Clay nanosheets for topical delivery of RNAi for sustained protection against plant viruses

Biosafety aspects of RNAi-based pests control

While the overuse of classical chemical pesticides has had a detrimental impact on the environment and human health, the discovery of RNA interference (RNAi) offered the opportunity to develop new and sustainable approaches for pest management. RNAi is a naturally occurring regulation and defense mechanism that can be exploited to effectively protect crops by silencing key genes affecting the growth, development, behavior or fecundity of pests. However, as with all technologies, there is a range of potential risks and challenges associated with the application of RNAi, such as dsRNA stability, the potential for off-target effects, the safety of non-target organisms, and other application challenges. A better understanding of the molecular mechanisms involved in RNAi and in-depth discussion and analysis of these associated safety risks, is required to limit or mitigate potential adverse effects. © 2024 Society of Chemical Industry.

Rational design of ROS scavenging and fluorescent gold nanoparticles to deliver siRNA to improve plant resistance to Pseudomonas syringae

Bacterial diseases are one of the most common issues that result in crop loss worldwide, and the increasing usage of chemical pesticides has caused the occurrence of resistance in pathogenic bacteria and environmental pollution problems. Nanomaterial mediated gene silencing is starting to display powerful efficiency and environmental friendliness for improving plant disease resistance. However, the internalization of nanomaterials and the physiological mechanisms behind nano-improved plant disease resistance are still rarely understood. We engineered the polyethyleneimine (PEI) functionalized gold nanoparticles (PEI-AuNPs) with fluorescent properties and ROS scavenging activity to act as siRNA delivery platforms. Besides the loading, protection, and delivery of nucleic acid molecules in plant mature leaf cells by PEI-AuNPs, its fluorescent property further enables the traceability of the distribution of the loaded nucleic acid molecules in cells. Additionally, the PEI-AuNPs-based RNAi delivery system successfully mediated the silencing of defense-regulated gene AtWRKY1. Compared to control plants, the silenced plants performed better resistance to Pseudomonas syringae, showing a reduced bacterial number, decreased ROS content, increased antioxidant enzyme activities, and improved chlorophyll fluorescence performance. Our results showed the advantages of AuNP-based RNAi technology in improving plant disease resistance, as well as the potential of plant nanobiotechnology to protect agricultural production.

Small Interfering RNAs (siRNAs) Negatively Impact Growth and Gene Expression of Environmentally Relevant Bacteria in In Vitro Conditions

Rising global populations have amplified food scarcity and ushered in the development of genetically modified (GM) crops containing small interference RNAs (siRNAs) that control gene expression to overcome these challenges. The use of RNA interference (RNAi) in agriculture remains controversial due to uncertainty regarding the unintended release of genetic material and downstream nontarget effects, which have not been assessed in environmental bacteria to date. To evaluate the impacts of siRNAs used in agriculture on environmental bacteria, this study assessed microbial growth and viability as well as transcription activity with and without the presence of environmental stressors. Results showed a statistically significant reduction in growth capacity and maximum biomass achieved when bacteria are exposed to siRNAs alone and with additional external stress (p < 0.05). Further transcriptomic analysis demonstrated that nutrient cycling gene activities were found to be consistently and significantly altered following siRNA exposure, particularly among carbon (xylA, FBPase, limEH, Chitinase, rgl, rgh, rgaE, mannanase, ara) and nitrogen (ureC, nasA, narB, narG, nirK) cycling genes (p < 0.05). Decreases in carbon cycling gene transcription profiles were generally significantly enhanced when siRNA exposure was coupled with nutrient or antimicrobial stress. Collectively, findings suggest that certain conditions facilitate the uptake of siRNAs from their surrounding environments that can negatively affect bacterial growth and gene expression activity, with uncertain downstream impacts on ecosystem homeostasis.

Antimicrobial efficacy of nano-particles for crop protection and sustainable agriculture

Plant diseases cause colossal crop loss worldwide and are the major yield constraining component in agriculture. Nanotechnology, which has the possible to revolutionize numerous fields of science, innovation, drug, and agriculture. Nanotechnology can be utilized for combating the plant infectious diseases and nano-materials can be utilized as transporter of dynamic elements of pesticides, host defense etc. to the pathogens. The analysis of diseases, finding of pathogens may turn out to be substantially more precise and fast with the utilization of nanosensors. As worldwide demand for food production raises against an evolving atmosphere, nanotechnology could reasonably alleviate numerous challenges in disease managing by diminishing chemical inputs and advancing quick recognition of pathogens. The major goal of this review is to increase growth and productivity using supplements with nanoparticles. (i.e., metals, metal oxides, and carbon) to treat crop diseases and make agricultural practices more productive and sustainable. Prominently, this improved crop may not only be straight connected to the diminished occurrence of pathogenic microorganisms, yet in might possibly add nutritional benefits of the nanoparticles themselves, particularly for the micronutrients important for generating host resistance.

DNA Delivery by Virus-Like Nanocarriers in Plant Cells

Tobacco mild green mosaic virus (TMGMV)-like nanocarriers were designed for gene delivery to plant cells. High aspect ratio TMGMVs were coated with a polycationic biopolymer, poly(allylamine) hydrochloride (PAH), to generate highly charged nanomaterials (TMGMV-PAH; 56.20 ± 4.7 mV) that efficiently load (1:6 TMGMV:DNA mass ratio) and deliver single-stranded and plasmid DNA to plant cells. The TMGMV-PAH were taken up through energy-independent mechanisms in Arabidopsis protoplasts. TMGMV-PAH delivered a plasmid DNA encoding a green fluorescent protein (GFP) to the protoplast nucleus (70% viability), as evidenced by GFP expression using confocal microscopy and Western blot analysis. TMGMV-PAH were inactivated (iTMGMV-PAH) using UV cross-linking to prevent systemic infection in intact plants. Inactivated iTMGMV-PAH-mediated pDNA delivery and gene expression of GFP in vivo was determined using confocal microscopy and RT-qPCR. Virus-like nanocarrier-mediated gene delivery can act as a facile and biocompatible tool for advancing genetic engineering in plants.

Using Synthetic Biology to Understand the Function of Plant Specialized Metabolites

Plant specialized metabolites (PSMs) are variably distributed across taxa, tissues, and ecological contexts; this variability has inspired many theories about PSM function, which, to date, remain poorly tested because predictions have outpaced the available data. Advances in mass spectrometry-based metabolomics have enabled unbiased PSM profiling, and molecular biology techniques have produced PSM-free plants; the combination of these methods has accelerated our understanding of the complex ecological roles that PSMs play in plants. Synthetic biology techniques and workflows are producing high-value, structurally complex PSMs in quantities and purities sufficient for both medicinal and functional studies. These workflows enable the reengineering of PSM transport, externalization, structural diversity, and production in novel taxa, facilitating rigorous tests of long-standing theoretical predictions about why plants produce so many different PSMs in particular tissues and ecological contexts. Plants use their chemical prowess to solve ecological challenges, and synthetic biology workflows are accelerating our understanding of these evolved functions.

Unveiling Dissolution Kinetics of CuO Nanofertilizer Using Bio-Based Ionic Liquids Envisaging Controlled Use Efficiency for Sustainable Agriculture

The need for sustainable agriculture amid a growing population and challenging climatic conditions is hindered by the environmental repercussions of widespread fertilizer use, resulting in the accumulation of metal ions and the loss of micronutrients. The present study provides an approach to improve the efficiency of nanofertilizers by controlling the release of copper (Cu) ions from copper oxide (CuO) nanofertilizers through bioionic liquids based on plant growth regulators (PGR-ILs). A 7-day study was conducted to understand the kinetics of Cu ion release in aqueous solution of five different PGR-ILs, with choline ascorbate ([Cho][Asc]) or choline salicylate ([Cho][Sal]) leading to 200- to 700-fold higher dissolution of Cu ions in comparison to choline indole-3-acetate ([Cho][IAA]), choline indole-3-butyrate ([Cho][IBA]), and choline gibberellate ([Cho][GA3]). The tunable diffusion of Cu ions from CuO nanofertilizers using PGR-ILs is then applied in a foliar spray study, evaluating its impact on the growth phenotype, photosynthetic parameters, and carbon dioxide (CO2) sequestration in Nicotiana tabacum in a greenhouse. The results indicate that nanoformulations with lower concentrations of Cu ions in PGR-IL solutions exhibit superior outcomes in terms of plant length, net photosynthetic rate, dry biomass yield, and CO2 sequestration, emphasizing the critical role of dissolution kinetics in determining the effectiveness of PGR-IL-based nanoformulations for sustainable agriculture.

