Search Results (220)

Plant viruses are major plant pathogens and account for nearly half of emerging plant diseases worldwide. To date, few effective management measures are available for the efficient control of plant viral diseases. Cross-protection based on attenuated vaccine is an effective strategy to prevent plant viral diseases. The primary requirement for the development of attenuated vaccines is a vector with excellent characteristics, such as low pathogenicity, genetic stability, and the capacity for stable insertion of exogenous fragments. In this study, the cucumber mosaic virus (Fny strain) was genetically modified to serve as an attenuated vaccine vector. Based on pre-termination of the 2b protein-coding region and deletion of the 3′ UTR in CMV RNA2, six RNA2 mutants, designated R2-2bPTI, R2-2bPTII, R2-2bPTIII, R2-2bPTIV, R2-2bPTV, and R2-2bPTVI, were constructed. Experiments with different lengths tobacco phytoene desaturase (PDS) fragment insertion evaluated the capacity of each mutant to accommodate exogenous fragment. Based on the R2-2bPTIV, a viral fragment insertion mutant R2-2bPTIV-TMPYTVPX targeting cucumber mosaic virus (CMV), tobacco mosaic virus (TMV), potato virus Y (PVY), tobacco vein banding mosaic virus (TVBMV), and potato virus X (PVX) was constructed. This mutant provided effective cross-protection against these targeted virulent viruses. This study developed a series of CMV-based vaccine vector, providing materials and data for the development of plant viral diseases attenuated vaccines. Full article

Dahlia is an economically important ornamental crop in the United States and worldwide. Dahlia is primarily propagated vegetatively through bulbs, which can result in vertical transmission of and constant accumulation of viruses. In this study, mosaic and yellowing symptoms were observed in Dahlia plants in a residential garden in California. Dahlia samples were collected and sequenced using high-throughput sequencing (HTS). HTS analysis was used to explore the Dahlia virome in the symptomatic plants, which revealed the presence of several contigs with homology to known Dahlia-infecting viruses, such as Dahlia common mosaic virus (DCMV) and tobacco streak virus (TSV), and Dahlia latent viroid. However, two contigs showed that they belong to the genera Potyvirus and Miraophiovirus with low to medium homology to previously known Potyvirus and Miraophiovirus species. Sequence identity showed that these two contigs represent two novel viruses tentatively named Dahlia potyvirus 1 (DaPoV1) and Dahlia miraophiovirus 1 (DaMV1). In addition, two other contigs showed low homology to a partitivirus and yue-like virus, indicating novelty. Mechanical inoculation of infected Dahlia tissue did not result in successful transmission onto indicator hosts. Electron microscopy of symptomatic plants showed typical potyviral-like flexuous virions. Phylogenetic analysis confirmed the placement of DaPoV1 and DaMV1 in their respective genera. This study represents a significant expansion of the known Dahlia virome and uncovers the complexity of viral infections where DCMV and TSV have been historically the primary focus in Dahlia. Widespread surveys should reveal the distribution of these viruses at commercial production sites. Full article

Phlox (Phlox spp., Polemoniaceae) are herbaceous ornamental plants that are cultivated around the world for their fascinating flowering. P. paniculata cultivar collections at the Tsitsin Main Botanical Garden and the Botanical Garden of Lomonosov Moscow State University (both in Moscow, Russia) were surveyed for virus diseases using high-throughput sequencing and RT-PCR. Twenty-seven plants with virus-like symptoms on the leaves were selected for analysis. Alfalfa mosaic virus (AMV), Arabis mosaic virus (ArMV), ArMV satellite RNA (satRNA), beet ringspot nepovirus (BRSV), BRSV satRNA, cucumber mosaic virus (CMV), Spiranthes mosaic virus 3 (SpiMV3), tobacco streak virus (TSV), and tobacco rattle virus (TRV) were identified. AMV and TSV were the most common viruses found in 22 and 25 out of the 27 samples tested, respectively. ArMV satRNA was detected in phlox for the first time, adding to the list of viruses infecting this crop. The nearly complete genomes of the detected viruses and satRNAs were assembled and characterized. The CMV and TRV genome sequences from phlox were first deposited in GenBank. Only RNA1 was detected in the TRV-infected ‘Fligelleutenant Bolke’ cultivar plant, suggesting that the so-called non-multiplying infection has been found for the first time in a plant species other than solanaceae. Full article

