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Palli SR. RNAi turns 25:contributions and challenges in insect science. FRONTIERS IN INSECT SCIENCE 2023; 3:1209478. [PMID: 38469536 PMCID: PMC10926446 DOI: 10.3389/finsc.2023.1209478] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 05/26/2023] [Indexed: 03/13/2024]
Abstract
Since its discovery in 1998, RNA interference (RNAi), a Nobel prize-winning technology, made significant contributions to advances in biology because of its ability to mediate the knockdown of specific target genes. RNAi applications in medicine and agriculture have been explored with mixed success. The past 25 years of research on RNAi resulted in advances in our understanding of the mechanisms of its action, target specificity, and differential efficiency among animals and plants. RNAi played a major role in advances in insect biology. Did RNAi technology fully meet insect pest and disease vector management expectations? This review will discuss recent advances in the mechanisms of RNAi and its contributions to insect science. The remaining challenges, including delivery to the target site, differential efficiency, potential resistance development and possible solutions for the widespread use of this technology in insect management.
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Affiliation(s)
- Subba Reddy Palli
- Department of Entomology, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, United States
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2
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Darlington M, Reinders JD, Sethi A, Lu AL, Ramaseshadri P, Fischer JR, Boeckman CJ, Petrick JS, Roper JM, Narva KE, Vélez AM. RNAi for Western Corn Rootworm Management: Lessons Learned, Challenges, and Future Directions. INSECTS 2022; 13:57. [PMID: 35055900 PMCID: PMC8779393 DOI: 10.3390/insects13010057] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/17/2021] [Accepted: 12/28/2021] [Indexed: 02/06/2023]
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is considered one of the most economically important pests of maize (Zea mays L.) in the United States (U.S.) Corn Belt with costs of management and yield losses exceeding USD ~1-2 billion annually. WCR management has proven challenging given the ability of this insect to evolve resistance to multiple management strategies including synthetic insecticides, cultural practices, and plant-incorporated protectants, generating a constant need to develop new management tools. One of the most recent developments is maize expressing double-stranded hairpin RNA structures targeting housekeeping genes, which triggers an RNA interference (RNAi) response and eventually leads to insect death. Following the first description of in planta RNAi in 2007, traits targeting multiple genes have been explored. In June 2017, the U.S. Environmental Protection Agency approved the first in planta RNAi product against insects for commercial use. This product expresses a dsRNA targeting the WCR snf7 gene in combination with Bt proteins (Cry3Bb1 and Cry34Ab1/Cry35Ab1) to improve trait durability and will be introduced for commercial use in 2022.
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Affiliation(s)
- Molly Darlington
- Department of Entomology, University of Nebraska, Lincoln, NE 68583, USA; (M.D.); (J.D.R.)
| | - Jordan D. Reinders
- Department of Entomology, University of Nebraska, Lincoln, NE 68583, USA; (M.D.); (J.D.R.)
| | - Amit Sethi
- Corteva Agriscience, Johnston, IA 50131, USA; (A.S.); (A.L.L.); (C.J.B.); (J.M.R.)
| | - Albert L. Lu
- Corteva Agriscience, Johnston, IA 50131, USA; (A.S.); (A.L.L.); (C.J.B.); (J.M.R.)
| | | | - Joshua R. Fischer
- Bayer Crop Science, Chesterfield, MO 63017, USA; (P.R.); (J.R.F.); (J.S.P.)
| | - Chad J. Boeckman
- Corteva Agriscience, Johnston, IA 50131, USA; (A.S.); (A.L.L.); (C.J.B.); (J.M.R.)
| | - Jay S. Petrick
- Bayer Crop Science, Chesterfield, MO 63017, USA; (P.R.); (J.R.F.); (J.S.P.)
| | - Jason M. Roper
- Corteva Agriscience, Johnston, IA 50131, USA; (A.S.); (A.L.L.); (C.J.B.); (J.M.R.)
| | | | - Ana M. Vélez
- Department of Entomology, University of Nebraska, Lincoln, NE 68583, USA; (M.D.); (J.D.R.)
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3
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Kottaipalayam-Somasundaram SR, Jacob JP, Aiyar B, Merzendorfer H, Nambiar-Veetil M. Chitin metabolism as a potential target for RNAi-based control of the forestry pest Hyblaea puera Cramer (Lepidoptera: Hyblaeidae). PEST MANAGEMENT SCIENCE 2022; 78:296-303. [PMID: 34487617 DOI: 10.1002/ps.6634] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Hyblaea puera, commonly known as the teak defoliator, is a serious pest in teak plantations. Despite the availability of control measures, this pest causes losses in yield and quality of timber through voracious feeding. RNA interference (RNAi) is a promising strategy for the control of this pest. Chitin metabolism, which is vital for the growth and development of arthropods, is a potential target for developing RNAi-based insecticides. RESULTS To assess the effects of chitin metabolism inhibition, H. puera larvae were treated with a chitin synthesis inhibitor, diflubenzuron (DFB). DFB treatment caused pupal deformities and disrupted eclosion. Partial gene sequences for three key genes of H. puera chitin metabolism were cloned and sequenced: chitin synthase 1 (HpCHS1), chitinase-h (HpChi-h) and ecdysone receptor (HpEcR). Feeding dsRNA cognate for these three target genes to the first instar of H. puera resulted in mortality and reduction in the corresponding transcript levels as assessed through qRT-PCR. This is the first report of RNAi in this forestry pest. The highest mortality was 45.9%, in response to dsHpEcR treatment; HpChi-h transcripts were the most down-regulated in response to dsHpEcR feeding. DsHpEcR RNAi resulted in growth inhibition and molting arrest. The mortalities were 29.7% and 32.4% for dsHpCHS1 and dsHpChi-h feeding, respectively. CONCLUSION Chitin metabolism could be a potential target for RNAi-based control of H. puera, and HpCHS1, HpChi-h and HpEcR could be suitable target genes. However, the RNAi efficacy needs to be improved through formulations that improve stability and uptake, and employing better delivery strategies. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Sowmiya R Kottaipalayam-Somasundaram
- Plant Biotechnology and Cytogenetics Division, Institute of Forest Genetics and Tree Breeding, Coimbatore, India
- Department Biology/Chemistry, Animal Physiology, University of Osnabrück, Osnabrück, Germany
| | - John P Jacob
- Forest Protection Division, Institute of Forest Genetics and Tree Breeding, Coimbatore, India
| | - Balasubramanian Aiyar
- Plant Biotechnology and Cytogenetics Division, Institute of Forest Genetics and Tree Breeding, Coimbatore, India
| | - Hans Merzendorfer
- Department Biology/Chemistry, Animal Physiology, University of Osnabrück, Osnabrück, Germany
| | - Mathish Nambiar-Veetil
- Plant Biotechnology and Cytogenetics Division, Institute of Forest Genetics and Tree Breeding, Coimbatore, India
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4
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Ossa Ossa GA, Villegas Estrada B, Valencia Jiménez A. CARACTERIZACIÓN Y DISMINUCIÓN EN LA EXPRESIÓN DE UNA QUITINA SINTASA MEDIADA POR ARNi EN Hypothenemus hampei (CURCULIONIDAE). ACTA BIOLÓGICA COLOMBIANA 2021. [DOI: 10.15446/abc.v27n2.89981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
La broca del café, Hypothenemus hampei, es un insecto plaga que causa daños significativos al grano de café y grandes pérdidas económicas a los productores en todo el mundo. Al igual que otros insectos, la broca de café requiere de quitina sintasas (CHS) para la biosíntesis de la quitina, componente principal del exoesqueleto del insecto, y de vital importancia para su crecimiento y desarrollo. En este estudio, el gen CHS1 de la broca del café (HhCHS1) fue identificado, caracterizado y posteriormente silenciado mediante el uso de ARNi, mecanismo que permite degradar el ARNm e interrumpir la expresión de proteínas de interés en un organismo. Los perfiles de expresión del gen HhCHS1, medidos por RT-qPCR, mostraron niveles de expresión diferencial en las diferentes etapas del desarrollo del insecto. Los niveles más altos de expresión se encontraron en larvas de segundo estadio (L2) y machos adultos. El ARNcd administrado por vía oral, a concentraciones de 2 µg/100 µL, generó un silenciamiento efectivo del gen HhCHS1 (84 %) después de 7 días de tratamiento. Estos resultados sugieren que el gen HhCHS1 desempeña un papel importante en el desarrollo del insecto, y que, por ende, podría usarse como objetivo para desarrollar nuevas estrategias de manejo de este insecto plaga, mediante el uso de ARNi.
Palabras Clave: ARNcd, café, insecto plaga, quitina-sintasa, RT-qPCR.
