Dual-Action Pesticide Carrier That Continuously Induces Plant Resistance, Enhances Plant Anti-Tobacco Mosaic Virus Activity, and Promotes Plant Growth

Identification of the odorant binding proteins of Western Flower Thrips (Frankliniella occidentalis), characterization and binding analysis of FoccOBP3 with molecular modelling, molecular dynamics simulations and a confirmatory field trial

Olfactory systems are indispensable for insects as they, including Western Flower Thrips (Frankliniella occidentalis), use olfactory cues for ovipositing and feeding. F. occidentalis use odorant binding proteins (OBPs) to transport semiochemicals to odorant receptors to induce a behavioural response from the sensillum lymph of the insect's antennae. This study identifies four OBPs of F. occidentalis and analyses their expression at three stages of growth: larvae, adult males and adult females. Further, it investigates the presence of conserved motifs and their phylogenetic relationship to other insect species. Moreover, FoccOBP3 was in silico characterized to analyse its structure along with molecular docking and molecular dynamics simulations to understand its binding with semiochemicals of F. occidentalis. Molecular docking revealed the interactions of methyl isonicotinate, p-anisaldehyde and (S)-(-)-verbenone with FoccOBP3. Moreover, molecular dynamics simulations showed bonding stability of these ligands with FoccOBP3, and field trials validated that Lurem TR (commercial product) and p-anisaldehyde had greater attraction as compared to (S)-(-)-verbenone, given the compound's binding with FoccOBP3. The current study helps in understanding the tertiary structure and interaction of FoccOBP3 with lures using computational and field data and will help in the identification of novel lures of insects in the future, given the importance of binding with OBPs.Communicated by Ramaswamy H. Sarma.

A high rain-erosion resistant bio-based nanogel with continuous immunity induction for plant virus inhibition

Tobacco mosaic virus (TMV) is the most widely spread and harmful virus in the world, causing serious economic losses annually. However, the low anti-erosion ability of the pesticides for TMV management make it easy to be washed by the rain, which makes the effective duration of the pesticides shorter. In this paper, a new bio-based nanogel with superior antiviral activity was reported, and its slow-release behavior, rain erosion resistance and the antiviral mechanism was systematically studied. The results determined that the nanogels (Zn2+@ALGNP and Zn2+@ALGNP@PL) exhibited sustained releasing of Zn2+ with a 7 days duration, and the ε-PL coating could enhance the releasing rate of Zn2+. Moreover, Zn2+@ALGNP@PL displayed a lower contact angle, indicating greater adhesion to the leaf surface, and in consequence imposed better resistance to simulate rain erosion than pure Zn2+. Strikingly, Zn2+@ALGNP@PL could inhibit plant virus infection by aggregating the virions and reducing its coat protein stability, as well as inducing the efficient expression of reactive oxygen species, antioxidant enzymes and resistance genes to enhance plant resistance and promote plant growth. Overall, this study had successfully developed a high rain-erosion resistant bio-based nanogel capable of continue to induce resistant plants and promote plant growth.

Washout-Resistant, pH-Responsive Anti-TMV Nanoimmune Inducer Based on Cellulose Nanocrystals

The application of antiplant virus agents on leaf surfaces faces challenges due to their vulnerability to wear, instability, and limited duration, which in turn jeopardizes plant health and yield. In recent years, high-aspect-ratio nanomaterials have gained prominence as powerful carriers for disease treatment, thanks to their exceptional penetrability and precise drug delivery capabilities. Here, we synthesized a pH-responsive nanoimmune inducer (CNC-AMO) with strong leaf adhesion through a Schiff base reaction, achieved by grafting amino-oligosaccharides (AMOs) on the surface of aldehyde-based CNC (CNC-CHO). Fourier transform infrared spectrometry, zeta potential, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis were used to characterize the CNC-AMO. The CNC-AMO displayed the capability for pH-responsive AMO release, showcasing its potential for targeted and controlled delivery. When applied to plants, the CNC-AMO exhibited impressive anti-TMV efficacy during a weeklong observation period. Meanwhile, the CNC-AMO exhibited remarkable adhesion and scouring resistance on the surfaces of the plant leaves. We strongly believe that the synergy of environmentally friendly synthetic materials, efficient plant virus control, and streamlined scalability positions CNC-AMOs as a promising pesticide for plant virus therapy.

Integrated non-targeted and targeted metabolomics analysis reveals the mechanism of inhibiting lignification and optimizing the quality of pea sprouts by combined application of nano-selenium and lentinans

BACKGROUND

Lignification causes a detrimental impact on the quality of edible sprouts. However, the mechanism of inhibition of lignification of edible sprouts by nano-selenium and lentinans remains unclear.