Viral diseases are one of the most destructive threats to global agriculture. Among plant viruses, tobacco mosaic virus (TMV) is a highly contagious pathogen infecting numerous economically vital crops. With no curable treatments, the only strategy to mitigate virus spread is early detection and plant removal. The gold standard for TMV detection is reverse transcriptase-polymerase chain reaction (RT-PCR), followed by agarose gel electrophoresis. To reduce TMV diagnosis time and eliminate the requirement for expensive equipment, this study developed and optimized a one-step RT-PCR-coupled cysteamine-functionalized gold nanoparticle assay for the colorimetric determination of the virus. By integrating cDNA synthesis and PCR amplification into a single tube and analyzing the results using cysteamine- functionalized gold nanoparticles (Au@Cys), the diagnosis turnaround time was significantly reduced. Furthermore, this AuNPs-based colorimetric assay enabled straightforward visual inspection with the naked eye, eliminating the need for costly optical devices. Additionally, our regression equation linking RT-PCR product color values, extracted as mean A value based on the CIELAB color space (green-red axis), and viral load allows for the accurate quantification of TMV infection levels in field samples. Our research lays the groundwork for the further development of more cost-effective, quantitative and rapid plant virus diagnosis methods. Full article

Chalcones are naturally occurring open-chain flavonoids widely distributed in plants and recognized for their broad spectrum of pharmacological activities. Their versatile scaffold allows for extensive structural modifications, leading to a diverse range of natural and synthetic derivatives with notable biological potential. In the context of viral infections, chalcones have demonstrated remarkable efficacy against a variety of human pathogens, including dengue virus, HIV, HCV, influenza A, SARS-CoV-2, and other emerging viruses. Beyond human health, several chalcones have shown potent activity against plant viruses such as tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV), and animal viruses including porcine reproductive and respiratory syndrome virus (PRRSV) and mammalian reovirus (MRV), underscoring their broad antiviral spectrum. These compounds act through multiple mechanisms, including the inhibition of viral enzymes (e.g., proteases, polymerases, and integrases), interference with viral entry and replication, and the modulation of host-related pathways. Recent advances in molecular docking, structure–activity relationship (SAR) studies, and synthetic optimization have further highlighted chalcones as a promising scaffold for antiviral drug discovery. Accordingly, this review summarizes and categorizes antiviral chalcones reported over the last two decades, emphasizing and critically discussing their molecular targets, mechanisms of action, and pharmacological potential as lead compounds. It also provides a comparative perspective on their pharmacological relevance by correlating their activities against standard therapeutic agents and reference inhibitors. Furthermore, the most recurrent viral targets were critically discussed regarding their conservation, expected genetic barriers to resistance, and the global SAR trends identified for the corresponding antiviral chalcones. Finally, in silico ADMET profiling of the most promising naturally occurring chalcones was performed to evaluate their drug-likeness and pharmacokinetic properties, offering guidance for future structural optimization and translational development. Collectively, these findings highlight the chalcone scaffold as a versatile platform for the development of novel antiviral agents targeting diverse viral and host pathways. Full article