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5
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Firmino AAP, Pinheiro DH, Moreira-Pinto CE, Antonino JD, Macedo LLP, Martins-de-Sa D, Arraes FBM, Coelho RR, Fonseca FCDA, Silva MCM, Engler JDA, Silva MS, Lourenço-Tessutti IT, Terra WR, Grossi-de-Sa MF. RNAi-Mediated Suppression of Laccase2 Impairs Cuticle Tanning and Molting in the Cotton Boll Weevil ( Anthonomus grandis). Front Physiol 2020; 11:591569. [PMID: 33329040 PMCID: PMC7717984 DOI: 10.3389/fphys.2020.591569] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/20/2020] [Indexed: 11/13/2022] Open
Abstract
The cotton boll weevil, Anthonomus grandis, is the most economically important pest of cotton in Brazil. Pest management programs focused on A. grandis are based mostly on the use of chemical insecticides, which may cause serious ecological impacts. Furthermore, A. grandis has developed resistance to some insecticides after their long-term use. Therefore, alternative control approaches that are more sustainable and have reduced environmental impacts are highly desirable to protect cotton crops from this destructive pest. RNA interference (RNAi) is a valuable reverse genetics tool for the investigation of gene function and has been explored for the development of strategies to control agricultural insect pests. This study aimed to evaluate the biological role of the Laccase2 (AgraLac2) gene in A. grandis and its potential as an RNAi target for the control of this insect pest. We found that AgraLac2 is expressed throughout the development of A. grandis with significantly higher expression in pupal and adult developmental stages. In addition, the immunolocalization of the AgraLac2 protein in third-instar larvae using specific antibodies revealed that AgraLac2 is distributed throughout the epithelial tissue, the cuticle and the tracheal system. We also verified that the knockdown of AgraLac2 in A. grandis resulted in an altered cuticle tanning process, molting defects and arrested development. Remarkably, insects injected with dsAgraLac2 exhibited defects in cuticle hardening and pigmentation. As a consequence, the development of dsAgraLac2-treated insects was compromised, and in cases of severe phenotypic defects, the insects subsequently died. On the contrary, insects subjected to control treatments did not show any visible phenotypic defects in cuticle formation and successfully molted to the pupal and adult stages. Taken together, our data indicate that AgraLac2 is involved in the cuticle tanning process in A. grandis and may be a promising target for the development of RNAi-based technologies.
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Affiliation(s)
- Alexandre Augusto Pereira Firmino
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | | | - Clidia Eduarda Moreira-Pinto
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,Department of Cell Biology, Federal University of Brasília (UnB), Brasília, Brazil
| | - José Dijair Antonino
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,Departamento de Agronomia/Entomologia, Universidade Federal Rural de Pernambuco (UFRPE), Recife, Brazil
| | | | - Diogo Martins-de-Sa
- Department of Cell Biology, Federal University of Brasília (UnB), Brasília, Brazil
| | - Fabrício Barbosa Monteiro Arraes
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,Department of Cellular and Molecular Biology, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,National Institute of Science and Technology - INCT PlantStress Biotech - Embrapa, Brasília, Brazil
| | | | - Fernando Campos de Assis Fonseca
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,Department of Cell Biology, Federal University of Brasília (UnB), Brasília, Brazil
| | - Maria Cristina Mattar Silva
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,National Institute of Science and Technology - INCT PlantStress Biotech - Embrapa, Brasília, Brazil
| | - Janice de Almeida Engler
- National Institute of Science and Technology - INCT PlantStress Biotech - Embrapa, Brasília, Brazil.,Département Santé des Plantes et Environnement, Institut National de la Recherche Agronomique and Institut Sophia Agrobiotech, Sophia Antipolis, France
| | | | | | | | - Maria Fátima Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, Brazil.,National Institute of Science and Technology - INCT PlantStress Biotech - Embrapa, Brasília, Brazil.,Department of Biological Sciences, Catholic University o Brasília (UCB), Brasília, Brazil
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6
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Dhandapani RK, Duan JJ, Palli SR. Orally delivered dsRNA induces knockdown of target genes and mortality in the Asian long-horned beetle, Anoplophora glabripennis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 104:e21679. [PMID: 32297387 DOI: 10.1002/arch.21679] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/17/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
The Asian long-horned beetle (ALB) Anoplophora glabripennis is a serious invasive forest pest in several countries, including the United States. Methods available to manage or eradicate this pest are extremely limited, but RNA interference (RNAi) technology is a potentially effective method to control ALB. In this study, we used sucrose feeding bioassay for oral delivery of double-strand RNA (dsRNA) to ALB larvae. 32 P-labeled dsRNA orally delivered to ALB larvae using the sucrose droplet feeding method was processed to small interfering RNA. Feeding neonate larvae with dsRNA targeting genes coding for the inhibitor of apoptosis (IAP), vacuolar sorting protein SNF7 (SNF7), and snakeskin (SSK) induced knockdown of target genes and mortality. Feeding 2 µg of dsRNA per day for 3 days did not induce a significant decrease in the expression of target genes or mortality. However, feeding 5 or 10 µg of dsRNA per day for 3 days induced a significant decrease in the expression of target genes and 50-90% mortality. Interestingly, feeding 2.5 µg each of dsIAP plus dsSNF7, dsIAP plus dsSSK, or dsSNF7 plus dsSSK per day for 3 days induced a significant decrease in the expression of both target genes and approximately 80% mortality. Our findings demonstrate that orally delivered dsRNA induces target gene knockdown and mortality in ALB neonate larvae and RNAi technology may have the potential for effective ALB control.
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Affiliation(s)
- Ramesh Kumar Dhandapani
- Department of Entomology, College of Agriculture, Food and Environment, University of Kentucky, Lexington, Kentucky
| | - Jian Jun Duan
- USDA ARS Beneficial Insects Introduction Research Unit, Newark, Delaware
| | - Subba Reddy Palli
- Department of Entomology, College of Agriculture, Food and Environment, University of Kentucky, Lexington, Kentucky
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7
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Diversity and function of multicopper oxidase genes in the stinkbug Plautia stali. Sci Rep 2020; 10:3464. [PMID: 32103072 PMCID: PMC7044228 DOI: 10.1038/s41598-020-60340-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 01/08/2020] [Indexed: 11/08/2022] Open
Abstract
Multicopper oxidase (MCO) genes comprise multigene families in bacteria, fungi, plants and animals. Two families of MCO genes, MCO1 (laccase1) and MCO2 (laccase2), are conserved among diverse insects and relatively well-characterized, whereas additional MCO genes, whose biological functions have been poorly understood, are also found in some insects. Previous studies reported that MCO1 participates in gut immunity and MCO2 plays important roles in cuticle sclerotization and pigmentation of insects. In mosquitoes, MCO2 was reported to be involved in eggshell sclerotization and pigmentation, on the ground that knockdown of MCO2 caused deformity and fragility of the eggshell. Here we identified a total of 7 MCO genes, including PsMCO1 and PsMCO2, and investigated their expression and function in the brown-winged green stinkbug Plautia stali. RNA interference (RNAi) knockdown of MCO genes by injecting double-stranded RNA (dsRNA) into nymphs revealed that MCO2, but not the other 6 MCOs, is required for cuticle sclerotization and pigmentation, and also for survival of P. stali. Trans-generational knockdown of MCO2 by injecting dsRNA into adult females (maternal RNAi) resulted in the production of unhatched eggs despite the absence of deformity or fragility of the eggshell. These results suggested that MCO2 plays an important role in sclerotization and pigmentation of the cuticle but not in eggshell integrity in P. stali. Maternal RNAi of any of the other 6 MCO genes and 3 tyrosinase genes affected neither survival nor eggshell integrity of P. stali. Contrary to the observations in the red flour beetle and the brown rice planthopper, RNAi knockdown of MCO6 (MCORP; Multicopper oxidase related protein) exhibited no lethal effects on P. stali. Taken together, our findings provide insight into the functional diversity and commonality of MCOs across hemipteran and other insect groups.
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8
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Basu S, Pereira AE, Pinheiro DH, Wang H, Valencia-Jiménez A, Siegfried BD, Louis J, Zhou X'J, Vélez AM. Evaluation of reference genes for real-time quantitative PCR analysis in southern corn rootworm, Diabrotica undecimpunctata howardi (Barber). Sci Rep 2019; 9:10703. [PMID: 31341190 PMCID: PMC6656754 DOI: 10.1038/s41598-019-47020-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 07/08/2019] [Indexed: 12/12/2022] Open
Abstract
Quantitative reverse transcription PCR (RT-qPCR) is one of the most efficient, reliable and widely used techniques to quantify gene expression. In this study, we evaluated the performance of six southern corn rootworm, Diabrotica undecimpunctata howardi (Barber), housekeeping genes (HKG), β-actin (Actin), β-tubulin (Tubulin), elongation factor 1 alpha (EF1α), glyceraldehyde-3 phosphate dehydrogenase (GAPDH), 40 S ribosomal protein S9 (RpS9) and ubiquitin-conjugating protein (Ubi), under different experimental conditions such as developmental stage, exposure of neonate and adults to dsRNA, exposure of adults to different temperatures, different 3rd instar larva tissues, and neonate starvation. The HKGs were analyzed with four algorithms, including geNorm, NormFinder, BestKeeper, and delta-CT. Although the six HKGs showed a relatively stable expression pattern among different treatments, some variability was observed. Among the six genes, EF1α exhibited the lowest Ct values for all treatments while Ubi exhibited the highest. Among life stages and across treatments, Ubi exhibited the least stable expression pattern. GAPDH, Actin, and EF1α were among the most stable HKGs in the majority of the treatments. This research provides HKG for accurate normalization of RT-qPCR data in the southern corn rootworm. Furthermore, this information can contribute to future genomic and functional genomic research in Diabrotica species.