Engineered Resistance to Tobamoviruses

Tobacco mosaic virus (TMV) was the first virus to be studied in detail and, for many years, TMV and other tobamoviruses, particularly tomato mosaic virus (ToMV) and tobamoviruses infecting pepper (Capsicum spp.), were serious crop pathogens. By the end of the twentieth and for the first decade of the twenty-first century, tobamoviruses were under some degree of control due to introgression of resistance genes into commercial tomato and pepper lines. However, tobamoviruses remained important models for molecular biology, biotechnology and bio-nanotechnology. Recently, tobamoviruses have again become serious crop pathogens due to the advent of tomato brown rugose fruit virus, which overcomes tomato resistance against TMV and ToMV, and the slow but apparently inexorable worldwide spread of cucumber green mottle mosaic virus, which threatens all cucurbit crops. This review discusses a range of mainly molecular biology-based approaches for protecting crops against tobamoviruses. These include cross-protection (using mild tobamovirus strains to 'immunize' plants against severe strains), expressing viral gene products in transgenic plants to inhibit the viral infection cycle, inducing RNA silencing against tobamoviruses by expressing virus-derived RNA sequences in planta or by direct application of double-stranded RNA molecules to non-engineered plants, gene editing of host susceptibility factors, and the transfer and optimization of natural resistance genes.

Challenges and Opportunities Arising from Host-Botrytis cinerea Interactions to Outline Novel and Sustainable Control Strategies: The Key Role of RNA Interference

The necrotrophic plant pathogenic fungus Botrytis cinerea (Pers., 1794), the causative agent of gray mold disease, causes significant losses in agricultural production. Control of this fungal pathogen is quite difficult due to its wide host range and environmental persistence. Currently, the management of the disease is still mainly based on chemicals, which can have harmful effects not only on the environment and on human health but also because they favor the development of strains resistant to fungicides. The flexibility and plasticity of B. cinerea in challenging plant defense mechanisms and its ability to evolve strategies to escape chemicals require the development of new control strategies for successful disease management. In this review, some aspects of the host-pathogen interactions from which novel and sustainable control strategies could be developed (e.g., signaling pathways, molecules involved in plant immune mechanisms, hormones, post-transcriptional gene silencing) were analyzed. New biotechnological tools based on the use of RNA interference (RNAi) are emerging in the crop protection scenario as versatile, sustainable, effective, and environmentally friendly alternatives to the use of chemicals. RNAi-based fungicides are expected to be approved soon, although they will face several challenges before reaching the market.

Exogenous Application of dsRNA in Plant Protection: Efficiency, Safety Concerns and Risk Assessment

The use of double-stranded RNA (dsRNA) for plant protection shows great potential as a sustainable alternative to traditional pesticides. This review summarizes the current state of knowledge on using exogenous dsRNA in plant protection and includes the latest findings on the safety and efficiency of this strategy. The review also emphasizes the need for a cautious and comprehensive approach, considering safety considerations such as off-target effects and formulation challenges. The regulatory landscape in different regions is also discussed, underscoring the need for specific guidelines tailored to dsRNA-based pesticides. The review provides a crucial resource for researchers, regulators, and industry stakeholders, promoting a balanced approach incorporating innovation with thorough safety assessments. The continuous dialog emphasized in this review is essential for shaping the future of dsRNA-based plant protection. As the field advances, collaboration among scientists, regulators, and industry partners will play a vital role in establishing guidelines and ensuring the responsible, effective, and sustainable use of dsRNA in agriculture.

Harnessing Multiscale Physiochemical Interactions on Nanobiointerface for Enhanced Stress Resilience in Rice

Nanoagrochemicals present promising solutions for augmenting conventional agriculture, while insufficient utilization of nanobiointerfacial interactions hinders their field application. This work investigates the multiscale physiochemical interactions between nanoagrochemicals and rice (Oryza sativa L.) leaves and devises a strategy for elevating targeting efficiency of nanoagrochemicals and stress resilience of rice. We identified multiple deposition behaviors of nanoagrochemicals on hierarchically structured leaves and demonstrated the crucial role of leaf microarchitectures. A transition from the Cassie-Baxter to the Wenzel state significantly changed the deposition behavior from superlattice assembly, ring-shaped aggregation to uniform monolayer deposition. By fine-tuning the formulation properties, we achieved a 415.9-fold surge in retention efficiency, and enhanced the sustainability of nanoagrochemicals by minimizing loss during long-term application. This biointerface design significantly relieved the growth inhibition of Cd(II) pollutant on rice plants with a 95.2% increase in biomass after foliar application of SiO2 nanoagrochemicals. Our research elucidates the intricate interplay between leaf structural attributes, nanobiointerface design, and biological responses of plants, fostering field application of nanoagrochemicals.

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.

Biochemical and nanotechnological approaches to combat phytoparasitic nematodes

The foundation of most food production systems underpinning global food security is the careful management of soil resources. Embedded in the concept of soil health is the impact of diverse soil-borne pests and pathogens, and phytoparasitic nematodes represent a particular challenge. Root-knot nematodes and cyst nematodes are severe threats to agriculture, accounting for annual yield losses of US$157 billion. The control of soil-borne phytoparasitic nematodes conventionally relies on the use of chemical nematicides, which can have adverse effects on the environment and human health due to their persistence in soil, plants, and water. Nematode-resistant plants offer a promising alternative, but genetic resistance is species-dependent, limited to a few crops, and breeding and deploying resistant cultivars often takes years. Novel approaches for the control of phytoparasitic nematodes are therefore required, those that specifically target these parasites in the ground whilst minimizing the impact on the environment, agricultural ecosystems, and human health. In addition to the development of next-generation, environmentally safer nematicides, promising biochemical strategies include the combination of RNA interference (RNAi) with nanomaterials that ensure the targeted delivery and controlled release of double-stranded RNA. Genome sequencing has identified more than 75 genes in root knot and cyst nematodes that have been targeted with RNAi so far. But despite encouraging results, the delivery of dsRNA to nematodes in the soil remains inefficient. In this review article, we describe the state-of-the-art RNAi approaches targeting phytoparasitic nematodes and consider the potential benefits of nanotechnology to improve dsRNA delivery.

Double-Stranded RNA Targeting White Mold Sclerotinia sclerotiorum Argonaute 2 for Disease Control via Spray-Induced Gene Silencing

Sclerotinia sclerotiorum, the causal agent of white mold infection, is a cosmopolitan fungal pathogen that causes major yield losses in many economically important crops. Spray-induced gene silencing has recently been shown to be a promising alternative method for controlling plant diseases. Based on our prior research, we focused on developing a spray-induced gene silencing approach to control white mold by silencing S. sclerotiorum argonaute 2 (SsAgo2), a crucial part of the fungal small RNA pathway. We compared the lesion size as a result of targeting each ∼500-bp segment of SsAgo2 from the 5' to the 3' end and found that targeting the PIWI/RNaseH domain of SsAgo2 is most effective. External application of double-stranded RNA (dsRNA)-suppressed white mold infection using either in vitro or in vivo transcripts was determined at the rate of 800 ng/0.2 cm2 area with a downregulation of SsAgo2 from infected leaf tissue confirmed by RT-qPCR. Furthermore, magnesium/iron-layered double hydroxide nanosheets loaded with in vitro- and in vivo-transcribed dsRNA segments significantly reduced the rate of S. sclerotiorum lesion expansion. In vivo-produced dsRNA targeting the PIWI/RNaseH domain of the SsAgo2 transcript showed increased efficacy in reducing the white mold symptoms of S. sclerotiorum when combined with layered double hydroxide nanosheets. This approach is promising to produce a large scale of dsRNA that can be deployed as an environmentally friendly fungicide to manage white mold infections in the field.

