Label-Free Quantitative Proteomic Analysis of Chitosan Oligosaccharide-Treated Rice Infected with Southern Rice Black-Streaked Dwarf Virus

The Past, Present, and Future of Plant Activators Targeting the Salicylic Acid Signaling Pathway

Plant activators have emerged as promising alternatives to conventional crop protection chemicals for managing crop diseases due to their unique mode of action. By priming the plant's innate immune system, these compounds can induce disease resistance against a broad spectrum of pathogens without directly inhibiting their proliferation. Key advantages of plant activators include prolonged defense activity, lower effective dosages, and negligible risk of pathogen resistance development. Among the various defensive pathways targeted, the salicylic acid (SA) signaling cascade has been extensively explored, leading to the successful development of commercial activators of systemic acquired resistance, such as benzothiadiazole, for widespread application in crop protection. While the action sites of many SA-targeting activators have been preliminarily mapped to different steps along the pathway, a comprehensive understanding of their precise mechanisms remains elusive. This review provides a historical perspective on plant activator development and outlines diverse screening strategies employed, from whole-plant bioassays to molecular and transgenic approaches. We elaborate on the various components, biological significance, and regulatory circuits governing the SA pathway while critically examining the structural features, bioactivities, and proposed modes of action of classical activators such as benzothiadiazole derivatives, salicylic acid analogs, and other small molecules. Insights from field trials assessing the practical applicability of such activators are also discussed. Furthermore, we highlight the current status, challenges, and future prospects in the realm of SA-targeting activator development globally, with a focus on recent endeavors in China. Collectively, this comprehensive review aims to describe existing knowledge and provide a roadmap for future research toward developing more potent plant activators that enhance crop health.

Physiological and Proteome Analysis of the Effects of Chitosan Oligosaccharides on Salt Tolerance of Rice Seedlings

Rice (Oryza sativa L.) is an important social-economic crop, and rice seedlings are easily affected by salt stress. Chitosan oligosaccharide (COS) plays a positive role in promoting plant growth and development. To gain a better understanding of the salt tolerance mechanism of rice under the action of COS, Nipponbare rice seedlings were selected as the experimental materials, and the physiological and biochemical indexes of rice seedlings in three stages (normal growth, salt stress and recovery) were measured. Unlabelled quantitative proteomics technology was used to study differential protein and signaling pathways of rice seedlings under salt stress, and the mechanism of COS to improve rice tolerance to salt stress was elucidated. Results showed that after treatment with COS, the chlorophyll content of rice seedlings was 1.26 times higher than that of the blank group (CK). The root activity during the recovery stage was 1.46 times that of the CK group. The soluble sugar in root, stem and leaf increased by 53.42%, 77.10% and 9.37%, respectively. The total amino acid content increased by 77% during the stem recovery stage. Furthermore, the malondialdehyde content in root, stem and leaf increased by 21.28%, 26.67% and 32.69%, respectively. The activity of oxide dismutase (SOD), peroxidase (POD) and oxygenase (CAT) were increased. There were more differentially expressed proteins in the three parts of the experimental group than in the CK group. Gene Ontology (GO) annotation of these differentially expressed proteins revealed that the experimental group was enriched for more entries. Then, through the Kyoto Encyclopedia of Genes and Genomes (KEGG), the top ten pathways enriched with differentially expressed proteins in the two groups (COS and CK groups) were utilized, and a detailed interpretation of the glycolysis and photosynthesis pathways was provided. Five key proteins, including phosphofructokinase, fructose bisphosphate aldolases, glycer-aldehyde-3-phosphate dehydrogenase, enolase and pyruvate kinase, were identified in the glycolysis pathway. In the photosynthesis pathway, oxygen evolution enhancement proteins, iron redox proteins and ferredoxin-NADPH reductase were the key proteins. The addition of COS led to an increase in the abundance of proteins, a response of rice seedlings to salt stress. COS helped rice seedlings resist salt stress. Furthermore, using COS as biopesticides and biofertilizers can effectively increase the utilization of saline-affected farmland, thereby contributing to the alleviating of the global food crisis.

Single-cell and spatial RNA sequencing reveal the spatiotemporal trajectories of fruit senescence

The senescence of fruit is a complex physiological process, with various cell types within the pericarp, making it highly challenging to elucidate their individual roles in fruit senescence. In this study, a single-cell expression atlas of the pericarp of pitaya (Hylocereus undatus) is constructed, revealing exocarp and mesocarp cells undergoing the most significant changes during the fruit senescence process. Pseudotime analysis establishes cellular differentiation and gene expression trajectories during senescence. Early-stage oxidative stress imbalance is followed by the activation of resistance in exocarp cells, subsequently senescence-associated proteins accumulate in the mesocarp cells at late-stage senescence. The central role of the early response factor HuCMB1 is unveiled in the senescence regulatory network. This study provides a spatiotemporal perspective for a deeper understanding of the dynamic senescence process in plants.

HNF4A as a potential target of PFOA and PFOS leading to hepatic steatosis: Integrated molecular docking, molecular dynamic and transcriptomic analyses

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are indeed among the most well known and extensively studied Per- and polyfluoroalkyl substances (PFASs), and increasing evidence confirm their effects on human health, especially liver steatosis. Nonetheless, the molecular mechanisms of their initiation of hepatic steatosis is still elusive. Therefore, potential targets of PFOA/PFOS must be explored to ameliorate its adverse consequences. This research aims to investigate the molecular mechanisms of PFOA and PFOS-induced liver steatosis, with emphasis on identifying a potential target that links these PFASs to liver steatosis. The potential target that causes PFOA and PFOS-induced liver steatosis have been explored and determined based on molecular docking, molecular dynamics (MD) simulation, and transcriptomics analysis. In silico results show that PFOA/PFOS can form a stable binding conformation with HNF4A, and PFOA/PFOS may interact with HNF4A to affect the downstream conduction mechanism. Transcriptome data from PFOA/PFOS-induced human stem cell spheres showed that HNF4A was inhibited, suggesting that PFOA/PFOS may constrain its function. PFOS mainly down-regulated genes related to cholesterol synthesis while PFOA mainly up-regulated genes related to fatty acid β-oxidation. This study explored the toxicological mechanism of liver steatosis caused by PFOA/PFOS. These compounds might inhibit and down-regulate HNF4A, which is the molecular initiation events (MIE) that induces liver steatosis.

A chitosan-coated lentinan-loaded calcium alginate hydrogel induces broad-spectrum resistance to plant viruses by activating Nicotiana benthamiana calmodulin-like (CML) protein 3

Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca2+ . This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca2+ .

Study on the binding of ningnanmycin to the helicase of Tobamovirus virus

The Tobamovirus helicase plays an important role in virus proliferation and host interaction. They can also be targets for antiviral drugs. Tobacco mosaic virus (TMV) is well controlled by ningnanmycin (NNM), but whether it acts on other virus helicases of Tobamovirus virus is not clear. In this study, we expressed and purified several Tobamovirus virus helicase proteins and analyzed the three-dimensional structures of several Tobamovirus virus helicases. In addition, the binding of Tobamovirus helicase to NNM was also studied. The docking study reveals the interaction between NNM and Tobamovirus virus helicase. Microscale Thermophoresis (MST) experiments have shown that NNM binds to Tobamovirus helicase with a dissociation constant of 4.64-12.63 μM. Therefore, these data are of great significance for the design and synthesis of new effective anti-plant virus drugs.

