Search Results (207)

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

The biological functions of the multiple members of the xyloglucan endotransglycosylase/hydrolase (XTH) protein family are rather diverse: XTHs are cell wall remodeling enzymes that participate in plant growth and development, are involved in responses to various environmental stresses and interactions with pathogenic and symbiotic microorganisms. However, XTHs’ role upon viral infection remains poorly understood. Here we identified and characterized Nicotiana benthamiana XTH (NbXTH) which is involved in responses to viral infection. We demonstrated that NbXTH is a positive regulator of intercellular transport. NbXTH suppression leads to the inhibition of tobacco mosaic virus (TMV) local spread, resulting in the increased tolerance of N. benthamiana plants to TMV. Therefore, NbXTH could be regarded as a susceptibility factor. Full article

Helper component-proteinase (HC-Pro), encoded by tobacco vein banding mosaic virus (TVBMV), can cause various viral symptoms and even abortion. HC-Pro counteracts host-mediated inhibition by interfering with the accumulation of microRNAs (miRNAs) and small interfering RNAs (siRNAs). However, it is unclear whether the abortion phenotype of transgenic plants expressing HC-Pro is related to the abnormal expression of TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING cell factors (TCPs), which are involved in regulating fertility. In this study, the molecular mechanisms through which HC-Pro causes various sterile phenotypes in plants were investigated. Reverse transcription–quantitative polymerase chain reaction (RT–qPCR) and Northern blotting revealed that in HC-Pro transgenic plants, the expression levels of TCP4 and TCP24 significantly increased. The increased expression of TCP4 further upregulated LIPOXYGENASE2 (LOX2), a gene encoding a key enzyme in the synthesis of jasmonic acid (JA) precursors. Further studies confirmed that the aberrant expression of TCP3, TCP4 and TCP24 blocks the elongation of petals and anthers and that the aberrant expression of TCP4 and TCP24 blocks the release of pollen. This study demonstrated that HC-Pro affects the expression levels of the miR319-targeted genes TCP2, TCP3, TCP4, TCP10 and TCP24, thereby affecting the normal development of floral organs and resulting in plant abortion. Both tobacco and Arabidopsis thaliana were used as model systems in this study on virus-mediated fertility, which provides important information for understanding how viral pathogenicity affects the regulation of fertility in crops. Full article

This article provides a comprehensive analysis of Virus-Induced Gene Silencing (VIGS), which is an effective tool for studying the functional genomics of organisms that are poorly amenable to genomic editing. The VIGS method is grounded in the plant’s post-transcriptional gene silencing (PTGS) machinery and utilizes recombinant viral vectors to trigger systemic suppression of endogenous plant gene expression, leading to visible phenotypic changes that enable gene function characterization. This article details the application of VIGS in model organisms (Arabidopsis thaliana, Nicotiana benthamiana) and a wide range of crops, with a special focus on the Solanaceae family, particularly pepper (Capsicum annuum L.). This review analyzes the design and structural elements of viral vectors used for VIGS, such as Tobacco Rattle Virus (TRV), Broad Bean Wilt Virus 2 (BBWV2), Cucumber Mosaic Virus (CMV), geminiviruses (CLCrV, ACMV), and satellite virus-based systems. It also critically examines the key factors that determine silencing efficiency. These factors encompass insert design, agroinfiltration methodology, plant developmental stage, agroinoculum concentration, plant genotype, and environmental factors (temperature, humidity, photoperiod). Particular attention is given to optimization strategies, such as the use of viral suppressors of RNA silencing (VSRs). This article concludes with the achievements in using VIGS to identify pepper genes governing fruit quality (color, biochemical composition, pungency), resistance to biotic (bacteria, oomycetes, insects) and abiotic (temperature, salt, osmotic stress) factors, as well as genes regulating plant architecture and development. The results obtained demonstrate the advantages and limitations of VIGS, alongside future perspectives for its integration with multi-omics technologies to accelerate breeding and advance functional genomics studies in pepper. Full article