Tools and Techniques to Accelerate Crop Breeding

As climate changes and a growing global population continue to escalate the need for greater production capabilities of food crops, technological advances in agricultural and crop research will remain a necessity. While great advances in crop improvement over the past century have contributed to massive increases in yield, classic breeding schemes lack the rate of genetic gain needed to meet future demands. In the past decade, new breeding techniques and tools have been developed to aid in crop improvement. One such advancement is the use of speed breeding. Speed breeding is known as the application of methods that significantly reduce the time between crop generations, thereby streamlining breeding and research efforts. These rapid-generation advancement tactics help to accelerate the pace of crop improvement efforts to sustain food security and meet the food, feed, and fiber demands of the world's growing population. Speed breeding may be achieved through a variety of techniques, including environmental optimization, genomic selection, CRISPR-Cas9 technology, and epigenomic tools. This review aims to discuss these prominent advances in crop breeding technologies and techniques that have the potential to greatly improve plant breeders' ability to rapidly produce vital cultivars.

Novel Environmentally Friendly RNAi Biopesticides: Targeting V-ATPase in Holotrichia parallela Larvae Using Layered Double Hydroxide Nanocomplexes

RNA interference (RNAi)-based biopesticides offer an attractive avenue for pest control. Previous studies revealed high RNAi sensitivity in Holotrichia parallela larvae, showcasing its potential for grub control. In this study, we aimed to develop an environmentally friendly RNAi method for H. parallela larvae. The double-stranded RNA (dsRNA) of the V-ATPase-a gene (HpVAA) was loaded onto layered double hydroxide (LDH). The dsRNA/LDH nanocomplex exhibited increased environmental stability, and we investigated the absorption rate and permeability of dsRNA-nanoparticle complexes and explored the RNAi controlling effect. Silencing the HpVAA gene was found to darken the epidermis of H. parallela larvae, with growth cessation or death or mortality, disrupting the epidermis and midgut structure. Quantitative reverse transcription-polymerase chain reaction and confocal microscopy confirmed the effective absorption of the dsRNA/LDH nanocomplex by peanut plants, with distribution in roots, stems, and leaves. Nanomaterial-mediated RNAi silenced the target genes, leading to the death of pests. Therefore, these findings indicate the successful application of the nanomaterial-mediated RNAi system for underground pests, thus establishing a theoretical foundation for developing a green, safe, and efficient pest control strategy.

Enhancing iron content and growth of cucumber seedlings with MgFe-LDHs under low-temperature stress

The development of cost-effective and eco-friendly fertilizers is crucial for enhancing iron (Fe) uptake in crops and can help alleviate dietary Fe deficiencies, especially in populations with limited access to meat. This study focused on the application of MgFe-layered double hydroxide nanoparticles (MgFe-LDHs) as a potential solution. We successfully synthesized and characterized MgFe-LDHs and observed that 1-10 mg/L MgFe-LDHs improved cucumber seed germination and water uptake. Notably, the application of 10 mg/L MgFe-LDHs to roots significantly increased the seedling emergence rate and growth under low-temperature stress. The application of 10 mg/L MgFe-LDHs during sowing increased the root length, lateral root number, root fresh weight, aboveground fresh weight, and hypocotyl length under low-temperature stress. A comprehensive analysis integrating plant physiology, nutrition, and transcriptomics suggested that MgFe-LDHs improve cold tolerance by upregulating SA to stimulate CsFAD3 expression, elevating GA3 levels for enhanced nitrogen metabolism and protein synthesis, and reducing levels of ABA and JA to support seedling emergence rate and growth, along with increasing the expression and activity of peroxidase genes. SEM and FTIR further confirmed the adsorption of MgFe-LDHs onto the root hairs in the mature zone of the root apex. Remarkably, MgFe-LDHs application led to a 46% increase (p < 0.05) in the Fe content within cucumber seedlings, a phenomenon not observed with comparable iron salt solutions, suggesting that the nanocrystalline nature of MgFe-LDHs enhances their absorption efficiency in plants. Additionally, MgFe-LDHs significantly increased the nitrogen (N) content of the seedlings by 12% (p < 0.05), promoting nitrogen fixation in the cucumber seedlings. These results pave the way for the development and use of LDH-based Fe fertilizers.

Systems for Targeted Silencing of Gene Expression and Their Application in Plants and Animals

At present, there are a variety of different approaches to the targeted regulation of gene expression. However, most approaches are devoted to the activation of gene transcription, and the methods for gene silencing are much fewer in number. In this review, we describe the main systems used for the targeted suppression of gene expression (including RNA interference (RNAi), chimeric transcription factors, chimeric zinc finger proteins, transcription activator-like effectors (TALEs)-based repressors, optogenetic tools, and CRISPR/Cas-based repressors) and their application in eukaryotes-plants and animals. We consider the advantages and disadvantages of each approach, compare their effectiveness, and discuss the peculiarities of their usage in plant and animal organisms. This review will be useful for researchers in the field of gene transcription suppression and will allow them to choose the optimal method for suppressing the expression of the gene of interest depending on the research object.

Effective Control of Sclerotinia Stem Rot in Canola Plants Through Application of Exogenous Hairpin RNA of Multiple Sclerotinia sclerotiorum Genes

Sclerotinia stem rot is a globally destructive plant disease caused by Sclerotinia sclerotiorum. Current management of Sclerotinia stem rot primarily relies on chemical fungicides and crop rotation, raising environmental concerns. In this study, we developed an eco-friendly RNA bio-fungicide targeting S. sclerotiorum. Six S. sclerotiorum genes were selected for double-stranded RNA (dsRNA) synthesis. Four genes, a chitin-binding domain, mitogen-activated protein kinase, oxaloacetate acetylhydrolase, and abhydrolase-3, were combined to express hairpin RNA in Escherichia coli HT115. The effect of application of total RNA extracted from E. coli HT115 expressing hairpin RNA on disease progressive and necrosis lesions was evaluated. Gene expression analysis using real-time PCR showed silencing of the target genes using 5 ng/µl of dsRNA in a fungal liquid culture. A detached leaf assay and greenhouse application of dsRNA on canola stem and leaves showed variation in the reduction of necrosis symptoms by dsRNA of different genes, with abhydrolase-3 being the most effective. The dsRNA from a combination of four genes reduced disease severity significantly (P = 0.01). Plants sprayed with hairpin RNA from four genes had lesions that were almost 30% smaller than those of plants treated with abhydrolase-3 alone, in lab and greenhouse assays. The results of this study highlight the potential of RNA interference to manage diseases caused by S. sclerotiorum; however, additional research is necessary to optimize its efficacy.

Development and application of an RNA nanostructure to induce transient RNAi in difficult transgenic plants

The development of RNA interference (RNAi) is crucial for studying plant gene function. Its use, is limited to a few plants with well-established transgenic techniques. Spray-induced gene silencing (SIGS) introduces exogenous double-stranded RNA (dsRNA) into plants by spraying, injection, or irrigation, triggering the RNAi pathway to instantly silence target genes. As is a transient RNAi technology that does not rely on transgenic methods, SIGS has significant potential for studying gene function in plants lacking advanced transgenic technology. In this study, to enhance their stability and delivery efficiency, siRNAs were used as structural motifs to construct RNA nanoparticles (NPs) of four shapes: triangle, square, pentagon, and hexagon. These NPs, when synthesized by Escherichia coli, showed that triangular and square shapes accumulated more efficiently than pentagon and hexagon shapes. Bioassays revealed that RNA squares had the highest RNAi efficiency, followed by RNA triangles, with GFP-dsRNA showing the lowest efficiency at 4 and 7 days post-spray. We further explored the use of RNA squares in inducing transient RNAi in plants that are difficult to transform genetically. The results indicated that Panax notoginseng-derived MYB2 (PnMYB2) and Camellia oleifera-derived GUT (CoGUT) were significantly suppressed in P. notoginseng and C. oleifera, respectively, following the application of PnMYB2- and CoGUT-specific RNA squares. These findings suggest that RNA squares are highly effective in SIGS and can be utilized for gene function research in plants.