Molecular insights into the responses of barley to yellow mosaic disease through transcriptome analysis

BACKGROUND

Barley (Hordeum vulgare L.) represents the fourth most essential cereal crop in the world, vulnerable to barley yellow mosaic virus (BaYMV) and/or barley mild mosaic virus (BaMMV), leading to the significant yield reduction. To gain a better understanding of the mechanisms regarding barley crop tolerance to virus infection, we employed a transcriptome sequencing approach and investigated global gene expression among three barley varieties under both infected and control conditions.

RESULTS

High-throughput sequencing outputs revealed massive genetic responses, reflected by the barley transcriptome after BaYMV and/or BaMMV infection. Significant enrichments in peptidase complex and protein processing in endoplasmic reticulum were clustered through Gene ontology and KEGG analysis. Many genes were identified as transcription factors, antioxidants, disease resistance genes and plant hormones and differentially expressed between infected and uninfected barley varieties. Importantly, general response genes, variety-specific and infection-specific genes were also discovered. Our results provide useful information for future barley breeding to resist BaYMV and BaMMV.

CONCLUSIONS

Our study elucidates transcriptomic adaptations in barley response to BaYMV/BaMMV infection through high-throughput sequencing technique. The analysis outcome from GO and KEGG pathways suggests that BaYMV disease induced regulations in multiple molecular-biology processes and signalling pathways. Moreover, critical DEGs involved in defence and stress tolerance mechanisms were displayed. Further functional investigations focusing on these DEGs contributes to understanding the molecular mechanisms of plant response to BaYMV disease infection, thereby offering precious genetic resources for breeding barley varieties resistant to BaYMV disease.

CsMYC2 is involved in the regulation of phenylpropanoid biosynthesis induced by trypsin in cucumber (Cucumis sativus) during storage

Trypsin has a new activity of scavenging superoxide anion and generating hydrogen peroxide. Trypsin can significantly improve the storage quality of C. sativus. To illustrate the mechanism of trypsin-induced resistance in fruits and vegetables, an integrated analysis of widely targeted metabolomics and transcriptomics was carried out. Transcriptomic results showed that 1068 genes highly related to phenylpropanoid biosynthesis gathered in the brown module were obtained by WGCNA. In KEGG analysis, differentially expressed genes (DEGs) were also highly enriched in EIP (Environmental Information Processing) pathways "Plant hormone signal transduction (map04075)" and "MAPK signaling pathway-plant (map04016)". Next, 87 genes were identified as the leading edge by GSEA analysis. So far, CsMYC2 was highlighted as a key transcription factor that regulates phenylpropanoid biosynthesis identified by GSEA and WGCNA. Furthermore, the major route of biosynthesis of phenylpropanoid compounds including coumarins, lignins, chlorogenic acid, flavonoids, and derivatives regulated by trypsin was also illustrated by both transcriptomic and metabolomic data. Results of O2PLS showed that CsMYC2 was positively correlated with Rosmarinic acid-3-O-glucoside, Epigallocatechin, Quercetin-3-O-sophoroside (Baimaside), and so on. Correlation between CsMYC2, phenylpropanoid related genes, and metabolites in C. sativus was illustrated by co-expression networks. Roles of CsMYC2 were further checked in C. sativus by VIGS. The results of this study might give new insight into the exploration of the postharvest resistance mechanism of C. sativus induced by trypsin and provide useful information for the subsequent mining of resistance genes in C. sativus.

A Proteomics Insight into Advancements in the Rice-Microbe Interaction

Rice is one of the most-consumed foods worldwide. However, the productivity and quality of rice grains are severely constrained by pathogenic microbes. Over the last few decades, proteomics tools have been applied to investigate the protein level changes during rice-microbe interactions, leading to the identification of several proteins involved in disease resistance. Plants have developed a multi-layered immune system to suppress the invasion and infection of pathogens. Therefore, targeting the proteins and pathways associated with the host's innate immune response is an efficient strategy for developing stress-resistant crops. In this review, we discuss the progress made thus far with respect to rice-microbe interactions from side views of the proteome. Genetic evidence associated with pathogen-resistance-related proteins is also presented, and challenges and future perspectives are highlighted in order to understand the complexity of rice-microbe interactions and to develop disease-resistant crops in the future.

Plant Protection against Viruses: An Integrated Review of Plant Immunity Agents

Plant viruses are an important class of pathogens that seriously affect plant growth and harm crop production. Viruses are simple in structure but complex in mutation and have thus always posed a continuous threat to agricultural development. Low resistance and eco-friendliness are important features of green pesticides. Plant immunity agents can enhance the resilience of the immune system by activating plants to regulate their metabolism. Therefore, plant immune agents are of great importance in pesticide science. In this paper, we review plant immunity agents, such as ningnanmycin, vanisulfane, dufulin, cytosinpeptidemycin, and oligosaccharins, and their antiviral molecular mechanisms and discuss the antiviral applications and development of plant immunity agents. Plant immunity agents can trigger defense responses and confer disease resistance to plants, and the development trends and application prospects of plant immunity agents in plant protection are analyzed in depth.

Immune Mechanism of Ethylicin-Induced Resistance to Xanthomonas oryzae pv. oryzae in Rice

Ethylicin (ET) was reported to be promising in the control of rice bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo). The detailed mechanism for this process remains unknown. Disclosed here is an in-depth study on the action mode of ET to Xoo. Through plant physiological and biochemical analysis, it was found that ET could inhibit the proliferation of Xoo by increasing the content of defense enzymes and chlorophyll in rice (Oryza sativa ssp. Japonica cv. Nipponbare). Label-free quantitative proteomic analysis showed that ET affected the rice abscisic acid (ABA) signal pathway and made the critical differential calcium-dependent protein kinase 24 (OsCPK24) more active. In addition, the biological function of OsCPK24 as a mediator for rice resistance to Xoo was determined through the anti-Xoo phenotypic test of OsCPK24 transgenic rice and the affinity analysis of the OsCPK24 recombinant protein in vitro and ET. This study revealed the molecular mechanism of ET-induced resistance to Xoo in rice via OsCPK24, which provided a basis for the development of new bactericides based on the OsCPK24 protein.

Chitinase-Assisted Bioconversion of Chitinous Waste for Development of Value-Added Chito-Oligosaccharides Products

Chito-oligosaccharides (COSs) are the partially hydrolyzed products of chitin, which is abundant in the shells of crustaceans, the cuticles of insects, and the cell walls of fungi. These oligosaccharides have received immense interest in the last few decades due to their highly promising bioactivities, such as their anti-microbial, anti-tumor, and anti-inflammatory properties. Regarding environmental concerns, COSs are obtained by enzymatic hydrolysis by chitinase under milder conditions compared to the typical chemical degradation. This review provides updated information about research on new chitinase derived from various sources, including bacteria, fungi, plants, and animals, employed for the efficient production of COSs. The route to industrialization of these chitinases and COS products is also described.