RESULTS

To reveal the mechanism of lignification regulation of sprouts by nano-selenium and lentinans, this study investigated the changes in antioxidant indicators, phytohormones, polyphenols, and metabolites in the lignin biosynthesis in pea sprouts following sprays of nano-selenium or/and lentinans twice. There was an overall increase in the aforementioned indices following treatment. In particular, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans was more effective than their individual applications in enhancing peroxidase, catalase, DPPH free-radical scavenging rate, luteolin, and sinapic acid, as well as inhibiting malondialdehyde generation and lignin accumulation. Combined with the results from correlation analysis, nano-selenium and lentinans may inhibit lignification by enhancing antioxidant systems, inducing phytohormone-mediated signaling, and enriching precursor metabolites (caffeyl alcohol, sinapyl alcohol, 4-coumaryl alcohol). In terms of the results of non-targeted metabolomics, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans mainly affected biosynthesis of plant secondary metabolites, biosynthesis of phenylpropanoids, phenylpropanoid biosynthesis, arginine and proline metabolism, and linoleic acid metabolism pathways, which supported and complemented results from targeted screenings.

CONCLUSION

Overall, the combined sprays of nano-selenium and lentinans showed synergistic effects in delaying lignification and optimizing the quality of pea sprouts. This study provides a novel and practicable technology for delaying lignification in the cultivation of edible sprouts. © 2023 Society of Chemical Industry.

Novel cinnamic acid derivatives as a versatile tool for developing agrochemicals for controlling plant virus and bacterial diseases by enhancing plant defense responses

BACKGROUND

Plant pathogens have led to large yield and quality losses in crops worldwide. The discovery and study of novel agrochemical alternatives based on the chemical modification of bioactive natural products is a highly efficient approach. Here, two series of novel cinnamic acid derivatives incorporating diverse building blocks with alternative linking patterns were designed and synthesized to identify their antiviral capacity and antibacterial activity.

RESULTS

The bioassay results demonstrated that most cinnamic acid derivatives had excellent antiviral competence toward tobacco mosaic virus (TMV) in vivo, especially compound A₅ (median effective concentration [EC₅₀ ] = 287.7 μg mL^-1 ), which had a notable protective effect against TMV when compared with the commercial virucide ribavirin (EC₅₀  = 622.0 μg mL^-1 ). In addition, compound A₁₇ had a protective efficiency of 84.3% at 200 μg mL^-1 against Xac in plants. Given these outstanding results, the engineered title compounds could be regarded as promising leads for controlling plant virus and bacterial diseases. Preliminary mechanistic studies suggest that compound A₅ could enhance the host's defense responses by increasing the activity of defense enzymes and upregulating defense genes, thereby suppressing phytopathogen invasion.

CONCLUSION

This research lays a foundation for the practical application of cinnamic acid derivatives containing diverse building blocks with alternative linking patterns in pesticide exploration. © 2023 Society of Chemical Industry.

Trifluoromethylpyridine piperazine derivatives: synthesis and anti-plant virus activity

BACKGROUND

The cucumber mosaic virus (CMV) is well-known for its expansive host range and distribution, resulting in a detrimental effect on agricultural production, thus making it imperative to implement measures for its control.

RESULTS

Novel compounds S1-S28 were synthesized by connecting trifluoromethyl pyridine, amide and piperazine scaffolds. Bioassays indicated that most of the synthesized compounds exhibited good curative effects against CMV, with half maximal effective concentration (EC₅₀ ) values of compounds S1, S2, S7, S8, S10, S11, S15, and S28 being 119.6, 168.9, 197.6, 169.1, 97.9, 73.9, 224.4, and 125.2 μg mL^-1 , respectively, which were lower than the EC₅₀ of ningnanmycin (314.7 μg mL^-1 ). Compounds S5 and S8 exhibited protective activities with EC₅₀ of 170.8 and 95.0 μg mL^-1 , respectively, which were lower than ningnanmycin at 171.4 μg mL^-1 . The inactivation activities of S6 and S8 at 500 μg mL^-1 were remarkably high at 66.1% and 78.3%, respectively, surpassing that of ningnanmycin (63.5%). Additionally, their EC₅₀ values were more favorable at 22.2 and 18.1 μg mL^-1 , respectively, than ningnanmycin (38.4 μg mL^-1 ). And molecular docking and molecular dynamics simulation showed compound S8 had better binding with CMV-coat protein, providing a possible explanation for the anti-CMV activity of compound S8.

CONCLUSIONS

Compound S8 showed a strong binding affinity to CMV-coat protein and impacted the self-assemble of CMV particles. Compound S8 could be a potential lead compound for discovering a new anti-plant virus candidate. © 2023 Society of Chemical Industry.