Kaolinite nanoclay-shielded dsRNA drenching for management of Globodera pallida: An environmentally friendly pest management approach

Globodera pallida, an obligate sedentary endoparasite, is a major economic pest that causes substantial potato yield losses. This research aimed to study the effects of gene silencing of three FMRFamide-like peptides (FLPs) genes to reduce G. pallida infestation on potato plants by using kaolinite nanoclay as a carrier to deliver dsRNAs via drenching. A dsRNA dosage of 2.0 mg/ml silenced flp-32c by 89.5%, flp-32p by 94.6%, and flp-2 by 94.3%. J2s incubated for 5 and 10 h showed no phenotypic changes. However, J2s of G. pallida efficiently uptake dsRNA of all targeted genes after 15 h of incubation. On the other hand, J2s that had been kept for 24 h had a rigid and straight appearance. Under fluorescence microscopy, all dsRNA-treated nematodes showed fluorescein isothiocyanate (FITC) signals in the mouth, nervous system, and digestive system. The untreated population of J2s did not show any FITC signals and was mobile as usual. The drenching of potato cultivar Kufri Jyoti with the dsRNA-kaolinite formulations induced deformation and premature death of J2s, compared with untreated J2s that entered J3 or J4 stages. This study validates that the nanocarrier-delivered RNAi system could be employed effectively to manage G. pallida infestations.

RNA interference-based exogenous double-stranded RNAs confer resistance to Rhizoctonia solani AG-3 on Nicotiana tabacum

BACKGROUND

Rhizoctonia solani Kühn is a pathogenic fungus causing tobacco target spot disease, and leads to great losses worldwide. At present, resistant varieties and effective control strategy on tobacco target spot disease are very limited. Host-induced gene silencing (HIGS) as well as the exogenous dsRNA can be used to suppress disease progression, and reveal the function of crucial genes involved in the growth and pathogenesis of the fungus.

RESULTS

The silencing of endoPGs or RPMK1 in host plants by TRV-based HIGS resulted in a significant reduction in disease development in Nicotiana benthamiana. In vitro analysis validated that red fluorescence signals were consistently observed in the hyphae treated with Cy3-fluorescein-labeled dsRNA at 12, 24, 48 and 72 h postinoculation (hpi). Additionally, application of dsRNA-endoPGs, dsRNA-RPMK1 and dsRNA-PGMK (fusion of partial endoPGs and RPMK1 sequences) effectively inhibited the hyphal growth of R. solani YC-9 in vitro and suppressed disease progression in the leaves, and quantitative real-time PCR confirmed that the application of dsRNAs significantly reduced the expression levels of endoPGs and RPMK1.

CONCLUSION

These results provide theoretical basis and new direction for RNAi approaches on the prevention and control of disease caused by R. solani. © 2024 Society of Chemical Industry.

Enhancing plant biotechnology by nanoparticle delivery of nucleic acids

Plant biotechnology plays a crucial role in developing modern agriculture and plant science research. However, the delivery of exogenous genetic material into plants has been a long-standing obstacle. Nanoparticle-based delivery systems are being established to address this limitation and are proving to be a feasible, versatile, and efficient approach to facilitate the internalization of functional RNA and DNA by plants. The nanoparticle-based delivery systems can also be designed for subcellular delivery and controlled release of the biomolecular cargo. In this review, we provide a concise overview of the recent advances in nanocarriers for the delivery of biomolecules into plants, with a specific focus on applications to enhance RNA interference, foreign gene transfer, and genome editing in plants.

Methionine biosynthetic genes and methionine sulfoxide reductase A are required for Rhizoctonia solani AG1-IA to cause sheath blight disease in rice

Rhizoctonia solani is a polyphagous necrotrophic fungal pathogen that causes sheath blight disease in rice. It deploys effector molecules as well as carbohydrate-active enzymes and enhances the production of reactive oxygen species for killing host tissues. Understanding R. solani ability to sustain growth under an oxidative-stress-enriched environment is important for developing disease control strategies. Here, we demonstrate that R. solani upregulates methionine biosynthetic genes, including Rs_MET13 during infection in rice, and double-stranded RNA-mediated silencing of these genes impairs the pathogen's ability to cause disease. Exogenous treatment with methionine restores the disease-causing ability of Rs_MET13-silenced R. solani and facilitates its growth on 10 mM H2O2-containing minimal-media. Notably, the Rs_MsrA gene that encodes methionine sulfoxide reductase A, an antioxidant enzyme involved in the repair of oxidative damage of methionine, is upregulated upon H2O2 treatment and also during infection in rice. Rs_MsrA-silenced R. solani is unable to cause disease, suggesting that it is important for the repair of oxidative damage in methionine during host colonization. We propose that spray-induced gene silencing of Rs_MsrA and designing of antagonistic molecules that block MsrA activity can be exploited as a drug target for effective control of sheath blight disease in rice.

Synthesis of eco-friendly layered double hydroxide and nanoemulsion for jasmine and peppermint oils and their larvicidal activities against Culex pipiens Linnaeus

Mosquito-borne diseases represent a growing health challenge over time. Numerous potential phytochemicals are target-specific, biodegradable, and eco-friendly. The larvicidal activity of essential oils, a jasmine blend consisting of Jasmine oil and Azores jasmine (AJ) (Jasminum sambac and Jasminum azoricum) and peppermint (PP) Mentha arvensis and their nanoformulations against 2nd and 4th instar larvae of Culex pipiens, was evaluated after subjecting to different concentrations (62.5, 125, 250, 500, 1000, and 2000 ppm). Two forms of phase-different nanodelivery systems of layered double hydroxide LDH and oil/water nanoemulsions were formulated. The synthesized nanoemulsions showed particle sizes of 199 and 333 nm for AJ-NE and PP-NE, with a polydispersity index of 0.249 and 0.198, respectively. Chemical and physiochemical analysis of TEM, SEM, XRD, zeta potential, drug loading capacity, and drug release measurements were done to confirm the synthesis and loading efficiencies of essential oils' active ingredients. At high concentrations of AJ and PP nanoemulsions (2000 ppm), O/W nanoemulsions showed higher larval mortality than both LDH conjugates and crude oils. The mortality rate reached 100% for 2nd and 4th instar larvae. The relative toxicities revealed that PP nanoemulsion (MA-NE) was the most effective larvicide, followed by AJ nanoemulsion (AJ-NE). There was a significant increase in defensive enzymes, phenoloxidase, and α and β-esterase enzymes in the treated groups. After treatment of L4 with AJ, AJ-NE, PP, and PP-NE, the levels of phenoloxidase were 545.67, 731.00, 700.00, and 799.67 u/mg, respectively, compared with control 669.67 u/mg. The activity levels of α-esterase were 9.71, 10.32, 8.91, and 10.55 mg α-naphthol/min/mg protein, respectively. It could be concluded that the AJ-NE and PP-NE nanoformulations have promising larvicidal activity and could act as safe and effective alternatives to chemical insecticides.