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Affiliation(s)
- Saumik Basu
- Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.,Department of Entomology, Washington State University, Pullman, WA, 99164, USA
| | - Adriano E Pereira
- Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA. .,Plant Genetics Research Unit, USDA/ARS, University of Missouri-Columbia, Columbia, MO, 65211-7020, USA.
| | | | - Haichuan Wang
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, 68583-0915, USA
| | | | - Blair D Siegfried
- Entomology and Nematology Department, University of Florida, Gainesville, FL, 32611-0620, USA
| | - Joe Louis
- Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.,Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | - Xuguo 'Joe' Zhou
- Department of Entomology, University of Kentucky, Lexington, KY, 40546-0091, USA
| | - Ana Maria Vélez
- Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
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Hu X, Steimel JP, Kapka-Kitzman DM, Davis-Vogel C, Richtman NM, Mathis JP, Nelson ME, Lu AL, Wu G. Molecular characterization of the insecticidal activity of double-stranded RNA targeting the smooth septate junction of western corn rootworm (Diabrotica virgifera virgifera). PLoS One 2019; 14:e0210491. [PMID: 30629687 PMCID: PMC6328145 DOI: 10.1371/journal.pone.0210491] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 12/24/2018] [Indexed: 01/14/2023] Open
Abstract
The western corn rootworm (WCR, Diabrotica virgifera virgifera) gene, dvssj1, is a putative homolog of the Drosophila melanogaster gene, snakeskin (ssk). This gene encodes a membrane protein associated with the smooth septate junction (SSJ) which is required for the proper barrier function of the epithelial lining of insect intestines. Disruption of DVSSJ integrity by RNAi technique has been shown previously to be an effective approach for corn rootworm control, by apparent suppression of production of DVSSJ1 protein leading to growth inhibition and mortality. To understand the mechanism that leads to the death of WCR larvae by dvssj1 double-stranded RNA, we examined the molecular characteristics associated with SSJ functions during larval development. Dvssj1 dsRNA diet feeding results in dose-dependent suppression of mRNA and protein; this impairs SSJ formation and barrier function of the midgut and results in larval mortality. These findings suggest that the malfunctioning of the SSJ complex in midgut triggered by dvssj1 silencing is the principal cause of WCR death. This study also illustrates that dvssj1 is a midgut-specific gene in WCR and its functions are consistent with biological functions described for ssk.
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Affiliation(s)
- Xu Hu
- DuPont Pioneer, Johnston, Iowa, United States of America
- * E-mail: (XH); (MEN)
| | | | | | | | | | - John P. Mathis
- DuPont Pioneer, Johnston, Iowa, United States of America
| | - Mark E. Nelson
- DuPont Pioneer, Johnston, Iowa, United States of America
- * E-mail: (XH); (MEN)
| | - Albert L. Lu
- DuPont Pioneer, Johnston, Iowa, United States of America
| | - Gusui Wu
- DuPont Pioneer, Hayward, California, United States of America
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10
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Hiltpold I, Hibbard BE. Indirect Root Defenses Cause Induced Fitness Costs in Bt-Resistant Western Corn Rootworm. JOURNAL OF ECONOMIC ENTOMOLOGY 2018; 111:2349-2358. [PMID: 30085164 DOI: 10.1093/jee/toy220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Indexed: 06/08/2023]
Abstract
Plants genetically modified to produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt) have been extensively used to manage the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) in the United States. Evolution of WCR resistance to Bt toxins has forced the consideration of alternative pest management and improved insect resistance management. Entomopathogenic nematodes (EPNs), obligate insect parasites, are attracted toward volatile organic compounds (VOCs) emitted by maize roots after WCR herbivory. The production of VOCs of two types of Bt maize (MON88017 and MIR604) and their near-isolines was evaluated after induction with Bt-susceptible and resistant WCR. The attraction of EPNs toward the Bt hybrids was tested in the laboratory and the field. Bt hybrids emitted VOCs when induced by Bt-resistant insects whereas induction by Bt-susceptible WCR did not elicit a plant response. Survival of Bt-resistant WCR was lower on the hybrid attracting EPNs and similar to the survival of Bt-susceptible WCR without EPNs. This trade-off of Bt-resistance is defined here as an induced fitness cost, and offers a viable tool to management of Bt-resistant WCR.
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Affiliation(s)
- Ivan Hiltpold
- Department of Entomology and Wildlife Ecology, College of Agriculture and Natural Resources, University of Delaware, Newark, DE
| | - Bruce E Hibbard
- USDA-ARS, Plant Genetic Unit, University of Missouri, Columbia, MO
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11
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Wu K, Taylor CE, Fishilevich E, Narva KE, Siegfried BD. Rapid and persistent RNAi response in western corn rootworm adults. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 150:66-70. [PMID: 30195389 DOI: 10.1016/j.pestbp.2018.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/28/2018] [Accepted: 07/08/2018] [Indexed: 06/08/2023]
Abstract
RNA interference (RNAi) has proven effective for controlling pest insects such as western corn rootworm (WCR), Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). Previous studies have shown that WCR adults display a robust RNAi response to orally-administered double-stranded RNA (dsRNA). However, it is unclear how quickly the response occurs after ingestion or how long RNAi effect lasts after WCR stop ingesting diet containing dsRNA. In the current study, WCR adult females were provided with diet treated with dsRNAs of Laccase 2 and Argonaute 2, two nonessential genes, for 8 days. RNAi response in WCR females commenced as early as 10 h after exposure to dsRNA and lasted up to 40 days after exposure to dsRNA ended. Our results show that dsRNA-mediated RNAi response in WCR females is rapid and long-lasting. These findings suggest that even a short-term ingestion of transgenic plants expressing dsRNA by WCR may have a sustained impact on this insect.
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Affiliation(s)
- Ke Wu
- Department of Entomology and Nematology, PO Box 11620, University of Florida, Gainesville, FL 32611, USA.
| | - Caitlin E Taylor
- Department of Entomology and Nematology, PO Box 11620, University of Florida, Gainesville, FL 32611, USA
| | - Elane Fishilevich
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN 46268, USA
| | - Kenneth E Narva
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN 46268, USA
| | - Blair D Siegfried
- Department of Entomology and Nematology, PO Box 11620, University of Florida, Gainesville, FL 32611, USA
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12
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Clathrin-dependent endocytosis is associated with RNAi response in the western corn rootworm, Diabrotica virgifera virgifera LeConte. PLoS One 2018; 13:e0201849. [PMID: 30092086 PMCID: PMC6084943 DOI: 10.1371/journal.pone.0201849] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/22/2018] [Indexed: 12/21/2022] Open
Abstract
The cellular uptake of dsRNA after dietary exposure is critical for RNAi efficiency; however, the mechanism of its uptake in many insects remains to be understood. In this study, we evaluated the roles of the endocytic pathway genes Clathrin heavy chain (Chc), Clathrin adaptor protein AP50, ADP ribosylation factor-like 1 (Arf72A), Vacuolar H+ATPase 16 kDa subunit (Vha16), and small GTPase Rab7 and putative sid-1-like genes (silA and silC) in RNAi response in western corn rootworm (WCR) using a two-stage dsRNA exposure bioassay. Silencing of Chc, Vha16, and AP50 led to a significant decrease in the effects of laccase2 dsRNA reporter, indicating that these genes are involved in RNAi response. However, the knockdown of either Arf72A or Rab7 did not suppress the response to laccase2 dsRNA. The silencing of the silC gene did not lead to a significant reduction in mortality or increase in the expression of V-ATPase A reporter. While the silencing of the silA gene significantly decreased insect mortality, significant changes in V-ATPase A expression were not detected. These results suggest that clathrin-dependent endocytosis is a biological mechanism that plays an important role during RNAi response in WCR adults. The fact that no definitive support for the roles of silA or silC in RNAi response was obtained support the idea that RNAi response varies greatly in different insect species, demanding additional studies focused on elucidating their involvement in this mechanism.
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13
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Chu FC, Wu PS, Pinzi S, Grubbs N, Lorenzen MD. Microinjection of Western Corn Rootworm, Diabrotica virgifera virgifera, Embryos for Germline Transformation, or CRISPR/Cas9 Genome Editing. J Vis Exp 2018. [PMID: 29757280 DOI: 10.3791/57497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The western corn rootworm (WCR) is an important pest of corn and is well known for its ability to rapidly adapt to pest management strategies. Although RNA interference (RNAi) has proved to be a powerful tool for studying WCR biology, it has its limitations. Specifically, RNAi itself is transient (i.e. does not result in long-term Mendelian inheritance of the associated phenotype), and it requires knowing the DNA sequence of the target gene. The latter can be limiting if the phenotype of interest is controlled by poorly conserved, or even novel genes, because identifying useful targets would be challenging, if not impossible. Therefore, the number of tools in WCR's genomic toolbox should be expanded by the development of methods that could be used to create stable mutant strains and enable sequence-independent surveys of the WCR genome. Herein, we detail the methods used to collect and microinject precellular WCR embryos with nucleic acids. While the protocols described herein are aimed at the creation of transgenic WCR, CRISPR/Cas9-genome editing could also be performed using the same protocols, with the only difference being the composition of the solution injected into the embryos.
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Affiliation(s)
- Fu-Chyun Chu
- Department of Entomology and Plant Pathology, North Carolina State University
| | - Pei-Shan Wu
- Department of Entomology and Plant Pathology, North Carolina State University
| | - Sofia Pinzi
- Department of Entomology and Plant Pathology, North Carolina State University
| | - Nathaniel Grubbs
- Department of Entomology and Plant Pathology, North Carolina State University
| | - Marcé D Lorenzen
- Department of Entomology and Plant Pathology, North Carolina State University;
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14
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Gene silencing in Tribolium castaneum as a tool for the targeted identification of candidate RNAi targets in crop pests. Sci Rep 2018; 8:2061. [PMID: 29391456 PMCID: PMC5794766 DOI: 10.1038/s41598-018-20416-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/12/2018] [Indexed: 01/15/2023] Open
Abstract
RNAi shows potential as an agricultural technology for insect control, yet, a relatively low number of robust lethal RNAi targets have been demonstrated to control insects of agricultural interest. In the current study, a selection of lethal RNAi target genes from the iBeetle (Tribolium castaneum) screen were used to demonstrate efficacy of orthologous targets in the economically important coleopteran pests Diabrotica virgifera virgifera and Meligethes aeneus. Transcript orthologs of 50 selected genes were analyzed in D. v. virgifera diet-based RNAi bioassays; 21 of these RNAi targets showed mortality and 36 showed growth inhibition. Low dose injection- and diet-based dsRNA assays in T. castaneum and D. v. virgifera, respectively, enabled the identification of the four highly potent RNAi target genes: Rop, dre4, ncm, and RpII140. Maize was genetically engineered to express dsRNA directed against these prioritized candidate target genes. T0 plants expressing Rop, dre4, or RpII140 RNA hairpins showed protection from D. v. virgifera larval feeding damage. dsRNA targeting Rop, dre4, ncm, and RpII140 in M. aeneus also caused high levels of mortality both by injection and feeding. In summary, high throughput systems for model organisms can be successfully used to identify potent RNA targets for difficult-to-work with agricultural insect pests.