Research Progress of a Pesticide Polymer-Controlled Release System Based on Polysaccharides

In recent years, with the development of the nanomaterials discipline, many new pesticide drug-carrying systems-such as pesticide nano-metal particles, nano-metal oxides, and other drug-carrying materials-had been developed and applied to pesticide formulations. Although these new drug-loading systems are relatively friendly to the environment, the direct exposure of many metal nanoparticles to the environment will inevitably lead to potential effects. In response to these problems, organic nanomaterials have been rapidly developed due to their high-quality biodegradation and biocompatibility. Most of these organic nanomaterials were mainly polysaccharide materials, such as chitosan, carboxymethyl chitosan, sodium alginate, β-cyclodextrin, cellulose, starch, guar gum, etc. Some of these materials could be used to carry inorganic materials to develop a temperature- or pH-sensitive pesticide drug delivery system. Herein, the pesticide drug-carrying system developed based on polysaccharide materials, such as chitosan, was referred to as the pesticide polymer drug-carrying system based on polysaccharide materials. This kind of drug-loading system could be used to protect the pesticide molecules from harsh environments, such as pH, light, temperature, etc., and was used to develop the function of a sustained release, targeted release of pesticides in the intestine of insects, and achieve the goal of precise application, reduction, and efficiency of pesticides. In this review, the recent progress in the field of polysaccharide-based polymer drug delivery systems for pesticides has been discussed, and suggestions for future development were proposed based on the current situation.

Novel 1,3,4-Thiadiazole Derivatives: Synthesis, Antiviral Bioassay and Regulation the Photosynthetic Pathway of Tobacco against TMV Infection

Tobacco mosaic virus (TMV) is a systemic virus that poses a serious threat to crops worldwide. In the present study, a series of novel 1-phenyl-4-(1,3,4-thiadiazole-5-thioether)-1H-pyrazole-5-amine derivatives was designed and synthesized. In vivo antiviral bioassay results indicated that some of these compounds exhibited excellent protective activity against TMV. Among the compounds, E₂ (EC₅₀ = 203.5 μg/mL) was superior to the commercial agent ningnanmycin (EC₅₀ = 261.4 μg/mL). Observation of tobacco leaves infected with TMV-GFP revealed that E₂ could effectively inhibit the spread of TMV in the host. Further plant tissue morphological observation indicated that E₂ could induce the tight arrangement and alignment of the spongy mesophyll and palisade cells while causing stomatal closure to form a defensive barrier to prevent viral infection in the leaves. In addition, the chlorophyll content of tobacco leaves was significantly increased after treatment with E₂, and the net photosynthesis (Pn) value was also increased, which demonstrated that the active compound could improve the photosynthetic efficiency of TMV-infected tobacco leaves by maintaining stable chlorophyll content in the leaves, thereby protecting host plants from viral infection. The results of MDA and H₂O₂ content determination revealed that E₂ could effectively reduce the content of peroxides in the infected plants, reducing the damage to the plants caused by oxidation. This work provides an important support for the research and development of antiviral agents in crop protection.

Composite Hydrogel for the Targeted Capture and Photothermal Killing of Bacteria toward Facilitating Wound Healing

Pathogenic infections pose a significant risk to public health and are regarded as one of the most difficult clinical treatment obstacles. A reliable and safe photothermal antibacterial platform is a promising technique for the treatment of bacterial infections. Given the damage that high temperatures cause in normal tissues and cells, a multifunctional hydrogel driven by photothermal energy is created by trapping bacteria to reduce heat transfer loss and conduct low-temperature photothermal sterilization efficiently. The 3-aminobenzene boronic acid (ABA)-modified graphene oxide is combined with carboxymethyl chitosan (CMCS) and cellulose nanocrystalline (CNC) networks to create the ABA-GO/CNC/CMCS composite hydrogel (composite gel). The obtained composite gel displays a uniform three-dimensional network structure, which can be rapidly heated to 48 °C under infrared light irradiation and is beneficial for killing wound infection bacteria and promoting wound healing. The results of animal experiments show that the composite gel significantly reduces inflammation by killing >99.99% of bacteria under near-infrared light irradiation. The result also demonstrates that it increases the granulation tissue thickness and collagen distribution and promotes wound healing. After treatment for 14 days, compared with the remaining 27.73% of the remaining wound area in the control group, the wound area in the composite gel with NIR group is only 0.91%. It significantly accelerates the wound healing process of Staphylococcus aureus infection and shows great potential for clinical application.

Multifunctional Nanoparticles and Nanopesticides in Agricultural Application

The unscientific application of pesticides can easily cause a series of ecological environmental safety issues, which seriously restrict the sustainable development of modern agriculture. The great progress in nanotechnology has allowed the continuous development of plant protection strategies. The nanonization and delivery of pesticides offer many advantages, including their greater absorption and conduction by plants, improved efficacy, reduced dosage, delayed resistance, reduced residues, and protection from natural enemies and beneficial insects. In this review, we focus on the recent advances in multifunctional nanoparticles and nanopesticides. The definition of nanopesticides, the types of nanoparticles used in agriculture and their specific synergistic mechanisms are introduced, their safety is evaluated, and their future application prospects, about which the public is concerned, are examined.