Graphene Quantum Dots (GQD)-Mediated dsRNA Delivery for the Control of Fusarium Head Blight Disease in Wheat

Graphene quantum dots (GQDs), a class of fluorescent carbon materials, have displayed significant potential in various fields such as energy devices, catalysis, sensing, bioimaging, and drug delivery. Because of their extremely small size, generally less than 100 nm, they also have tremendous potential in plant science research, especially for the delivery of nucleic acids, breaking the barrier of cell walls. In this study, we synthesized GQDs with a size range of 2-5 nm, characterized them, and surface-functionalized them with branched polyethylenimine (bPEI). We then used the surface-functionalized GQDs as carriers to deliver double-stranded RNA (dsRNA) that target two growth-and-development-related genes in Fusarium graminearum─the causative organism of the Fusarium head blight disease of wheat. The successful binding of dsRNA to GQDs-bPEIs was demonstrated through gel-shifting assays, showcasing the potential for efficient dsRNA delivery. We designed dsRNAs targeting the MGV1 and RAS1 genes of F. graminearum by using the pssRNAit pipeline, ensuring high specificity and no off-target effects. The coding sequences of the designed dsRAS1 and dsMGV1 were cloned into the L4440 vector and transformed into the Escherichia coli HT115 strain for dsRNA production. Fungal culture analysis revealed that the inclusion of dsRNAs in potato dextrose agar (PDA) media effectively slowed down the growth. Exogenous spraying experiments both in plate cultures and in intact wheat spikes demonstrated that the dsRNA:GQDs-bPEIs treatment was more effective in restricting fungal mycelium growth or the number of infected spikelets compared to naked dsRNA treatment. Our study demonstrates the promising potential of graphene quantum dots as carriers for dsRNA-based fungal disease management in wheat and other crops.

Application of TNB in dual photo-controlled release of phenamacril, imidacloprid, and imidacloprid synergist

Pesticides can improve crops' yield and quality, but unreasonable applications of pesticides lead to waste of pesticides which are further accumulated in the environment and threaten human health. Developing the release of controlled drugs can improve the utilization rate of pesticides. Among these methods, light-controlled release is a new technology of controlled release, which can realize spatiotemporal delivery of drugs by light. Four compounds, named Imidacloprid-Thioacetal o-nitrobenzyl-Phenamacril (IMI-TNB-PHE), Imidacloprid-Thioacetal o-nitrobenzyl- Imidacloprid (IMI-TNB-IMI), Phenamacril-Thioacetal o-nitrobenzyl-Phenamacril (PHE-TNB-PHE), and Imidacloprid-Thioacetal o-nitrobenzyl-Imidacloprid Synergist (IMI-TNB-IMISYN), were designed and synthesized by connecting thioacetal o-nitrobenzyl (TNB) with pesticides TNB displaying simple and efficient optical properties in this work. Dual photo-controlled release of pesticides including two molecules of IMI or PHE, both IMI and PHE, as well as IMI and IMISYN were, respectively, studied in this paper. Insecticidal/fungicidal activities of the photosensitive pesticides showed 2-4 times increments if they were exposed to light. In addition, a synergistic effect was observed after the light-controlled release of IMI-TNB-IMISYN, which was consistent with the effect of IMISYN. The results demonstrated whether dual photo-controlled release of the same or different pesticide molecules could be achieved with a TNB linker with spatiotemporal precision. We envisioned that TNB will be an innovative photosensitive protective group for light-dependent application of agrochemicals in the future.

Mesoporous Silica Nanoparticles Mediate SiRNA Delivery for Long-Term Multi-Gene Silencing in Intact Plants

RNA interference (RNAi) is a powerful tool for understanding and manipulating signaling pathways in plant science, potentially facilitating the accelerated development of novel plant traits and crop yield improvement. The common strategy for delivering siRNA into intact plants using agrobacterium or viruses is complicated and time-consuming, limiting the application of RNAi in plant research. Here, a novel delivery method based on mesoporous silica nanoparticles (MSNs) is reported, which allows for the efficient delivery of siRNA into mature plant leaves via topical application without the aid of mechanical forces, achieving transient gene knockdown with up to 98% silencing efficiency at the molecular level. In addition, this method is nontoxic to plant leaves, enabling the repeated delivery of siRNA for long-term silencing. White spots and yellowing phenotypes are observed after spraying the MSN-siRNA complex targeted at phytoene desaturase and magnesium chelatase genes. After high light treatment, photobleaching phenotypes are also observed by spraying MSNs-siRNA targeted at genes into the Photosystem II repair cycle. Furthermore, the study demonstrated that MSNs can simultaneously silence multiple genes. The results suggest that MSN-mediated siRNA delivery is an effective tool for long-term multi-gene silencing, with great potential for application in plant functional genomic analyses and crop improvement.

Comparing the antibacterial activity of chitin nanocrystals with chitin: exploring the feasibility of chitin nanocrystals as novel pesticide nanocarriers in agriculture

BACKGROUND

In recent years, nanomaterials-based pesticide carriers have garnered significant attention and sparked extensive research. However, most studies have primarily focused on investigating the impact of physical properties of nanomaterials, such as size and modifiable sites, on drug delivery efficiency of nano-pesticides. The limited exploration of biologically active nanomaterials poses a significant obstacle to the advancement and widespread adoption of nano-pesticides. In this study, we prepared chitin nanocrystals (ChNC) based on acid hydrolysis and systematically investigated the differences between nano- and normal chitin against plant bacteria (Pseudomonas syringae pv. tabaci). The primary objective was to seek out nanocarriers with heightened biological activity for the synthesis of nano-pesticides.

RESULTS

Zeta potential analysis, Fourier Transform infrared spectrometry (FTIR), X-Ray diffraction (XRD), Atomic force microscopy (AFM) and Transmission electron microscopy (TEM) identified the successful synthesis of ChNC. ChNC showcased remarkable bactericidal activity at comparable concentrations, surpassing that of chitin, particularly in its ability to inhibit bacterial biofilm formation. Furthermore, ChNC displayed heightened effectiveness in disrupting bacterial cell membranes, resulting in the leakage of bacterial cell contents, structural DNA damage, and impairment of DNA replication. Lastly, potting experiments revealed that ChNC is notably more effective in inhibiting the spread and propagation of bacteria on plant leaves.

CONCLUSION

ChNC exhibited higher antibacterial activity compared to chitin, enabling efficient control of plant bacterial diseases through enhanced interaction with bacteria. These findings offer compelling evidence of ChNC's superior bacterial inhibition capabilities, underscoring its potential as a promising nanocarrier for nano-pesticide research. © 2023 Society of Chemical Industry.

DsRNA-based pesticides: Considerations for efficiency and risk assessment

In view of the ongoing climate change and the ever-growing world population, novel agricultural solutions are required to ensure sustainable food supply. Microbials, natural substances, semiochemicals and double stranded RNAs (dsRNAs) are all considered potential low risk pesticides. DsRNAs function at the molecular level, targeting specific regions of specific genes of specific organisms, provided that they share a minimal sequence complementarity of approximately 20 nucleotides. Thus, dsRNAs may offer a great alternative to conventional chemicals in environmentally friendly pest control strategies. Any low-risk pesticide needs to be efficient and exhibit low toxicological potential and low environmental persistence. Having said that, in the current review, the mode of dsRNA action is explored and the parameters that need to be taken into consideration for the development of efficient dsRNA-based pesticides are highlighted. Moreover, since dsRNAs mode of action differs from those of synthetic pesticides, custom-made risk assessment schemes may be required and thus, critical issues related to the risk assessment of dsRNA pesticides are discussed here.

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.

RNA Interference in Insects: From a Natural Mechanism of Gene Expression Regulation to a Biotechnological Crop Protection Promise

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.

