Rep 2017; 7:46555. [PMID: 28488696 PMCID: PMC5424343 DOI: 10.1038/srep46555] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/17/2017] [Indexed: 11/08/2022] Open
Abstract
A pyramid strategy combining the Cry1A and Cry2A toxins in Bt crops has been widely used throughout the world to delay pest adaption to transgenic crops and broaden the insecticidal spectrum. Midgut membrane-bound cadherin (CAD), aminopeptidase-N (APN) and alkaline phosphatase (ALP) are important for Cry1A toxicity in some lepidopteran larvae, but the proteins that bind Cry2A in the midgut of target insects and their role in the Cry2A mechanism of action are still unclear. In this study, we found that heterologously expressed CAD, APN4 and ALP2 peptides from the midgut of Helicoverpa armigera could bind to the Cry2Aa toxin with a high affinity. Additionally, the efficiency of Cry2Aa insecticidal activity against H. armigera larvae was obviously reduced after the genes encoding these proteins were silenced with specific siRNAs: CAD- and ALP2-silenced larvae showed significantly similar reductions in mortality due to the Cry2Aa toxin (41.67% and 43.06%, respectively), whereas a larger reduction in mortality was observed in APN4-silenced larvae (61.11%) than in controls. These results suggest that CAD, APN4 and ALP2 are involved in the mechanism of action of Cry2Aa in H. armigera and may play important functional roles in the toxicity of the Cry2Aa toxin.
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Affiliation(s)
- Man Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiangdong Yuan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jizhen Wei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Wanna Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bingjie Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Myint Myint Khaing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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