Tobacco mosaic virus (TMV) poses a serious threat to global agricultural production. It is an exceptionally stable virus with a broad host range and is widespread across diverse agroecosystems. Concerning TMV management, plant-derived metabolites have emerged as promising and eco-friendly antiviral agents. To date, numerous plant-derived metabolites with potent anti-TMV activity and their underlying mechanisms of action have been identified. However, a comprehensive understanding of their mechanisms of action is still lacking. This review summarizes the diversity of anti-TMV mechanisms triggered by natural and plant-sourced semisynthetic compounds. These metabolites mainly include alkaloids, flavonoids, terpenoids, phenylpropanoids, and glycosides, which act either directly targeting virus particles or indirectly by eliciting host immunity. Together, these mechanisms form an integrated defence network that restricts viral replication and movement within the host. This mechanistic understanding will be essential for the rational development of sustainable and effective plant-derived antiviral agents. Full article

Background: Translational regulation constitutes a critical layer of gene expression control in plants, yet the contribution of endogenous 5′ untranslated regions (5′ UTRs) to translational efficiency remains incompletely defined. While viral and synthetic leader sequences have been widely used to enhance protein production, comparatively few native plant 5′ UTRs have been systematically characterised. The objective of this study was to identify and functionally evaluate endogenous plant 5′ UTR elements that promote translation through post-transcriptional mechanisms. Methods: A 79-nucleotide fragment (CYSTM α) derived from the 5′ UTR of Arabidopsis thaliana CYSTM1 (AT1G05340) was cloned upstream of reporter genes and assessed using dual-luciferase assays in transient expression systems (Nicotiana benthamiana and A. thaliana) and in stable transgenic Arabidopsis lines. Translational activity was further evaluated in monocot wheat germ extract and in Escherichia coli. Transcript abundance was quantified by qRT-PCR. Publicly available ribosome profiling and m⁶A datasets were analysed to assess translational efficiency and RNA modification status. Results: In N. benthamiana and A. thaliana, CYSTM α increases reporter protein production 3–7 fold relative to the control and 30–130% above the benchmark Tobacco Mosaic Virus (TMV) Ω leader, without altering mRNA abundance. The CYSTM α sequence also enhances luciferase translation in monocot wheat germ extract and elevates translation 5-fold in E. coli. CYSTM α contains three motifs that may promote translation, namely three CAA repeats that are associated with translation initiation, an AMAYAA motif that is associated with eIF3 binding, and two N6-adenosine DRACH sites that are associated with cap-independent translation. Additionally, ribosome profiling revealed high translational efficiency (TE = 3.25) of native CYSTM1. Conclusions: CYSTM α represents a compact endogenous 5′ UTR element that enhances translation across multiple experimental systems. These findings expand the repertoire of plant-derived translational enhancers and provide insight into sequence features associated with efficient mRNA translation in plants. Full article

F-box-LRR (FBXL) proteins are crucial components of the SCF ubiquitin ligase complex, regulating diverse processes such as development and stress responses in plants. However, the FBXL family in tobacco (Nicotiana tabacum L.) remains poorly characterized. This study performed the first genome-wide analysis of the FBXL gene family in tobacco and identified 47 NtaFBXL genes. Phylogenetic analysis classified them into five clades, among which Clade III exhibited notable expansion. Promoter analysis revealed abundant stress- and hormone-related cis-elements. Expression profiling demonstrated tissue-specific patterns and strong responses to drought, ABA, IAA, and TMV infection. Importantly, six genes exhibited a significant negative correlation with TMV accumulation, suggesting their potential roles in antiviral defense. Moreover, both drought and TMV stress triggered a disturbance of redox homeostasis, a dynamic process that was closely associated with the expression of specific NtaFBXL genes, characterized by upregulated antioxidant enzymes (SOD, POD, CAT) and accumulated oxidative markers (H₂O₂, MDA). Collectively, this study provided a foundational resource for understanding the function of NtaFBXLs and identified key candidate genes for the genetic improvement of stress resistance in tobacco. Full article