Nanotechnology, a frontier in agricultural science, a novel approach in abiotic stress management and convergence with new age medicine-A review

Climate change imposes various environmental stresses which substantially impact plant growth and productivity. Salinity, drought, temperature extremes, heavy metals, and nutritional imbalances are among several abiotic stresses contributing to high yield losses of crops in various parts of the world, resulting in food insecurity. Many interesting strategies are being researched in the attempt to improve plants' environmental stress tolerance. These include the application of nanoparticles, which have been found to improve plant function under stress situations. Nanotechnology will be a key driver in the upcoming agri-tech and pharmaceutical revolution, which promises a more sustainable, efficient, and resilient agricultural and medical system Nano-fertilizers can help plants utilise nutrients more efficiently by releasing nutrients slowly and sustainably. Plant physiology and nanomaterial features (such as size, shape, and charge) are important aspects influencing the impact on plant growth. Here, we discussed the most promising new opportunities and methodologies for using nanotechnology to increase the efficiency of critical inputs for crop agriculture, as well as to better manage biotic and abiotic stress. Potential development and implementation challenges are highlighted, emphasising the importance of designing suggested nanotechnologies using a systems approach. Finally, the strengths, flaws, possibilities, and risks of nanotechnology are assessed and analysed in order to present a comprehensive and clear picture of the nanotechnology potentials, as well as future paths for nano-based agri-food applications towards sustainability. Future research directions have been established in order to support research towards the long-term development of nano-enabled agriculture and evolution of pharmaceutical industry.

The fatty acid 2-hydroxylase CsSCS7 is a key hyphal growth factor and potential control target in Colletotrichum siamense

SCS7 is a fatty acid 2-hydroxylase required for the synthesis of inositol phosphorylceramide but is not essential for normal growth in Saccharomyces cerevisiae. Here, we demonstrate that the Colletotrichum siamense SCS7 homolog CsSCS7 plays a key role in hyphal growth. The CsSCS7 deletion mutant showed strong hyphal growth inhibition, small conidia, and marginally reduced sporulation and also resulted in a sharp reduction in the full virulence and increasing the fungicide sensitivity. The three protein domains (a cytochrome b5 domain, a transmembrane domain, and a hydroxylase domain) are important to CsSCS7 protein function in hyphal growth. The fatty acid assay results revealed that the CsSCS7 gene is important for balancing the contents of multiple mid-long- and short-chain fatty acids. Additionally, the retarded growth and virulence of C. siamense ΔCsSCS7 can be recovered partly by the reintroduction of homologous sequences from Magnaporthe oryzae and Fusarium graminearum but not SCS7 of S. cerevisiae. In addition, the spraying of C. siamense with naked CsSCS7-double-stranded RNA (dsRNAs), which leads to RNAi, increases the inhibition of hyphal growth and slightly decreases disease lesions. Then, we used nano material Mg-Al-layered double hydroxide as carriers to deliver dsRNA, which significantly enhanced the control effect of dsRNA, and the lesion area was obviously reduced. These data indicated that CsSCS7 is an important factor for hyphal growth and affects virulence and may be a potential control target in C. siamense and even in filamentous plant pathogenic fungi.IMPORTANCECsSCS7, which is homologous to yeast fatty acid 2-hydroxylase SCS7, was confirmed to play a key role in the hyphal growth of Colletotrichum siamense and affect its virulence. The CsSCS7 gene is involved in the synthesis and metabolism of fatty acids. Homologs from the filamentous fungi Magnaporthe oryzae and Fusarium graminearum can recover the retarded growth and virulence of C. siamense ΔCsSCS7. The spraying of double-stranded RNAs targeting CsSCS7 can inhibit hyphal growth and reduce the disease lesion area to some extent. After using nano material Mg-Al layered double hydroxide as carrier, the inhibition rates were significantly increased. We demonstrated that CsSCS7 is an important factor for hyphal growth and affects virulence and may be a potential control target in C. siamense and even in filamentous plant pathogenic fungi.

Manipulating epigenetic diversity in crop plants: Techniques, challenges and opportunities

Epigenetic modifications act as conductors of inheritable alterations in gene expression, all while keeping the DNA sequence intact, thereby playing a pivotal role in shaping plant growth and development. This review article presents an overview of techniques employed to investigate and manipulate epigenetic diversity in crop plants, focusing on both naturally occurring and artificially induced epialleles. The significance of epigenetic modifications in facilitating adaptive responses is explored through the examination of how various biotic and abiotic stresses impact them. Further, environmental chemicals are explored for their role in inducing epigenetic changes, particularly focusing on inhibitors of DNA methylation like 5-AzaC and zebularine, as well as inhibitors of histone deacetylation including trichostatin A and sodium butyrate. The review delves into various approaches for generating epialleles, including tissue culture techniques, mutagenesis, and grafting, elucidating their potential to induce heritable epigenetic modifications in plants. In addition, the ground breaking CRISPR/Cas is emphasized for its accuracy in targeting specific epigenetic changes. This presents a potent tools for deciphering the intricacies of epigenetic mechanisms. Furthermore, the intricate relationship between epigenetic modifications and non-coding RNA expression, including siRNAs and miRNAs, is investigated. The emerging role of exo-RNAi in epigenetic regulation is also introduced, unveiling its promising potential for future applications. The article concludes by addressing the opportunities and challenges presented by these techniques, emphasizing their implications for crop improvement. Conclusively, this extensive review provides valuable insights into the intricate realm of epigenetic changes, illuminating their significance in phenotypic plasticity and their potential in advancing crop improvement.

Tiny but Mighty: Nanoscale Materials in Plant Disease Management

Nanoscale materials are promising tools for managing plant diseases and are becoming important players in the current agritech revolution. However, adopting modern methodologies requires a broad understanding of their effectiveness in solving target problems and their effects on the environment and food chain. Furthermore, it is paramount that such technologies are mechanistically and economically feasible for growers to adopt in order to be sustainable in the long run. This Feature Article summarizes the latest findings on the role of nanoscale materials in managing agricultural plant pathogens. Herein, we discussed the benefits and limitations of using nanoscale materials in plant disease management and their potential impacts on the environment and global food security.

Synthesis and Characterization of Mesoporous Silica Nanoparticles Loaded with P-Cymene against Rice Bacterial Blight

Mesoporous silica nanoparticles (MSNs) can be used as carrier materials for the controlled release of pesticides while reducing their negative environmental impact. In this study, we screened an active ingredient, p-cymene (PC), with an excellent inhibitory effect on rice bacterial blight. Subsequently, the PC was successfully loaded onto MSNs via physisorption (PC@MSNs). PC@MSNs, characterized by a regular spherical shape, smooth surface, and an MSN average size of 262.9 nm, achieved an 8.6% drug loading capacity. The release kinetics of the PC from the PC@MSNs demonstrated a sustained release (288 h) pattern influenced by drug diffusion. The efficacy of the PC@MSNs against Xanthomonas oryzae pv. Oryzae paralleled those of PC. Acute toxicity assays revealed that the PC@MSNs were less toxic to aquatic life (LC50 = 257.867 mg/L) and that the formulation showed no adverse effects on rice seedling growth. In summary, these results suggest that PC@MSNs can broaden PC's scope of application in managing rice diseases.

Agrobacterium-mediated transfer of the Fusarium graminearum Tri6 gene into barley using mature seed-derived shoot tips as explants

KEY MESSAGE

We transferred the Tri6 gene into the elite barley GemCraft via new transformation method through shoot organogenesis and identified the rearrangements of transgenes and phenotypic variations in the transgenic plants. Despite its agronomic and economic importance, barley transformation is still very challenging for many elite varieties. In this study, we used direct shoot organogenesis to transform the elite barley cultivar GemCraft with the RNAi constructs containing Tri6 gene of Fusarium graminearum, which causes fusarium head blight (FHB). We isolated 4432 shoot tips and co-cultured these explants with Agrobacterium tumefaciens. A total of 25 independent T0 transgenic plants were generated including 15 events for which transgene-specific PCR amplicons were observed. To further determine the presence of transgenes, the T1 progenies of all 15 T0 plants were analyzed, and the expected PCR products were obtained in 10 T1 lines. Droplet digital (dd) PCR analysis revealed various copy numbers of transgenes in the transgenic plants. We determined the insertion site of transgenes using long-read sequencing data and observed the rearrangements of transgenes. We found phenotypic variations in both T1 and T2 generation plants. FHB disease was evaluated under growth chamber conditions, but no significant differences in disease severity or deoxynivalenol accumulation were observed between two Tri6 transgenic lines and the wildtype. Our results demonstrate the feasibility of the shoot tip transformation and may open the door for applying this system for genetic improvement and gene function research in other barley genotypes.