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15
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Kumar D, Gong C. Insect RNAi: Integrating a New Tool in the Crop Protection Toolkit. TRENDS IN INSECT MOLECULAR BIOLOGY AND BIOTECHNOLOGY 2017. [PMCID: PMC7121382 DOI: 10.1007/978-3-319-61343-7_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protecting crops against insect pests is a major focus area in crop protection. Over the past two decades, biotechnological interventions, especially Bt proteins, have been successfully implemented across the world and have had major impacts on reducing chemical pesticide applications. As insects continue to adapt to insecticides, both chemical and protein-based, new methods, molecules, and modes of action are necessary to provide sustainable solutions. RNA interference (RNAi) has emerged as a significant tool to knock down or alter gene expression profiles in a species-specific manner. In the past decade, there has been intense research on RNAi applications in crop protection. This chapter looks at the current state of knowledge in the field and outlines the methodology, delivery methods, and precautions required in designing targets. Assessing the targeting of specific gene expression is also an important part of a successful RNAi strategy. The current literature on the use of RNAi in major orders of insect pests is reviewed, along with a perspective on the regulatory aspects of the approach. Risk assessment of RNAi would focus on molecular characterization, food/feed risk assessment, and environmental risk assessment. As more RNAi-based products come through regulatory systems, either via direct application or plant expression based, the impact of this approach on crop protection will become clearer.
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Affiliation(s)
- Dhiraj Kumar
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China
| | - Chengliang Gong
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China
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16
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Chu F, Klobasa W, Wu P, Pinzi S, Grubbs N, Gorski S, Cardoza Y, Lorenzen MD. Germline transformation of the western corn rootworm, Diabrotica virgifera virgifera. INSECT MOLECULAR BIOLOGY 2017; 26:440-452. [PMID: 28397990 DOI: 10.1111/imb.12305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The western corn rootworm (WCR), a major pest of maize, is notorious for rapidly adapting biochemically, behaviourally and developmentally to a variety of control methods. Despite much effort, the genetic basis of WCR adaptation remains a mystery. Since transformation-based applications such as transposon tagging and enhancer trapping have facilitated genetic dissection of model species such as Drosophila melanogaster, we developed a germline-transformation system for WCR in an effort to gain a greater understanding of the basic biology of this economically important insect. Here we report the use of a fluorescent-marked Minos element to create transgenic WCR. We demonstrate that the transgenic strains express both an eye-specific fluorescent marker and piggyBac transposase. We identified insertion-site junction sequences via inverse PCR and assessed insertion copy number using digital droplet PCR (ddPCR). Interestingly, most WCR identified as transgenic via visual screening for DsRed fluorescence proved to carry multiple Minos insertions when tested via ddPCR. A total of eight unique insertion strains were created by outcrossing the initial transgenic strains to nontransgenic WCR mates. Establishing transgenic technologies for this beetle is the first step towards bringing a wide range of transformation-based tools to bear on understanding WCR biology.
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Affiliation(s)
- F Chu
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - W Klobasa
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - P Wu
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - S Pinzi
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - N Grubbs
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - S Gorski
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - Y Cardoza
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - M D Lorenzen
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
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17
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Galdeano DM, Breton MC, Lopes JRS, Falk BW, Machado MA. Oral delivery of double-stranded RNAs induces mortality in nymphs and adults of the Asian citrus psyllid, Diaphorina citri. PLoS One 2017; 12:e0171847. [PMID: 28282380 PMCID: PMC5345766 DOI: 10.1371/journal.pone.0171847] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/26/2017] [Indexed: 12/17/2022] Open
Abstract
The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most important citrus pests. ACP is the vector of the phloem-limited bacteria Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, the causal agents of the devastating citrus disease huanglongbing (HLB). The management of HLB is based on the use of healthy young plants, eradication of infected plants and chemical control of the vector. RNA interference (RNAi) has proven to be a promising tool to control pests and explore gene functions. Recently, studies have reported that target mRNA knockdown in many insects can be induced through feeding with double-stranded RNA (dsRNA). In the current study, we targeted the cathepsin D, chitin synthase and inhibitor of apoptosis genes of adult and nymph ACP by feeding artificial diets mixed with dsRNAs and Murraya paniculata leaves placed in dsRNAs solutions, respectively. Adult ACP mortality was positively correlated with the amount of dsRNA used. Both nymphs and adult ACP fed dsRNAs exhibited significantly increased mortality over time compared with that of the controls. Moreover, qRT-PCR analysis confirmed the dsRNA-mediated RNAi effects on target mRNAs. These results showed that RNAi can be a powerful tool for gene function studies in ACP and perhaps for HLB control.
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Affiliation(s)
- Diogo Manzano Galdeano
- Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
- Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Michèle Claire Breton
- Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
| | - João Roberto Spotti Lopes
- Escola Superior de Agricultura Luiz de Queiróz, Universidade de São Paulo, Piracicaba, São Paulo, Brazil
| | - Bryce W. Falk
- Plant Pathology Department, University of California Davis, Davis, California, United States of America
| | - Marcos Antonio Machado
- Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo, Brazil
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Macedo L, Antonino de Souza Junior J, Coelho R, Fonseca F, Firmino A, Silva M, Fragoso R, Albuquerque E, Silva M, de Almeida Engler J, Terra W, Grossi-de-Sa M. Knocking down chitin synthase 2 by RNAi is lethal to the cotton boll weevil. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.biori.2017.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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RNA Interference in Insect Vectors for Plant Viruses. Viruses 2016; 8:v8120329. [PMID: 27973446 PMCID: PMC5192390 DOI: 10.3390/v8120329] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 12/05/2016] [Accepted: 12/06/2016] [Indexed: 01/09/2023] Open
Abstract
Insects and other arthropods are the most important vectors of plant pathogens. The majority of plant pathogens are disseminated by arthropod vectors such as aphids, beetles, leafhoppers, planthoppers, thrips and whiteflies. Transmission of plant pathogens and the challenges in managing insect vectors due to insecticide resistance are factors that contribute to major food losses in agriculture. RNA interference (RNAi) was recently suggested as a promising strategy for controlling insect pests, including those that serve as important vectors for plant pathogens. The last decade has witnessed a dramatic increase in the functional analysis of insect genes, especially those whose silencing results in mortality or interference with pathogen transmission. The identification of such candidates poses a major challenge for increasing the role of RNAi in pest control. Another challenge is to understand the RNAi machinery in insect cells and whether components that were identified in other organisms are also present in insect. This review will focus on summarizing success cases in which RNAi was used for silencing genes in insect vector for plant pathogens, and will be particularly helpful for vector biologists.
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20
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Christiaens O, Prentice K, Pertry I, Ghislain M, Bailey A, Niblett C, Gheysen G, Smagghe G. RNA interference: a promising biopesticide strategy against the African Sweetpotato Weevil Cylas brunneus. Sci Rep 2016; 6:38836. [PMID: 27941836 PMCID: PMC5150260 DOI: 10.1038/srep38836] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 11/04/2016] [Indexed: 11/13/2022] Open
Abstract
The African sweetpotato weevil Cylas brunneus is one of the most devastating pests affecting the production of sweetpotatoes, an important staple food in Sub-Saharan Africa. Current available control methods against this coleopteran pest are limited. In this study, we analyzed the potential of RNA interference as a novel crop protection strategy against this insect pest. First, the C. brunneus transcriptome was sequenced and RNAi functionality was confirmed by successfully silencing the laccase2 gene. Next, 24 potential target genes were chosen, based on their critical role in vital biological processes. A first screening via injection of gene-specific dsRNAs showed that the dsRNAs were highly toxic for C. brunneus. Injected doses of 200ng/mg body weight led to mortality rates of 90% or higher for 14 of the 24 tested genes after 14 days. The three best performing dsRNAs, targeting prosα2, rps13 and the homolog of Diabrotica virgifera snf7, were then used in further feeding trials to investigate RNAi by oral delivery. Different concentrations of dsRNAs mixed with artificial diet were tested and concentrations as low as 1 μg dsRNA/ mL diet led to significant mortality rates higher than 50%.These results proved that dsRNAs targeting essential genes show great potential to control C. brunneus.
