Synthetic Nanoscale RNAi Constructs as Pesticides for the Control of Locust Migratoria

Assessing nanoparticle-enabled dsRNA delivery for oral RNAi in two orthopteran pests: Schistocerca gregaria and Melanoplus sanguinipes

Locusts and pest grasshoppers (Orthoptera: Acrididae) cause significant economic losses to agricultural crops and rangeland forage and can even cause humanitarian crises during periodic plagues. Current management methods for these insects rely heavily on broad-spectrum chemical insecticides and growth regulators, which can affect non-target organisms and may eventually develop resistance in the targeted species. Therefore, we assessed the potential of RNA interference (RNAi)-based alternative strategies that could supplement the current management methods. In insects, RNAi efficiency is known to vary with the method of double-stranded RNA (dsRNA) delivery. In this study, we tested two different delivery methods (injection and oral feeding) in the desert locust (Schistocerca gregaria) and the migratory grasshopper (Melanoplus sanguinipes) and showed that both species are sensitive to the injection but not to the oral feeding of dsRNA, likely due to high nuclease activity or poor uptake in the midgut. To address these limitations, we explored the utility of using nanoparticles that are often used for drug delivery in humans as a carrier (poly lactic-co-glycolic acid [PLGA] and poly(L-arginine)-polyethylene glycol [PLA-PEG]) for orally delivering dsRNA to the insect pests. Although the PLGA nanoparticles successfully permeated the digestive system into the hemolymph and the PLA-PEG-dsRNA complexes remained stable in the midgut juice and were detected in the fat body, neither dsRNA-encapsulating nanoparticle elicited gene knockdown upon oral feeding. These results suggest that nanoparticle-based oral delivery improves dsRNA stability and midgut permeation. However, additional barriers must be overcome to achieve efficient oral RNAi in these orthopteran pest species.

Engineered nanotransporters for efficient RNAi delivery in plant protection applications

RNA interference (RNAi) is increasingly used for plant protection against pathogens and pests. However, the traditional delivery method causes plant tissue damage, is affected by environmental factors, and faces difficulties in penetrating the barriers of cell walls and the limitations of plant species, ultimately leading to low delivery efficiency. With advances in nanotechnology, nanomaterials (NMs) have been identified as effective carriers for nucleic acid delivery because of their ability to operate independently of external mechanical forces, prevent degradation by bioenzymes, exhibit good biocompatibility, and offer high loading capacity. This review summarizes the application of NM-mediated RNAi against plant pathogens and pests, focusing on how different NMs break through the cell barriers of plants, pathogens, and pests according to their size, morphology, and charge characteristics. Furthermore, we discuss the advantages and improvement strategies of NMs as nucleic acid delivery carriers, alongside assessing their potential application for the management of plant pathogens and pests.

pH-responsive nanoparticles for oral delivery of RNAi for sustained protection against Spodoptera exigua

To enhance the RNAi efficiency of dsRNA against the Spodoptera exigua through a feeding method, we developed a pH-responsive nanoparticle, chitosan-polyethylene glycol-carboxyl (CS-PEG-COOH). This nanoparticle enhances RNAi efficiency by improving dsRNA stability in the midgut of S. exigua and can intelligently release dsRNA under alkaline conditions. Firstly, the CS-PEG-COOH carrier was prepared via cross-linking reactions, and the mass ratio of dsRNA to CS-PEG-COOH was obtained using electrophoretic mobility. The carrier composite materials were then characterized using isothermal titration calorimetry (ITC), transmission electron microscopy (TEM), atomic force microscopy (AFM), and Zeta potential analysis. The stability and delivery efficiency of the dsRNA/CS-PEG-COOH complex were then verified using electrophoretic mobility and fluorescence labeling methods. Finally, the RNAi efficiency and synergistic mechanism of the complex were analyzed using feeding methods and RNA-seq. The results show that CS-PEG-COOH (40.16 nm size, + 6.44 mV charge) forms a clustered complex with dsRNA through hydrogen bonding and hydrophobic interactions. CS-PEG-COOH significantly enhancing the stability and delivery efficiency of dsRNA in the midgut of S. exigua. Additionally, at pH > 8, dsRNA could be released from dsRNA/CS-PEG-COOH. The RNAi results showed that, dsRNA/CS-PEG-COOH could effectively inhibit the expression of the Acetylcholinesterase (Ace1 + Ace2) gene (65 %), and led to significantly increase mortality (51.82 %), a prolonged developmental period (25 %) and reduced egg production (22.02 %). The physiological and molecular synergistic mechanisms were revealed by RNA-seq analysis. The CS-PEG-COOH-loaded dsACE1 + dsACE2 led to down-regulation of genes related to drug metabolism, hormone synthesis, and stratum corneum biosynthesis, which inhibited insect growth and development. Overall, We developed an appropriate delivery method for dsRNA application in Lepidoptera, providing a basis for developing RNA pesticides with high efficiency and environmental safety.

