Search

Efficient replication and assembly of virus particles are integral to the establishment of infection. In addition to the primary role of the capsid protein (CP) in encapsidating the RNA progeny, experimental evidence on positive sense single-stranded RNA viruses suggests that the CP also regulates RNA synthesis. Here, we demonstrate that replication of Satellite tobacco mosaic virus (STMV) is controlled by the cooperative interaction between STMV CP and the helper virus (HV) Tobacco mosaic virus (TMV) replicase. We identified that the STMV CP-HV replicase interaction requires a positively charged residue at the third position (3R) in the N-terminal 13 amino acid (aa) motif. Far-Northwestern blotting showed that STMV CP promotes binding between HV-replicase and STMV RNA. An STMV CP variant having an arginine to alanine substitution at position 3 in the N-terminal 13aa motif abolished replicase-CP binding. The N-terminal 13aa motif of the CP bearing alanine substitutions for positively charged residues located at positions 5, 7, 10 and 11 are defective in packaging full-length STMV, but can package a truncated STMV RNA lacking the 3' terminal 150 nt region. These findings provide insights into the mechanism underlying the regulation of STMV replication and packaging.

A recombinant vaccine candidate has been developed based on the major coronaviruses' antigen (S protein) fragments and a novel adjuvant—spherical particles (SPs) formed during tobacco mosaic virus thermal remodeling. The receptor-binding domain and the highly conserved antigenic fragments of the S2 protein subunit were chosen for the design of recombinant coronavirus antigens. The set of three antigens (Co1, CoF, and PE) was developed and used to create a vaccine candidate composed of antigens and SPs (SPs + 3AG). Recognition of SPs + 3AG compositions by commercially available antibodies against spike proteins of SARS-CoV and SARS-CoV-2 was confirmed. The immunogenicity testing of these compositions in a mouse model showed that SPs improved immune response to the CoF and PE antigens. Total IgG titers against both proteins were 9–16 times higher than those to SPs. Neutralizing activity against SARS-CoV-2 in serum samples collected from hamsters immunized with the SPs + 3AG was demonstrated. [ABSTRACT FROM AUTHOR]

Based on the broad-spectrum biological activities of echinopsine and acylhydrazones, a series of echinopsine derivatives containing acylhydrazone moieties have been designed, synthesized and their biological activities were evaluated for the first time. The bioassay results indicated that most of the compounds showed moderate to good antiviral activities against tobacco mosaic virus (TMV), among which echinopsine (I) (inactivation activity, 49.5 ± 4.4%; curative activity, 46.1 ± 1.5%; protection activity, 42.6 ± 2.3%) and its derivatives 1 (inactivation activity, 44.9 ± 4.6%; curative activity, 39.8 ± 2.6%; protection activity, 47.3 ± 4.3%), 3 (inactivation activity, 47.9 ± 0.9%; curative activity, 43.7 ± 3.1%; protection activity, 44.6 ± 3.3%), 7 (inactivation activity, 46.2 ± 1.6%; curative activity, 45.0 ± 3.7%; protection activity, 41.7 ± 0.9%) showed higher anti-TMV activity in vivo at 500 mg/L than commercial ribavirin (inactivation activity, 38.9 ± 1.4%; curative activity, 39.2 ± 1.8%; protection activity, 36.4 ± 3.4%). Some compounds exhibited insecticidal activities against Plutella xylostella, Mythimna separate and Spodoptera frugiperda. Especially, compounds 7 and 27 displayed excellent insecticidal activities against Plutella xylostell (mortality 67 ± 6% and 53 ± 6%) even at 0.1 mg/L. Additionally, most echinopsine derivatives exhibited high fungicidal activities against Physalospora piricola and Sclerotinia sclerotiorum. [ABSTRACT FROM AUTHOR]

Tobamovirus species represent a threat to solanaceous crops worldwide, due to their extreme stability and because they are seed borne. In particular, recent outbreaks of tomato brown rugose fruit virus in tomato and pepper crops led to the establishment of prompt control measures, and the need for reliable diagnosis was urged. Another member of the genus, tomato mottle mosaic virus, has recently gained attention due to reports in different continents and its common features with tomato brown rugose fruit virus. In this study, a new real-time RT-PCR detection system was developed for tomato brown rugose fruit virus and tomato mottle mosaic virus on tomato leaves and seeds using TaqMan chemistry. This test was designed to detect tomato mottle mosaic virus by amplifying the movement protein gene in a duplex assay with the tomato brown rugose fruit virus target on the CP-3'NTR region, which was previously validated as a single assay. The performance of this test was evaluated, displaying analytical sensitivity 10−5–10−6-fold dilution for seeds and leaves, respectively, and good analytical specificity, repeatability, and reproducibility. Using the newly developed and validated test, tomato brown rugose fruit virus detection was 100% concordant with previously performed analyses on 106 official samples collected in 2021 from different continents. [ABSTRACT FROM AUTHOR]

