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Ross SJ, Owen GR, Hough J, Philips A, Maddelein W, Ray J, Kilby PM, Dickman MJ. Optimizing the production of dsRNA biocontrols in microbial systems using multiple transcriptional terminators. Biotechnol Bioeng 2024. [PMID: 39030834 DOI: 10.1002/bit.28805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 06/26/2024] [Accepted: 07/03/2024] [Indexed: 07/22/2024]
Abstract
Crop pests and pathogens annually cause over $220 billion in global crop damage, with insects consuming 5%-20% of major grain crops. Current crop pest and disease control strategies rely on insecticidal and fungicidal sprays, plant genetic resistance, transgenes, and agricultural practices. Double-stranded RNA (dsRNA) is emerging as a novel sustainable method of plant protection as an alternative to traditional chemical pesticides. Successful commercialization of dsRNA-based biocontrols requires the economical production of large quantities of dsRNA combined with suitable delivery methods to ensure RNAi efficacy against the target pest. In this study, we have optimized the design of plasmid DNA constructs to produce dsRNA biocontrols in Escherichia coli, by employing a wide range of alternative synthetic transcriptional terminators before measurement of dsRNA yield. We demonstrate that a 7.8-fold increase of dsRNA was achieved using triple synthetic transcriptional terminators within a dual T7 dsRNA production system compared to the absence of transcriptional terminators. Moreover, our data demonstrate that batch fermentation production dsRNA using multiple transcriptional terminators is scalable and generates significantly higher yields of dsRNA generated in the absence of transcriptional terminators at both small-scale batch culture and large-scale fermentation. In addition, we show that application of these dsRNA biocontrols expressed in E. coli cells results in increased insect mortality. Finally, novel mass spectrometry analysis was performed to determine the precise sites of transcriptional termination at the different transcriptional terminators providing important further mechanistic insight.
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Affiliation(s)
- Sebastian J Ross
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Gareth R Owen
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - James Hough
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | | | | | - John Ray
- Syngenta, Jealott's Hill International Research Centre , Bracknell, Berkshire, UK
| | - Peter M Kilby
- Syngenta, Jealott's Hill International Research Centre , Bracknell, Berkshire, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
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2
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Mouton S, Mougel A, Ustyantsev K, Dissous C, Melnyk O, Berezikov E, Vicogne J. Optimized protocols for RNA interference in Macrostomum lignano. G3 (BETHESDA, MD.) 2024; 14:jkae037. [PMID: 38421640 PMCID: PMC11075559 DOI: 10.1093/g3journal/jkae037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 03/02/2024]
Abstract
Macrostomum lignano, a marine free-living flatworm, has emerged as a potent invertebrate model in developmental biology for studying stem cells, germline, and regeneration processes. In recent years, many tools have been developed to manipulate this worm and to facilitate genetic modification. RNA interference is currently the most accessible and direct technique to investigate gene functions. It is obtained by soaking worms in artificial seawater containing dsRNA targeting the gene of interest. Although easy to perform, the original protocol calls for daily exchange of dsRNA solutions, usually until phenotypes are observed, which is both time- and cost-consuming. In this work, we have evaluated alternative dsRNA delivery techniques, such as electroporation and osmotic shock, to facilitate the experiments with improved time and cost efficiency. During our investigation to optimize RNAi, we demonstrated that, in the absence of diatoms, regular single soaking in artificial seawater containing dsRNA directly produced in bacteria or synthesized in vitro is, in most cases, sufficient to induce a potent gene knockdown for several days with a single soaking step. Therefore, this new and highly simplified method allows a very significant reduction of dsRNA consumption and lab work. In addition, it enables performing experiments on a larger number of worms at minimal cost.