Nanocarrier-mediated transdermal delivery of Lmidgf4 dsRNA expedites biological control of locusts by Beauveria bassiana

Locusts have been a major global agricultural pest that poses a serious threat to crop and livestock production. Entomopathogenic fungi (EPF) provide an eco-friendly control method; however, their efficacy usually takes slow and is unstable. To achieve an enhancement of the biocontrol efficacy of Beauveria bassiana (B. bassiana) against locusts, we developed a new strategy by which B. bassiana and nanocarrier-mediated dsRNA are co-applied across the locust cuticle. The nanocarrier star polycation (SPc) effectively delivers Lmidgf4 dsRNA (dsLmidgf4) into the locust, which targets Locusta migratoria imaginal disc growth factor 4 (Lmidgf4). SPc protects dsLmidgf4 from degradation by the hemolymph and enables efficient gene silencing. Furthermore, SPc has no adverse effects on B. bassiana spore germination and growth. Lmidgf4 interference leads to a thinner layer of endocuticle, thus facilitates infection of B. bassiana, and finally reduces the median lethal time of locusts infected with B. bassiana. In conclusion, the combination of B. bassiana and dsRNA/SPc complex overcomes the slow action of fungi, providing a novel strategy for field control of locusts.

PEI-SWNT improves RNAi efficiency in Locusta migratoria via dsRNA injection delivery system

The instability of double-stranded RNA (dsRNA) restricts the application of RNA interference (RNAi) technology in agricultural pest management. Various types of nanocarriers have been developed and employed for the stable delivery of dsRNA. Nonetheless, it remains unclear which type of nanomaterial could deliver dsRNA stably and efficiently for gene knockdown in Locusta migratoria. In this study, we evaluated the ability of three biocompatible and low-toxicity inorganic nanomaterials-polyethylenimine (PEI)-functionalized single-walled carbon nanotube (PEI-SWNT), polyethylenimine-functionalized carbon quantum dots (PEI-CQDs), and layered double hydroxide (LDH)-to bind and stabilize dsRNA. The results revealed that, compared to PEI-CQDs and LDH, PEI-SWNT more effectively protected dsRNA from degradation in locust gut fluids, across various temperatures, and under different pH conditions. Furthermore, we investigated the efficacy of PEI-SWNT/dsRNA complexes in suppressing endogenous genes in locusts through both injection and oral administration methods. Compared to bare dsRNA, PEI-SWNT/dsRNA complexes enhanced RNAi efficiency by up to 46.0 % and increased mortality by up to 39.0 %. Moderate levels of PEI-SWNT could improve the germination rate of wheat, while not affecting leaf growth in the short term. To our knowledge, this study is the first to apply PEI-SWNT inorganic nanomaterials in insects, which provides a foundational basis and compelling evidence for the development of nanomaterial-based nucleic acid pesticides.