This article presents a torsional harmonic Kelvin probe force microscopy (TH-KPFM) working in amplitude modulation (AM) mode for high-sensitivity mapping of surface potential (SP). Compared with frequency modulation KPFM with higher spatial resolution, AM-KPFM has higher potential sensitivity and scanning speed. However, the traditional AM-KPFM is usually limited in the crosstalk from topography measurement and cantilever homogenization effect which causes the measured SP to be seriously affected by the substrate. TH-KPFM can effectively suppress the artifacts induced by the cantilever homogenization effect, and the coupling crosstalk caused by the topography measurement. The torsional harmonic cantilever suitable for TH-KPFM is fabricated and calibrated using the nanorobotic system first. Then, this technique is applied to determine the SP of the tobacco mosaic virus (TMV), and detect surface contaminants of a silicon wafer. Experimental results show that TH-KPFM has a 3 $\sim$ 4 mV energy resolution and sub-20 nm spatial resolution. Compared with the proposed TH-KPFM, the energy level of TMV obtained by the traditional AM-KPFM is pulled down by 80 meV. TH-KPFM is a powerful and useful technique to study the SP on the nanoscale, and greatly simplifies the difficulty of high-sensitivity measurement of the actual SP of many important nanoscale systems. [ABSTRACT FROM AUTHOR]

The reaction of 636 Solanum (sections Lycopersicon and Juglandifolia) accessions were evaluated under greenhouse conditions after mechanical inoculation with a Jordanian isolate of the new tobamovirus tomato brown rugose fruit virus (ToBRFV). Local and systemic infections were assayed by symptoms evaluation and virus detection via biotests and RT-PCR. All cultivated tomatoes (Solanum lycopersicum) and the great majority of wild tomato accessions proved susceptible to ToBRFV. They showed a wide range of symptoms (mosaic, leaf deformations, mottling, shoestring, and stunting). Twenty-six accessions representing S. lycopersicum var. cerasiforme, S. pimpinellifolium, S. habrochaites, and S. chilense were tolerant. High levels of resistance have been demonstrated in three accessions of S. ochrantum, a close relative to wild tomatoes (member of the sect. Juglandifolia) not only to ToBRFV but also to the tobamoviruses, tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV). After mechanical inoculation, the three tobamoviruses could be detected only in inoculated leaves in the accessions LA2160, LA2162, and LA 2166, which remained symptomless. However, two other S. ochrantum accessions PI 473,498 and PI 230,519 reacted unusually. They were demonstrated highly resistant to TMV and ToMV, but proved transiently susceptible to ToBRFV showing mild systemic mosaic followed by total recovery from symptoms and the virus. [ABSTRACT FROM AUTHOR]

In order to effectively prevent and control the disease caused by common tobacco mosaic virus (TMV), a bacterium strain, Z5, resistant to TMV was isolated from soil and was identified as Bacillus velezensis through morphological, physiological, biochemical and molecular biological tests. The culture solution of this bacterium had an in vitro inhibition rate against TMV up to 96.40% and a control effect of 50.43% on TMV in field plot experiments. After the optimization of fermentation condition through a single factor experiment, the optimal medium for strain Z5 was NB medium with glucose and yeast extract as carbon and nitrogen sources respectively, and the optimum conditions were initial pH 7.0, medium volume 100 mL/250mL and fermentation at 28 ° for 60-72 h. Under the optimized condition, the bacterial count increased by 44.38% and the fermentation broth had a stable inhibitory effect against TMV with an inhibition rate of 98.71%. [ABSTRACT FROM AUTHOR]

