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Voloudakis AE, Kaldis A, Patil BL. RNA-Based Vaccination of Plants for Control of Viruses. Annu Rev Virol 2022; 9:521-548. [PMID: 36173698 DOI: 10.1146/annurev-virology-091919-073708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plant viruses cause nearly half of the emerging plant diseases worldwide, contributing to 10-15% of crop yield losses. Control of plant viral diseases is mainly accomplished by extensive chemical applications targeting the vectors (i.e., insects, nematodes, fungi) transmitting these viruses. However, these chemicals have a significant negative effect on human health and the environment. RNA interference is an endogenous, cellular, sequence-specific RNA degradation mechanism in eukaryotes induced by double-stranded RNA molecules that has been exploited as an antiviral strategy through transgenesis. Because genetically modified crop plants are not accepted for cultivation in several countries globally, there is an urgent demand for alternative strategies. This has boosted research on exogenous application of the RNA-based biopesticides that are shown to exhibit significant protective effect against viral infections. Such environment-friendly and efficacious antiviral agents for crop protection will contribute to global food security, without adverse effects on human health.
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Affiliation(s)
- Andreas E Voloudakis
- Laboratory of Plant Breeding and Biometry, Department of Crop Science, Agricultural University of Athens, Athens, Greece;
| | - Athanasios Kaldis
- Laboratory of Plant Breeding and Biometry, Department of Crop Science, Agricultural University of Athens, Athens, Greece;
| | - Basavaprabhu L Patil
- Division of Basic Sciences, ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka State, India
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Yang W, Wang B, Lei G, Chen G, Liu D. Advances in nanocarriers to improve the stability of dsRNA in the environment. Front Bioeng Biotechnol 2022; 10:974646. [PMID: 36051593 PMCID: PMC9424858 DOI: 10.3389/fbioe.2022.974646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 07/14/2022] [Indexed: 11/20/2022] Open
Abstract
RNAi technology, known as a revolutionary technology in the history of pesticides, has been identified as a very promising novel approach for crop protection, which is of great significance for achieving the sustainable agricultural development of the United Nations Food and Agriculture Organization. Although many studies have shown that RNA biopesticides have strong application prospects, its stability seriously restricts the commercial use. As the core component of RNAi, double-stranded RNA (dsRNA) is unstable in its natural form. Therefore, how to ensure the stability of dsRNA is one of the most significant challenges in realizing the commercial use of RNA biopesticides. Nanomaterials such as cationic polymers and lipofectamine can improve the stability of dsRNA in the environment, which has been proved. This paper reviews the recent research progress of nanomaterials that can be used to improve the environmental stability of dsRNA, and discusses the advantages and limitations of different nanomaterials combined with dsRNA, which provides reference for the selection of dsRNA nanoformulations.
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Affiliation(s)
| | | | | | | | - Dehai Liu
- *Correspondence: Dehai Liu, ; Guocan Chen,
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Uslu VV, Dalakouras A, Steffens VA, Krczal G, Wassenegger M. High-pressure sprayed siRNAs influence the efficiency but not the profile of transitive silencing. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 109:1199-1212. [PMID: 34882879 DOI: 10.1111/tpj.15625] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 11/18/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
In plants, small interfering RNAs (siRNAs) are a quintessential class of RNA interference (RNAi)-inducing molecules produced by the endonucleolytic cleavage of double-stranded RNAs (dsRNAs). In order to ensure robust RNAi, siRNAs are amplified through a positive feedback mechanism called transitivity. Transitivity relies on RNA-DIRECTED RNA POLYMERASE 6 (RDR6)-mediated dsRNA synthesis using siRNA-targeted RNA. The newly synthesized dsRNA is subsequently cleaved into secondary siRNAs by DICER-LIKE (DCL) endonucleases. Just like primary siRNAs, secondary siRNAs are also loaded into ARGONAUTE proteins (AGOs) to form an RNA-induced silencing complex reinforcing the cleavage of the target RNA. Although the molecular players underlying transitivity are well established, the mode of action of transitivity remains elusive. In this study, we investigated the influence of primary target sites on transgene silencing and transitivity using the green fluorescent protein (GFP)-expressing Nicotiana benthamiana 16C line, high-pressure spraying protocol, and synthetic 22-nucleotide (nt) long siRNAs. We found that the 22-nt siRNA targeting the 3' of the GFP transgene was less efficient in inducing silencing when compared with the siRNAs targeting the 5' and middle region of the GFP. Moreover, sRNA sequencing of locally silenced leaves showed that the amount but not the profile of secondary RNAs is shaped by the occupancy of the primary siRNA triggers on the target RNA. Our findings suggest that RDR6-mediated dsRNA synthesis is not primed by primary siRNAs and that dsRNA synthesis appears to be generally initiated at the 3'-end of the target RNA.