Myricetin Derivative Targets Cucumber Mosaic Virus 2b Protein to Achieve In Vivo Antiviral Activity in Plants

Cucumber mosaic virus (CMV) 2b protein plays a key role in the process of CMV infecting plants and symptom formation and is a potential molecular target for the control of this important plant virus. The exploitation of antiviral compounds is one of the strategies with the highest input: output ratio in plant protection. In this study, the CMV 2b recombinant protein was cloned, purified, and identified as the target protein by mass spectrometry. Subsequently, we carried out preliminary functional screening of the LP series of myricetin derivatives designed and synthesized in our laboratory and commercial antiviral compounds by microscale thermophoresis (MST), which showed that LP compounds LP4, LP11, LP13, and LP20 interacted well with CMV 2b, with dissociation constant (K_d) values of 1.39, 0.88, 1.52, and 1.77 μM, respectively. Among the commercially available antiviral compounds, ningnanmycin (NNM) was the most active, with a K_d value of 4.09 μM. Then, the strongest binding force to CMV 2b was identified to be from LP11 by isothermal titration calorimetry (ITC) experiments, with a K_d of 1.19 μM. Among the commercial compounds, NNM had the strongest binding force with CMV 2b, with a K_d of 4.62 μM. Through the screening of commercial compounds and LP series compounds by MST and ITC, LP11, NNM (positive control), LP16 (negative control), and the blank control group were selected to test the in vivo impact of LP11 on CMV. Specifically, the screened compounds were sprayed onto CMV-inoculated Nicotiana benthamiana plants to determine their impact on the regulation of CMV pathogenic gene expression, symptoms, and virus titer. The results showed that LP11 had a strong ability to inhibit CMV infection of tobacco at the transcriptional and translational levels. By mutating the CMV 2b protein, the 15th amino acid leucine and the 18th amino acid methionine at the N-terminal region were shown to be potential sites for binding to compound LP11. This finding provided a theoretical basis for screening and developing anti-CMV agents.

Transcriptome analyses and virus-induced gene silencing identify HuWRKY40 acting as a hub transcription factor in the preservation of Hylocereus undatus by trypsin

Trypsin can significantly improve the storage quality of Hylocereus undatus (H. undatus). To verify the hub WRKY gene of H. undatus in trypsin preservation, joint analysis of transcriptome and protein-protein interaction (PPI) network was carried out, and virus-induced gene silencing (VIGS) was conducted. In the transcriptome of H. undatus, GO directed acyclic graph (DAG) showed that the GO terms of 55 WRKY genes were mainly enriched in sequence-specific DNA binding, DNA binding transcription factor activity, and so on. The GO enrichment chord diagram showed that HuWRKY40 was significantly up-regulated in the enriched top10 GO terms. KEGG enrichment analysis showed that 55 WRKY genes were mainly enriched in plant-pathogen interaction and MAPK pathway. The results of PPI network showed that HuWRKY40 was a hub protein of WRKY transcription factors (TFs) family regulated by trypsin, which was consistent with the results of transcriptome analysis. Bioinformatics analysis showed that HuWRKY40 of H. undatus had the highest homology with Beta vulgaris L. and Spinacia oleracea L. The function of the core regulatory protein HuWRKY40 was further clarified by VIGS technology. The results of VIGS showed that there was a big difference between the phenotype of the pTRV2-HuWRKY40 group and that of the control group. Finally, it was confirmed that HuWRKY40 accelerated the synthesis of flavonoids and improved the fruit quality during the storage of H. undatus. This study found that trypsin may regulate HuWRKY40 activity through the MAPK cascade pathway, affect the participation of flavonoid synthesis, and then delay fruit corruption. PRACTICAL APPLICATIONS: With attention of people to the safety and freshness of fruits and vegetables, biological preservation technology has become one of the hotspots in the field of preservation in recent years. Trypsin can significantly improve the antioxidant capacity of fruits and vegetables. As a new biological preservative, it is convenient to operate and economical. In the current work, the mechanism of trypsin on the WRKY TFs during H. undatus storage was investigated. The application of trypsin would provide a new strategy for the storage quality control of fruits and vegetables.

EuRBG10 involved in indole alkaloids biosynthesis in Eucommia ulmoides induced by drought and salt stresses

Alkaloids are natural products with many important medicinal activities. To explore the mechanism of abiotic stress promoting alkaloid biosynthesis in Eucommia ulmoides, transcriptomic analysis and metabonomic analysis were used, virus-induced gene silencing (VIGS) lines of target gene were constructed. The results showed that drought and salt stress caused wilting and blackening of leaves, decreased chlorophyll level, and significantly induced MDA and relative conductivity. To resist the damage of stress to cells, the level of secondary metabolites such as alkaloids increased significantly with the extension of stress time. Transcriptomic results showed that, were. Six alkaloid related genes (AWGs) were gathered in five modules positively correlated with either salt stress or alkaloid contents by WGCNA. Results of GO and KEGG enrichment revealed that biosynthesis of alkaloid, especially indole alkaloid was induced, and degradation of alkaloid was inhibited under salt stress. Combining the results of transcriptome and metabolomics, it was suggested that EuRBG10 promotes the production of indole alkaloids and EuAMO5 inhibits the degradation of alkaloids, which may be the core mechanism of the indole alkaloid biosynthesis pathway (map00901) induced by salt stress. The results of these hub proteins were also consistent with the chordal graph of KEGG enrichment. Hub roles of EuRGB10 was checked in E. ulmoides by VIGS. Our findings provide a preliminary understanding of abiotic stress regulating secondary metabolites such as alkaloids, and propose hub genes that can be used to improve the level of bioactive components in medicinal plant.

Identification of molecular initiating events and key events leading to endocrine disrupting effects of PFOA: Integrated molecular dynamic, transcriptomic, and proteomic analyses

Perfluorooctanoic acid (PFOA) can rapidly activate signaling pathways independent of nuclear hormone receptors through membrane receptor regulation, which leads to endocrine disrupting effects. In the present work, the molecular initiating event (MIE) and the key events (KEs) which cause the endocrine disrupting effects of PFOA have been explored and determined based on molecular dynamics simulation (MD), fluorescence analysis, transcriptomics, and proteomics. MD modeling and fluorescence analysis proved that, on binding to the G protein-coupled estrogen receptor-1 (GPER), PFOA could induce a conformational change in the receptor, turning it into an active state. The results also indicated that the binding to GPER was the MIE that led to the adverse outcome (AO) of PFOA. In addition, the downstream signal transduction pathways of GPER, as regulated by PFOA, were further investigated through genomics and proteomics to identify the KEs leading to thr endocrine disrupting effects. Two pathways (Endocrine resistance, ERP and Estrogen signaling pathway, ESP) containing GPER were regulated by different concentration of PFOA and identified as the KEs. The knowledge of MIE, KEs, and AO of PFOA is necessary to understand the links between PFOA and the possible pathways that lead to its negative effects.

Discovery of Mesoionic Derivatives Containing a Dithioacetal Skeleton as Novel Potential Antibacterial Agents and Mechanism Research

In this study, the design and synthesis of novel pyrido[1,2-a]pyrimidinone mesoionic derivatives incorporating dithioacetal structures were carried out. The three-dimensional quantitative structure-activity relationship (3D-QSAR) model was built according to the EC₅₀ values and directed the synthesis of compound A32. The biological activity test against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) indicated that compound A32 showed good antibacterial activity with EC₅₀ values of 10.9 and 17.5 mg/L, which were lower than the EC₅₀ values of bismerthiazol (29.3 and 39.8 mg/L) and thiodiazole copper (64.8 and 78.1 mg/L). Furthermore, the in vivo antibacterial activity against bacterial leaf blight (BLB) and bacterial leaf streak (BLS) revealed that the protective activity of compound A32 was 43.9 and 41.7%, respectively, which was better than the protective activity of thiodiazole copper (40.6 and 35.0%). In addition, the protective activity against bacterial leaf blight of compound A32 was associated with the increasing rice defensive enzyme activity and the upregulation of proteins involved in oxidative phosphorylation. Moreover, compound A32 could upregulate the expression of complex I (nicotinamide adenine dinucleotide hydrogen (NADH) dehydrogenase) in the oxidative phosphorylation pathway, which was verified by complex I activity evaluation.