Fabrication of an alginate-based ZhiNengCong gel showed an enhanced antiviral and plant growth promoting functions

Tobacco mosaic disease is a worldwide viral disease that can cause huge economic losses. Plant immune inducers have become the main force in the prevention and treatment of viral disease own to their high efficiency and rapid effect. However, since tobacco mosaic disease can occur at any point in the plant growth cycle, a single application period cannot guarantee the completely management. In this study, an extract from Paecilomyces variotii named ZhiNengCong (ZNC), which can fight against tobacco mosaic disease with 65% control effect, and improve the promotion of tobacco stem girth, was selected from five commercial antiviral medicines, and a sustained release sodium alginate (Alg)-based ZNC (ZNC@Alg) was prepared by physical absorption. ZNC@Alg, who contains only 5 mg/mL ZNC, can release ZNC for 7 consecutive days, and displayed an enhanced effect in inducing the PAL-mediated salicylic acid signaling pathway activation to participate in the inhibition of green fluorescent protein (GFP)-tagged tobacco mosaic virus (TMV-GFP) infection, even after 7 days of the application. Notably, field experiments showed that the control effect of ZNC@Alg was up to 88%, which was significantly better than that of ZNC with the same concentration (10 μg per plant). In addition, ZNC@Alg exhibited a stronger growth-promoting effect than ZNC, which significantly increased the wet weight of tobacco. Taken together, we screened out a plant immune inducer ZNC that can effectively inhibit tobacco virus disease, and created ZNC@Alg with higher control effect and growth promotion effect, laying a foundation for effective field management of tobacco mosaic disease.

Fabrication of polydopamine reduced CuO nanoparticle-alginate composite nanogels for management of Pseudomonas synringae pv. tabaci in tobacco

BACKGROUND

The wildfire disease on tobacco can seriously hinder plants. Meanwhile, its pathogen, Pseudomonas syringae, can also infect over 200 plants and threat agriculture production. However, the disease usually occurs after summer rains which washes away most copper (Cu)-based bactericides, allowing the disease to invade. Therefore, we fabricate a new nanogel with high disease control and anti-erosion ability and study the effects of the reductant on the performance of the copper oxide nanoparticle (CuONP) composite nanogel.

RESULTS

Polydopamine (PDA) is a polycation for both in situ reduction of CuONP in alginate nanogels and for adjusting the copper ion (Cu²⁺ ) releasing rate in this work. The composite nanogel fabricated by PDA (PDA-CuONP@ALGNP@CTAC) had a higher Cu²⁺ releasing rate, damaging the pathogen membrane more efficiently, allowing for better disease control and plant growth promotion when compared to sodium borohydride (SBH)-fabricated nanogel (SBH-CuONP@ALGNP@CTAC) or the commercial bactericide, thiodiazole copper. The PDA-CuONP@ALGNP@CTAC had a high anti-erosion ability and could remain adhered to the leaf surface even after five rain event simulations.

CONCLUSION

The addition of polycations (like PDA) into CuONP composite nanogel could increase the Cu²⁺ releasing rate, resulting in improved disease management when compared to SBH-CuONP@ALGNP@CTAC or thiodiazole copper. The PDA containing gel had an improved anti-erosion ability and water resistance. This new composite nanogel has a high potential for wildfire disease control, improving agricultural production. © 2022 Society of Chemical Industry.

Novel trifluoromethylpyridine piperazine derivatives as potential plant activators

Plant virus diseases seriously affect crop yield, especially tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). The development of plant immune activators has been an important direction in the innovation of new pesticides. Therefore, we designed and synthesized a series of trifluoromethyl pyridine piperazine derivatives (A1-A27), and explored the action mechanism of active compound. The antiviral activity test showed that compounds A1, A2, A3, A9, A10, A16, A17 and A21 possessed higher activities than commercialized ningnanmycin. Particularly, the in vivo antiviral activity indicated that compound A16 showed the most potent protective activity toward TMV (EC50 = 18.4 μg/mL) and CMV (EC50 = 347.8 μg/mL), compared to ningnanmycin (50.2 μg /mL for TMV, 359.6 μg/mL for CMV). The activities of defense enzyme, label -free proteomic and qRT-PCR analysis showed that compound A16 could enhance the defensive enzyme activities of superoxide dismutase (SOD),polyphenol oxidase (PPO) and phenylalanine ammonialyase (PAL), and activate the phenylpropanoid biosynthesis pathway to strenthen the antiviral activities of tobacco. This study provides reliable support for the development of new antiviral pesticides and potential antiviral mechanism.

Interactive Effect of Biological Agents Chitosan, Lentinan and Ningnanmycin on Papaya Ringspot Virus Resistance in Papaya (Carica papaya L.)