Coat protein I genes are essential for the morphogenesis of the intestinal tract in Locusta migratoria

The coat protein I (COPI) complex is crucial in several significant physiological processes in eukaryotes. The assembly of COPI vesicles is initiated by the recruitment of adenosine diphosphate-ribosylation factor 1 (Arf1) to the membrane. Previous studies have primarily focused on the roles of COPI in yeast, humans, insects, and beyond Drosophila. However, the function of COPI during the development of insects remains largely unknown. In this study, we first identified eight COPI assembly genes, including α-, β-, β'-, γ-, δ-, ε-, ζ-COPI, and Arf1 in Locusta migratoria. Quantitative reverse-transcription polymerase chain reaction revealed that these genes were uniformly expressed in multiple tissues, including wing pads, leg, foregut, midgut, hindgut, and gastric cecum, and on all developmental days in 5th-instar nymphs. The injection of double-stranded RNAs (dsRNAs) against LmCOPI and LmArf1 induced high silencing efficiency in the 3rd- and 5th-instar nymphs. Locusts treated with dsLmCOPIs and dsLmArf1 exhibited feeding cessation, leading to 100 % mortality. LmCOPIs and LmArf1 knockdown resulted in midgut and gastric cecum atrophy. Histological observation and hematoxylin-eosin staining indicated that the midgut and gastric cecum exhibited deformed structures, with defective microvilli and midgut peritrophic matrix. These results suggest that LmCOPIs and LmArf1 significantly affect the intestinal tract morphogenesis in locust nymphs. Thus, COPI assembly genes are promising RNA interference targets for managing L. migratoria, reducing the dependence on chemical pesticides for pest control.

Nano-delivery platform with strong protection and efficient delivery: preparation of self-assembled RNA pesticide with dual RNAi targets against Apolygus lucorum

BACKGROUND

RNA pesticide is regarded as the "third revolution in the history of pesticides". However, the double-stranded RNA (dsRNA) is easily degraded in the environment, and its delivery efficiency is not sufficient for pest management. This study aimed to construct a star polycation (SPc)-based delivery platform with strong protection and efficient delivery to develop a self-assembled RNA pesticide with dual RNA interference (RNAi) targets.

RESULTS

The nanocarrier SPc was applied to assemble with dsRNA via electrostatic interaction, hydrogen bond and Van der Waals force, and the self-complexation with SPc formed nanoscale dsRNA/SPc complex. The SPc could protect the dsRNA from the degradation by midgut fluid or RNase A, thus significantly increasing the stability of dsRNA under various environmental conditions. Meanwhile, the SPc was able to improve the translocation of dsRNA across insect cuticle, and increase its plant uptake. Then, dsECR-A and dsTre-1 fragments were individually screened, and the dsECR-A and dsTre-1 fragments with good control effects were co-expressed in pET28-BL21 (DE3) RNase III - system to prepare the dsECR-A + Tre-1/SPc complex. Both topical application and spraying of dsECR-A + Tre-1/SPc complex could effectively control a piercing-sucking agricultural pest Apolygus lucorum. The SPc-loaded dsECR-A + Tre-1 could up-regulate endocytosis-related genes and down-regulate cuticle biosynthesis-related genes, which primarily inhibited insect growth and development.

CONCLUSIONS

Our study comprehensively demonstrated the advantages of SPc-based dsRNA delivery platform, and developed a self-assembled RNA pesticide with dual RNAi targets, which provided a reference for the design of novel RNA pesticides.

Characterization of CYP303A1 and its potential application based on ZIF-8 nanoparticle-wrapped dsRNA in Nilaparvata lugens (Stål)

BACKGROUND

RNA interference (RNAi) technology has been put forward as a promising method for pest control and resistance management. Mining highly efficient lethal genes and constructing stable double-stranded RNA (dsRNA) delivery systems are of great significance to improve the application potential of RNAi technology.

RESULTS

In this study, we characterized a molting-related gene, NlCYP303A1, in Nilaparvata lugens that was highly expressed in the cuticle and at the end stages of each instar in nymphs. Silencing the expression of NlCYP303A1 in N. lugens resulted in a deformed phenotype and a significant increase in mortality. Furthermore, interfering with NlCYP303A1 changed the relative expression of key genes in the chitin synthesis and degradation pathway. Finally, we used the nanocarrier zeolitic imidazolate framework-8 (ZIF-8) to load dsNlCYP303A1, forming a complex denoted as dsNlCYP303A1@ZIF-8. The results of both feeding and rice-seedling dip experiments indicated that the expression of NlCYP303A1 was dramatically and persistently suppressed by the dsNlCYP303A1@ZIF-8 treatment, compared with treatment with dsNlCYP303A1, suggesting that ZIF-8 can enhance the interference efficiency as well as the stability of dsNlCYP303A1.