Coumarin Derivatives Containing Sulfonamide and Dithioacetal Moieties: Design, Synthesis, Antiviral Activity, and Mechanism

Cucumber mosaic virus (CMV) is currently a known plant virus with the most hosts, broadest distribution, and economic hazard. To develop new antiviral drugs against this serious virus, a new range of coumarin derivatives containing sulfonamide and dithioacetal structures were designed and synthesized, and their anti-CMV activities were detected by the half-leaf dead spot method. The results of the biological activity assay showed that most of the compounds exhibited outstanding anti-CMV activity. Especially, compound C23 displayed the optimal in vivo anti-CMV activity, with an EC50 value of 128 μg/mL, which was remarkably better than that of COS (781 μg/mL) and ningnanmycin (436 μg/mL). Excitingly, we found that compound C23 could be a promising plant activator that significantly increased defense-related enzyme activities and the tobacco chlorophyll content. Furthermore, compound C23 enhanced defense responses against viral infection by inducing the abscisic acid (ABA) pathway in tobacco. This work established a basis for multifunction pesticide discovery involving mechanism of action study and structure optimization.

Ferulic acid derivatives with piperazine moiety as potential antiviral agents

BACKGROUND

Plant virus diseases are difficult to control and severely threaten the productivity of crops, which leads to huge financial losses. To discover the new antiviral drugs, 34 novel ferulic acid derivatives with piperazine moiety were synthesized, and the antiviral activities were systematically screened as well.

RESULTS

Bioassay results indicated that most of the target compounds had outstanding antiviral activities against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV) in vivo. In particular, compound E2 exhibited remarkable curative activities to TMV and CMV with EC₅₀ values of 189.0 and 401.7 μg/mL compared to those for ningnanmycin (387.0, 519.3 μg/mL) and ribavirin (542.1, 721.5 μg/mL). And then the mechanisms of compound E2 were studied by chlorophyll content, differentially expressed proteins and genes tests.

CONCLUSION

The excellent antiviral activity of compound E2 was closely associated with the increase in host photosynthesis, which was confirmed by chlorophyll content, differentially expressed proteins and genes assays. Compound E2 can be considered as a lead structure for the discovery of new antiviral agents. © 2022 Society of Chemical Industry.

Insights into a rapid screening method for anti-cucumber mosaic virus compounds

Cucumber mosaic virus (CMV) is a detrimental plant virus in agricultural production. Traditionally, the half-leaf method using Nicotiana glutinosa has been used for screening agrochemicals to control CMV. However, this forms a time-consuming experimental bottleneck. In this study, we constructed a rapid screening model for anti-CMV compounds using CMV. In short, purified CMV particles were labeled through amine reactions and then subjected to binding studies with commercial compounds. The relative gene expression levels were then confirmed. Additionally, the rapid screening model results were verified using synthesized compounds. The commercial compounds ningnanmycin, ribavirin, and moroxydine hydrochloride bound to CMV with dissociation constants of 0.012, 2.870, and 0.069 μM, respectively, and they significantly inhibited expression of the gene for the CMV coat protein in CMV-infected tobacco leaves. This rapid screening model was assessed using our synthetic compounds N12, N16, and N18 through binding, which were shown to have dissociation constants 0.008, 0.025, and 70.800 μM, respectively, as well as via gene expression studies. Thus, a rapid method for screening anti-CMV commercial compounds and our synthetic compounds was constructed and confirmed.

Discovery of Novel Benzo[4,5]thiazolo(oxazolo)[3,2-a]pyrimidinone Mesoionic Derivatives as Potential Antibacterial Agents and Mechanism Research

A series of benzo[4,5]thiazole(oxazole)[3,2-a]pyrimidine mesoionic compounds were designed and synthesized. Antibacterial activity tests revealed that compound A23 showed good in vitro activities against Xanthomonas oryzae pv. Oryzicola (Xoc) and Xanthomonas oryzae pv. oryzae (Xoo), with half-maximal effective concentration (EC₅₀) values of 47.6 and 36.8 μM, respectively, which were better than positive control agents thiodiazole copper (281 and 259 μM) and bismerthiazol (245 and 220 μM). The protective activities of compound A23 anti-Xoc and anti-Xoo were 39.7% and 49.2%, respectively, which were better than those of bismerthiazol (31.5% and 40.7%). Compound A23 improved defensive enzyme activities in rice. In addition, compound A23 could upregulate the expression of succinate dehydrogenase (SDH) in the oxidative phosphorylation (OXPHOS) pathway through proteomics analysis, which was consistent with the result of the SDH activity test. Thus, compound A23 is a novel potential antibacterial agent that can be further developed.

PFOA regulate adenosine receptors and downstream concentration-response cAMP-PKA pathway revealed by integrated omics and molecular dynamics analyses

As an important pollutant, perfluorooctane acid (PFOA) has been widely concerned and reported by thousands of times, while less is known about the concentration-response pathway of PFOA. The aim of the present work was to reveal the concentration-response mechanism of PFOA in human cells. Omics results showed that calcium-related pathways play key roles in PFOA injury mechanisms. The results of GO and KEGG analyses showed that the cAMP signaling pathway was presented as the top one in all of the regulatory patterns and concentrations groups of PFOA. In the cAMP signaling pathway, the adenosine A₁ receptor (ADORA1) recognized the low concentration of PFOA and induced pathway "G_i-cAMP-PKA" to decrease the concentration of cAMP. This indicated that the low concentration of PFOA may promote breast hyperplasia and inhibit lactation. While adenosine A_2A receptor (ADORA2A) recognized the high concentration of PFOA and induced pathway "G_S-AC-cAMP-RKA" to increase the concentration of cAMP, induce cell damage and may lead to the deterioration of breast cancer. The results of molecular dynamics simulation showed that PFOA could bind to ADORA1 and ADORA2A, thus cause subsequent signal transduction. Furthermore, considering the strong binding ability of PFOA with ADORA1, PFOA tends to bind to ADORA1 at a low concentration. On the other side, PFOA at high concentration will continue to bind to another receptor protein, ADORA2A, and activate subsequent signaling pathways. Combined analyses of transcriptomic and proteomic revealed that different concentrations of PFOA regulate cellular calcium-related pathways. The cAMP pathway showed a concentration-response effect of PFOA. After treatment with different concentrations of PFOA, ADORA1 and ADORA2A were activated respectively, showing opposite cellular effects, leading to kinds of breast lesions. In the nervous system, PFOA might induce a variety of nervous system diseases. The present work was an exploration on the toxicological mechanism of PFOA, providing important information on the health impacts of PFOA in humans.

LsrB, the hub of ABC transporters involved in the membrane damage mechanisms of heavy ion irradiation in Escherichia coli

BACKGROUND

Ionizing radiation, especially heavy ion (HI) beams, has been widely used in biology and medicine. However, the mechanism of membrane damage by such radiation remains primarily uncharacterized.

PURPOSE

Transcriptomic profiles of Escherichia coli (E. coli) treated with HI illustrated the response mechanisms of the membrane, mainly ABC transporters, related genes regulated by antibiotics treatment through enrichment analyses of GO and KEGG. The networks of protein-protein interactions indicated that LsrB was the crucial one among the ABC transporters specially regulated by HI through the calculation of plugins MCODE and cytoHubba of Cytoscape. Finally, the expression pattern, GO/KEGG enrichment terms, and the interaction between nine LuxS/AI-2 quorum sensing system members were investigated.