The papaya industry is mainly impacted by viral diseases, especially papaya ringspot disease (PRSD) caused by papaya ringspot virus (PRSV). So far, research on the interaction between Chitosan, Lentinan and Ningnanmycin on PRSD has not been reported. This research studied the controlled and interactive effect of three biological agents, namely, Chitosan (C), Lentinan (L) and Ningnanmycin (N), on PRSV in papaya, individually and collectively. The changes in disease index, controlled effect, Peroxidase (POD), Polyphenol oxidase (PPO), Superoxide dismutase (SOD), growth and development of plants were observed at the seedling stage, in pots, and at the fruiting stage, in the field. The appearance and nutrient contents of fruits were measured during the fruit stage. The disease index of PRSV, at seedling and fruiting stages, was significantly lower for chitosan, lentinan and ningnanmycin and their interactive effect, compared to a control check treatment. The activity of the defense enzymes could be improved by the three kinds of biological agents and their interactive effect, especially lentinan and ningnanmycin. The chlorophyll content, plant height, stem diameter and fruit quality rose significantly under chitosan, lentinan and ningnanmycin treatments. The interaction of LN could inhibit PRSV disease at the seedling and fruiting stages of papaya, and promote the growth of plants and the quality of fruit at the fruit stage. Hence, this study provides the theoretical foundation for the biological control of papaya ringspot disease.

Pectin functionalized metal-organic frameworks as dual-stimuli-responsive carriers to improve the pesticide targeting and reduce environmental risks

Encapsulation of active ingredients into intelligent response controlled release carriers has been recognized as a promising approach to enhance the utilization efficiency and reduce the environmental risks of pesticides. In this work, an intelligent redox and pectinase dual stimuli-responsive pesticide delivery system was constructed by bonding pectin with metal-organic frameworks (FeMOF nanoparticles) which were loaded with pyraclostrobin (PYR@FeMOF-pectin nanoparticles). The successful fabrication of PYR@FeMOF-pectin nanoparticles was proved by a series of physicochemical characterizations. The results indicated that the loading capacity of PYR@FeMOF-pectin nanoparticles for pyraclostrobin was approximately 20.6%. The pectin covered on the surface of PYR@FeMOF nanoparticles could protect pyraclostrobin from photolysis and improve their spreadability on rice blades effectively. Different biological stimuli associated with Magnaporthe oryzae could trigger the release of pyraclostrobin from the pesticide-loaded core-shell nanoparticles, resulting in the death of pathogens. The bioactivity survey determined that PYR@FeMOF-pectin nanoparticles had a superior fungicidal activity and a longer duration against Magnaporthe oryzae than pyraclostrobin suspension concentrate. In addition, the FeMOF-pectin nanocarriers showed no obvious phytotoxicity and could enhance the shoot length and root length of rice plants. More importantly, PYR@FeMOF-pectin nanoparticles had an 8-fold reduction in acute toxicity to zebrafish than that of pyraclostrobin suspension concentrate. Therefore, the dual-responsive FeMOF-pectin nanocarriers have great potential for realizing site-specific pesticide delivery and promoting plant growth.

1,3,4-Oxadiazole Derivatives as Plant Activators for Controlling Plant Viral Diseases: Preparation and Assessment of the Effect of Auxiliaries

Plant viral diseases cause the loss of millions of dollars to agriculture around the world annually. Therefore, the development of highly efficient, ultra-low-dosage agrochemicals is desirable for protecting the health of crops and ensuring food security. Herein, a series of 1,3,4-oxadiazole derivatives bearing an isopropanol amine moiety was prepared, and the inhibitory activity against tobacco mosaic virus (TMV) was assessed. Notably, compound A₁₄ exhibited excellent anti-TMV protective activity with an EC₅₀ value of 137.7 mg L^-1, which was superior to that of ribavirin (590.0 mg L^-1) and ningnanmycin (248.2 mg L^-1). Moreover, the anti-TMV activity of some compounds could be further enhanced (by up to 5-30%) through supplementation with 0.1% auxiliaries. Biochemical assays suggested that compound A₁₄ could suppress the biosynthesis of TMV and induce the plant's defense response. Given these merits, designed compounds had outstanding bioactivities and unusual action mechanisms and were promising candidates for controlling plant viral diseases.

Alginate-Induced Disease Resistance in Plants

Plants are continuously exposed to a wide range of pathogens, including fungi, bacteria, nematodes, and viruses; therefore, survival under these conditions requires a sophisticated defense system. The activation of defense responses and related signals in plants is regulated mainly by the hormones salicylic acid, jasmonic acid, and ethylene. Resistance to pathogen infection can be induced in plants by various biotic and abiotic agents. For many years, the use of abiotic plant resistance inducers has been considered in integrated disease management programs. Recently, natural inducer compounds, such as alginates, have become a focus of interest due to their environmentally friendly nature and their ability to stimulate plant defense mechanisms and enhance growth. Polysaccharides and the oligosaccharides derived from them are examples of eco-compatible compounds that can enhance plant growth while also inducing plant resistance against pathogens and triggering the expression of the salicylic acid-dependent defense pathway.