Plant defensin-like proteins, as the core effector molecules of innate immunity, play an important role in resistance against fungi and bacteria. However, their function in plant antiviral resistance remains unclear. Here, NbDLP, a defensin-like protein from Nicotiana benthamiana (N. benthamiana), is identified through transcriptome analysis. NbDLP is upregulated upon viral infection of Tobacco Vein Mottling Virus (TVMV). Then, we cloned NbDLP into plant expression vector by gateway recombination to obtain pEAQ-NbDLP. We found that the transient expression of NbDLP in N. benthamiana could significantly inhibit TVMV, TuMV and TMV infection. Further, silencing NbDLP contributed to TuMV and TMV infection. In conclusion, the results indicate that NbDLP participates in the plant antiviral resistance against plant viral infection and might be used for defining antiviral strategies in application points. Full article

Lateral flow immunoassays (LFAs) are widely used for on-site testing; however, their use for the rapid detection of plant viruses in the field is often limited by inconvenient sample preparation. Here, we present a new sampling method and a simplified dipstick LFA format for the detection and monitoring of cowpea chlorotic mottle virus (CCMV) as a model plant pathogen. The assay employs a monoclonal mouse antibody for capture and a poly-clonal rabbit antibody conjugated to 80 nm gold nanoparticles for detection. Conventional sample and conjugate pads are omitted, allowing the test strips to be dipped directly into wells containing plant extract and antibody–gold conjugate. No plastic casing was required, which could lead to a reduction in waste. It was shown that CCMV concentrations as low as 3.5 µg/L or 350 pg per sample could be reliably detected in 15 min. Specificity tests confirmed that other plant viruses, cowpea mosaic virus (CPMV) and tobacco mosaic virus (TMV), did not produce false-positive results. In addition, we describe a new method for on-site sampling using a manual punch and a syringe equipped with a frit. This step combines grinding the sample, extraction, filtration, and reconstitution and mixing of the antibody-gold conjugate, enabling the analysis of punched leaf disks without laboratory equipment. When applied to CCMV-infected cowpea plants, the assay revealed systemic infection before visual symptoms became apparent. This work demonstrates that simplified LFAs combined with innovative sampling techniques can provide sensitive, specific, and rapid diagnostics for crop monitoring and support early intervention strategies in agriculture. Full article

GmSRC7 is a broad-spectrum antiviral R gene from soybean, but its downstream and functionally related genes remain unclear. Virus-induced gene silencing (VIGS) assays in Nicotiana benthamiana (Nb) showed that suppression of several gene families—WRKY transcription factors, chaperones, ethylene pathway components, MAPK cascade elements, salicylic acid (SA) signaling genes, calcium-dependent protein kinases, nuclear migration proteins, RNA replication-related genes, and immune regulators—consistently weakened GmSRC7-mediated resistance to Soybean Mosaic Virus (SMV) and Tobacco Mosaic Virus (TMV). Targeted silencing of four regulatory genes—NbEDS1, NbARF1, NbSGT1, and NbCOI1—markedly enhanced GmSRC7-mediated resistance to SMV and TMV in our experiments. Silencing the serine/threonine kinase gene NbPBS1 increased GmSRC7-conferred resistance to SMV but did not significantly alter its resistance to TMV. Transient expression assays showed that NbARF1, NbSGT1, and NbCOI1 antagonize GmSRC7-mediated defense against SMV and TMV, whereas NbPBS1 specifically suppresses anti-SMV activity without affecting TMV resistance. Transient overexpression of SA-degrading enzymes (AtS3H, AtS5H, and NahG) significantly reduced GmSRC7-conferred resistance to SMV, indicating that SA is essential for this R protein-mediated defense. Genes were also grouped by immune pathways and function: co-expression of chaperone family genes inhibited GmSRC7 activity against SMV and TMV, while co-expression of WRKY family genes enhanced anti-SMV activity of GmSRC7. Finally, transient silencing of soybean genes GmEDS1, GmSGT1-1, GmSGT1-2, GmJAR1, and GmSGS3 compromised GmSRC7-mediated resistance to SMV. Full article