CONCLUSIONS

Above all, results suggested that HI might perform membrane damage through regulated material transport, inhibited LuxS/AI-2 system, finally impeded biofilm formation. This work provides further evidence for the role of ABC transporters, especially LsrB, in membrane damage of E. coli to HI. It will provide new strategies for improving the precise application of HI.

Omics analyses indicate the routes of lignin related metabolites regulated by trypsin during storage of pitaya (Hylocereus undatus)

The storage quality of Hylocereus undatus was significantly improved by trypsin, a novel preservative. The transcriptomic results revealed that antioxidant signal pathways were induced, while lignin catabolic process was impeded by trypsin. In addition, the results of protein-protein interaction (PPI) network networks suggested that flavone 3'-O-methyltransferase 1 (OMT1), ferulic acid 5-hydroxylase 1 (CYP84A1), cellulose synthase isomer (CEV1), and 4-coumarate-CoA ligase 3 (4CL3) act as hubs of peroxidases, lignin related proteins, and proteins involved in the phenylpropanoid metabolism (PLPs) induced by trypsin. Trypsin also regulated the biosynthesis of lignin, chlorogenic acid, and flavonoids. Caffeic acid might be the hub in the metabolic network of the early pathways of phenylpropanoid biosynthesis. It has been hypothesized that trypsin might quickly induce lignin biosynthesis and then up-regulated bioactive metabolites to enhance storage quality of H. undatus.

Synthesis of trans- methyl ferulate bearing an oxadiazole ether as potential activators for controlling plant virus

A series of new ferulic acid derivatives bearing an oxadiazole ether was synthesized by introducing a structure of oxadiazole into trans-ferulic acid via an ether linkage. The synthesized target compounds were evaluated in vivo for their anti-TMV (tobacco mosaic virus) activity, which indicated that some synthesized compounds displayed strong activity for controlling TMV. For protective activity, compounds 6f and 6h had the most activities of 65% and 69.8% at 500 mg L^-1, respectively. Compounds 6a, 6b, 6e, 6f and 6h showed > 60% curative activities at 500 mg L^-1. Preliminary proteomics analysis showed that compound 6h could regulate the phenylpropanoid biosynthesis pathway and chloroplast function. These results indicated that synthesized novel ferulic acid derivatives could be used for controlling TMV.

Design, Synthesis, Antibacterial Activity, and Mechanisms of Novel 1,3,4-Thiadiazole Derivatives Containing an Amide Moiety

To discover novel antibacterial agents, a series of novel 1,3,4-thiadiazole derivatives containing an amide moiety were designed and synthesized, and their antibacterial activities were tested. Compound 30 was designed and synthesized according to the CoMFA model. Compound 30 exhibited higher antibacterial activities against Xanthomonas oryzae pv. oryzicola and Xanthomonas oryzae pv. oryzae, with EC₅₀ values of 2.1 and 1.8 mg/L, respectively, which were superior to those of thiodiazole copper (99.6 and 92.5 mg/L). The protective and curative activities of compound 30 against rice bacterial leaf blight were 51.3 and 46.1%, respectively, which were better than those of thiodiazole copper (37.8 and 38.5%). The protective and curative activities of compound 30 against rice bacterial leaf streak were 45.9 and 40.5%, respectively, which were better than those of thiodiazole copper (36.2 and 31.1%). In addition, the protective activity of compound 30 against rice bacterial leaf streak was related to increased activities of related defense enzymes and upregulated the differentially expressed proteins of the glycolysis/gluconeogenesis pathway.

The Potential of Using Chitosan on Cereal Crops in the Face of Climate Change

This review presents the main findings from measurements carried out on cereals using chitosan, its derivatives, and nanoparticles. Research into the use of chitosan in agriculture is growing in popularity. Since 2000, 188 original scientific articles indexed in Web of Science, Scopus, and Google Scholar databases have been published on this topic. These have focused mainly on wheat (34.3%), maize (26.3%), and rice (24.2%). It was shown that research on other cereals such as millets and sorghum is scarce and should be expanded to better understand the impact of chitosan use. This review demonstrates that this chitosan is highly effective against the most dangerous diseases and pathogens for cereals. Furthermore, it also contributes to improving yield and chlorophyll content, as well as some plant growth parameters. Additionally, it induces excellent resistance to drought, salt, and low temperature stress and reduces their negative impact on cereals. However, further studies are needed to demonstrate the full field efficacy of chitosan.

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.

Synthesis, Antibacterial Activity, and Mechanisms of Novel 6-Sulfonyl-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole Derivatives

A series of novel 6-sulfonyl-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives were designed and synthesized. CoMFA models were established to analyze the quantitative structure-activity relationships on the basis of the EC₅₀ values of the compounds. The models were used to design and synthesize compounds 32 and 33 with higher activities. The EC₅₀ values of compound 33 against Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) were 0.59 and 1.63 mg/L, respectively, which were higher than those of thiodiazole copper (90.43 and 97.93 mg/L) and bismerthiazol (68.37 and 75.59 mg/L). Moreover, protective activities of compound 33 against bacterial leaf streak (BLS) and bacterial leaf blight (BLB) were 49.65% and 49.42%, respectively, which were superior to those of thiodiazole copper (44.28% and 41.51%) and bismerthiazol (38.89% and 40.09%). Protective activity of compound 33 against BLS was closely related to the improvement of defense-related enzyme activities, chlorophyll content, and photosynthesis activation. This is consistent with the upregulated expression of defense responses and photosynthesis-related proteins.

Research on the Interaction Mechanism Between α Mino-Phosphonate Derivative Q-R and Harpin-Binding Protein 1 in Tobacco (Nicotiana tabacum) Plants

Amino-phosphonate derivative R-diphenyl-1-(4-methylbenzothiazole-2-amino)-1-(thiphene-2-yl)-methylphosphonate (Q-R) has a high protective anti-tobacco mosaic virus (TMV) activity. However, the mechanism responsible for Q-R's effect on TMV infection is largely unknown. Here, we studied the expression levels of harpin-binding protein 1 (HrBP1) and pathogenesis-related protein-1a (PR-1a) in TMV-infected tobacco plants by using reverse transcription quantitative real-time PCR. Then, we verified the interactions between Q-R and the HrBP1 protein from Escherichia coli using isothermal titration calorimetry and studied the Q-R-associated assembly of HrBP1 using size-exclusion chromatography. The results showed that the expression levels of HrBP1 and PR-1a genes were significantly increased by Q-R at the transcriptional level in TMV-infected tobacco plants, and the E. coli-expressed HrBP1 protein was assembled into oligomers by Q-R via binding to HrBP1 with a dissociation constant of 1.19 μM. We, therefore, concluded that Q-R activated the HrBP1 and PR-1a genes and enhanced the ability of HrBP1 to assemble in tobacco plants.