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Affiliation(s)
- Veli Vural Uslu
- AlPlanta-Institute for Plant Research, RLP AgroScience GmbH, Neustadt an der Weinstraße, Germany
| | - Athanasios Dalakouras
- Institute of Industrial and Forage Crops, Hellenic Agricultural Organization ELGO-DEMETER, Larissa, Greece
| | - Victor A Steffens
- AlPlanta-Institute for Plant Research, RLP AgroScience GmbH, Neustadt an der Weinstraße, Germany
| | - Gabi Krczal
- AlPlanta-Institute for Plant Research, RLP AgroScience GmbH, Neustadt an der Weinstraße, Germany
| | - Michael Wassenegger
- AlPlanta-Institute for Plant Research, RLP AgroScience GmbH, Neustadt an der Weinstraße, Germany
- Centre for Organismal Studies Heidelberg, University of Heidelberg, Heidelberg, Germany
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Rank AP, Koch A. Lab-to-Field Transition of RNA Spray Applications - How Far Are We? FRONTIERS IN PLANT SCIENCE 2021; 12:755203. [PMID: 34721485 PMCID: PMC8554022 DOI: 10.3389/fpls.2021.755203] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 09/15/2021] [Indexed: 05/15/2023]
Abstract
The drastic loss of biodiversity has alarmed the public and raised sociopolitical demand for chemical pesticide-free plant production, which is now treated by governments worldwide as a top priority. Given this global challenge, RNAi-based technologies are rapidly evolving as a promising substitute to conventional chemical pesticides. Primarily, genetically modified (GM) crops expressing double-stranded (ds)RNA-mediating gene silencing of foreign transcripts have been developed. However, since the cultivation of GM RNAi crops is viewed negatively in numerous countries, GM-free exogenous RNA spray applications attract tremendous scientific and political interest. The sudden rise in demand for pesticide alternatives has boosted research on sprayable RNA biopesticides, generating significant technological developments and advancing the potential for field applications in the near future. Here we review the latest advances that could pave the way for a quick lab-to-field transition for RNA sprays, which, as safe, selective, broadly applicable, and cost-effective biopesticides, represent an innovation in sustainable crop production. Given these latest advances, we further discuss technological limitations, knowledge gaps in the research, safety concerns and regulatory requirements that need to be considered and addressed before RNA sprays can become a reliable and realistic agricultural approach.
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Affiliation(s)
| | - Aline Koch
- Institute of Phytomedicine, University of Hohenheim, Stuttgart, Germany
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Hendrix B, Zheng W, Bauer MJ, Havecker ER, Mai JT, Hoffer PH, Sanders RA, Eads BD, Caruano-Yzermans A, Taylor DN, Hresko C, Oakes J, Iandolino AB, Bennett MJ, Deikman J. Topically delivered 22 nt siRNAs enhance RNAi silencing of endogenous genes in two species. PLANTA 2021; 254:60. [PMID: 34448043 PMCID: PMC8390415 DOI: 10.1007/s00425-021-03708-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 08/16/2021] [Indexed: 05/23/2023]
Abstract
MAIN CONCLUSION 22 nt siRNAs applied to leaves induce production of transitive sRNAs for targeted genes and can enhance local silencing. Systemic silencing was only observed for a GFP transgene. RNA interference (RNAi) is a gene silencing mechanism important in regulating gene expression during plant development, response to the environment and defense. Better understanding of the molecular mechanisms of this pathway may lead to future strategies to improve crop traits of value. An abrasion method to deliver siRNAs into leaf cells of intact plants was used to investigate the activities of 21 and 22 nt siRNAs in silencing genes in Nicotiana benthamiana and Amaranthus cruentus. We confirmed that both 21 and 22 nt siRNAs were able to silence a green fluorescent protein (GFP) transgene in treated leaves of N. benthamiana, but systemic silencing of GFP occurred only when the guide strand contained 22 nt. Silencing in the treated leaves of N. benthamiana was demonstrated for three endogenous genes: magnesium cheletase subunit I (CHL-I), magnesium cheletase subunit H (CHL-H), and GENOMES UNCOUPLED4 (GUN4). However, systemic silencing of these endogenous genes was not observed. Very high levels of transitive siRNAs were produced for GFP in response to treatment with 22 nt siRNAs but only low levels were produced in response to a 21 nt siRNA. The endogenous genes tested also produced transitive siRNAs in response to 22 nt siRNAs. 22 nt siRNAs produced greater local silencing phenotypes than 21 nt siRNAs for three of the genes. These special properties of 22 nt siRNAs were also observed for the CHL-H gene in A. cruentus. These experiments suggest a functional role for transitive siRNAs in amplifying the RNAi response.
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Affiliation(s)
- Bill Hendrix
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
- Bayer U.S. LLC, Research and Development, Crop Science, Biologics Pest Control, 890 Embarcadero Drive, West Sacramento, CA, 95605, USA
| | - Wei Zheng
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Matthew J Bauer
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Ericka R Havecker
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Jennifer T Mai
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Paul H Hoffer
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
- California Governor's Office of Emergency Services, 3650 Schriever Avenue, Mather, CA, 95655, USA
| | - Rick A Sanders
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Brian D Eads
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | | | - Danielle N Taylor
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Chelly Hresko
- Bayer Crop Science, 700 Chesterfield Parkway West, Chesterfield, MO, 63017, USA
| | - Janette Oakes
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | | | - Michael J Bennett
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA
| | - Jill Deikman
- Bayer Crop Science, 37437 State Highway 16, Woodland, CA, 95695, USA.
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