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Affiliation(s)
- Olivier Christiaens
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Katterinne Prentice
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
- International Potato Center (CIP), Genomics and Biotechnology Program, Nairobi 00603, Kenya
| | - Ine Pertry
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
- Institute of Plant Biotechnology Outreach, VIB, Technologiepark 3, B-9052 Ghent, Belgium
| | - Marc Ghislain
- International Potato Center (CIP), Genomics and Biotechnology Program, Nairobi 00603, Kenya
| | - Ana Bailey
- Venganza Inc., St. Augustine, FL 32080, USA
| | | | - Godelieve Gheysen
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
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21
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Taning CNT, Andrade EC, Hunter WB, Christiaens O, Smagghe G. Asian Citrus Psyllid RNAi Pathway - RNAi evidence. Sci Rep 2016; 6:38082. [PMID: 27901078 PMCID: PMC5128860 DOI: 10.1038/srep38082] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/03/2016] [Indexed: 12/20/2022] Open
Abstract
Diaphorina citri, known as the Asian citrus psyllid, is an important pest of citrus because it transmits a phloem-limited bacteria strongly implicated in huanglongbing (citrus greening disease). Emerging biotechnologies, such as RNA interference, could provide a new sustainable and environmentally friendly strategy for the management of this pest. In this study, genome and functional analysis were performed to verify whether the RNAi core genes are present in the Asian psyllid genome and if the RNAi machinery could be exploited to develop a management strategy for this pest. Analyses of RNAi-related genes in the Asian citrus psyllid genome showed an absence of sequences encoding R2D2, a dsRNA-binding protein that functions as a cofactor of Dicer-2 in Drosophila. Nevertheless, bioassays using an in Planta System showed that the Asian citrus psyllid was very sensitive to ingested dsRNA, demonstrating a strong RNAi response. A small dose of dsRNA administered through a citrus flush was enough to trigger the RNAi mechanism, causing significant suppression of the targeted transcript, and increased psyllid mortality. This study provides evidence of a functional RNAi machinery, which could be further exploited to develop RNAi based management strategies for the control of the Asian citrus psyllid.
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Affiliation(s)
- Clauvis N. T. Taning
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Eduardo C. Andrade
- EMBRAPA Cassava and Fruits, Rua Embrapa, s/n, Cruz das Almas, Bahia, Cep 44380-000, Brazil
| | - Wayne B. Hunter
- U.S. Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Fort Pierce, FL 34945, USA
| | - Olivier Christiaens
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium
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22
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Joga MR, Zotti MJ, Smagghe G, Christiaens O. RNAi Efficiency, Systemic Properties, and Novel Delivery Methods for Pest Insect Control: What We Know So Far. Front Physiol 2016; 7:553. [PMID: 27909411 PMCID: PMC5112363 DOI: 10.3389/fphys.2016.00553] [Citation(s) in RCA: 251] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/03/2016] [Indexed: 01/01/2023] Open
Abstract
In recent years, the research on the potential of using RNA interference (RNAi) to suppress crop pests has made an outstanding growth. However, given the variability of RNAi efficiency that is observed in many insects, the development of novel approaches toward insect pest management using RNAi requires first to unravel factors behind the efficiency of dsRNA-mediated gene silencing. In this review, we explore essential implications and possibilities to increase RNAi efficiency by delivery of dsRNA through non-transformative methods. We discuss factors influencing the RNAi mechanism in insects and systemic properties of dsRNA. Finally, novel strategies to deliver dsRNA are discussed, including delivery by symbionts, plant viruses, trunk injections, root soaking, and transplastomic plants.
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Affiliation(s)
- Mallikarjuna R Joga
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University Gent, Belgium
| | - Moises J Zotti
- Department of Crop Protection, Molecular Entomology, Federal University of Pelotas Pelotas, Brazil
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University Gent, Belgium
| | - Olivier Christiaens
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University Gent, Belgium
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23
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Fishilevich E, Vélez AM, Storer NP, Li H, Bowling AJ, Rangasamy M, Worden SE, Narva KE, Siegfried BD. RNAi as a management tool for the western corn rootworm, Diabrotica virgifera virgifera. PEST MANAGEMENT SCIENCE 2016; 72:1652-1663. [PMID: 27218412 DOI: 10.1002/ps.4324] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 04/27/2016] [Accepted: 05/13/2016] [Indexed: 06/05/2023]
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera, is the most important pest of corn in the US Corn Belt. Economic estimates indicate that costs of control and yield loss associated with WCR damage exceed $US 1 billion annually. Historically, corn rootworm management has been extremely difficult because of its ability to evolve resistance to both chemical insecticides and cultural control practices. Since 2003, the only novel commercialized developments in rootworm management have been transgenic plants expressing Bt insecticidal proteins. Four transgenic insecticidal proteins are currently registered for rootworm management, and field resistance to proteins from the Cry3 family highlights the importance of developing traits with new modes of action. One of the newest approaches for controlling rootworm pests involves RNA interference (RNAi). This review describes the current understanding of the RNAi mechanisms in WCR and the use of this technology for WCR management. Further, the review addresses ecological risk assessment of RNAi and insect resistance management of RNAi for corn rootworm. © 2016 Society of Chemical Industry.
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Affiliation(s)
| | - Ana M Vélez
- Department of Entomology, University of Nebraska, Lincoln, NE, USA
| | | | | | | | | | | | | | - Blair D Siegfried
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
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24
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Hu X, Richtman NM, Zhao JZ, Duncan KE, Niu X, Procyk LA, Oneal MA, Kernodle BM, Steimel JP, Crane VC, Sandahl G, Ritland JL, Howard RJ, Presnail JK, Lu AL, Wu G. Discovery of midgut genes for the RNA interference control of corn rootworm. Sci Rep 2016; 6:30542. [PMID: 27464714 PMCID: PMC4964579 DOI: 10.1038/srep30542] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/06/2016] [Indexed: 01/18/2023] Open
Abstract
RNA interference (RNAi) is a promising new technology for corn rootworm control. This paper presents the discovery of new gene targets - dvssj1 and dvssj2, in western corn rootworm (WCR). Dvssj1 and dvssj2 are orthologs of the Drosophila genes snakeskin (ssk) and mesh, respectively. These genes encode membrane proteins associated with smooth septate junctions (SSJ) which are required for intestinal barrier function. Based on bioinformatics analysis, dvssj1 appears to be an arthropod-specific gene. Diet based insect feeding assays using double-stranded RNA (dsRNA) targeting dvssj1 and dvssj2 demonstrate targeted mRNA suppression, larval growth inhibition, and mortality. In RNAi treated WCR, injury to the midgut was manifested by "blebbing" of the midgut epithelium into the gut lumen. Ultrastructural examination of midgut epithelial cells revealed apoptosis and regenerative activities. Transgenic plants expressing dsRNA targeting dvssj1 show insecticidal activity and significant plant protection from WCR damage. The data indicate that dvssj1 and dvssj2 are effective gene targets for the control of WCR using RNAi technology, by apparent suppression of production of their respective smooth septate junction membrane proteins located within the intestinal lining, leading to growth inhibition and mortality.
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Affiliation(s)
- Xu Hu
- DuPont Pioneer, Johnston, IA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Gusui Wu
- DuPont Pioneer, Johnston, IA, USA
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25
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Knockdown of RNA Interference Pathway Genes in Western Corn Rootworms (Diabrotica virgifera virgifera Le Conte) Demonstrates a Possible Mechanism of Resistance to Lethal dsRNA. PLoS One 2016; 11:e0157520. [PMID: 27310918 PMCID: PMC4911125 DOI: 10.1371/journal.pone.0157520] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 06/01/2016] [Indexed: 01/28/2023] Open
Abstract
RNA interference (RNAi) is being developed as a potential tool for insect pest management. Increased understanding of the RNAi pathway in target insect pests will provide information to use this technology effectively and to inform decisions related to resistant management strategies for RNAi based traits. Dicer 2 (Dcr2), an endonuclease responsible for formation of small interfering RNA’s and Argonaute 2 (Ago2), an essential catalytic component of the RNA-induced silencing complex (RISC) have both been associated with the RNAi pathway in a number of different insect species including the western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). We identified both genes from a transcriptome library generated from different tissues and developmental stages of the western corn rootworm, an important target pest for transgenic plants expressing dsRNA targeting essential genes. The expression of these genes was suppressed by more than 90% after injecting gene specific dsRNA into adult rootworms. The injected beetles were then fed vATPase A dsRNA which has previously been demonstrated to cause mortality in western corn rootworm adults. The suppression of both RNAi pathway genes resulted in reduced mortality after subsequent exposure to lethal concentrations of vATPase A dsRNA as well as increased vATPase A expression relative to control treatments. Injections with dsRNA for a non-lethal target sequence (Laccase 2) did not affect mortality or expression caused by vATPase A dsRNA indicating that the results observed with Argo and Dicer dsRNA were not caused by simple competition among different dsRNA’s. These results confirm that both genes play an important role in the RNAi pathway for western corn rootworms and indicate that selection pressures that potentially affect the expression of these genes may provide a basis for future studies to understand potential mechanisms of resistance.
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26
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Shukla JN, Kalsi M, Sethi A, Narva KE, Fishilevich E, Singh S, Mogilicherla K, Palli SR. Reduced stability and intracellular transport of dsRNA contribute to poor RNAi response in lepidopteran insects. RNA Biol 2016; 13:656-69. [PMID: 27245473 PMCID: PMC4962799 DOI: 10.1080/15476286.2016.1191728] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RNA interference (RNAi) has become a widely used reverse genetic tool to study gene function in eukaryotic organisms and is being developed as a technology for insect pest management. The efficiency of RNAi varies among organisms. Insects from different orders also display differential efficiency of RNAi, ranging from highly efficient (coleopterans) to very low efficient (lepidopterans). We investigated the reasons for varying RNAi efficiency between lepidopteran and coleopteran cell lines and also between the Colorado potato beetle, Leptinotarsa decemlineata and tobacco budworm, Heliothis virescens. The dsRNA either injected or fed was degraded faster in H. virescens than in L. decemlineata. Both lepidopteran and coleopteran cell lines and tissues efficiently took up the dsRNA. Interestingly, the dsRNA administered to coleopteran cell lines and tissues was taken up and processed to siRNA whereas the dsRNA was taken up by lepidopteran cell lines and tissues but no siRNA was detected in the total RNA isolated from these cell lines and tissues. The data included in this paper showed that the degradation and intracellular transport of dsRNA are the major factors responsible for reduced RNAi efficiency in lepidopteran insects.