Antiviral Strategies Using Natural Source-Derived Sulfated Polysaccharides in the Light of the COVID-19 Pandemic and Major Human Pathogenic Viruses

Only a mere fraction of the huge variety of human pathogenic viruses can be targeted by the currently available spectrum of antiviral drugs. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has highlighted the urgent need for molecules that can be deployed quickly to treat novel, developing or re-emerging viral infections. Sulfated polysaccharides are found on the surfaces of both the susceptible host cells and the majority of human viruses, and thus can play an important role during viral infection. Such polysaccharides widely occurring in natural sources, specifically those converted into sulfated varieties, have already proved to possess a high level and sometimes also broad-spectrum antiviral activity. This antiviral potency can be determined through multifold molecular pathways, which in many cases have low profiles of cytotoxicity. Consequently, several new polysaccharide-derived drugs are currently being investigated in clinical settings. We reviewed the present status of research on sulfated polysaccharide-based antiviral agents, their structural characteristics, structure-activity relationships, and the potential of clinical application. Furthermore, the molecular mechanisms of sulfated polysaccharides involved in viral infection or in antiviral activity, respectively, are discussed, together with a focus on the emerging methodology contributing to polysaccharide-based drug development.

Synthesis and Biological Evaluation of 1,2,4-Triazole Thioethers as Both Potential Virulence Factor Inhibitors against Plant Bacterial Diseases and Agricultural Antiviral Agents against Tobacco Mosaic Virus Infections

Targeting the virulence factors of phytopathogenic bacteria is an innovative strategy for alleviating or eliminating the pathogenicity and rapid outbreak of plant microbial diseases. Therefore, several types of 1,2,4-triazole thioethers bearing an amide linkage were prepared and screened to develop virulence factor inhibitors. Besides, the 1,2,4-triazole scaffold was exchanged by a versatile 1,3,4-oxadiazole core to expand molecular diversity. Bioassay results revealed that a 1,2,4-triazole thioether A₁₀ bearing a privileged N-(3-nitrophenyl)acetamide fragment was extremely bioactive against Xanthomonas oryzae pv. oryzae (Xoo) with an EC₅₀ value of 5.01 μg/mL. Label-free quantitative proteomics found that compound A₁₀ could significantly downregulate the expression of Xoo's type III secretion system (T3SS) and transcription activator-like effector (TALE) correlative proteins. Meanwhile, qRT-PCR detection revealed that the corresponding gene transcription levels of these virulence factor-associated proteins were substantially inhibited after being triggered by compound A₁₀. As a result, the hypersensitive response and pathogenicity were strongly depressed, indicating that a novel virulence factor inhibitor (A₁₀) was probably discovered. In vivo anti-Xoo trials displayed that compound A₁₀ yielded practicable control efficiency (54.2-59.6%), which was superior to thiadiazole-copper and bismerthiazol (38.1-44.9%). Additionally, compound A₁₀ showed an appreciable antiviral activity toward tobacco mosaic virus (TMV) with the curative and protective activities of 54.6 and 76.4%, respectively, which were comparable to ningnanmycin (55.2 and 60.9%). This effect was further validated and visualized by the inoculation test using GFP-labeled TMV, thereby leading to the reduced biosynthesis of green-fluorescent TMV on Nicotiana benthamiana. Given the outstanding features of compound A₁₀, it should be deeply developed as a versatile agricultural chemical.

Pesticide-loaded colloidal nanodelivery systems; preparation, characterization, and applications

The fast developments in pesticide-loaded nanodelivery systems over the last decade have inspired many companies and research organizations to highlight potential applications by employing encapsulation approaches in order to protect the agricultural crops. This approach is being used to retard the indiscriminate application of conventional pesticides, as well as, to make ensure the environmental safety. This article shed light on the potential of colloidal delivery systems, particularly controlled releasing profiles of several pesticides with enhanced stability and improved solubility. Colloidal nanodelivery systems, being efficient nanoformulations, have the ability to boost up the pest-control competence for prolonged intervals thru averting the early degradation of active ingredients under severe ecofriendly circumstances. This work is thus aimed to provide critical information on the meaningful role of nanocarriers for loading of pesticides. The smart art of pesticide-loaded nanocarriers can be more fruitful owing to the use of lower amount of active ingredients with improved efficiency along with minimizing the pesticide loss. Also, the future research gaps regarding nano-pesticide formulations, such as role of nanomaterials as active ingredients are discussed briefly. In addition, this article can deliver valuable information to the readers while establishing novel pesticide-loaded nanocarriers for a wide range of applications in the agriculture sectors.