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Affiliation(s)
- Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9700AD, The Netherlands
| | - Alexandra Mougel
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR9017—CIIL—Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Kirill Ustyantsev
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9700AD, The Netherlands
| | - Colette Dissous
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR9017—CIIL—Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Oleg Melnyk
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR9017—CIIL—Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Eugene Berezikov
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9700AD, The Netherlands
| | - Jérôme Vicogne
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR9017—CIIL—Center for Infection and Immunity of Lille, F-59000 Lille, France
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3
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Ortolá B, Daròs JA. RNA Interference in Insects: From a Natural Mechanism of Gene Expression Regulation to a Biotechnological Crop Protection Promise. BIOLOGY 2024; 13:137. [PMID: 38534407 DOI: 10.3390/biology13030137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/14/2024] [Accepted: 02/19/2024] [Indexed: 03/28/2024]
Abstract
Insect pests rank among the major limiting factors in agricultural production worldwide. In addition to direct effect on crops, some phytophagous insects are efficient vectors for plant disease transmission. Large amounts of conventional insecticides are required to secure food production worldwide, with a high impact on the economy and environment, particularly when beneficial insects are also affected by chemicals that frequently lack the desired specificity. RNA interference (RNAi) is a natural mechanism gene expression regulation and protection against exogenous and endogenous genetic elements present in most eukaryotes, including insects. Molecules of double-stranded RNA (dsRNA) or highly structured RNA are the substrates of cellular enzymes to produce several types of small RNAs (sRNAs), which play a crucial role in targeting sequences for transcriptional or post-transcriptional gene silencing. The relatively simple rules that underlie RNAi regulation, mainly based in Watson-Crick complementarity, have facilitated biotechnological applications based on these cellular mechanisms. This includes the promise of using engineered dsRNA molecules, either endogenously produced in crop plants or exogenously synthesized and applied onto crops, as a new generation of highly specific, sustainable, and environmentally friendly insecticides. Fueled on this expectation, this article reviews current knowledge about the RNAi pathways in insects, and some other applied questions such as production and delivery of recombinant RNA, which are critical to establish RNAi as a reliable technology for insect control in crop plants.
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Affiliation(s)
- Beltrán Ortolá
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, 46022 Valencia, Spain
| | - José-Antonio Daròs
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, 46022 Valencia, Spain
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4
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Guan R, Miao X, Li H. Bacteria-Based Double-Stranded RNA Production to Develop Cost-Effective RNA Interference Application for Insect Pest Management. Methods Mol Biol 2024; 2771:73-81. [PMID: 38285393 DOI: 10.1007/978-1-0716-3702-9_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Since the discovery of the RNA interference (RNAi) mechanism, it has been widely used in the fields of gene function, biomedicine, and crop pest control. In the direction of agricultural application, this technology is highly expected, especially in the field of pest control, which is called "the third revolution in the history of pesticides". Currently, RNA biopesticides are developing rapidly all over the world. A genetically modified product (MON87411) has been approved for marketing, and a large number of agricultural companies are developing products based on direct spraying RNA biopesticides and submitting them for regulatory approval. The biggest problem that has emerged for spray RNA biopesticides is the technology for large-scale and low-cost production of dsRNA. At present, the bacterial fermentation production technology can realize large-scale dsRNA production with a yield of 4.23~182 mg/L bacterial solution. This article describes the experimental protocol for dsRNA production technology based on bacterial fermentation.
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Affiliation(s)
- Ruobing Guan
- Henan International Laboratory for Green Pest Control, Henan Engineering Laboratory of Pest Biological Control, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Xuexia Miao
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Haichao Li
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.
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5
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Uma GS, Saakre M, Singh J, Kalia VK. Double-stranded RNA mediated knockdown of sucrase gene induced mortality and reduced offspring production in Aphis gossypii. Funct Integr Genomics 2023; 23:305. [PMID: 37726585 DOI: 10.1007/s10142-023-01233-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 09/21/2023]
Abstract
The importance of gut sucrase in maintaining osmotic equilibrium and utilizing phloem contents as a carbon source has been widely investigated and proven in sap-sucking insects. In the present study, silencing of Aphis gossypii sucrase1 (Agsuc1) was carried out by double-stranded RNA (dsRNA), which would be lethal to it due to disruption of osmotic balance. The dsRNA corresponding to Agsuc1 was synthesized by two methods, i.e., in vitro synthesis using T7/SP6 RNA polymerase and in vivo synthesis by bacterial expression, i.e., Escherichia coli strain HT115 transformed with the L4440 vector system. Oral delivery of double-stranded Agsuc1 synthesized in vitro (dsAgsuc1) and in vivo (HT115Agsuc1) induced around 50% mortality in nymphs of A. gossypii. Moreover, the number of offspring produced by the survived aphids decreased by 39-43%. Parthenogenetic reproduction of the aphids is the critical factor for their fast population build-up, leading to yield losses of economic significance. Thus, the present study demonstrated that the silencing of the Agsuc1 gene reduced the aphid population by killing it and inhibited the population buildup by reducing the number of offspring produced by the survived aphids, likely to result in a significant reduction in crop damage. The production of dsRNA by bacterial expression is a cost-effective method. It has the potential to be used as a biopesticide. The sucrase gene is an excellent putative target gene for RNAi against A. gossypii. It could be used to develop a transgenic plant that produces dsAgsuc1 to keep A. gossypii populations below the economic threshold level.
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Affiliation(s)
- Gadigavarahalli Subbareddy Uma
- Division of Entomology, Indian Agricultural Research Institute, New Delhi, India
- Forest Protection Division, Forest Research Institute, Uttarakhand, India
| | - Manjesh Saakre
- Division of Molecular Biology and Biotechnology, National Institute for Plant Biotechnology, Delhi, India
| | - Jyoti Singh
- Division of Entomology, Indian Agricultural Research Institute, New Delhi, India
| | - Vinay K Kalia
- Division of Entomology, Indian Agricultural Research Institute, New Delhi, India.