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Affiliation(s)
- Jayendra Nath Shukla
- a Department of Entomology , College of Agriculture, Food and Environment, Agriculture Science Center North, University of Kentucky , Lexington , KY , USA
| | - Megha Kalsi
- a Department of Entomology , College of Agriculture, Food and Environment, Agriculture Science Center North, University of Kentucky , Lexington , KY , USA
| | - Amit Sethi
- b Agricultural Biotechnology Research and Development, DuPont Pioneer , Johnston , IA , USA
| | | | | | - Satnam Singh
- a Department of Entomology , College of Agriculture, Food and Environment, Agriculture Science Center North, University of Kentucky , Lexington , KY , USA
| | - Kanakachari Mogilicherla
- a Department of Entomology , College of Agriculture, Food and Environment, Agriculture Science Center North, University of Kentucky , Lexington , KY , USA
| | - Subba Reddy Palli
- a Department of Entomology , College of Agriculture, Food and Environment, Agriculture Science Center North, University of Kentucky , Lexington , KY , USA
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Cuticular protein with a low complexity sequence becomes cross-linked during insect cuticle sclerotization and is required for the adult molt. Sci Rep 2015; 5:10484. [PMID: 25994234 PMCID: PMC4440208 DOI: 10.1038/srep10484] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 04/15/2015] [Indexed: 01/03/2023] Open
Abstract
In the insect cuticle, structural proteins (CPs) and the polysaccharide chitin are the major components. It has been hypothesized that CPs are cross-linked to other CPs and possibly to chitin by quinones or quinone methides produced by the laccase2-mediated oxidation of N-acylcatechols. In this study we investigated functions of TcCP30, the third most abundant CP in protein extracts of elytra (wing covers) from Tribolium castaneum adults. The mature TcCP30 protein has a low complexity and highly polar amino acid sequence. TcCP30 is localized with chitin in horizontal laminae and vertically oriented columnar structures in rigid cuticles, but not in soft and membranous cuticles. Immunoblot analysis revealed that TcCP30 undergoes laccase2-mediated cross-linking during cuticle maturation in vivo, a process confirmed in vitro using recombinant rTcCP30. We identified TcCPR27 and TcCPR18, the two most abundant proteins in the elytra, as putative cross-linking partners of TcCP30. RNAi for the TcCP30 gene had no effect on larval and pupal growth and development. However, during adult eclosion, ~70% of the adults were unable to shed their exuvium and died. These results support the hypothesis that TcCP30 plays an integral role as a cross-linked structural protein in the formation of lightweight rigid cuticle of the beetle.
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Kola VSR, Renuka P, Madhav MS, Mangrauthia SK. Key enzymes and proteins of crop insects as candidate for RNAi based gene silencing. Front Physiol 2015; 6:119. [PMID: 25954206 PMCID: PMC4406143 DOI: 10.3389/fphys.2015.00119] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/31/2015] [Indexed: 11/23/2022] Open
Abstract
RNA interference (RNAi) is a mechanism of homology dependent gene silencing present in plants and animals. It operates through 21-24 nucleotides small RNAs which are processed through a set of core enzymatic machinery that involves Dicer and Argonaute proteins. In recent past, the technology has been well appreciated toward the control of plant pathogens and insects through suppression of key genes/proteins of infecting organisms. The genes encoding key enzymes/proteins with the great potential for developing an effective insect control by RNAi approach are actylcholinesterase, cytochrome P450 enzymes, amino peptidase N, allatostatin, allatotropin, tryptophan oxygenase, arginine kinase, vacuolar ATPase, chitin synthase, glutathione-S-transferase, catalase, trehalose phosphate synthase, vitellogenin, hydroxy-3-methylglutaryl coenzyme A reductase, and hormone receptor genes. Through various studies, it is demonstrated that RNAi is a reliable molecular tool which offers great promises in meeting the challenges imposed by crop insects with careful selection of key enzymes/proteins. Utilization of RNAi tool to target some of these key proteins of crop insects through various approaches is described here. The major challenges of RNAi based insect control such as identifying potential targets, delivery methods of silencing trigger, off target effects, and complexity of insect biology are very well illustrated. Further, required efforts to address these challenges are also discussed.
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Affiliation(s)
| | | | - Maganti Sheshu Madhav
- Department of Biotechnology, Directorate of Rice Research, ICAR-Indian Institute of Rice ResearchHyderabad, India
| | - Satendra K. Mangrauthia
- Department of Biotechnology, Directorate of Rice Research, ICAR-Indian Institute of Rice ResearchHyderabad, India
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Miyata K, Ramaseshadri P, Zhang Y, Segers G, Bolognesi R, Tomoyasu Y. Establishing an in vivo assay system to identify components involved in environmental RNA interference in the western corn rootworm. PLoS One 2014; 9:e101661. [PMID: 25003334 PMCID: PMC4086966 DOI: 10.1371/journal.pone.0101661] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/09/2014] [Indexed: 12/14/2022] Open
Abstract
The discovery of environmental RNA interference (RNAi), in which gene expression is suppressed via feeding with double-stranded RNA (dsRNA) molecules, opened the door to the practical application of RNAi-based techniques in crop pest management. The western corn rootworm (WCR, Diabrotica virgifera virgifera) is one of the most devastating corn pests in North America. Interestingly, WCR displays a robust environmental RNAi response, raising the possibility of applying an RNAi-based pest management strategy to this pest. Understanding the molecular mechanisms involved in the WCR environmental RNAi process will allow for determining the rate limiting steps involved with dsRNA toxicity and potential dsRNA resistance mechanisms in WCR. In this study, we have established a two-step in vivo assay system, which allows us to evaluate the involvement of genes in environmental RNAi in WCR. We show that laccase 2 and ebony, critical cuticle pigmentation/tanning genes, can be used as marker genes in our assay system, with ebony being a more stable marker to monitor RNAi activity. In addition, we optimized the dsRNA dose and length for the assay, and confirmed that this assay system is sensitive to detect well-known RNAi components such as Dicer-2 and Argonaute-2. We also evaluated two WCR sid1- like (sil) genes with this assay system. This system will be useful to quickly survey candidate systemic RNAi genes in WCR, and also will be adaptable for a genome-wide RNAi screening to give us an unbiased view of the environmental/systemic RNAi pathway in WCR.
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Affiliation(s)
- Keita Miyata
- Department of Biology, Miami University, Oxford, Ohio, United States of America
| | | | - Yuanji Zhang
- Biotechnology Division, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Gerrit Segers
- Biotechnology Division, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Renata Bolognesi
- Biotechnology Division, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Yoshinori Tomoyasu
- Department of Biology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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Chu CC, Sun W, Spencer JL, Pittendrigh BR, Seufferheld MJ. Differential effects of RNAi treatments on field populations of the western corn rootworm. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2014; 110:1-6. [PMID: 24759044 DOI: 10.1016/j.pestbp.2014.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 02/17/2014] [Accepted: 02/17/2014] [Indexed: 05/03/2023]
Abstract
RNA interference (RNAi) mediated crop protection against insect pests is a technology that is greatly anticipated by the academic and industrial pest control communities. Prior to commercialization, factors influencing the potential for evolution of insect resistance to RNAi should be evaluated. While mutations in genes encoding the RNAi machinery or the sequences targeted for interference may serve as a prominent mechanism of resistance evolution, differential effects of RNAi on target pests may also facilitate such evolution. However, to date, little is known about how variation of field insect populations could influence the effectiveness of RNAi treatments. To approach this question, we evaluated the effects of RNAi treatments on adults of three western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) populations exhibiting different levels of gut cysteine protease activity, tolerance of soybean herbivory, and immune gene expression; two populations were collected from crop rotation-resistant (RR) problem areas and one from a location where RR was not observed (wild type; WT). Our results demonstrated that RNAi targeting DvRS5 (a highly expressed cysteine protease gene) reduced gut cysteine protease activity in all three WCR populations. However, the proportion of the cysteine protease activity that was inhibited varied across populations. When WCR adults were treated with double-stranded RNA of an immune gene att1, different changes in survival among WT and RR populations on soybean diets occurred. Notably, for both genes, the sequences targeted for RNAi were the same across all populations examined. These findings indicate that the effectiveness of RNAi treatments could vary among field populations depending on their physiological and genetic backgrounds and that the consistency of an RNAi trait's effectiveness on phenotypically different populations should be considered or tested prior to wide deployment. Also, genes that are potentially subjected to differential selection in the field should be avoided for RNAi-based pest control.
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Affiliation(s)
- Chia-Ching Chu
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, United States
| | - Weilin Sun
- Department of Entomology, University of Illinois, Urbana, IL 61801, United States
| | - Joseph L Spencer
- Illinois Natural History Survey, University of Illinois, Champaign, IL 61820, United States
| | - Barry R Pittendrigh
- Department of Entomology, University of Illinois, Urbana, IL 61801, United States
| | - Manfredo J Seufferheld
- Department of Entomology, University of Illinois, Urbana, IL 61801, United States; Illinois Natural History Survey, University of Illinois, Champaign, IL 61820, United States.