A coordinated and generalized plant response to adverse environmental factors largely depends on the proper and finely-tuned regulation of intercellular transport via plasmodesmata (PD). However, the knowledge of the whole network of PD-controlling mechanisms is far from complete. Earlier, a cellular factor, Kunitz peptidase inhibitor-like protein (KPILP), that affects PD gating and plays a proviral role, was identified in Nicotiana benthamiana plants. Here we characterized its homolog from N. tabacum, NtKPILP, which is hardly detectable in leaves of intact plants, in contrast to roots, flowers and seeds where NtKPILP is highly expressed. However, its mRNA accumulation in leaves increases in response to various stresses, including viral infection. NtKPILP was demonstrated to affect chloroplast functioning. Using the virus-induced gene silencing approach, we have shown that NtKPILP downregulation negatively affects intercellular transport of macromolecules, inducing callose deposition at PD and suppressing beta-1,3-glucanase mRNA accumulation. Together, the obtained results indicate that NtKPILP is a viral infection-responsive cellular factor that is involved in PD permeability regulation, sharing thus the features of KPILPs from other Nicotiana species. Full article

The genus Tobamovirus belongs to the family Virgaviridae, and the genome consists of monopartite, positive, single-strand RNA. Most species contain four open reading frames encoding four essential proteins. Transmission occurs primarily through mechanical contact between plants, and in some cases, via seed dispersal. Tobamovirus fructirugosum (tomato brown rugose fruit virus, ToBRFV), the most recently described species in the genus, was first reported in 2015. It overcame genetic resistance that had been effective in tomato for sixty years, causing devastating losses in tomato production worldwide, and highlights the importance of understanding Tobamovirus genomic variation and evolution. In this study, we measured and characterized nucleotide variation for the entire genome and for all species in the genus Tobamovirus. Additionally, we measured the selection pressure acting on each open reading frame. Results showed that low nucleotide diversity and negative selection pressure are general features of tobamoviruses, with values that are approximately the same across open reading frames and without hypervariable areas. A comparison of nucleotide diversity between T. fructirugosum and its close relatives, T. tomatotessellati (tomato mosaic virus, ToMV) and T. tabaci (tobacco mosaic virus, TMV), showed low nucleotide diversity in the movement protein region harboring the resistance-breaking mutation. Furthermore, phylogenetic and diversity analyses showed that T. fructirugosum continues to evolve, and geographical distribution and host influence genomic diversity. Full article

Genes involved in disease resistance are crucial for plant immune systems, yet their transcriptional regulatory mechanisms remain poorly understood. SRC4, a key member of the soybean mosaic virus resistance cluster (SRC), encodes a Ca²⁺-binding EF-hand domain and possesses antiviral activity, but its expression regulation is unclear. Here, we systematically analyzed 4085 soybean (Glycine max) transcriptome datasets and conducted SMV inoculation experiments to characterize SRC4 expression patterns. Cis-acting element analysis identified 12 regulatory elements in the SRC4 promoter, including salicylic acid (SA)-responsive elements. Furthermore, a Pro_SRC4::GUS reporter vector was constructed and functional analysis was performed in tobacco (Nicotiana benthamiana) and transgenic Arabidopsis thaliana. SRC4 exhibited significantly higher basal expression than typical resistance genes (R genes) and was induced by SMV infection, SA treatment, and Ca²⁺ supplementation, with peak expression at 2–5 h post-treatment (hpi). In transgenic tobacco overexpressing NahG, neither SMV nor Ca²⁺ could induce Pro_SRC4::GUS expression, demonstrating that SRC4 transcriptional regulation is mediated through SA signaling pathways. SRC4 showed predominant expression in roots and leaves and responded to temperature stress. Transgenic plants overexpressing SRC4 exhibited enhanced tolerance to both 12 °C and 37 °C temperature stress. This study elucidates the molecular mechanisms underlying SRC4 transcriptional regulation through Ca²⁺ and SA signaling pathways, revealing its dual role in both biotic and abiotic stress responses, especially in temperature stress. Full article

Our previous research has demonstrated the role of optimal temperatures and reactive oxygen species (ROS) in maintaining symptomless nonhost resistance (NHR) of barley to powdery mildews. However, the exact functions of temperature and ROS in NHR of plants, including barley, to viral infections are not known. Although barley is a nonhost for Tobacco mosaic virus (TMV), this virus can replicate in barley leaves at temperatures of ca. 30 °C. Here we elucidated the influence of short-term heat stress pre-treatments (30 °C, 3 h; heat shock at 49 °C, 20 s) on the symptomless NHR of barley to TMV and the role of the ROS superoxide (O₂^.−) in maintaining NHR. Heat stress and antioxidant (superoxide dismutase and catalase, SOD + CAT) treatments resulted in 50–100% higher TMV levels, while combined heat shock and SOD + CAT application caused further increases in TMV and appearance of cell and tissue death resembling a hypersensitive response (HR). An early (from 2 h after inoculation) burst of O₂^.− was essentially absent in TMV-infected barley exposed to short-term heat stress pre-treatments. Expression of barley genes regulating ROS (O₂^.−) metabolism (HvRBOHF2, HvSOD1) and cell death (HvBI-1) displayed an inverse correlation with TMV levels even at later time points (1–4 days after inoculation), implying a role in symptomless NHR, while increased levels of the antioxidant glutathione marked heat stress-induced suppression of NHR. We demonstrated that short-term heat stress and antioxidant treatments result in compromised NHR of barley to TMV, pointing to the role of optimal temperatures and ROS (O₂^.−) in symptomless NHR to virus infections. Full article