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Ding J, Cui C, Wang G, Wei G, Bai L, Li Y, Sun P, Dong L, Liu Z, Yun J, Li F, Li K, He L, Wang S. Engineered Gut Symbiotic Bacterium-Mediated RNAi for Effective Control of Anopheles Mosquito Larvae. Microbiol Spectr 2023; 11:e0166623. [PMID: 37458601 PMCID: PMC10433860 DOI: 10.1128/spectrum.01666-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/25/2023] [Indexed: 08/19/2023] Open
Abstract
Anopheles mosquitoes are the primary vectors for the transmission of malaria parasites, which poses a devastating burden on global public health and welfare. The recent invasion of Anopheles stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. To address this issue, we developed a new approach for mosquito larvae control using gut microbiota-mediated RNA interference (RNAi). We engineered a mosquito symbiotic gut bacterium, Serratia fonticola, by deleting its RNase III gene to produce double-stranded RNAs (dsRNAs) in the mosquito larval gut. We found that the engineered S. fonticola strains can stably colonize mosquito larval guts and produce dsRNAs dsMet or dsEcR to activate RNAi and effectively suppress the expression of methoprene-tolerant gene Met and ecdysone receptor gene EcR, which encode receptors for juvenile hormone and ecdysone pathways in mosquitoes, respectively. Importantly, the engineered S. fonticola strains markedly inhibit the development of A. stephensi larvae and leads to a high mortality, providing an effective dsRNA delivery system for silencing genes in insects and a novel RNAi-mediated pest control strategy. Collectively, our symbiont-mediated RNAi (smRNAi) approach offers an innovative and sustainable method for controlling mosquito larvae and provides a promising strategy for combating malaria. IMPORTANCE Mosquitoes are vectors for various diseases, imposing a significant threat to public health globally. The recent invasion of A. stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. RNA interference (RNAi) is a promising approach that uses dsRNA to silence specific genes in pests. This study presents the use of a gut symbiotic bacterium, Serratia fonticola, as an efficient delivery system of dsRNA for RNAi-mediated pest control. The knockout of RNase III, a dsRNA-specific endonuclease gene, in S. fonticola using CRISPR-Cas9 led to efficient dsRNA production. Engineered strains of S. fonticola can colonize the mosquito larval gut and effectively suppress the expression of two critical genes, Met and EcR, which inhibit mosquito development and cause high mortality in mosquito larvae. This study highlights the potential of exploring the mosquito microbiota as a source of dsRNA for RNAi-based pest control.
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Affiliation(s)
- Jinjin Ding
- School of Life Science, East China Normal University, Shanghai, China
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Chunlai Cui
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Guandong Wang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ge Wei
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Liang Bai
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Yifei Li
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Peilu Sun
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ling Dong
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Zicheng Liu
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Jiaqi Yun
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Fang Li
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Kai Li
- School of Life Science, East China Normal University, Shanghai, China
| | - Lin He
- School of Life Science, East China Normal University, Shanghai, China
| | - Sibao Wang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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7
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Charoonnart P, Taunt HN, Yang L, Webb C, Robinson C, Saksmerprome V, Purton S. Transgenic Microalgae Expressing Double-Stranded RNA as Potential Feed Supplements for Controlling White Spot Syndrome in Shrimp Aquaculture. Microorganisms 2023; 11:1893. [PMID: 37630453 PMCID: PMC10459155 DOI: 10.3390/microorganisms11081893] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
Viral infection of farmed fish and shellfish represents a major issue within the aquaculture industry. One potential control strategy involves RNA interference of viral gene expression through the oral delivery of specific double-stranded RNA (dsRNA). In previous work, we have shown that recombinant dsRNA can be produced in the chloroplast of the edible microalga Chlamydomonas reinhardtii and used to control disease in shrimp. Here, we report a significant improvement in antiviral dsRNA production and its use to protect shrimp against white spot syndrome virus (WSSV). A new strategy for dsRNA synthesis was developed that uses two convergent copies of the endogenous rrnS promoter to drive high-level transcription of both strands of the WSSV gene element in the chloroplast. Quantitative RT-PCR indicated that ~119 ng dsRNA was produced per liter of culture of the transgenic microalga. This represents an ~10-fold increase in dsRNA relative to our previous report. The engineered alga was assessed for its ability to prevent WSSV infection when fed to shrimp larvae prior to a challenge with the virus. The survival of shrimp given feed supplemented with dried alga containing the dsRNA was significantly enhanced (~69% survival) relative to a negative control (<10% survival). The findings suggest that this new dsRNA production platform could be employed as a low-cost, low-tech control method for aquaculture.