CONCLUSIONS

Our results demonstrate that the lethal gene NlCYP303A1 can be employed as an excellent target for RNAi technology by loading onto a nano-delivery system, and provide new insights into the creation of innovative pest control approaches. © 2024 Society of Chemical Industry.

Advances on polymeric nanocarriers for sustainable agriculture: Enhancing dsRNA/siRNA delivery to combat agricultural pests

The application of exogenous RNA for gene-silencing strategies has gained significant traction in agriculture, offering a highly efficient and eco-friendly alternative to conventional plant protection methods. This success has been driven by advances in biotechnology, from the design of long double-stranded RNA (dsRNA) and small interfering RNA (siRNA) molecules to the development of nanocarrier systems that address the challenge of RNA delivery into plant cells. In particular, polymer-based nanocarriers have emerged as a promising solution for enhancing the stability and delivery efficiency of RNA molecules. This review provides a comprehensive overview of the current state of research on the use of polymeric nanocarriers in RNA interference (RNAi) systems for crop protection. It examines key technological developments that have enabled the effective delivery of dsRNA/siRNA to target organisms, with a focus on the unique advantages polymers offer as carriers. Recent studies highlight significant progress in the preparation, characterization, and application of polymeric nanocarriers for RNA encapsulation and delivery. The review also explores the environmental and health challenges posed by these technologies, emphasizing the need for sustainable approaches in their development. Specifically, the production of nanocarriers must adhere to the principles of green chemistry, prioritizing chemical modification routes that reduce harmful residues, such as toxic solvents. Finally, this paper discusses both the current challenges and future prospects of using polymer-based nanocarriers in sustainable agriculture, offering critical insights into their potential to transform crop protection through RNAi technologies.

Triple-transformable dynamic surroundings for programmed transportation of bio-vulnerable mRNA payloads towards systemic treatment of intractable solid tumors

The surface physiochemical properties of nanomedicine play a crucial role in modulating biointerfacial reactions in sequential biological compartments, accordingly accomplishing the desired programmed delivery scenario to intracellular targets. PEGylation, which involves modifying the surface with a layer of poly(ethylene glycol), has been validated as an effective strategy for minimizing adverse biointerfacial interactions. However, it has also been observed to impede cellular uptake and intracellular trafficking activities. To address this dilemma, we propose a dynamic surface chemistry approach that actively prevents non-specific reactions in systemic circulation, while readily facilitating cellular uptake by converting into a highly cytomembrane-adhesive state. Moreover, the surface becomes more adhesive to endolysosomal membranes, enabling translocation into the cytosol. In this study, PEGylated mRNA delivery nanoparticulates were tethered with charge-reversible polymers to create dynamic surroundings through click chemistry. Importantly, the dynamic surroundings exhibited negative charges under physiological conditions (pH 7.4). This property prevented degradation by anionic nucleases and structural disassembly induced by endogenous charged biological species. Consequently, the nanoparticles exhibited appreciable stealth function, effectively managing the first pass effect, leading to prolonged blood retention and improved bioavailabilities at targeted cells. Furthermore, the dynamic surroundings shifted towards relatively positive charges in the tumor microenvironment (pH 6.8). As a result, the nanoparticles were more likely to be taken up by tumors due to their electrostatic affinities towards polyanionic cytomembranes. Eventually, the internalized mRNA nanomedicine transformed responsive to the surrounding microenvironment into highly positive charges within acidic endolysosomes (pH 5.0), exerting explosive disruptive potencies on the endolysosomal structures, thus facilitating translocation of mRNA from the digestive endolysosomes into the targeted cytosol. Notably, the dynamic surroundings also reduced the immunogenicity of naked mRNA due to their stealthy properties and rapid endolysosomal translocation functions. In summary, our proposed unique triple-transformable dynamic surface chemistry provided an intriguing delivery scenario that overcomes sequential biological barriers, contributing to efficient expression of the encapsulated mRNA at targeted tumors.