Preparation of Active Chitooligosaccharides with a Novel Chitosanase AqCoA and Their Application in Fungal Disease Protection

Enzymes that degrade fungal cell walls and the resulting oligosaccharides are promising weapons to combat plant fungal disease. In this study, we identified a novel endo-chitosanase, AqCoA, from Aquabacterium sp. A7-Y. The enzyme showed a specific activity of 18 U/mg toward 95% deacetylated chitosan at pH 5.0 and 40 °C. AqCoA also showed activity toward sodium carboxymethylcellulose, indicating substrate promiscuity. AqCoA hydrolyzed chitosan into chitooligosaccharides (CoA-COSs) with degrees of polymerization (DPs) of 3-5 but showed no activity toward CoA-COSs with DPs <6, indicating an endo-type activity. At 2.5 μg/mL, AqCoA inhibited appressorium formation of Magnaporthe oryzae; the produced CoA-COSs also inhibited the growth of M. oryzae and Fusarium oxysporum. Furthermore, CoA-COSs acted as immune elicitors in rice by inducing the reactive oxygen species burst and the expression of defense genes. These results demonstrated that AqCoA and its resulting CoA-COSs might be effective tools for protecting plants against pathogenic fungi.

Detection of Southern Rice Black-Streaked Dwarf Virus Using Western Blotting With P6

The southern rice black-streaked dwarf virus (SRBSDV) is a severe threat to the yield and quality of rice products worldwide. Traditional detection methods for diagnosing SRBSDV infection show several false positives and thus provide inaccurate findings. However, Western blotting (WB) can precisely solve this problem. In this study, P6—a viral RNA-silencing suppressor—was expressed and purified in vitro. Two polyclonal P6 antibodies were obtained and quantified by enzyme-linked immunosorbent assay and WB. Subsequently, WB was performed using the P6 antibodies to identify SRBSDV antigens derived from the suspected rice samples collected from nine districts in Guizhou, China. The assay results showed that Libo, Pingtang, Huishui, Dushan, and Anshun districts had experienced an SRBSDV outbreak. The virus content in the sampled rice tissues was quantified by WB. Our results revealed that SRBSDV mainly accumulated in rice stems rather than rice leaves. Thus, the findings of our study show that the SRBSDV P6 antibody can be used in WB for detecting and monitoring SRBSDV infection in infected rice plants.

Catechin gallate acts as a key metabolite induced by trypsin in Hylocereus undatus during storage indicated by omics

Trypsin is a novel superoxide scavenger. The storage quality of H. undatus was significantly improved by trypsin. To investigate the mechanism of flavonoid metabolism regulated by trypsin, combined analysis of widely targeted metabolomic and transcriptome were performed. GO and KEGG enrichment analyses of the transcriptome profiles of H. undatus revealed that some of the flavonoid related biosynthesis pathways were regulated by up or down patterns with the treatment of trypsin. Correlation analysis of flavonoid related genes expression in H. undatus provided a rationale for the functional significance of them. Furthermore, it has been revealed that the most significantly regulated flavonoid was catechin gallate in metabolomic profiles of H. undatus. The major route of flavonoid biosynthesis regulated by trypsin was also illustrated by both transcriptomic and metabolomic data. Finally, the results of PPI network revealed that C4H, HCT, and CYP75B1 acted as hub proteins involved in flavonoid metabolism regulated by trypsin.

Hub genes and sub-networks of stoma-related genes in Hylocereus undatus through trypsin treatment during storage revealed by transcriptomic analysis

To further investigate the preservation mechanisms of trypsin, the synergistic mechanisms of trypsin and stoma-related genes were evaluated in Hylocereus undatus. Trypsin significantly induced the stoma closure and improved the storage quality of H. undatus. Transcriptomic analyses of H. undatus revealed that important antioxidant signal pathway, such as SREBP signaling pathway, cellular response to H₂ O₂ or cellular response to molecule of bacterial origin, were induced; while responses to water deprivation were impeded by trypsin. These results indicated that trypsin relieved pitaya of pressure of water deprivation and exhibited the protection on pitaya during storage. Furthermore, the analyses of networks of protein-protein interaction suggested that OST1, HK5, AT4G27585, and HIR1 act as hubs of stoma-related proteins induced by trypsin during storage of H. undatus. PRACTICAL APPLICATIONS: Preservation of fruit is becoming increasingly important to the world. Keep the balance of production and scavenging of reactive oxygen species is efficient to improve the storage quality of fruit. Trypsin had a novel superoxide anion scavenging activity and protect fruit cells from cellular injury induced by excess ROS. This article investigates the hub genes and interaction mechanisms of stoma closure induced by trypsin during the storage of H. undatus. The application of trypsin provides a new strategy for the quality control of fruit storage. Trypsin will have a broad market and development potential in the area of food additives.

Data-independent acquisition proteomic analysis of biochemical factors in rice seedlings following treatment with chitosan oligosaccharides

Chitosan oligosaccharides (COS) can elicit plant immunity and defence responses in rice plants, but exactly how this promotes plant growth remains largely unknown. Herein, we explored the effects of 0.5 mg/L COS on plant growth promotion in rice seedlings by measuring root and stem length, investigating biochemical factors in whole plants via proteomic analysis, and confirming upregulated and downregulated genes by real-time quantitative PCR. Pathway enrichment results showed that COS promoted root and stem growth, and stimulated metabolic (biosynthetic and catabolic processes) and photosynthesis in rice plants during the seedling stage. Expression levels of genes related to chlorophyll a-b binding, RNA binding, catabolic processes and calcium ion binding were upregulated following COS treatment. Furthermore, comparative analysis indicated that numerous proteins involved in the biosynthesis, metabolic (catabolic) processes and photosynthesis pathways were upregulated. The findings indicate that COS may upregulate calcium ion binding, photosynthesis, RNA binding, and catabolism proteins associated with plant growth during the rice seedling stage.

Chitosan oligosaccharide induces resistance to Pst DC3000 in Arabidopsis via a non-canonical N-glycosylation regulation pattern

Roles of protein N-glycosylation in chitosan oligosaccharide (COS) induced resistance were investigated in the present study. Results demonstrated that N-glycosylation deficient Arabidopsis mutants (stt3a and ManI) were more susceptible against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) than wild type (WT) plants. Surprisingly, in stt3a and ManI, COS-induced resistance to Pst DC3000 was mostly intact, and the up-regulation effect on SA- and JA-mediated signalling pathways also similar like WT. Nucleotide sugars accumulation and N-glycosylation related genes expression were differently regulated after COS treatment. Global glycomics analysis quantified 157 N-glycan isomers, and 56.7, 50.3 and 47.1 % of them were significantly changed in COS, mock + Pst, and COS + Pst treated plants, respectively. Moreover, COS pretreatment could reverse the effect of Pst DC3000 on many N-glycans, suggesting that COS regulates protein N-glycosylation via a non-canonical pattern compared with plant defense, which may contribute to its obvious disease control effect when N-glycosylation impairment occurs.

Proteome-Wide Analyses Provide New Insights into the Compatible Interaction of Rice with the Root-Knot Nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola is an important pathogen in rice, causing huge yield losses annually worldwide. Details of the interaction between rice and M. graminicola and the resistance genes in rice still remain unclear. In this study, proteome-wide analyses of the compatible interaction of the japonica rice cultivar “Nipponbare” (NPB) with M. graminicola were performed. In total, 6072 proteins were identified in NPB roots with and without infection of M. graminicola by label-free quantitative mass spectrometry. Of these, 513 specifically or significantly differentially expressed proteins were identified to be uniquely caused by nematode infection. Among these unique proteins, 99 proteins were enriched on seven Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. By comparison of protein expression and gene transcription, LOC_Os01g06600 (ACX, a glutaryl-CoA dehydrogenase), LOC_Os09g23560 (CAD, a cinnamyl-alcohol dehydrogenase), LOC_Os03g39850 (GST, a glutathione S-transferase) and LOC_Os11g11960 (RPM1, a disease resistance protein) on the alpha-linolenic acid metabolism, phenylpropanoid biosynthesis, glutathione metabolism and plant–pathogen interaction pathways, respectively, were all associated with disease defense and identified to be significantly down-regulated in the compatible interaction of NPB with nematodes, while the corresponding genes were remarkably up-regulated in the roots of a resistant rice accession “Khao Pahk Maw” with infection of nematodes. These four genes likely played important roles in the compatible interaction of rice with M. graminicola. Conversely, these disease defense-related genes were hypothesized to be likely involved in the resistance of resistant rice lines to this nematode. The proteome-wide analyses provided many new insights into the interaction of rice with M. graminicola.

