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Zhang H, Chen J, Gao J, Zhang Q, Liu X, Han Z. New insights into transmission pathways and possible off-target effects of insecticidal dsRNA released by treated plants. Pestic Biochem Physiol 2022; 188:105281. [PMID: 36464336 DOI: 10.1016/j.pestbp.2022.105281] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/29/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
RNAi has shown great potential in controlling pests and pathogens, and dsRNA-based pesticides have been used in different ways. Due to off-target effects, the transmission pathways and possible impacts of dsRNA on non-target organisms after release should be researched. Here, we tested pathways of dsRNA transmission through the rice-hopper-spider food chain and their efficiency for triggering RNAi. The results revealed five new pathways by which plants transfer dsRNA into the environment through the food chain. We found that ingestion of the tissues or guttation droplets of treated plant could trigger both targeted and off-target RNAi both in consumers and predators. Ingestion of consumer hoppers could also result in localized RNAi in the midguts of the predator spiders. Trace amounts of dsRNA were detected in plant root excretions and in hopper honeydew. Cutting the root tips dramatically increased the levels of dsRNA in root excretions. Host shifting experiments proved that hoppers could transfer a trace amount of dsRNA via vomit. With specially designed dsRNAs, we showed that dsRNA sharing matching sequences of 29 bp or 32 bp in length with non-target genes could trigger off-target RNAi, but that dsRNA sharing 13 bp matching sequences could not. We conclude that field-released pesticidal dsRNA could be transmitted via the hydrophilic transport system in plants, and that this may pose a safety risk to non-target animal consumers that are closely related to target pests. Rational use of pesticidal dsRNAs should involve careful consideration of dsRNA design to manage the biosafety risk.
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Affiliation(s)
- Hainan Zhang
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects/Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiasheng Chen
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects/Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; School of Plant Protection, Anhui Agricultural University, Hefei 230036, China
| | - Jing Gao
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects/Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Qi Zhang
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects/Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaolong Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Zhaojun Han
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects/Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
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Schlemmer T, Lischka R, Wegner L, Ehlers K, Biedenkopf D, Koch A. Extracellular vesicles isolated from dsRNA-sprayed barley plants exhibit no growth inhibition or gene silencing in Fusarium graminearum. Fungal Biol Biotechnol 2022; 9:14. [PMID: 35836276 PMCID: PMC9284790 DOI: 10.1186/s40694-022-00143-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 06/14/2022] [Indexed: 11/11/2022] Open
Abstract
Numerous reports have shown that incorporating a double-stranded RNA (dsRNA)-expressing transgene into plants or applying dsRNA by spraying it onto their leaves successfully protects them against invading pathogens exploiting the mechanism of RNA interference (RNAi). How dsRNAs or siRNAs are transferred between donor host cells and recipient fungal cells is largely unknown. It is speculated that plant extracellular vesicles (EVs) function as RNA shuttles between plants and their pathogens. Recently, we found that EVs isolated from host-induced gene silencing (HIGS) or spray-induced gene silencing (SIGS) plants contained dsRNA-derived siRNAs. In this study, we evaluated whether isolated EVs from dsRNA-sprayed barley (Hordeum vulgare) plants affected the growth of the phytopathogenic ascomycete Fusarium graminearum. Encouraged by our previous finding that dropping barley-derived EVs on F. graminearum cultures caused fungal stress phenotypes, we conducted an in vitro growth experiment in microtiter plates where we co-cultivated F. graminearum with plant EVs isolated from dsRNA-sprayed barley leaves. We observed that co-cultivation of F. graminearum macroconidia with barley EVs did not affect fungal growth. Furthermore, plant EVs containing SIGS-derived siRNA appeared not to affect F. graminearum growth and showed no gene silencing activity on F. graminearum CYP51 genes. Based on our findings, we concluded that either the amount of SIGS-derived siRNA was insufficient to induce target gene silencing in F. graminearum, indicating that the role of EVs in SIGS is minor, or that F. graminearum uptake of plant EVs from liquid cultures was inefficient or impossible.
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Affiliation(s)
- Timo Schlemmer
- Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology, Justus Liebig University, Heinrich-Buff-Ring 26, 35392, Giessen, Germany.,Institute of Phytomedicine, University of Hohenheim, Otto-Sander-Strasse 5, 70599, Stuttgart, Germany
| | - Richard Lischka
- Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology, Justus Liebig University, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Linus Wegner
- Intitute of Botany, Justus Liebig University, Heinrich-Buff-Ring 38, 35292, Giessen, Germany
| | - Katrin Ehlers
- Intitute of Botany, Justus Liebig University, Heinrich-Buff-Ring 38, 35292, Giessen, Germany
| | - Dagmar Biedenkopf
- Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology, Justus Liebig University, Heinrich-Buff-Ring 26, 35392, Giessen, Germany
| | - Aline Koch
- Institute of Phytomedicine, University of Hohenheim, Otto-Sander-Strasse 5, 70599, Stuttgart, Germany.
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