Nanocarrier-Based Eco-Friendly RNA Pesticides for Sustainable Management of Plant Pathogens and Pests

The production of healthy agricultural products has increased the demand for innovative and sustainable plant protection technologies. RNA interference (RNAi), described as post-transcriptional gene silencing, offers great opportunities for developing RNA pesticides for sustainable disease and pest control. Compared with traditional synthesized pesticides, RNA pesticides possess many advantages, such as strong targeting, good environmental compatibility, and an easy development process. In this review, we systematically introduce the development of RNAi technology, highlight the advantages of RNA pesticides, and illustrate the challenges faced in developing high-efficiency RNA pesticides and the benefits of nanocarriers. Furthermore, we introduce the process and mechanism of nanocarrier-mediated RNAi technology, summarize the applications of RNA pesticides in controlling plant pathogens and pests, and finally outline the current challenges and future prospects. The current review provides theoretical guidance for the in-depth research and diversified development of RNA pesticides, which can promote the development and practice of nanocarrier-mediated RNAi.

Trypsin-encoding gene function of efficient star polycation nanomaterial-mediated dsRNA feeding delivery system of Grapholita molesta

BACKGROUND

Grapholita molesta is an important and harmful fruit pest worldwide, with widespread feeding hosts. Trypsin, an indispensable hydrolytic digestive protease in the insect gut, is crucial in digestion, growth and development. We analyzed the characteristics of the trypsin-encoding genes, screened for the optimal dose of RNAi mediated by nanocarriers, and investigated various indices of larval growth and development of G. molesta.

RESULTS

Gut content (GC) and RNase A degraded double-stranded RNA (dsRNA), with a faster degradation rate at higher concentrations. Star polycation (SPc) nanomaterials protected dsGFP from degradation by anion-cation binding and did not migrate through agarose gel. The key conserved motifs of the trypsin-encoding genes were similar, exhibiting high homology with those in other lepidopteran insects. An interference efficiency of ≈70% was achieved with SPc nanomaterial-mediated RNA interference with 0.05 μg dsRNA. The efficiency of continuous interference was stable. Trypsin activity, body weight of 8-day-old larvae, pupal weight and emergence rate were significantly reduced, and the larval stage was significantly prolonged.

CONCLUSION

The investigated trypsin gene is a key target gene in the growth and development of G. molesta. We investigated the efficiency and convenience of feeding SPc nanomaterials in a functional study of insects. Our results provide valuable data for the development of efficient trypsin-targeting pesticides. © 2024 Society of Chemical Industry.

Knock down to level up: Reframing RNAi for invertebrate ecophysiology

Comparative ecophysiologists strive to understand physiological problems in non-model organisms, but molecular tools such as RNA interference (RNAi) are under-used in our field. Here, we provide a framework for invertebrate ecophysiologists to use RNAi to answer questions focused on physiological processes, rather than as a tool to investigate gene function. We specifically focus on non-model invertebrates, in which the use of other genetic tools (e.g., genetic knockout lines) is less likely. We argue that because RNAi elicits a temporary manipulation of gene expression, and resources to carry out RNAi are technically and financially accessible, it is an effective tool for invertebrate ecophysiologists. We cover the terminology and basic mechanisms of RNA interference as an accessible introduction for "non-molecular" physiologists, include a suggested workflow for identifying RNAi gene targets and validating biologically relevant gene knockdowns, and present a hypothesis-testing framework for using RNAi to answer common questions in the realm of invertebrate ecophysiology. This review encourages invertebrate ecophysiologists to use these tools and workflows to explore physiological processes and bridge genotypes to phenotypes in their animal(s) of interest.