Advances in Controlled-Release Pesticide Formulations with Improved Efficacy and Targetability

Pesticides are commonly used in modern agriculture and are important for global food security. However, postapplication losses due to degradation, photolysis, evaporation, leaching, surface runoff, and other processes may substantially reduce their efficacy. Controlled-release formulations can achieve the permeation-regulated transfer of an active ingredient from a reservoir to a target surface. Thus, they can maintain an active ingredient at a predetermined concentration for a specified period. This can reduce degradation and dissipation and other losses and has the potential to improve efficacy. Recent developments in controlled-release technology have adapted the concepts of intelligence and precision from the pharmaceutical industry. In this review, we present recent advances in the development of controlled-release formulations and discuss details of the preparation methods, material improvements, and application technologies.

Emamectin benzoate nanogel suspension constructed from poly(vinyl alcohol)-valine derivatives and lignosulfonate enhanced insecticidal efficacy

To reduce the negative impact of nanopesticide carriers of on the environment, a greener nanodelivery system is necessary. Nanogels are nontoxic and degradable carriers, however, the potential of nanogels for delivering pesticides has not been proven. In this study, poly(vinyl alcohol)-valine, an ecofriendly polymer, was synthesized and used to fabricate emamectin benzoate nanogel suspension (EB NS). The nanoformulation showed favorable stability at low temperature, high temperature or one year storage, and in water with different hardnesses. The retention of the EB NS solution on leaves was higher than that of an EB emulsifiable concentrate (EC) by approximately 9% at a concentration of 10 mg L^-1. The half-life of EB nanogels under Ultra Violet irradiation was prolonged by 3.3-fold. Moreover, the bioactivity of the EB NS against Plutella xylostella was higher than that of the EB EC. These advantages resulted in a relatively long duration of pest control. The response of nanogels to laccase, a digestive enzyme in the digestive tract of lepidopteran pests, enables pesticide release on demand. Nanogels have the advantages of being ecofriendly carriers, exhibiting higher utilization, and prolonged pest control periods, and they have a brilliant future in pesticide delivery.

A systematic study to unravel the potential of using polysaccharides based organic-nanoparticles versus hybrid-nanoparticles for pesticide delivery

To daze conventional pesticide release limitations, nanotechnology-mediated pesticide delivery using natural polymers has been actively investigated. However, the lack of information on what are the beneficial/non-beneficial aspects of using hybrid- and organic-nanoparticles (NP) and among the polysaccharides which are better suited concerning pesticide loading efficiency (PLE wt%), entrapment efficiency, and sustained pesticide release (SPR %) has prompted us to investigate this study. In this report, we systematically investigated a series of polysaccharides such as starch (S), cellulose (C), aminocellulose (AC), and sodium carboxymethylcellulose (NaCMC) coated on magnetite NP (MNP, Fe₃O₄) and complete organic nanocarrier systems (starch and cellulose) that have no MNP part were compared for the PLE wt% and SPR % efficiencies for chlorpyrifos (ChP) insecticide. Overall, all nanocarriers (NCs) have shown good to excellent PLE wt% due to the smaller-sized NP obtained through optimal conditions. However, among the hybrid polysaccharides studied, starch MNP has shown a maximum PLE of 111 wt% in comparison with other polysaccharides (80-94 wt%) coated hybrid-NCs as well as with organic-NCs (81-87 wt%). The use of inorganic support does improve the PLE wt% markedly for starch but not for cellulose derivatives. Similarly, the SPR results of S-NP showed a remarkably better sustained release profile for ChP of 88% in 14 d. In contrast, other unfunctionalized and functionalized celluloses exhibited poor release profiles of 60%-20% for the same period. This study may help the researchers choose the right system for designing and achieving enhanced pesticide efficiency.

Antiviral Properties of Alginate-Based Biomaterials: Promising Antiviral Agents against SARS-CoV-2

The COVID-19 pandemic has made it essential to explore alternative antiviral materials. Alginate is a biodegradable, renewable, biocompatible, water-soluble and antiviral biopolymer with many potential biomedical applications. In this regard, this review shows 17 types of viruses that have been tested in contact with alginate and its related biomaterials. Most of these studies show that alginate-based materials possess little or no toxicity and are able to inhibit a wide variety of viruses affecting different organisms: in humans by the human immunodeficiency virus type 1, the hepatitis A, B, and C viruses, Sindbis virus, herpes simplex virus type 1 and 2, poliovirus type 1, rabies virus, rubella virus, and the influenza virus; in mice by the murine norovirus; in bacteria by the T4 coliphage, and in plants by the tobacco mosaic virus and the potato virus X. Many of these are enveloped positive-sense single-stranded RNA viruses, like SARS-CoV-2, which render alginate-based materials highly promising in the COVID-19 pandemic.