Marine natural products have gained increasing interest in drug research and development because of their unique structures, diverse biological activities, and novel mechanisms of action. Using the antiviral alkaloid aldisine as the lead compound and utilizing the hydrogen bond effects common in drug design, novel derivatives containing an acylhydrazone moiety were designed and synthesized. The structures of these derivatives were systematically analyzed using variable-temperature ¹H-NMR. Antiviral activity tests showed that most derivatives were active against tobacco mosaic virus (TMV), with some compounds outperforming the commercial antiviral drug ribavirin. Notably, 3-methylphenyl- and 3-pyridyl-substituted acylhydrazones 5-6 and 5-12 displayed activity comparable to ningnanmycin, one of the most effective commercial antiviral agents. Molecular docking results indicated that incorporating the acylhydrazone moiety enhances hydrogen bonding between the molecules and target proteins. Additionally, we evaluated the fungicidal and larvicidal activities of these derivatives. Most exhibited significant larvicidal effects against Mythimna separata and Plutella xylostella, along with broad-spectrum fungicidal activity. Four related compounds (5-11, 5-12, 5-13, and 5-17) exhibited high fungicidal activities, and another four compounds (2-4, 5-6, 5-13, and 5-17) exhibited high larvicidal activities. Full article

Plant viruses have been traditionally considered pathogens restricted to plant hosts. However, recent studies have shown that some plant viruses can infect and replicate in filamentous fungi and oomycetes, suggesting that their host range is broader than previously thought, and that their ecological interactions are more complex. In this study, we investigated the ability of the well-characterized positive-sense RNA plant virus Tobacco mosaic virus (TMV) to replicate in four major phytopathogenic fungi from different taxonomic groups: Botrytis cinerea, Fusarium oxysporum f. sp. lycopersici, Verticillium dahliae, and Monilinia fructicola. Using a recombinant TMV-based vector expressing a green fluorescent protein (TMV-GFP-1056) as reporter, we demonstrated that TMV can enter, replicate, and persist within the mycelia of B. cinerea and V. dahliae—at least through the first subculture. However, it cannot replicate in F. oxysporum f. sp. lycopersici and M. fructicola. RNA interference (RNAi) is a conserved eukaryotic epigenetic mechanism that provides an efficient defence against viruses. We explored the role of RNAi in the interaction between TMV and the mycelia of V. dahliae and B. cinerea. Our results revealed a strong induction of the Dicer-like 1 and Argonaute 1 genes, which are key compounds of the RNA silencing pathway. This RNAi-based response impaired TMV-GFP replication in both fungi. Notably, despite viral replication and RNAi activation, the virulence of V. dahliae and B. cinerea on their respective host plants remained unaffected. These findings reinforce the emerging recognition of cross-kingdom virus transmission and interactions, which likely play a crucial role in pathogen ecology and viral evolution. Understanding these virus–fungus interactions not only sheds light on RNAi interference silencing mechanisms but also suggests that plant viruses like TMV could serve as simple and effective tools for functional genomic studies in fungi, such as in V. dahliae and B. cinerea. Full article

Tomato brown rugose fruit virus (ToBRFV) has been causing severe agricultural damage worldwide since its recent discovery. While related to tobacco mosaic virus, its properties and infection mechanisms are poorly understood. To uncover their structure and nanomechanics, we carried out atomic force microscopy (AFM) measurements on individual ToBRFV particles. The virions are rod-shaped with a height and width of 9 and 30 nm, respectively. Length is widely distributed (5–1000 nm), with a mode at 30 nm. ToBRFV rods displayed a 22.4 nm axial periodicity related to structural units. Force spectroscopy revealed a Young’s modulus of 8.7 MPa, a spring constant of 0.25 N/m, and a rupture force of 1.7 nN. In the force curves a step was seen at a height of 3.3 nm, which is related to virion wall thickness. Wall thickness was also estimated by predicting coat protein structure with AlphaFold, yielding a protein with a length of 7.3 nm. Accordingly, the structural element of ToBRFv is a right circular cylinder with an equal height and diameter of ~22 nm and a wall thickness between 3.3 and 7.3 nm. Thus, at least four to nine serially linked units are required to encapsidate a single, helically organized RNA genome. Fragmentation of ToBRFV into these cylindrical structural units may result in a facilitated release of the genome and thus efficient infection. Full article