The Circumsporozoite Protein (CSP) of Plasmodium falciparum contains an N-terminal region, a conserved Region I (RI), a junctional region, 25–42 copies of major (NPNA) and minor repeats followed by a C-terminal domain. The recently approved malaria vaccine, RTS,S/AS01 contains NPNAx19 and the C-terminal region of CSP. The efficacy of RTS,S against natural infection is low and short-lived, and mapping epitopes of inhibitory monoclonal antibodies may allow for rational improvement of CSP vaccines. Tobacco Mosaic Virus (TMV) was used here to display the junctional epitope (mAb CIS43), Region I (mAb 5D5), NPNAx5, and NPNAx20 epitope of CSP (mAbs 317 and 580). Protection studies in mice revealed that Region I did not elicit protective antibodies, and polyclonal antibodies against the junctional epitope showed equivalent protection to NPNAx5. Combining the junctional and NPNAx5 epitopes reduced immunogenicity and efficacy, and increasing the repeat valency to NPNAx20 did not improve upon NPNAx5. TMV was confirmed as a versatile vaccine platform for displaying small epitopes defined by neutralizing mAbs. We show that polyclonal antibodies against engineered VLPs can recapitulate the binding specificity of the mAbs and immune-focusing by reducing the structural complexity of an epitope may be superior to immune-broadening as a vaccine design approach. Most importantly the junctional and restricted valency NPNA epitopes can be the basis for developing highly effective second-generation malaria vaccine candidates. [ABSTRACT FROM AUTHOR]

Small GTPases play critical roles in the regulation of plant growth and development. However, the mechanism of action of small GTPases in plant response to virus infection remains largely unknown. Here, the gene encoding a Rho-type GTPase, NtRHO1 , was identified as one of the genes up-regulated after tobacco mosaic virus (TMV) infection. Subcellular localization of NtRHO1 showed that it was located in the cytoplasm, plasma membrane, and nucleus. Transient overexpression of NtRHO1 in Nicotiana benthamiana accelerated TMV reproduction and led to the production of reactive oxygen species. By contrast, silencing of NtRHO1 reduced the sensitivity of N. benthamiana to TMV-GFP. Further exploration revealed a direct interaction between NtRHO1 and NtWRKY50, a positive regulator of the N. benthamiana response to virus infection. Yeast one-hybrid and electrophoretic mobility shift assays showed that this regulation was related to the capacity of NtWRKY50 to bind to the WK-box of the PR1 promoter, which was weakened by the interaction between NtRHO1 and NtWRKY50. Thus, our results indicate that the small GTPase NtRHO1 plays a negative role in tobacco response to TMV infection by interacting with transcription factor NtWRKY50, resulting in reduced plant immunity. [ABSTRACT FROM AUTHOR]

Several MYB transcription factors are known to play important roles in plant resistance to environmental stressors. However, the mechanism governing the involvement of MYBs in regulating tobacco mosaic virus (TMV) resistance in plants is still unclear. In this study, we found that not only is Nicotiana benthamiana MYB4‐like involved in defence against TMV, but also that the ethylene pathway participates in MYB4L‐mediated resistance. Transcription of NbMYB4L was up‐regulated in N. benthamiana infected with TMV. Silencing of NbMYB4L led to intensified TMV replication, whereas overexpression of NbMYB4L induced significant resistance to TMV. Transcription of NbMYB4L was greater in 1‐aminocyclopropanecarboxylic acid (ACC, ethylene precursor)‐pretreated plants but lower when the ethylene signalling pathway was blocked during TMV infection. Gene expression analysis showed that the transcription of NbMYB4L was largely suppressed in ETHYLENE INSENSITIVE 3‐like 1(EIL1)‐silenced plants. The results of electrophoretic mobility shift assay and chromatin immunoprecipitation‐quantitative PCR (ChIP‐qPCR) experiments indicated that NbEIL1 could directly bind to two specific regions of the NbMYB4L promoter. Furthermore, a luciferase assay revealed that NbEIL1 significantly induced the reporter activity of the MYB4L promoter in N. benthamiana. These results point to NbEIL1 functioning as a positive regulator of NbMYB4L transcription in N. benthamiana against TMV. Collectively, our work reveals that EIL1 and MYB4L constitute a coherent feed‐forward loop involved in the robust regulation of resistance to TMV in N. benthamiana. [ABSTRACT FROM AUTHOR]