Nematicidal effects of silencing arginine kinase in the pine wood nematode, Bursaphelenchus xylophilus, determined using a dsRNA-like siRNA assembly

The pine wood nematode Bursaphelenchus xylophilus is a highly invasive species responsible for the widespread pine wilt disease. Double-stranded RNA (dsRNA) biopesticides represent a novel strategy for controlling plant-parasitic nematodes. The B. xylophilus arginine kinase (BxAK) features a conserved ATP-binding domain and exhibits nematode-specific divergence in the phylogenetic tree. Notably, whole-mount in situ hybridization signals are evident in the nematode head and middle sections, particularly in the juvenile stage before sex differentiation. In this study, we developed a novel dsRNA-like small interfering RNA (siRNA) assembly that specifically targets BxAK and presents highly nematicidal effects. The RNA interference (RNAi) efficiency achieved a 95.9 % reduction in second-stage juveniles. In bioassays, the median lethal concentrations of this siRNA assembly against B. xylophilus were 168.5 ng/μl for juveniles and 603.8 ng/μl for adults within 48 h. Moreover, transcriptomic results revealed significantly downregulated expression levels of genes related to metabolism and development, suggesting that the mode of action of BxAK silencing is related to disruptions in energy homeostasis and juvenile development. In conclusion, BxAK is a molecular target for controlling B. xylophilus, and our siRNA assembly significantly enhances RNAi efficiency and lowers the lethal concentration required, making it a promising candidate for future biocontrol applications.

RNAi-mediated knockdown of papilin gene affects the egg hatching in Nilaparvata lugens

BACKGROUND

The brown planthopper (BPH), Nilaparvata lugens, is one of the most destructive pests of rice. Owing to the rapid adaptation of BPH to many pesticides and resistant varieties, identifying putative gene targets for developing RNA interference (RNAi)-based pest management strategies has received much attention for this pest. The glucoprotein papilin is the most abundant component in the basement membranes of many organisms, and its function is closely linked to development.

RESULTS

In this study, we identified a papilin homologous gene in BPH (NlPpn). Quantitative Real-time PCR analysis showed that the transcript of NlPpn was highly accumulated in the egg stage. RNAi of NlPpn in newly emerged BPH females caused nonhatching phenotypes of their eggs, which may be a consequence of the maldevelopment of their embryos. Moreover, the transcriptomic analysis identified 583 differentially expressed genes between eggs from the dsGFP- and dsNlPpn-treated insects. Among them, the 'structural constituent of cuticle' cluster ranked first among the top 15 enriched GO terms. Consistently, ultrastructural analysis unveiled that dsNlPpn-treated eggs displayed a discrete and distorted serosal endocuticle lamellar structure. Furthermore, the hatchability of BPH eggs was also successfully reduced by the topical application of NlPpn-dsRNA-layered double hydroxide nanosheets onto the adults.

CONCLUSION

Our findings demonstrate that NlPpn is essential to maintaining the regular structure of the serosal cuticle and the embryonic development in BPH, indicating NlPpn could be a potential target for pest control during the egg stage. © 2024 Society of Chemical Industry.

Nanoparticle-mediated dsRNA delivery for precision insect pest control: a comprehensive review

Nanoparticle-based delivery systems have emerged as powerful tools in the field of pest management, offering precise and effective means of delivering double-stranded RNA (dsRNA), a potent agent for pest control through RNA interference (RNAi). This comprehensive review aims to evaluate and compare various types of nanoparticles for their suitability in dsRNA delivery for pest management applications. The review begins by examining the unique properties and advantages of different nanoparticle materials, including clay, chitosan, liposomes, carbon, gold and silica. Each material's ability to protect dsRNA from degradation and its potential for targeted delivery to pests are assessed. Furthermore, this review delves into the surface modification strategies employed to enhance dsRNA delivery efficiency. Functionalization with oligonucleotides, lipids, polymers, proteins and peptides is discussed in detail, highlighting their role in improving stability, cellular uptake, and specificity of dsRNA delivery.This review also provides valuable guidance on choosing the most suitable nanoparticle-based system for delivering dsRNA effectively and sustainably in pest management. Moreover, it identifies existing knowledge gaps and proposes potential research directions aimed at enhancing pest control strategies through the utilization of nanoparticles and dsRNA.