Transcriptomic analysis reveals hub genes and subnetworks related to ROS metabolism in Hylocereus undatus through novel superoxide scavenger trypsin treatment during storage

BACKGROUND

It was demonstrated in our previous research that trypsin scavenges superoxide anions. In this study, the mechanisms of storage quality improvement by trypsin were evaluated in H. undatus.

RESULTS

Trypsin significantly delayed the weight loss and decreased the levels of ROS and membrane lipid peroxidation. Transcriptome profiles of H. undatus treated with trypsin revealed the pathways and regulatory mechanisms of ROS genes that were up- or downregulated following trypsin treatment by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses. The current results showed that through the regulation of the expression of hub redox enzymes, especially thioredoxin-related proteins, trypsin can maintain low levels of endogenous active oxygen species, reduce malondialdehyde content and delay fruit aging. In addition, the results of protein-protein interaction networks suggested that the downregulated NAD(P) H and lignin pathways might be the key regulatory mechanisms governed by trypsin.

CONCLUSIONS

Trypsin significantly prolonged the storage life of H. undatus through regulatory on the endogenous ROS metabolism. As a new biopreservative, trypsin is highly efficient, safe and economical. Therefore, trypsin possesses technical feasibility for the quality control of fruit storage.

Antibacterial Activities of Novel Dithiocarbamate-Containing 4H-Chromen-4-one Derivatives

To aid the development of novel antibacterial agents that possess a innovative mechanism of action, we built a series of novel dithiocarbamate-containing 4H-chromen-4-one derivatives. We evaluated the activities of the derivatives against three plant pathogens Xanthomonas oryzae pv oryzae (X. oryzae pv o.), Ralstonia solanacearum (R. solanacearum), and Xanthomonas axonopodis pv citri (X. axonopodis pv c.). The results of the antibacterial bioassay showed that most of the target compounds displayed good inhibitory effects against X. oryzae pv o. and X. axonopodis pv c. Remarkably, compound E6 showed the best in vitro antibacterial activity against X. axonopodis pv c., with an EC₅₀ value of 0.11 μg/mL, which was better than those of thiodiazole copper (59.97 μg/mL) and bismerthiazol (48.93 μg/mL). Compound E14 exhibited the best in vitro antibacterial activity against X. oryzae pv o., with an EC₅₀ value of 1.58 μg/mL, which was better than those of thiodiazole copper (83.04 μg/mL) and bismerthiazol (56.05 μg/mL). Scanning electron microscopy analysis demonstrated that compounds E6 and E14 caused the rupture or deformation of the cell membranes for X. axonopodis pv c. and X. oryzae pv o., respectively. In vivo antibacterial activity test and the defensive enzymes activity test results indicated that the compound E14 could reduce X. oryzae pv o. more effectively than thiodiazole-copper or bismerthiazol.

Proteomics analysis reveals the defense priming effect of chitosan oligosaccharides in Arabidopsis-Pst DC3000 interaction

Chitosan oligosaccharides (COS) worked effectively in multiple plant-pathogen interactions as plant immunity regulator, however, due to the complexity of the COS-induced immune signaling network, the topic requires further investigation. In the present study, quantitative analysis of proteins was performed to investigate the underlying mechanism of COS induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) in Arabidopsis thaliana. 4303 proteins were successfully quantified, 186, 217 and 207 proteins were differently regulated in mock + Pst, COS, and COS + Pst treated plants, respectively, compared with mock plants. From detailed functional and hierarchical clustering analysis, a priming effect of COS on plant immune system by pre-regulated the key proteins related to signaling transduction, defense response, cell wall biosynthesis and modification, plant growth and development, gene transcription and translation, which confers enhanced resistance when Pst DC3000 infection in Arabidopsis. Moreover, RACK1B which has the potential to be the key kinase receptor for COS signals was found out by protein-protein interaction network analysis of COS responsive proteins. In conclusion, COS treatment enable plant to fine-tuning its defense mechanisms for a more rapid and stronger response to future pathogen attacks, which obviously enhances plants defensive capacity that makes COS worked effectively in multiple plant-pathogen interactions.

Transcriptomic Analysis Reveals Cu/Zn SODs Acting as Hub Genes of SODs in Hylocereus undatus Induced by Trypsin during Storage

It has been revealed by us that superoxide scavenging is a new activity of trypsin. In this study, the synergistic mechanisms of trypsin and superoxide dismutases (SODs) were evaluated in Hylocereus undatus (pitaya). Trypsin significantly improved the storage quality of H. undatus, including weight loss impediment and decrease of cellular injury. The regulatory mechanisms of 16 SOD genes by trypsin were revealed using transcriptomic analysis on H. undatus. Results revealed that important physiological metabolisms, such as antioxidant activities or metal ion transport were induced, and defense responses were inhibited by trypsin. Furthermore, the results of protein–protein interaction (PPI) networks showed that besides the entire ROS network, the tiny SODs sub-network was also a scale-free network. Cu/Zn SODs acted as the hub that SODs synergized with trypsin during the storage of H. undatus.

Alginate Oligosaccharide (AOS) induced resistance to Pst DC3000 via salicylic acid-mediated signaling pathway in Arabidopsis thaliana

Alginate Oligosaccharide (AOS) is a natural biological carbohydrate extracted from seaweed. In our study, Arabidopsis thaliana was used to evaluate the AOS-induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Resistance was vitally enhanced at 25 mg/L in wild type (WT), showing the decreased disease index and bacteria colonies, burst of ROS and NO, high transcription expression of resistance genes PR1 and increased content of salicylic acid (SA). In SA deficient mutant (sid2), AOS-induced disease resistance dropped obviously compared to WT. The disease index was significantly higher than WT and the expression of recA and avrPtoB are two and four times lower than WT, implying that AOS induces disease resistance injecting Pst DC3000 after three days treatment by arousing the SA pathway. Our results provide a reference for the profound research and application of AOS in agriculture.

Dufulin Intervenes the Viroplasmic Proteins as the Mechanism of Action against Southern Rice Black-Streaked Dwarf Virus

Southern rice black-streaked dwarf virus (SRBSDV) causes disease in crops, which reduces the quality and yield. Several commercial antiviral agents are available to control the SRBSDV induced disease. However, the mechanism of antiviral agents controlling SRBSDV is largely unknown. Identifying targets in SRBSDV is a key step of antiviral agent discovery. Here, we investigated the potential protein target of the antiviral agent dufulin. We cloned and expressed a soluble viroplasmic P6 protein in the prokaryote Escherichia coli and the eukaryote Spodoptera frugiperda 9. The dissociation constants of dufulin with the purified P6 protein from E. coli and S. frugiperda 9 expression systems were 4.49 and 4.95 μM, respectively, indicating a strong binding affinity between dufulin and P6 protein. In vivo, dufulin significantly inhibited the expression of both P6 protein and P6 gene in the SRBSDV-infected rice leaves. This inhibition on P6 protein expression was also observed in transformed Nicotiana benthamiana where the P6 was overexpressed. Our data also showed that dufulin inhibited the duplication of SRBSDV in a dose-dependent manner in infected rice leaves with a half maximum effective concentration of 3.32 mM. It is therefore concluded that dufulin targets the viroplasmic protein P6 to inhibit the virulence of SRBSDV.