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Affiliation(s)
- Patai Charoonnart
- Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; (P.C.); (V.S.)
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathum Thani 12120, Thailand
| | - Henry Nicholas Taunt
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Luyao Yang
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Conner Webb
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Colin Robinson
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Vanvimon Saksmerprome
- Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok 10400, Thailand; (P.C.); (V.S.)
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathum Thani 12120, Thailand
| | - Saul Purton
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
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8
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Figueiredo Prates LH, Merlau M, Rühl-Teichner J, Schetelig MF, Häcker I. An Optimized/Scale Up-Ready Protocol for Extraction of Bacterially Produced dsRNA at Good Yield and Low Costs. Int J Mol Sci 2023; 24:ijms24119266. [PMID: 37298215 DOI: 10.3390/ijms24119266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
Double-stranded RNA (dsRNA) can trigger RNA interference (RNAi) and lead to directed silencing of specific genes. This natural defense mechanism and RNA-based products have been explored for their potential as a sustainable and ecofriendly alternative for pest control of species of agricultural importance and disease vectors. Yet, further research, development of new products and possible applications require a cost-efficient production of dsRNA. In vivo transcription of dsRNA in bacterial cells has been widely used as a versatile and inducible system for production of dsRNA combined with a purification step required to extract the dsRNA. Here, we optimized an acidic phenol-based protocol for extraction of bacterially produced dsRNA at low cost and good yield. In this protocol, bacterial cells are efficiently lysed, with no viable bacterial cells present in the downstream steps of the purification. Furthermore, we performed a comparative dsRNA quality and yield assessment of our optimized protocol and other protocols available in the literature and confirmed the cost-efficiency of our optimized protocol by comparing the cost of extraction and yields of each extraction method.
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Affiliation(s)
| | - Maximilian Merlau
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, 35394 Giessen, Germany
| | - Johanna Rühl-Teichner
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, 35394 Giessen, Germany
| | - Marc F Schetelig
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, 35394 Giessen, Germany
| | - Irina Häcker
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, 35394 Giessen, Germany
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9
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He L, Huang Y, Tang X. RNAi-based pest control: Production, application and the fate of dsRNA. Front Bioeng Biotechnol 2022; 10:1080576. [PMID: 36524052 PMCID: PMC9744970 DOI: 10.3389/fbioe.2022.1080576] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 11/17/2022] [Indexed: 10/21/2023] Open
Abstract
The limitations of conventional pesticides have raised the demand for innovative and sustainable solutions for plant protection. RNA Interference (RNAi) triggered by dsRNA has evolved as a promising strategy to control insects in a species-specific manner. In this context, we review the methods for mass production of dsRNA, the approaches of exogenous application of dsRNA in the field, and the fate of dsRNA after application. Additionally, we describe the opportunities and challenges of using nanoparticles as dsRNA carriers to control insects. Furthermore, we provide future directions to improve pest management efficiency by utilizing the synergistic effects of multiple target genes. Meanwhile, the establishment of a standardized framework for assessment and regulatory consensus is critical to the commercialization of RNA pesticides.
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Affiliation(s)
- Li He
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture, Ministry of Agriculture and Rural Affairs, Shanghai, China
- Shanghai Yangtze River Delta Eco-Environmental Change and Management Observation and Research Station, Ministry of Science and Technology, Ministry of Education, Shanghai, China
| | - Yanna Huang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture, Ministry of Agriculture and Rural Affairs, Shanghai, China
- Shanghai Yangtze River Delta Eco-Environmental Change and Management Observation and Research Station, Ministry of Science and Technology, Ministry of Education, Shanghai, China
| | - Xueming Tang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture, Ministry of Agriculture and Rural Affairs, Shanghai, China
- Shanghai Yangtze River Delta Eco-Environmental Change and Management Observation and Research Station, Ministry of Science and Technology, Ministry of Education, Shanghai, China
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10
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Nie W, Chen X, Tang Y, Xu N, Zhang H. Potential dsRNAs can be delivered to aquatic for defense pathogens. Front Bioeng Biotechnol 2022; 10:1066799. [PMID: 36466329 PMCID: PMC9712207 DOI: 10.3389/fbioe.2022.1066799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/03/2022] [Indexed: 10/29/2023] Open
Abstract
The use of antibiotics to facilitate resistance to pathogens in aquatic animals is a traditional method of pathogen control that is harmful to the environment and human health. RNAi is an emerging technology in which homologous small RNA molecules target specific genes for degradation, and it has already shown success in laboratory experiments. However, further research is needed before it can be applied in aquafarms. Many laboratories inject the dsRNA into aquatic animals for RNAi, which is obviously impractical and very time consuming in aquafarms. Therefore, to enable the use of RNAi on a large scale, the methods used to prepare dsRNA need to be continuously in order to be fast and efficient. At the same time, it is necessary to consider the issue of biological safety. This review summarizes the key harmful genes associated with aquatic pathogens (viruses, bacteria, and parasites) and provides potential targets for the preparation of dsRNA; it also lists some current examples where RNAi technology is used to control aquatic species, as well as how to deliver dsRNA to the target hydrobiont.