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31
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Ultrastructural changes caused by Snf7 RNAi in larval enterocytes of western corn rootworm (Diabrotica virgifera virgifera Le Conte). PLoS One 2014; 9:e83985. [PMID: 24409288 PMCID: PMC3883649 DOI: 10.1371/journal.pone.0083985] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/08/2013] [Indexed: 11/28/2022] Open
Abstract
The high sensitivity to oral RNA interference (RNAi) of western corn rootworm (WCR, Diabrotica virgifera virgifera Le Conte) provides a novel tool for pest control. Previous studies have shown that RNAi of DvSnf7, an essential cellular component of endosomal sorting complex required for transport (ESCRT), caused deficiencies in protein de-ubiquitination and autophagy, leading to WCR death. Here we investigated the detailed mechanism leading to larval death by analyzing the ultrastructural changes in midgut enterocytes of WCR treated with double-stranded RNA (ds-DvSnf7). The progressive phases of pathological symptoms caused by DvSnf7-RNAi in enterocytes include: 1) the appearance of irregularly shaped macroautophagic complexes consisting of relatively large lysosomes and multi-lamellar bodies, indicative of failure in autolysosome formation; 2) cell sloughing and loss of apical microvilli, and eventually, 3) massive loss of cellular contents indicating loss of membrane integrity. These data suggest that the critical functions of Snf7 in insect midgut cells demonstrated by the ultrastructural changes in DvSnf7 larval enterocytes underlies the conserved essential function of the ESCRT pathway in autophagy and membrane stability in other organisms.
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32
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Swevers L, Huvenne H, Menschaert G, Kontogiannatos D, Kourti A, Pauchet Y, ffrench-Constant R, Smagghe G. Colorado potato beetle (Coleoptera) gut transcriptome analysis: expression of RNA interference-related genes. INSECT MOLECULAR BIOLOGY 2013; 22:668-684. [PMID: 24580832 DOI: 10.1111/imb.12054] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the search for new methods of pest control, the potential of RNA interference (RNAi) is being explored. Because the gut is the first barrier for the uptake of double-stranded (ds)RNA, pyrosequencing of the gut transcriptome is a powerful tool for obtaining the necessary sequences for specific dsRNA-mediated pest control. In the present study, a dataset representing the gut transcriptome of the Colorado potato beetle (CPB; Leptinotarsa decemlineata) was generated and analysed for the presence of RNAi-related genes. Almost all selected genes that were implicated in silencing efficiency at different levels in the RNAi pathway (core machinery, associated intracellular factors, dsRNA uptake, antiviral RNAi, nucleases), which uses different types of small RNA (small interfering RNA, microRNA and piwi-RNA), were expressed in the CPB gut. Although the database is of lower quality, the majority of the RNAi genes are also found to be present in the gut transcriptome of the tobacco hornworm [TH; Manduca sexta (19 out of 35 genes analysed)]. The high quality of the CPB transcriptome database will lay the foundation for future gene expression and functional studies regarding the gut and RNAi.
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Affiliation(s)
- L Swevers
- Insect Molecular Genetics and Biotechnology, NCSR 'Demokritos', Institute of Biosciences & Applications, Athens, Greece
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Zhang X, Liu X, Ma J, Zhao J. Silencing of cytochrome P450 CYP6B6 gene of cotton bollworm (Helicoverpa armigera) by RNAi. BULLETIN OF ENTOMOLOGICAL RESEARCH 2013; 103:584-591. [PMID: 23590813 DOI: 10.1017/s0007485313000151] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
RNA interference (RNAi) induced through double-stranded RNA (dsRNA) has been used widely to study gene function in insects. In this paper we demonstrate the efficacy of RNAi in the cotton bollworm, Helicoverpa armigera. Using CYP6B6 as the target gene, which is expressed in the fat baby and midgut of the lepidopteran pest H. armigera, we constructed the vector which expressed dsRNA of CYP6B6. Northern blot analysis showed that dsRNA expressed in the Escherichia coli (HT115) was target gene. The results also showed that the gene expression level and protein expression level of H. armigera larvae fed with dsRNA expressed by E. coli were significantly lower than those of all controls, but the gene expression level was more obvious than that at the protein level; significant lethality differences were also found between HT115 bacteria containing L4440-dsC1 treatment and HT115 bacteria containing L4440 vector or CK (ddH2O) in instar larvae on 4 day when continuous feeding, 32.45% mortality was recorded in the group of feeding HT115 bacteria containing L4440-dsC1 on 10 day. Our results suggest that the RNAi pathway can be exploited to control insect pests.
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Affiliation(s)
- X Zhang
- College of Life Science and Technology, Xinjiang University, Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, Urumqi 830046, China
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34
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Ramaseshadri P, Segers G, Flannagan R, Wiggins E, Clinton W, Ilagan O, McNulty B, Clark T, Bolognesi R. Physiological and cellular responses caused by RNAi- mediated suppression of Snf7 orthologue in western corn rootworm (Diabrotica virgifera virgifera) larvae. PLoS One 2013; 8:e54270. [PMID: 23349844 PMCID: PMC3548817 DOI: 10.1371/journal.pone.0054270] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 12/11/2012] [Indexed: 11/19/2022] Open
Abstract
Ingestion of double stranded RNA (dsRNA) has been previously demonstrated to be effective in triggering RNA interference (RNAi) in western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte), providing potential novel opportunities for insect pest control. The putative Snf7 homolog of WCR (DvSnf7) has previously been shown to be an effective RNAi target for insect control, as DvSnf7 RNAi leads to lethality of WCR larvae. Snf7 functions as a part of the ESCRT (Endosomal Sorting Complex Required for Transport) pathway which plays a crucial role in cellular housekeeping by internalization, transport, sorting and lysosomal degradation of transmembrane proteins. To understand the effects that lead to death of WCR larvae by DvSnf7 RNAi, we examined some of the distinct cellular processes associated with ESCRT functions such as de-ubiquitination of proteins and autophagy. Our data indicate that ubiquitinated proteins accumulate in DvSnf7 dsRNA-fed larval tissues and that the autophagy process seems to be impaired. These findings suggest that the malfunctioning of these cellular processes in both midgut and fat body tissues triggered by DvSnf7 RNAi were the main effects leading to the death of WCR. This study also illustrates that Snf7 is an essential gene in WCR and its functions are consistent with biological functions described for other eukaryotes.
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Affiliation(s)
| | - Gerrit Segers
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Ronald Flannagan
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Elizabeth Wiggins
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - William Clinton
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Oliver Ilagan
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Brian McNulty
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Thomas Clark
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
| | - Renata Bolognesi
- Department of Biotechnology, Monsanto Company, Chesterfield, Missouri, United States of America
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35
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Transgenic approaches to western corn rootworm control. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2013; 136:135-62. [PMID: 23604211 DOI: 10.1007/10_2013_195] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a significant corn pest throughout the United States corn belt. Rootworm larvae feed on corn roots causing yield losses and control expenditures that are estimated to exceed US$1 billion annually. Traditional management practices to control rootworms such as chemical insecticides or crop rotation have suffered reduced effectiveness due to the development of physiological and behavioral resistance. Transgenic maize expressing insecticidal proteins are very successful in protecting against rootworm damage and preserving corn yield potential. However, the high rate of grower adoption and early reliance on hybrids expressing a single mode of action and low-dose traits threatens the durability of commercialized transgenic rootworm technology for rootworm control. A summary of current transgenic approaches for rootworm control and the corresponding insect resistance management practices is included. An overview of potential new modes of action based on insecticidal proteins, and especially RNAi targeting mRNA coding for essential insect proteins is provided.
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36
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Knorr E, Bingsohn L, Kanost MR, Vilcinskas A. Tribolium castaneum as a model for high-throughput RNAi screening. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2013; 136:163-78. [PMID: 23748349 DOI: 10.1007/10_2013_208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Coleopteran insects are a highly diverse and successful order, and many beetle species are significant agricultural pests. New biorational strategies for managing populations of beetles and other insect species are needed as pests develop resistance to chemical insecticides and Bt toxins. There is now an opportunity to use genome sequence data to identify genes that are essential for insect growth, development, or survival as new targets for designing control technology. This goal requires a method for high-throughput in vivo screening of thousands of genes to identify candidate genes that, when their expression is disrupted, have a phenotype that may be useful in insect pest control. Tribolium castaneum, the red flour beetle, is a model organism that offers considerable advantages for such screening, including ease of rearing in large numbers, a sequenced genome, and a strong, systemic RNAi response for specific depletion of gene transcripts. The RNAi effect in T. castaneum can be elicited in any tissue and any stage by the injection of dsRNA into the hemocoel, and injection of dsRNA into adult females can even be used to identify phenotypes in offspring. A pilot RNAi screen (iBeetle) is underway. Several T. castaneum genes with promising RNAi phenotypes for further development as mechanisms for plant protection have been identified. These include heat shock protein 90, chitin synthase, the segmentation gene hairy, and a matrix metalloprotease. Candidate genes identified in T. castaneum screens can then be tested in agricultural pest species (in which screening is not feasible), to evaluate their effectiveness for use in potential plant-based RNAi control strategies. Delivery of dsRNA expressed by genetically modified crops to the midgut of phytophagous insects is under investigation as a new tool for very specific protection of plants from insect pest species. The T. castaneum screening platform offers a system for discovery of candidate genes with high potential benefit.