Identification of Carbazole Alkaloid Derivatives with Acylhydrazone as Novel Anti-TMV Agents with the Guidance of a Digital Fluorescence Visual Screening

Difficulty in preventing crops from plant viruses urges to discover novel efficient antiviral chemicals, which is sped up by precise screening methods. Fluorescence-based methods have recently been applied as innovative and rapid tools for visually monitoring the replication of viruses and screening of antivirals, whereas the quantification of fluorescence signals mainly depends on manually calculating the fluorescent spots, which is time-consuming and imprecise. In the present work, the fluorescence spots were automatically identified, and the fluorescence area was directly quantified by a program developed in our group, which avoided subjective errors from the operators. We further employed this digital and visual screening assay to identify antivirals using the tobacco mosaic virus-green fluorescence protein (TMV-GFP) construct, in which the expression of GFP intuitively reflected the efficacy of antivirals. The accuracy of this assay was validated by quantifying the activities of the commercial antiviral inhibitors ribavirin and ningnanmycin and then was applied to evaluate the subtle activity differences of a series of newly synthesized carbazole and β-carboline alkaloid derivatives. Among them, compounds 5 (76%) and 11 (63%) exhibited anti-TMV activities comparable to that of ningnanmycin (65%) at 50 μM, and they delayed the multiplication of TMV in the early stage of infection without phytotoxicity. Taken together, these findings demonstrated that the digital and visual TMV-GFP screening method was competent to test the antiviral activities of compounds with subtle modifications and facilitated the discovery of novel antivirals.

The Enhancement of Antiviral Activity of Chloroinconazide by Aglinate-based Nanogel and Its Plant Growth Promotion Effect

Improving the efficiency and prolonging the duration of pesticides are of great significance in agricultural production. In this work, based on the antiviral compound chloroinconazide (CHI) synthesized previously, the improvement of the fabricated CHI-loaded alginate-based nanogel (CHI@ALGNP) was studied. It was found that CHI@ALGNP showed higher foliar adhesion than CHI and exhibited a sustained release for up to 7 days. CHI@ALGNP could also continuously activate the reactive oxygen species and antioxidant levels and induce the increase of salicylic acid content and the expression of its responsive gene PR2 for a long time, thus achieving sustained resistance to tobacco mosaic virus infection in Nicotiana benthamiana. Strikingly, CHI@ALGNP could release Ca2+ and Mg2+ to promote the growth of N. benthamiana. Taken together, for the first time, we have shown the improvement of a nanogel carrier to the antiviral activity and growth promotion of small molecular pesticides. As the alginate-based nanogel can be easily applied to the spray-based pesticide delivery technology, our study provides a new strategy for the development of new pesticide preparations and the application of multifunctional pesticides.

Study of the in vivo antiviral activity against TMV treated with novel 1-(t-butyl)-5-amino-4-pyrazole derivatives containing a 1,3,4-oxadiazole sulfide moiety

A series of new 1-tert-butyl-5-amino-4-pyrazole bioxadiazole sulfide derivatives containing a 1,3,4-oxadiazole moiety were designed and synthesized. The bioactivity results showed that some title compounds exhibited excellent protective activity against TMV and certain insecticidal activity. Among the tested compounds, the EC₅₀ values of 5d, 5j, 5k and 5l were 165.8, 163.2, 159.7 and 193.1 mg/L, respectively, which are better than the EC₅₀ value of ningnanmycin (271.3 mg/L). The chlorophyll contents and the defense enzyme activities of the tobacco leaves after treatment with 5j were significantly increased, which indicated that this series of title compounds may induce the systemic acquired resistance of host to defend against diseases. Further in vivo protective activity research on 5j using TMV with a GFP gene tag found that it can effectively inhibit the spread of TMV in inoculated tobacco. A morphological study with TEM revealed that title compound 5h can cause a distinct break of the rod-shaped TMV. Moreover, the insecticidal activity revealed that the fatality rates of 5a, 5b and 5m against aphidoidea were 85%, 83% and 87%, respectively, which indicated that the title compounds can effectively block the common carrier of plant viruses, thereby effectively reducing the TMV infection risk of tobacco. This series of synergistic effects provide key information for the research and development of antiviral agents.

Advances in controlled release pesticide formulations: Prospects to safer integrated pest management and sustainable agriculture

As the world is striving hard towards sustainable agricultural practices for a better tomorrow, one of the primary focuses is on effective pest management for enhanced crop productivity. Despite newer and potent chemicals as pesticides, there are still substantial crop losses, and if by any means this loss can be tackled; it will alleviate unwanted excessive use of chemical pesticides. Scientific surveys have already established that pesticides are not being utilized by the crops completely rather a significant amount remains unused due to various limiting factors such as leaching and bioconversion, etc., resulting in an adverse effect on human health and ecosystems. Concerted efforts from scientific diaspora toward newer and innovative strategies are already showing promise, and one such viable approach is controlled release systems (CRS) of pesticides. Moreover, to bring these smart formulations within the domain of current pesticide regulatory framework is still under debate. It is thus, paramount to discuss the pros and cons of this new technology vis-à-vis the conventional agrarian methods. This review deliberates on the developmental updates in this innovative field from the past decades and also appraises the challenges encumbered. Additionally, critical information and the foreseeable research gaps in this emerging area are highlighted.