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Affiliation(s)
| | | | | | | | - Hao Zhang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, China
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11
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Hough J, Howard JD, Brown S, Portwood DE, Kilby PM, Dickman MJ. Strategies for the production of dsRNA biocontrols as alternatives to chemical pesticides. Front Bioeng Biotechnol 2022; 10:980592. [PMID: 36299286 PMCID: PMC9588923 DOI: 10.3389/fbioe.2022.980592] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/23/2022] [Indexed: 01/09/2023] Open
Abstract
Current crop pest control strategies rely on insecticidal and fungicidal sprays, plant genetic resistance, transgenes and agricultural practices. However, many insects, plant viruses, and fungi have no current means of control or have developed resistance against traditional pesticides. dsRNA is emerging as a novel sustainable method of plant protection as an alternative to traditional chemical pesticides. The successful commercialisation of dsRNA based biocontrols for effective pest management strategies requires the economical production of large quantities of dsRNA combined with suitable delivery methods to ensure RNAi efficacy against the target pest. A number of methods exist for the production and delivery of dsRNA based biocontrols and here we review alternative methods currently employed and emerging new approaches for their production. Additionally, we highlight potential challenges that will need to be addressed prior to widespread adoption of dsRNA biocontrols as novel sustainable alternatives to traditional chemical pesticides.
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Affiliation(s)
- James Hough
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingtom
| | - John D Howard
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingtom
| | - Stephen Brown
- Sheffield RNAi Screening Facility, School of Biosciences, University of Sheffield, Sheffield, United Kingtom
| | - David E Portwood
- Syngenta, Jealott's Hill International Research Centre, Bracknell, United Kingdom
| | - Peter M Kilby
- Syngenta, Jealott's Hill International Research Centre, Bracknell, United Kingdom
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingtom
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12
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Nwokeoji AO, Nwokeoji EA, Chou T, Togola A. A novel sustainable platform for scaled manufacturing of double-stranded RNA biopesticides. BIORESOUR BIOPROCESS 2022; 9:107. [PMID: 38647833 PMCID: PMC10992233 DOI: 10.1186/s40643-022-00596-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 09/22/2022] [Indexed: 04/25/2024] Open
Abstract
RNA interference (RNAi) represents one of the most conserved pathways evolved by eukaryotic cells for regulating gene expression. RNAi utilises non-translatable double-stranded RNA (dsRNA) molecules to sequester or degrade mRNA molecules gene. In RNAi, specifically designed exogenous dsRNA delivered to the cell can silence a target gene, a phenomenon that has been exploited in many functional studies and explored in biopesticide applications. The search for safe and sustainable crop pest management options drives the need to offset the effect of inorganic pesticides on biodiversity. The prospect of replacing inorganic pesticides with dsRNA crop spray is gaining popularity, enhanced by its high-target specificity and low environmental impact. However, for dsRNA to reach the pesticide market, it must be produced cost-effectively and sustainably. In this paper, we develop a high-yield expression media that generates up to 15-fold dsRNA yield compared to existing expression media utilising 1 mM IPTG. We also optimise a low-cost purification method that generates high-quality and purified dsRNA. The developed method circumvents the need for hazardous chemical reagents often found in commercial kits or commercial nucleases to eliminate contaminating DNA or single-stranded RNA (ssRNA) species. We also demonstrate that the production platform is scalable, generating 6.29 mg dsRNA from 259 mg wet E. coli cell pellet. The results also provide structural insights into the heterogeneous dsRNA species within the microbial-derived dsRNA pool. Finally, we also show that the purified 'naked' dsRNA, without prior formulation, can induce insect toxicity under field conditions. This study provides a novel, complete, low-cost process dsRNA platform with potential for application in industrial dsRNA production.