A Core Structural Protein That Builds the Locust Mandible with a Mechanical Gradient

Natural materials, such as locust mandibles and squid beaks, define significant mechanical gradients that have been attributed to the chemical gradients of their specialized structural proteins (SPs). However, the mechanism by which SPs form chemical gradients in these materials remains unknown. In this study, a highly abundant histidine-rich structural protein (LmMHSP) was identified in the mandible of a migratory locust (Locusta migratoria). LmMHSP was proven by both in vivo and in vitro evidence to act as a core building block of the mandible with a variety of synergistic functions including chitin binding, matrix formation via liquid-liquid phase separation, chemical cross-linking, and metal coordination. Furthermore, we found that the SP gradient in the locust mandible stems from the chitin-binding activity of LmMHSP and different microstructures of chitin scaffolds in different regions. These findings advance our understanding of the formation mechanisms of natural biomaterials and have implications for the fabrication of biomimetic materials.

An oral dsRNA delivery system based on chitosan induces G protein-coupled receptor kinase 2 gene silencing for Apolygus lucorum control

RNA interference (RNAi) is recognized as a new and environmentally friendly pest control strategy due to its high specificity. However, the RNAi efficiency is relatively low in many sucking insect pests, such as Apolygus lucorum. Therefore, there is an urgent need to develop new and effective ways of dsRNA delivery. Bacterially expressed or T7 synthesized dsRNA targeting a G Protein-Coupled Receptor Kinase 2 gene was mixed with chitosan in a 1:2 ratio by mass. The size of the chitosan/dsRNA nanoparticles was 69 ± 12 nm, and the TEM and AFM images showed typical spherical or ellipsoidal structures. The chitosan nanoparticles protected the dsRNA from nuclease activity, and pH and temperature-dependent degradation, and the fluorescently-tagged nanoparticles were found to be stable on the surface of green bean plants (48 h) (Phaseolus vulgaris) and were absorbed by midgut epithelial cells and transported to hemolymph. Once fed to the A. lucorum nymph, chitosan/dsRNA could effectively inhibit the expression of the G protein-coupled receptor kinase 2 gene (70%), and led to significantly increase mortality (50%), reduced weight (26.54%) and a prolonged developmental period (8.04%). The feeding-based and chitosan-mediated dsRNA delivery method could be a new strategy for A. lucorum management, providing an effective tool for gene silencing of piercing-sucking insects.

Recent Advances in Nanoparticle-Mediated Co-Delivery System: A Promising Strategy in Medical and Agricultural Field

Drug and gene delivery systems mediated by nanoparticles have been widely studied for life science in the past decade. The application of nano-delivery systems can dramatically improve the stability and delivery efficiency of carried ingredients, overcoming the defects of administration routes in cancer therapy, and possibly maintaining the sustainability of agricultural systems. However, delivery of a drug or gene alone sometimes cannot achieve a satisfactory effect. The nanoparticle-mediated co-delivery system can load multiple drugs and genes simultaneously, and improve the effectiveness of each component, thus amplifying efficacy and exhibiting synergistic effects in cancer therapy and pest management. The co-delivery system has been widely reported in the medical field, and studies on its application in the agricultural field have recently begun to emerge. In this progress report, we summarize recent progress in the preparation and application of drug and gene co-delivery systems and discuss the remaining challenges and future perspectives in the design and fabrication.

Core-Shell Polymeric Nanostructures with Intracellular ATP-Fueled dsRNA Delivery toward Genetic Control of Insect Pests

Transgenic RNA interference (RNAi) represents a burgeoning and promising alternative avenue to manage plant diseases and insect pests in plants. Nonviral nanostructured dsRNA carriers have been demonstrated to possess great potential to facilitate the application of RNAi. However, it remains a critical challenge to achieve the targeted and effective release of dsRNA into the pest cells, limiting the efficiency of the biological control of pests and diseases in practical applications. In this study, we designed and constructed a new type of core-shell polymeric nanostructure (CSPN) with controllable structure, eco-friendliness, and good biocompatibility, on which dsRNA can be efficiently loaded. Once loaded into CSPNs, the dsRNA can be effectively prevented from nonsense degradation by enzymes before entering cells, and it shows targeted and image-guided release triggered by intracellular ATP, which significantly increases the efficiency of gene transfection. Significantly, the in vivo study of the typical lepidoptera silkworm after oral feeding demonstrates the potential of dsCHT10 in CSPNs for a much better knockdown efficiency than that of naked dsCHT10. This innovation enables the nanotechnology developed for the disease microenvironment-triggered release of therapeutic genes for application in sustainable crop protection.