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Affiliation(s)
- Eileen Knorr
- Institute of Phytopathology and Applied Zoology, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 26-32, 39592, Giessen, Germany
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Valencia A, Alves AP, Siegfried BD. Molecular cloning and functional characterization of an endogenous endoglucanase belonging to GHF45 from the western corn rootworm, Diabrotica virgifera virgifera. Gene 2012; 513:260-7. [PMID: 23137634 DOI: 10.1016/j.gene.2012.10.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 09/14/2012] [Accepted: 10/10/2012] [Indexed: 11/30/2022]
Abstract
A novel insect β-1,4-endoglucanase (DvvENGaseI) gene belonging to the glycoside hydrolase family (GHF) 45 was identified from the western corn rootworm, Diabrotica virgifera virgifera. The cDNA of the DvvENGaseI consisted of a 720 bp open reading frame encoding a 239 amino-acid protein. Analysis of the amino acid sequence revealed that DvvENGaseI exhibits 60% protein sequence identity when compared with an endoglucanase belonging to GHF45 from another beetle, Leptinotarsa decemlineata. Western blot analyses using a polyclonal antiserum developed from a partial peptide sequence revealed that DvvENGaseI expression coincided with body regions corresponding to the fore-, mid- and hindgut, although regions corresponding to the midgut and hindgut were the primary sites for DvvENGaseI expression. Functional analysis of the DvvENGaseI by RNA interference (RNAi) indicated that nearly complete knock-down of gene expression could be obtained by injection of dsRNA based on qRT-PCR and western blot analysis. However, suppression only resulted in slight developmental delays suggesting that this gene may be part of a larger system of cellulose degrading enzymes.
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Affiliation(s)
- Arnubio Valencia
- Departamento de Producción Agropecuaria, Facultad de Ciencias Agropecuarias, Universidad de Caldas, Calle 65#26-10, Manizales, Colombia
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Tang T, Zhao C, Feng X, Liu X, Qiu L. Knockdown of several components of cytochrome P450 enzyme systems by RNA interference enhances the susceptibility of Helicoverpa armigera to fenvalerate. PEST MANAGEMENT SCIENCE 2012; 68:1501-11. [PMID: 22689565 DOI: 10.1002/ps.3336] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 03/15/2012] [Accepted: 04/04/2012] [Indexed: 05/03/2023]
Abstract
BACKGROUND The function of cytochrome P450 proteins (P450s) in the metabolism of a variety of compounds by oxidation and reduction is well elucidated, but its interactions with other electron transfer components in the pyrethroid resistance of insect pests have been a mystery for a long time. In previous studies the authors cloned and characterised CYP6B7 and cytochrome b(5) (Cyt-b(5)) in the fenvalerate-resistant HDFR strain of cotton bollworm (Helicoverpa armigera Hübner) and showed that CYP6B7 mRNA was overexpressed and important for resistance to fenvalerate. In the present study, the functional interactions of CYP6B7, NADPH-dependent cytochrome P450 reductase (CPR) and Cyt-b(5) were assessed using RNA interference (RNAi) strategies and monitoring for fenvalerate resistance levels. RESULTS RT-qPCR analyses indicated that the expression levels of CYP6B7, CPR and Cyt-b(5) mRNA were decreased drastically in the midgut of fourth-instar larvae of the H. armigera HDFR strain after corresponding double-stranded RNA (dsRNA) injection, compared with that of the control. The knockdown of CYP6B7, CPR and Cyt-b(5) transcripts was time course dependent during a 12-48 h period after dsRNA injection. At the earlier time points analysed, significant suppression of CYP6B7 mRNA levels was observed in larvae injected with dsCYP6B7-313 as compared with controls, and further suppression was observed in larvae injected with dsCYP6B7-313, dsCPR-403 and dsCyt-b(5) . The injection of dsCYP6B7-313 together with dsCPR-403 and dsCyt-b(5) increased larval susceptibility of the HDFR strain to fenvalerate. CONCLUSION The results demonstrated that silencing of CYP6B7 alone or CYP6B7 together with CPR and/or Cyt-b(5) increased the susceptibility of H. armigera to fenvalerate, suggesting that CYP6B7, CPR and Cyt-b(5) collaboratively participated in enhanced metabolism of fenvalerate and played an important role in the resistance of H. armigera to fenvalerate.
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Affiliation(s)
- Tao Tang
- Key Laboratory of Pesticide Chemistry and Application Technology, Ministry of Agriculture, College of Science, China Agricultural University, Beijing, China
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39
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Bansal R, Mian MAR, Mittapalli O, Michel AP. Characterization of a chitin synthase encoding gene and effect of diflubenzuron in soybean aphid, Aphis glycines. Int J Biol Sci 2012; 8:1323-34. [PMID: 23139631 PMCID: PMC3492791 DOI: 10.7150/ijbs.4189] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 10/01/2012] [Indexed: 11/06/2022] Open
Abstract
Chitin synthases are critical enzymes for synthesis of chitin and thus for subsequent growth and development in insects. We identified the cDNA of chitin synthase gene (CHS) in Aphis glycines, the soybean aphid, which is a serious pest of soybean. The full-length cDNA of CHS in A. glycines (AyCHS) was 5802 bp long with an open reading frame of 4704 bp that encoded for a 1567 amino acid residues protein. The predicted AyCHS protein had a molecular mass of 180.05 kDa and its amino acid sequence contained all the signature motifs (EDR, QRRRW and TWGTR) of chitin synthases. The quantitative real-time PCR (qPCR) analysis revealed that AyCHS was expressed in all major tissues (gut, fat body and integument); however, it had the highest expression in integument (~3.5 fold compared to gut). Interestingly, the expression of AyCHS in developing embryos was nearly 7 fold higher compared to adult integument, which probably is a reflection of embryonic molts in hemimetabolus insects. Expression analysis in different developmental stages of A. glycines revealed a consistent AyCHS expression in all stages. Further, through leaf dip bioassay, we tested the effect of diflubenzuron (DFB, Dimilin ®), a chitin-synthesis inhibitor, on A. glycines' survival, fecundity and body weight. When fed with soybean leaves previously dipped in 50 ppm DFB solution, A. glycines nymphs suffered significantly higher mortality compared to control. A. glycines nymphs feeding on diflubenzuron treated leaves showed a slightly enhanced expression (1.67 fold) of AyCHS compared to nymphs on untreated leaves. We discussed the potential applications of the current study to develop novel management strategies using chitin-synthesis inhibitors and using RNAi by knocking down AyCHS expression.
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Affiliation(s)
- Raman Bansal
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
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40
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Characterizing the mechanism of action of double-stranded RNA activity against western corn rootworm (Diabrotica virgifera virgifera LeConte). PLoS One 2012; 7:e47534. [PMID: 23071820 PMCID: PMC3469495 DOI: 10.1371/journal.pone.0047534] [Citation(s) in RCA: 273] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/12/2012] [Indexed: 01/17/2023] Open
Abstract
RNA interference (RNAi) has previously been shown to be effective in western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) larvae via oral delivery of synthetic double-stranded RNA (dsRNA) in an artificial diet bioassay, as well as by ingestion of transgenic corn plant tissues engineered to express dsRNA. Although the RNAi machinery components appear to be conserved in Coleopteran insects, the key steps in this process have not been reported for WCR. Here we characterized the sequence of events that result in mortality after ingestion of a dsRNA designed against WCR larvae. We selected the Snf7 ortholog (DvSnf7) as the target mRNA, which encodes an essential protein involved in intracellular trafficking. Our results showed that dsRNAs greater than or equal to approximately 60 base-pairs (bp) are required for biological activity in artificial diet bioassays. Additionally, 240 bp dsRNAs containing a single 21 bp match to the target sequence were also efficacious, whereas 21 bp short interfering (si) RNAs matching the target sequence were not. This result was further investigated in WCR midgut tissues: uptake of 240 bp dsRNA was evident in WCR midgut cells while a 21 bp siRNA was not, supporting the size-activity relationship established in diet bioassays. DvSnf7 suppression was observed in a time-dependent manner with suppression at the mRNA level preceding suppression at the protein level when a 240 bp dsRNA was fed to WCR larvae. DvSnf7 suppression was shown to spread to tissues beyond the midgut within 24 h after dsRNA ingestion. These events (dsRNA uptake, target mRNA and protein suppression, systemic spreading, growth inhibition and eventual mortality) comprise the overall mechanism of action by which DvSnf7 dsRNA affects WCR via oral delivery and provides insights as to how targeted dsRNAs in general are active against insects.
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Rangasamy M, Siegfried BD. Validation of RNA interference in western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) adults. PEST MANAGEMENT SCIENCE 2012; 68:587-91. [PMID: 22500293 DOI: 10.1002/ps.2301] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
BACKGROUND RNA interference (RNAi) is commonly used in insect functional genomics studies and usually involves direct injection of double-stranded RNA (dsRNA). Only a few studies have involved exposure to dsRNAs through feeding. For western corn rootworm (Diabrotica virgifera virgifera) larvae, ingestion of dsRNA designed from the housekeeping gene, vacuolar ATPase (vATPase) triggers RNAi causing growth inhibition and mortality; however, the effect of dsRNA feeding on adults has not been examined. In this research, WCR adults were fed with vATPase-dsRNA-treated artificial diet containing a cucurbitacin bait, which is a proven feeding stimulant for chrysomelid beetles of the subtribe Diabroticina to which rootworms belong. RESULTS Real-time PCR confirmed suppression of vATPase expression and western blot analysis indicated reduced signal of a protein that cross-reacted with a vATPase polyclonal antiserum in WCR adults exposed to artificial diet treated with dsRNA and cucurbitacin bait. Continuous feeding on cucurbitacin and dsRNA-treated artificial diet resulted in more than 95% adult mortality within 2 weeks while mortality in control treatments never exceeded 20%. CONCLUSIONS This research clearly demonstrates the effect of RNAi on WCR adults that have been exposed to dsRNA by feeding and establishes a tool to screen dsRNAs of potential target genes in adults. This technique may serve as an alternative to target screening of larvae which are difficult to maintain on artificial diets.
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Affiliation(s)
- Murugesan Rangasamy
- Department of Entomology, University of Nebraska, Lincoln, NE 68583-0816, USA
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