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Affiliation(s)
| | | | - Tachung Chou
- School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
- All First Technologies Co. Ltd, No.208, Longnan Rd, Pingzhen Dist, Taoyuan City, Taiwan
| | - Abou Togola
- International Institute of Tropical Agriculture (IITA) Kano Station, PMB 3112, Sabo Bakin Zuwo road, Kano, Kano State, Nigeria
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13
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Verdonckt TW, Vanden Broeck J. Methods for the Cost-Effective Production of Bacteria-Derived Double-Stranded RNA for in vitro Knockdown Studies. Front Physiol 2022; 13:836106. [PMID: 35492592 PMCID: PMC9043282 DOI: 10.3389/fphys.2022.836106] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/08/2022] [Indexed: 11/16/2022] Open
Abstract
RNA interference (RNAi) is a highly conserved pathway for the post-transcriptional regulation of gene expression. It has become a crucial tool in life science research, with promising potential for pest-management applications. To induce an RNAi response, long double-stranded RNA (dsRNA) sequences specific to the target gene must be delivered to the cells. This dsRNA substrate is then processed to small RNA (sRNA) fragments that direct the silencing response. A major obstacle to applying this technique is the need to produce sufficiently large amounts of dsRNA in a very cost-effective manner. To overcome this issue, much attention has been given to the development and optimization of biological production systems. One such system is the E. coli HT115 strain transformed with the L4440 vector. While its effectiveness at inducing knockdowns in animals through feeding of the bacteria has been demonstrated, there is only limited knowledge on the applicability of bacteria-derived dsRNA for in vitro experiments. In this paper, we describe and compare methods for the economical (43.2 €/mg) and large-scale (mg range) production of high-quality dsRNA from the HT115 bacterial system. We transformed the bacteria with constructs targeting the Helicoverpa-specific gene Dicer2 and, as a non-endogenous control, the Green Fluorescent Protein gene (GFP). First, we compared the total RNA extraction yields of four cell-lysis treatments: heating, lysozyme digestion, sonication, and a control protocol. Second, we assessed the quality and purity of these extracted dsRNAs. Third, we compared methods for the further purification of dsRNAs from crude RNA extracts. Finally, we demonstrated the efficiency of the produced dsRNAs at inducing knockdowns in a lepidopteran cell line. The insights and results from this paper will empower researchers to conduct otherwise prohibitively expensive knockdown studies, and greatly reduce the production times of routinely or large-scale utilized dsRNA substrates.
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14
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RNA Interference-Based Pesticides and Antiviral Agents: Microbial Overproduction Systems for Double-Stranded RNA for Applications in Agriculture and Aquaculture. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12062954] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RNA interference (RNAi)-based pesticides are pest control agents that use RNAi mechanisms as the basis of their action. They are regarded as environmentally friendly and are a promising alternative to conventional chemical pesticides. The effective substance in RNAi-based pesticides is double-stranded RNA (dsRNA) designed to match the nucleotide sequence of a target essential gene of the pest of concern. When taken up by the pest, this exerts an RNAi effect and inhibits some vital biochemical/biological process in the pest. dsRNA products are also expected to be applied for the control of viral diseases in aquaculture by RNAi, especially in shrimp farming. A critical issue in the practical application of RNAi agents is that production of the dsRNA must be low-cost. Here, we review recent methods for microbial production of dsRNAs using representative microorganisms (Escherichia coli, Pseudomonas syringae, Corynebacterium glutamicum, Chlamydomonas reinhardtii, and others) as host strains. The characteristics of each dsRNA production system are discussed.
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15
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Gupta D, Singh OW, Basavaraj YB, Roy A, Mukherjee SK, Mandal B. Direct Foliar Application of dsRNA Derived From the Full-Length Gene of NSs of Groundnut Bud Necrosis Virus Limits Virus Accumulation and Symptom Expression. FRONTIERS IN PLANT SCIENCE 2021; 12:734618. [PMID: 34950158 PMCID: PMC8688928 DOI: 10.3389/fpls.2021.734618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/09/2021] [Indexed: 05/31/2023]
Abstract
Groundnut bud necrosis virus (GBNV) is the most significant member of the genus Orthotospovirus occurring in the Indian subcontinent. There is hardly any effective measure to prevent GBNV in crop plants. In order to develop GBNV infection prevention procedure, we examined the effect of the direct foliar application of double-stranded RNA (dsRNA) derived from the full-length NSs gene (1,320 nucleotides) of GBNV. The bacterially expressed dsRNA to the non-structural (dsNSs) gene of GBNV was purified and delivered to plants as an aqueous suspension containing 0.01% Celite for evaluating its efficacy in preventing GBNV infection in systemic host, Nicotiana benthamiana as well as in local lesion and systemic host, cowpea cv. Pusa Komal (Vigna unguiculata). The dsNSs application and challenge-inoculation were conducted in three different combinations, where plants were challenge-inoculated with GBNV a day after, immediately, and a day before the application of dsNSs. N. benthamiana plants, which were not treated with dsRNA showed severe systemic wilting and death by 9-16 days post-inoculation (dpi). The non-treated cowpea plants exhibited many chlorotic and necrotic lesions on the cotyledonary leaves followed by systemic necrosis and death of the plants by 14-16 dpi. The dsNSs treated plants in all the combinations showed significant reduction of disease severity index in both N. benthamiana and cowpea. The treatment combination where the GBNV inoculation was conducted immediately after the dsNSs treatment was found to be the most effective treatment in preventing symptom expression. The viral RNA analysis by real time PCR also showed 20 and 12.5 fold reduction of GBNV in cowpea and N. benthamiana, respectively. Our results suggest that the foliar application of dsRNA derived from the full-length NSs gene of GBNV through Celite is successful in delivering long dsRNA leading to effective prevention of GBNV infection.