Tobacco mosaic virus (TMV) threatens crop yield and quality, while chemical antivirals offer limited efficacy and potential environmental hazards. Marine fungal polysaccharides are promising eco-friendly alternatives due to their biocompatibility and biodegradability. Here, extracellular polysaccharides (EPSs) from the deep-sea fungus Beauveria bassiana T2-2 was isolated, characterized, and produced under optimized conditions (28 °C, 200 rpm, 9 days, pH 8, inoculum 4%) using an L9 (3⁴) orthogonal medium, yielding 3.42 g/L, which is a 48% increase over unoptimized culture. EPSs were glucose-rich, with a molecular weight of 3.56 × 10⁴ Da, containing 90.05% total sugar, 0.28% protein, 1.15% uronic acid, and 1.18% sulfate. In a Nicotiana benthamiana–TMV model, EPSs alleviated viral symptoms, maintained chlorophyll content, enhanced antioxidant enzymes (SOD, POD, CAT), reduced malondialdehyde, and upregulated defense genes in SA, ET, ROS, and phenylpropanoid pathways. EPSs, alone or combined with Ribavirin, activated multi-pathway antiviral immunity, highlighting its potential as a sustainable plant-protective agent. Full article

Plant viruses are useful tools for quickly and easily producing recombinant proteins in plants. Compared to systems that use genetically modified plants, viral vectors are easier to work with and can produce recombinant proteins faster and in larger amounts. Recently, there has been growing interest in using plant viruses as vectors to make vaccines, either as whole proteins or as small parts displayed on plant virus particles. The best examples for this purpose are tobacco mosaic virus, cowpea mosaic virus and potato virus X. Vaccines made using these viruses target various human and animal diseases and have often triggered immune responses and provided protection against infections. This review looks at the benefits of using plant virus vectors, the progress in developing different viral vector systems, and immune studies that support the idea of vaccines made from plant viruses. Full article

Supramolecular proteins have emerged as promising templates for guiding metal ion mineralization into well-defined nanomaterials because of their structural versatility and chemical diversity. However, the precise control of metal ion nucleation on the different reactive sites of protein templates remains challenging. In this study, a genetically engineered hollow tobacco mosaic virus protein fiber (TMVF) with excellent structural stability was employed to achieve selective mineralization of noble metal nanostructures either on its external surface or within its internal channel. Moreover, the Pt/Pd bimetallic nanowire (NW) was also successfully prepared by co-depositing Pt and Pd on the TMVF. The bimetallic NWs demonstrated a peroxidase-like activity, which enabled their application for cholesterol detection by cooperating with cholesterol oxidase. Full article

Viral infection affects photosynthesis in plants, significantly reducing crop yield and quality. This study investigated the effects of isobavachalcone (IBC), a natural compound extracted from the plant Psoralea corylifolia L., on photosynthesis in tobacco under tobacco mosaic virus (TMV; species Tobamovirus tabaci, family Virgaviridae) stress. TMV infection significantly reduced the chlorophyll content, Rubisco activity, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), and transpiration rate (Tr) in tobacco leaves. However, exogenous application of IBC (40 mg/L) effectively alleviated the negative impacts of TMV. Compared with the inoculated control, IBC treatment increased the chlorophyll content by 16.00–100.68%, enhanced Rubisco activity by 3.72–115.84%, and improved Pn, Gs, Ci, and Tr by 155.65–347.65%, 89.43–408.00%, 17.51–56.18%, and 106.76–336.80%, respectively, at 3–9 days post inoculation (dpi). Tandem massed tag-based quantitative proteomics analysis revealed that IBC upregulated the abundance of photosynthesis-related proteins, including those involved in photosystem II, cytochrome b6/f complex, photosystem I, and ATP synthase, under TMV infection. GO and KEGG enrichment analyses further confirmed that IBC enhanced the expression of proteins associated with photosynthesis and energy production pathways. These findings suggest that IBC can mitigate TMV-induced photosynthesis inhibition by increasing photosynthetic pigment content, promoting carbon assimilation, and regulating photosynthesis-related proteins, providing new insights into the molecular mechanism of IBC-mediated plant protection. Full article