N′ resistance is intrinsically broken by tobacco mosaic virus but is still effective against pepper mild mottle virus (PMMoV), including those breaking L resistance in peppers. To evaluate the durability of N′ resistance to PMMoV, we performed random mutagenesis of the coat protein (CP) gene of PMMoV. We isolated 11 CP mutants with two to six amino acid changes that escaped the N′-mediated resistance response in Nicotiana sylvestris. Some mutants and their derivatives, which had minimal mutations to escape N′-mediated resistance, exhibited reduced accumulation in inoculated leaves and loss of systemic infectivity in a susceptible pepper (Capsicum annuum) cultivar, as determined by RT-PCR analysis. Although the mutant CPs also escaped recognition by L³ and L⁴ resistance proteins from pepper in transient expression assays, the loss of systemic infectivity suggests that the mutants are unlikely to overcome L-mediated resistance. In Nicotiana benthamiana, a highly susceptible systemic host of PMMoV, ELISA and RT-qPCR indicated that the mutants consistently infected the host systemically, albeit with attenuated virulence and reduced virus accumulation, especially in younger leaves. The results collectively suggest that the reduced virus accumulation enabled the mutant PMMoV to escape N′-mediated resistance, and as a trade-off, compromised its virulence. The results also suggest that PMMoV CP modulates the systemic symptoms. Full article

The role of WRKY transcription factor proteins in plant defense reactions against fungal and bacterial pathogens is well studied, but less information is available about plant–virus interactions. We observed the rapid and strong activation of the transcription factor gene, CaWRKY2, in pepper leaves following inoculation with Obuda pepper virus (ObPV). In contrast, CaWRKY2 was only weakly induced by pepper mild mottle virus (PMMoV) inoculation. To carry out a functional analysis of CaWRKY2, the gene was transiently overexpressed in Nicotiana benthamiana leaves by agroinfiltration. Four days later, CaWRKY2-overexpressing and empty vector control leaves were inoculated with tobacco mosaic virus (TMV). Transiently overexpressing CaWRKY2 did not affect the replication rate of TMV in the inoculated leaves. However, TMV inoculation up-regulated the expression of a pathogenesis-related gene (NbPR-1b) and a lipoxygenase (NbLOX1) gene significantly more strongly in N. benthamiana leaves overexpressing CaWRKY2 than in empty vector control leaves. Intriguingly, CaWRKY2 overexpression delayed (by 3 days) the development of systemic necrosis and plant death caused by TMV in N. benthamiana. These results suggest that CaWRKY2 is able to hinder the spread of TMV from inoculated leaves towards vascular tissues and systemic leaves in N. benthamiana. Full article

Lysozyme is an enzyme that hydrolyzes bacterial cell walls, which is functional for destroying the integrity of bacteria, enhancing the activity of immune cells, participating in immune signal transmission, helping to maintain the micro-ecological balance of the gastrointestinal tract, etc. Egg white lysozyme (EWL), as one of the typical representatives of lysozyme, is the most widely used enzyme in production so far, and is also one of the most complex structures of lysozyme. EWL also helps protect plants from fungal and bacterial diseases. Here, we report the effect of EWL on infections from plant viruses. The EWL gene was cloned and characterized. The EWL protein sequence analysis identified a conserved domain of lysozyme activity and the sharing of a 100% identical EWL protein from the Coturnix japonica lysozyme. Then, the EWL gene was cloned into the plant expression vector pEAQ-HT-DEST3 and transiently expressed in Nicotiana benthamiana (N. benthamiana). We found that EWL expression in N. benthamiana significantly contributed to infections by the turnip mosaic virus (TuMV) but not by the tobacco mosaic virus (TMV). Plants that transiently expressed EWL showed an obvious increase in resistance to Botrytis cinerea (B.cinerea). Our results suggested a new research point for the application of EWL on plant pathogen infections. Full article