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Guan R, Chu D, Han X, Miao X, Li H. Advances in the Development of Microbial Double-Stranded RNA Production Systems for Application of RNA Interference in Agricultural Pest Control. Front Bioeng Biotechnol 2021; 9:753790. [PMID: 34589476 PMCID: PMC8473835 DOI: 10.3389/fbioe.2021.753790] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/31/2021] [Indexed: 11/21/2022] Open
Abstract
RNA interference (RNAi) is a valuable and revolutionary technology that has been widely applied in medicine and agriculture. The application of RNAi in various industries requires large amounts of low-cost double-stranded RNA (dsRNA). Chemical synthesis can only produce short dsRNAs; long dsRNAs need to be synthesized biologically. Several microbial chassis cells, such as Escherichia coli, Saccharomyces cerevisiae, and Bacillus species, have been used for dsRNA synthesis. However, the titer, rate of production, and yield of dsRNA obtained by these microorganism-based strategies is still low. In this review, we summarize advances in microbial dsRNA production, and analyze the merits and faults of different microbial dsRNA production systems. This review provides a guide for dsRNA production system selection. Future development of efficient microbial dsRNA production systems is also discussed.
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Affiliation(s)
- Ruobing Guan
- State Key Laboratory of Wheat and Maize Crop Science/College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Dongdong Chu
- State Key Laboratory of Wheat and Maize Crop Science/College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Xinyi Han
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, China
| | - Xuexia Miao
- Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, China
| | - Haichao Li
- State Key Laboratory of Wheat and Maize Crop Science/College of Plant Protection, Henan Agricultural University, Zhengzhou, China.,Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Shanghai, China
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17
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Delgado-Martín J, Velasco L. An efficient dsRNA constitutive expression system in Escherichia coli. Appl Microbiol Biotechnol 2021; 105:6381-6393. [PMID: 34415390 DOI: 10.1007/s00253-021-11494-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 07/22/2021] [Accepted: 08/03/2021] [Indexed: 11/24/2022]
Abstract
Synthetic dsRNA are valuable tools for reverse genetics research and virus silencing applications. Its synthesis can be performed both in vivo or in vitro. Whilst the latter presents the drawback of high production cost, the former has the advantage of being less expensive and suitable for scalable production. In general, dsRNAs are obtained in vivo from Escherichia coli heterologous systems that require the gene for the T7 RNA polymerase inducible by IPTG. The (ds)RNAs for gene of interest are then synthesized under the T7 promoter. In this work, we present a reliable vector system that includes the insulated promoter proD for the constitutive expression of dsRNA in E. coli that does not require any inducer and that renders elevated dsRNA yield. In tandem, the T7 and proD promoters render the highest dsRNA yield. The accumulation of dsRNA in this system entails a high metabolic cost for the cell. Bacterial RNA extractions that included dsRNAs homologous to the m5GFPer gene and derived from both the synthetic and constitutive promoters induce silencing of GFP expression in Nicotiana benthamiana 16c.Key points• A vector system that includes a constitutive promoter and a T7 promoter in tandem for maximizing dsRNA synthesis.• The metabolic cost for bacteria is maximum when the two promoters are operating simultaneously and results from the accumulation of dsRNA.• Bacterial RNA extractions from both the induced and constitutive systems that include a mGFP5er-derived dsRNA are capable of silencing the GFP expression in Nicotiana benthamiana 16c plants.
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Affiliation(s)
- Josemaría Delgado-Martín
- Plant Protection, Centro de Málaga, Instituto Andaluz de Investigación Y Formación Agraria (IFAPA), Churriana, 29140, Málaga, Spain
- Universidad de Málaga, Málaga, Spain
| | - Leonardo Velasco
- Plant Protection, Centro de Málaga, Instituto Andaluz de Investigación Y Formación Agraria (IFAPA), Churriana, 29140, Málaga, Spain.