Improvement and regulation of steviol glycoside biosynthesis in Stevia rebaudiana Bertoni

Stevia rebaudiana Bertoni is a natural sweetener plant that is progressively used not only for its sweetening properties but also for its medicinal properties. The plant contains steviol glycoside (SG) which is reported to be up to 300 times sweeter than sucrose. The plant is said to have no side effects on human health and has been approved by FDA. On the basis of previous studies and available databases, this review discusses the extensive understanding of the different approaches for enhancements of SG in S. rebaudiana. To improve the SG biosynthesis, application of different stress, elicitors, induction of polyploidy, cell culture, genetic engineering, and transcriptomic approaches have been addressed. A brief discussion about the cloning and characterization of important genes of the metabolic pathway of SG biosynthesis is also discussed along with various metabolic engineering pathways viz. methylerythritol 4- phosphate (MEP) and mevalonate (MVA) pathways. This review paper also discusses the different aspects as well as the effects of various nanoparticles on S. rebaudiana growth and development, as well as SG biosynthesis.

Bioinspired silver nanoparticle-based nanocomposites for effective control of plant pathogens: A review

Plant pathogens, including bacteria, fungi, and viruses, pose significant challenges to the farming community due to their extensive diversity, the rapidly evolving phenomenon of multi-drug resistance (MDR), and the limited availability of effective control measures. Amid mounting global pressure, particularly from the World Health Organization, to limit the use of antibiotics in agriculture and livestock management, there is increasing consideration of engineered nanomaterials (ENMs) as promising alternatives for antimicrobial applications. Studies focusing on the application of ENMs in the fight against MDR pathogens are receiving increasing attention, driven by significant losses in agriculture and critical knowledge gaps in this crucial field. In this review, we explore the potential contributions of silver nanoparticles (AgNPs) and their nanocomposites in combating plant diseases, within the emerging interdisciplinary arena of nano-phytopathology. AgNPs and their nanocomposites are increasingly acknowledged as promising countermeasures against plant pathogens, owing to their unique physicochemical characteristics and inherent antimicrobial properties. This review explores recent advancements in engineered nanocomposites, highlights their diverse mechanisms for pathogen control, and draws attention to their potential in antibacterial, antifungal, and antiviral applications. In the discussion, we briefly address three crucial dimensions of combating plant pathogens: green synthesis approaches, toxicity-environmental concerns, and factors influencing antimicrobial efficacy. Finally, we outline recent advancements, existing challenges, and prospects in scholarly research to facilitate the integration of nanotechnology across interdisciplinary fields for more effective treatment and prevention of plant diseases.

Advances in RNA Interference for Plant Functional Genomics: Unveiling Traits, Mechanisms, and Future Directions

RNA interference (RNAi) is a conserved molecular mechanism that plays a critical role in post-transcriptional gene silencing across diverse organisms. This review delves into the role of RNAi in plant functional genomics and its applications in crop improvement, highlighting its mechanistic insights and practical implications. The review begins with the foundational discovery of RNAi's mechanism, tracing its origins from petunias to its widespread presence in various organisms. Various classes of regulatory non-coding small RNAs, including siRNAs, miRNAs, and phasiRNAs, have been uncovered, expanding the scope of RNAi-mediated gene regulation beyond conventional understanding. These RNA classes participate in intricate post-transcriptional and epigenetic processes that influence gene expression. In the context of crop enhancement, RNAi has emerged as a powerful tool for understanding gene functions. It has proven effective in deciphering gene roles related to stress resistance, metabolic pathways, and more. Additionally, RNAi-based approaches hold promise for integrated pest management and sustainable agriculture, contributing to global efforts in food security. This review discusses RNAi's diverse applications, such as modifying plant architecture, extending shelf life, and enhancing nutritional content in crops. The challenges and future prospects of RNAi technology, including delivery methods and biosafety concerns, are also explored. The global landscape of RNAi research is highlighted, with significant contributions from regions such as China, Europe, and North America. In conclusion, RNAi remains a versatile and pivotal tool in modern plant research, offering novel avenues for understanding gene functions and improving crop traits. Its integration with other biotechnological approaches such as gene editing holds the potential to shape the future of agriculture and sustainable food production.

Revolutionizing agriculture: Harnessing nano-innovations for sustainable farming and environmental preservation

The agricultural sector is currently confronted with a significant crisis stemming from the rapid changes in climate patterns, declining soil fertility, insufficient availability of essential macro and micronutrients, excessive reliance on chemical fertilizers and pesticides, and the presence of heavy metals in soil. These numerous challenges pose a considerable threat to the agriculture industry. Furthermore, the exponential growth of the global population has led to a substantial increase in food consumption, further straining agricultural systems worldwide. Nanotechnology holds great promise in revolutionizing the food and agriculture industry, decreasing the harmful effects of agricultural practices on the environment, and improving productivity. Nanomaterials such as inorganic, lipid, and polymeric nanoparticles have been developed for increasing productivity due to their unique properties. Various strategies can enhance product quality, such as the use of nano-clays, nano zeolites, and hydrogel-based materials to regulate water absorption and release, effectively mitigating water scarcity. The production of nanoparticles can be achieved through various methods, each of which has its own unique benefits and limitations. Among these methods, chemical synthesis is widely favored due to the impact that various factors such as concentration, particle size, and shape have on product quality and efficiency. This review provides a detailed examination of the roles of nanotechnology and nanoparticles in sustainable agriculture, including their synthetic methods, and presents an analysis of their associated advantages and disadvantages. To date, there are serious concerns and awareness about healthy agriculture and the production of healthy products, therefore the development of nanotech-enabled devices that act as preventive and early warning systems to identify health issues, offering remedial measures is necessary.

Application of dsRNA for Fungi Disease Management Sclerotinia sclerotiorum and Botrytis cinerea

Sclerotinia sclerotiorum and Botrytis cinerea are two closely related necrotrophic plant pathogenic fungi that have garnered significant attention due to their broad host range and persistent environmental presence. The use of double-stranded RNA (dsRNA) to inhibit specific genes has demonstrated promising potential in disease management. Various RNA interference (RNAi) strategies have been developed and applied in disease management, including the use of dsRNA to silence specific genes, as well as other RNA-based approaches. These strategies show promise in controlling fungal diseases and have the potential for broader application in plant protection. Here, we present a protocol that outlines techniques for preparing dsRNA and spraying it directly to control fungal diseases. This protocol offers a practical and effective solution for managing plant diseases and has the potential to be widely applied in disease management.

Can nanotechnology improve the application of bioherbicides?

Bioherbicides are composed of microorganisms or natural compounds and are used for weed control; however, they have specific weaknesses and constraints that hinder their development and success under field conditions. Nanotechnology can help to overcome these limitations by providing a good starting point for the design of specific formulations and carriers that minimize the deficiencies of natural compounds and microorganisms, such as low solubility, short shelf life or a loss of viability. In addition, nanoformulations can help to improve the efficacy of bioherbicides by increasing their effectiveness and bioavailability, reducing the amount required for a treatment, and enhancing their ability to target specific weeds while preserving the crop. However, it is important to choose the right materials and nanodevices depending on specific needs and considering several factors inherent to nanomaterials such as production cost, safety or possible toxic effects. © 2023 Society of Chemical Industry.