A polysaccharide found in Dendrobium nobile Lindl stimulates calcium signaling pathway and enhances tobacco defense against TMV

A neutral polysaccharide separated from Dendrobium nobile Lindl was designated as DNPE6(4). It was structurally characterized using a combination of spectral and chemical analysis. Its average molecule weight was 99.2 kDa. The monosaccharide composition was Araf, Glcp, Galp, and Manp in a molar ratio of 2.5:0.9:0.3:0.8. Their linkage types were →1)-L-Araf-(3→, →1)-D-Glcp-(4→, →1)-D-Galp-(3→, →1)-D-Galp-(6→, →1)-D-Manp-(3, 6→, and T-D-Manp. The polysaccharide was found to have anti-TMV and anti-CMV activities for the first time in vivo. Notably, DNPE6(4) exhibited excellent protective activity against TMV. Furthermore, several proteins related to calcium signaling pathway and pathogen related proteins were up-regulated, and we also found expression levels of EDS1, ICS1, and PR1 involved in SA pathway up-regulated after DNPE6(4) treatment. In addition, some defense enzymes increased in the same condition. All these findings revealed DNPE6(4) was an elicitor to stimulate calcium signaling pathway to enhance the tobacco defense against TMV. This study therefore revealed that DNPE6(4) was a promising antiviral agent for future study.

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

Improving plant resistance against systemic diseases remains a challenging research topic. In this study, we developed a dual-action pesticide-loaded hydrogel with the capacity to significantly induce plant resistance against tobacco mosaic virus (TMV) infection and promote plant growth. We produced an alginate-lentinan-amino-oligosaccharide hydrogel (ALA-hydrogel) by coating the surface of an alginate-lentinan drug-loaded hydrogel (AL-hydrogel) with amino-oligosaccharide using electrostatic action. We determined the formation of the amino-oligosaccharide film using various approaches, including Fourier transform infrared spectrometry, the ζ potential test, scanning electron microscopy, and elemental analysis. It was found that the ALA-hydrogel exhibited stable sustained-release activity, and the release time was significantly longer than that of the AL-hydrogel. In addition, we demonstrated that the ALA-hydrogel was able to continuously and strongly induce plant resistance against TMV and increase the release of calcium ions to promote Nicotiana benthamiana growth. Meanwhile, the ALA-hydrogel maintained an extremely high safety to organisms. Our findings provide an alternative to the traditional approach of applying pesticide for controlling plant viral diseases. In the future, this hydrogel with the simple synthesis method, green synthetic materials, and its efficiency in the induction of plant resistance will attract increasing attention and have good potential to be employed in plant protection and agricultural production.

Proximal Tubular Development Is Impaired with Downregulation of MAPK/ERK Signaling, HIF-1α, and Catalase by Hyperoxia Exposure in Neonatal Rats

Supplemental oxygen therapy (hyperoxia) is a widely used treatment for alveolar hypoxia in preterm infants. Despite being closely monitored, hyperoxia exposure is believed to undermine neonatal nephrogenesis and renal function caused by elevated oxidative stress. Previous studies have mostly focused on the hyperoxia-induced impairment of glomerular development, while the long-term impact of neonatal hyperoxia on tubular development and the regulatory component involved in this process remain to be clarified. Here, we examined tubular histology and apoptosis, along with the expression profile of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling, hypoxia-inducible factor 1α (HIF-1α), and catalase, following hyperoxia exposure in neonatal rats. Hematoxylin and eosin (H&E) staining revealed the early disappearance of the nephrogenic zone, as well as dilated lumens and reduced epithelial cells, of mature proximal tubules following neonatal hyperoxia. A robust increase in tubular cell apoptosis caused by neonatal hyperoxia was found using a TUNEL assay. Moreover, neonatal hyperoxia altered renal MAPK/ERK signaling activity and downregulated the expression of HIF-1α and catalase in the proximal tubules throughout nephrogenesis from S-shaped bodies to mature proximal tubules. Cell apoptosis in the proximal tubules was positively correlated with HIF-1α expression on the 14th postnatal day. Our data indicates that proximal tubular development is impaired by neonatal hyperoxia, which is accompanied by altered MAPK/ERK signaling as well as downregulated HIF-1α and catalase. Therapeutic management that targets MAPK/ERK signaling, HIF-1α, or catalase may serve as a protective agent against hyperoxia-induced oxidative damage to neonatal proximal tubules.

Synthesis, Antiviral Activity, and Mechanisms of Purine Nucleoside Derivatives Containing a Sulfonamide Moiety

Novel purine nucleoside derivatives containing a sulfonamide moiety were prepared, as well as their antiviral activities against potato virus Y (PVY), cucumber mosaic virus (CMV), and tobacco mosaic virus (TMV) were evaluated. The antiviral mechanisms of the compounds were investigated. Results showed that most of the compounds had good antiviral activities. Compound 5 at 500 μg/mL exhibited excellent curative and protective activities of 52.5% and 60.0% and of 52.0% and 60.2% for PVY and CMV, respectively, which are higher than those of ningnanmycin (48.1%, 49.6%; 45.3%, 47.7%), ribavirin (38.3%, 48.2%; 40.8%, 45.5%), and chitosan oligosaccharide (32.5%, 33.8%; 35.1%, 34.6%). Moreover, compound 5 displayed good inactivating activity against TMV, with an EC₅₀ value of 48.8 μg/mL, which is better than that of ningnanmycin (84.7 μg/mL), ribavirin (150.4 μg/mL), and chitosan oligosaccharide (521.3 μg/mL). The excellent antiviral activity of compound 5 is related to its immune induction effect which can regulate the physiological and biochemical processes in plants, including defense-related enzyme activities, defense-related genes, and photosynthesis-related proteins. These results indicate that purine nucleoside derivatives containing a sulfonamide moiety are worthy of further research and development as new antiviral agents.

The bioactivity of new chitin oligosaccharide dithiocarbamate derivatives evaluated against nematode disease (Meloidogyne incognita)

Plant-parasitic nematodes cause substantial crop losses annually; however, current nematicides are environmentally unfriendly and highly toxic to nontarget organisms. The development of green efficient nematicides from multifunctional natural bioactive substances such as chitin oligosaccharide (COS) is promising. In this paper, COS dithiocarbamate derivatives (COSDTC, COSDTA, COSDTB) were synthesized to increase nematicidal activity (against Meloidogyne incognita), and their structures were characterized by FTIR, NMR, TGA/DTG and elemental analysis. Furthermore, the nematicidal activities, egg hatching inhibitory activities, plant growth adjustment abilities, cytotoxicity and phytotoxicity of the derivatives were evaluated. The primary mechanism was assessed by heavy metal ion absorption and GSH-binding assays. The results showed COS dithiocarbamate derivatives could possess multiple efficacies, including high nematicidal activities and egg hatching inhibitory activities, plant growth regulating effects, low cell toxicities and phytotoxicities. Additionally, it was inferred that nematicidal activity may be correlated with GSH-binding activity but not heavy metal ion complexation. COS modification has immense potential for controlling plant-parasitic nematodes.