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18
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Ortolá B, Cordero T, Hu X, Daròs JA. Intron-assisted, viroid-based production of insecticidal circular double-stranded RNA in Escherichia coli. RNA Biol 2021; 18:1846-1857. [PMID: 33472518 PMCID: PMC8582998 DOI: 10.1080/15476286.2021.1872962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
RNA interference (RNAi) is a natural mechanism for protecting against harmful genetic elements and regulating gene expression, which can be artificially triggered by the delivery of homologous double-stranded RNA (dsRNA). This mechanism can be exploited as a highly specific and environmentally friendly pest control strategy. To this aim, systems for producing large amounts of recombinant dsRNA are necessary. We describe a system to efficiently produce large amounts of circular dsRNA in Escherichia coli and demonstrate the efficient insecticidal activity of these molecules against Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte), a highly damaging pest of corn crops. In our system, the two strands of the dsRNA are expressed in E. coli embedded within the very stable scaffold of Eggplant latent viroid (ELVd), a small circular non-coding RNA. Stability in E. coli of the corresponding plasmids with long inverted repeats was achieved by using a cDNA coding for a group-I autocatalytic intron from Tetrahymena thermophila as a spacer. RNA circularization and large-scale accumulation in E. coli cells was facilitated by co-expression of eggplant tRNA ligase, the enzyme that ligates ELVd during replication in the host plant. The inserted intron efficiently self-spliced from the RNA product during transcription. Circular RNAs containing a dsRNA moiety homologous to smooth septate junction 1 (DvSSJ1) gene exhibited excellent insecticide activity against WCR larvae. Finally, we show that the viroid scaffold can be separated from the final circular dsRNA product using a second T. thermophila self-splicing intron in a permuted form.
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Affiliation(s)
- Beltrán Ortolá
- Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universitat Politècnica de Valencia), Valencia, Spain
| | - Teresa Cordero
- Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universitat Politècnica de Valencia), Valencia, Spain
| | - Xu Hu
- Corteva Agriscience, Johnston, Iowa, USA
| | - José-Antonio Daròs
- Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universitat Politècnica de Valencia), Valencia, Spain
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19
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Cagliari D, Dias NP, Galdeano DM, dos Santos EÁ, Smagghe G, Zotti MJ. Management of Pest Insects and Plant Diseases by Non-Transformative RNAi. FRONTIERS IN PLANT SCIENCE 2019; 10:1319. [PMID: 31708946 PMCID: PMC6823229 DOI: 10.3389/fpls.2019.01319] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 09/23/2019] [Indexed: 05/17/2023]
Abstract
Since the discovery of RNA interference (RNAi), scientists have made significant progress towards the development of this unique technology for crop protection. The RNAi mechanism works at the mRNA level by exploiting a sequence-dependent mode of action with high target specificity due to the design of complementary dsRNA molecules, allowing growers to target pests more precisely compared to conventional agrochemicals. The delivery of RNAi through transgenic plants is now a reality with some products currently in the market. Conversely, it is also expected that more RNA-based products reach the market as non-transformative alternatives. For instance, topically applied dsRNA/siRNA (SIGS - Spray Induced Gene Silencing) has attracted attention due to its feasibility and low cost compared to transgenic plants. Once on the leaf surface, dsRNAs can move directly to target pest cells (e.g., insects or pathogens) or can be taken up indirectly by plant cells to then be transferred into the pest cells. Water-soluble formulations containing pesticidal dsRNA provide alternatives, especially in some cases where plant transformation is not possible or takes years and cost millions to be developed (e.g., perennial crops). The ever-growing understanding of the RNAi mechanism and its limitations has allowed scientists to develop non-transgenic approaches such as trunk injection, soaking, and irrigation. While the technology has been considered promising for pest management, some issues such as RNAi efficiency, dsRNA degradation, environmental risk assessments, and resistance evolution still need to be addressed. Here, our main goal is to review some possible strategies for non-transgenic delivery systems, addressing important issues related to the use of this technology.
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Affiliation(s)
- Deise Cagliari
- Laboratory of Molecular Entomology, Department of Crop Protection, Federal University of Pelotas, Pelotas, Brazil
- *Correspondence: Deise Cagliari, ; Guy Smagghe, ; Moisés João Zotti,
| | - Naymã P. Dias
- Laboratory of Molecular Entomology, Department of Crop Protection, Federal University of Pelotas, Pelotas, Brazil
| | | | - Ericmar Ávila dos Santos
- Laboratory of Molecular Entomology, Department of Crop Protection, Federal University of Pelotas, Pelotas, Brazil
| | - Guy Smagghe
- Department of Plants and Crops, Ghent University, Ghent, Belgium
- *Correspondence: Deise Cagliari, ; Guy Smagghe, ; Moisés João Zotti,
| | - Moisés João Zotti
- Laboratory of Molecular Entomology, Department of Crop Protection, Federal University of Pelotas, Pelotas, Brazil
- *Correspondence: Deise Cagliari, ; Guy Smagghe, ; Moisés João Zotti,
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