Exogenous application of nanocarrier-mediated double-stranded RNA manipulates physiological traits and defence response against bacterial diseases

Stability and delivery are major challenges associated with exogenous double-stranded RNA (dsRNA) application into plants. We report the encapsulation and delivery of dsRNA in cationic poly-aspartic acid-derived polymer (CPP6) into plant cells. CPP6 stabilizes the dsRNAs during long exposure at varied temperatures and pH, and protects against RNase A degradation. CPP6 helps dsRNA uptake through roots or foliar spray and facilitates systemic movement to induce endogenous gene silencing. The fluorescence of Arabidopsis GFP-overexpressing transgenic plants was significantly reduced after infiltration with gfp-dsRNA-CPP6 by silencing of the transgene compared to plants treated only with gfp-dsRNA. The plant endogenous genes flowering locus T (FT) and phytochrome interacting factor 4 (PIF4) were downregulated by a foliar spray of ft-dsRNA-CPP6 and pif4-dsRNA-CPP6 in Arabidopsis, with delayed flowering and enhanced biomass. The rice PDS gene targeted by pds-dsRNA-CPP6 through root uptake was effectively silenced and plants showed a dwarf and albino phenotype. The NaCl-induced OsbZIP23 was targeted through root uptake of bzip23-dsRNA-CPP6 and showed reduced transcripts and seedling growth compared to treatment with naked dsRNA. The negative regulators of plant defence SDIR1 and SWEET14 were targeted through foliar spray to provide durable resistance against bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Overall, the study demonstrates that transient silencing of plant endogenous genes using polymer-encapsulated dsRNA provides prolonged and durable resistance against Xoo, which could be a promising tool for crop protection and for sustaining productivity.

Nanobiosensors and nanoformulations in agriculture: new advances and challenges for sustainable agriculture

In the current scenario of climate change, global agricultural systems are facing remarkable challenges in order to increase production, while reducing the negative environmental impact. Nano-enabled technologies have the potential to revolutionise farming practices by increasing the efficiency of inputs and minimising losses, as well as contributing to sustainable agriculture. Two promising applications of nanotechnology in agriculture are nanobiosensors and nanoformulations (NFs). Nanobiosensors can help detect biotic and abiotic stresses in plants before they affect plant production, while NFs can make agrochemicals, more efficient and less polluting. NFs are becoming new-age materials with a wide variety of nanoparticle-based formulations such as fertilisers, herbicides, insecticides, and fungicides. They facilitate the site-targeted controlled delivery of agrochemicals enhancing their efficiency and reducing dosages. Smart farming aims to monitor and detect parameters related to plant health and environmental conditions in order to help sustainable agriculture. Nanobiosensors can provide real-time analytical data, including detection of nutrient levels, metabolites, pesticides, presence of pathogens, soil moisture, and temperature, aiding in precision farming practices, and optimising resource usage. In this review, we summarise recent innovative uses of NFs and nanobiosensors in agriculture that may boost crop protection and production, as well as reducing the negative environmental impact of agricultural activities. However, successful implementation of these smart technologies would require two special considerations: (i) educating farmers about appropriate use of nanotechnology, (ii) conducting field trials to ensure effectiveness under real conditions.

Double-stranded RNA prevents and cures infection by rust fungi

Fungal pathogens that impact perennial plants or natural ecosystems require management strategies beyond fungicides and breeding for resistance. Rust fungi, some of the most economically and environmentally important plant pathogens, have shown amenability to double-stranded RNA (dsRNA) mediated control. To date, dsRNA treatments have been applied prior to infection or together with the inoculum. Here we show that a dsRNA spray can effectively prevent and cure infection by Austropuccinia psidii (cause of myrtle rust) at different stages of the disease cycle. Significant reductions in disease coverage were observed in plants treated with dsRNA targeting essential fungal genes 48 h pre-infection through to 14 days post-infection. For curative treatments, improvements in plant health and photosynthetic capacity were seen 2-6 weeks post-infection. Two-photon microscopy suggests inhibitory activity of dsRNA on intercellular hyphae or haustoria. Our results show that dsRNA acts both preventively and curatively against myrtle rust disease, with treated plants recovering from severe infection. These findings have immediate potential in the management of the more than 10-year epidemic of myrtle rust in Australia.

The use of RNA interference for the management of arthropod pests in livestock farms

Pest management in farm animals is an important action to contain economic damage to livestock production and prevent transmission of severe diseases to the stock. The use of chemical insecticides is still the most common approach followed by farmers; however, avoiding possible toxic effects on animals is a fundamental task for pest control measures compatible with animal well-being. Moreover, legal constraints and insurgence of resistance by target species to the available insecticidal compounds are increasingly complicating farmers' operations. Alternatives to chemical pesticides have been explored with some promising results in the area of biological control or the use of natural products as sprays. The application of RNA interference techniques has enabled the production of new means of pest control in agriculture, and it is opening a promising avenue for controlling arthropod pests of livestock. Transcript depletion of specific target genes of the recipient organisms is based on the action of double-strand RNAs (dsRNA) capable of impairing the production of fundamental proteins. Their mode of action, based on the specific recognition of short genomic sequences, is expected to be highly selective towards non-target organisms potentially exposed; in addition, there are physical and chemical barriers to dsRNA uptake by mammalian cells that render these products practically innocuous for higher animals. Summarising existing literature on gene silencing for main taxa of arthropod pests of livestock (Acarina, Diptera, Blattoidea), this review explores the perspectives of practical applications of dsRNA-based pesticides against the main pests of farm animals. Knowledge gaps are summarised to stimulate additional research in this area.

Improving RNA-based crop protection through nanotechnology and insights from cross-kingdom RNA trafficking

Spray-induced gene silencing (SIGS) is a powerful and eco-friendly method for crop protection. Based off the discovery of RNA uptake ability in many fungal pathogens, the application of exogenous RNAs targeting pathogen/pest genes results in gene silencing and infection inhibition. However, SIGS remains hindered by the rapid degradation of RNA in the environment. As extracellular vesicles are used by plants, animals, and microbes in nature to transport RNAs for cross-kingdom/species RNA interference between hosts and microbes/pests, nanovesicles and other nanoparticles have been used to prevent RNA degradation. Efforts examining the effect of nanoparticles on RNA stability and internalization have identified key attributes that can inform better nanocarrier designs for SIGS. Understanding sRNA biogenesis, cross-kingdom/species RNAi, and how plants and pathogens/pests naturally interact are paramount for the design of SIGS strategies. Here, we focus on nanotechnology advancements for the engineering of innovative RNA-based disease control strategies against eukaryotic pathogens and pests.

Star polymer soil delivery nanoplatform for applying biological agents in the field to control plant rhizosphere diseases

As the main cause of destructive plant diseases, pathogenic oomycete in plant rhizosphere brings about enormous losses to agricultural production. Although chemical pesticides are still one of the most important prevention and control methods for phytopathogens, the usage of chemical pesticides was limited by the 3R (resistance, residue, and rampant) problem. In the early stage of our research, analysis and comparison of the metabolome of resistance to Phytophthora nicotianae and common strain suggested that naringenin might be a highly efficient potential biogenic antimicrobial agent to prevent and control soil rhizosphere diseases. Unfortunately, the bioactivity and absorption capacity of active ingredients in the environment made it unsuitable for field application; thus, for efficient field application of naringenin, the 24 nm-sized naringenin-loaded nano-star-shaped polymerized (NSPs) were prepared with good loading efficiency 37.3% for naringenin. The soil mobility test indicated that NSPs could effectively reduce the adsorption of active ingredients and enhance the mobility of active ingredients in soil. The bacteriostatic test proved that these NSPs had better antimicrobial activity than the naringenin used alone and could efficiently induce the expression of plant resistance phenylpropanoid compounds. Finally, pot and field experiments showed improved control efficiency of NSPs 41% loaded with naringenin. Transcriptome analysis found that a large number of energy-related genes were downregulated in NSPs nematodes, suggesting that disturbed energy-related genes might lead to the disturbance of energy synthesis and metabolism. Naringenin-loaded nano-carriers were used to prevent and control plant disease-causing pathogens in the rhizosphere, which is of great significance to improve the prevention and control effect and reduce the environmental load of these anti-pathogenic agents.