Asparagine synthetase is a key enzyme that catalyses the conversion of amide groups from glutamine or ammonium to aspartate, which leads to the generation of asparagine. However, the role of asparagine synthetase in plant immunity remains largely unknown. Here, we identified a Nicotiana benthamiana asparagine synthetase B (NbAS‐B) that associates with tomato mosaic virus coat protein‐interacting protein L (IP‐L) using the yeast two‐hybrid assay and examined its role in tobacco mosaic virus (TMV) resistance. The association of IP‐L with NbAS‐B was further confirmed by in vivo co‐immunoprecipitation, luciferase complementation imaging, and bimolecular fluorescence complementation assays. IP‐L and NbAS‐B interact in the nucleus and cytosol and IP‐L apparently stabilizes NbAS‐B, thus enhancing its accumulation. The expressions of IP‐L and NbAS‐B are continuously induced on TMV‐green fluorescent protein (GFP) infection. Co‐silencing of IP‐L and NbAS‐B facilitates TMV‐GFP infection. Overexpression of NbAS‐B in tobacco reduces TMV‐GFP infection by significantly improving the synthesis of asparagine. Furthermore, the external application of asparagine significantly inhibits the infection of TMV‐GFP by activating the salicylic acid signalling pathway. These findings hold the potential for the future application of asparagine in the control of TMV. [ABSTRACT FROM AUTHOR]

The whitefly is one of the most damaging pests to economical tomato crop in the world, it is considered the first plant virus's transgenic insects. Tomato mosaic virus (ToMV) is a major tomato viral disease transgenic by this insect. Many efforts have been done for controlling this virus infection. Among these many efforts was the whitefly biocontrol by using kairomonic bacteria and the endophytic bacterial lipopeptides to induce plant resistance against viral infection. The lipopeptides produced by Bacillus subtilis endophytic bacterial strains isolated from tomatoes showed a strong reduction in the symptoms caused by (ToMV) virus due to their responsibility for the elicitation of the Systemic Resistance Induction (SRI) mechanism in tomato seedlings. The re-insertion of these endophytic Bacillus subtilis BMG100 bacterial strains by tissue culture technique has also a negative ELISA result with complete severe viral symptoms reduction. The electron microscopical image confirmed the insertion and the huge spreading of endophyticus within tissues. While the spraying of mechanical or biological infected seedlings by the produced endophytic bacterial lipopeptides suspension showed negative ELISA and significant symptoms reduction by the same action happened on the endophyticus re-bacterized seedlings, thus confirming the promising antiviral activities of produced lipopeptides. However, the plant surfaces infected by whitefly and treated with Priestia endophytica BMG103 and Bacillus endophyticus BMG104 kairomone bacteria showed a big vanishment of whitefly stages on the opened field. Moreover, the levels of relative gene expression of the enzyme phenylalanine ammonia lyase (PAL) and the other β 1,3-glucanase 2 (BGL2) which they involved in the promoting of induced resistance phenomenon in tomato seedlings were elevated by lipopeptides treatment due to the relationship between the systemic resistance induction (SRI) with salicylate and jasmoniate involved substrates in defense mechanisms. [ABSTRACT FROM AUTHOR]

The multifunctional protein translationally controlled tumour protein (TCTP) was previously identified as necessary for infection by the potyvirus pepper yellow mosaic virus. Using turnip mosaic virus (TuMV) as a model to study potyvirus biology, we confirmed that TCTP has a positive effect on virus infection. Living cell confocal microscopy demonstrated that TCTP colocalises with 6K2‐tagged replication vesicles and with a perinuclear globular structure typically observed during potyvirus infection. Also, TCTP silenced protoplasts showed reduced virus accumulation, quantified by qRT‐PCR, which suggests an effect on virus replication, translation or other intracellular process. Finally, TCTP silencing in plants reduced the accumulation of two species belonging to Orthotospovirus and a Begomovirus genus, which are not closely related to potyviruses. The results suggest that TCTP is a general susceptibility factor to several unrelated viruses. [ABSTRACT FROM AUTHOR]

• Scanning probe microscopy provides 3D visualization of viruses in liquids and air. • Virus mass estimation may be performed using scanning probe microscopy data. • Atomic balances allow to measure the virus mass by resonant frequency shift. • Membrane charge determines the substrate choice: mica, graphite or glass. • Superlens-array has the resolution till 45 nm. Scanning probe microscopy is a group of measurements that provides 3D visualization of viruses in different environmental conditions including liquids and air. Besides 3D topography it is possible to measure the properties like mechanical rigidity and stability, adhesion, tendency to crystallization, surface charge, etc. Choosing the right substrate and scanning parameters makes it much easier to obtain reliable data. Rational interpretation of experimental results should take into account possible artifacts, proper filtering and data presentation using specially designed software packages. Animal and human virus characterization is in the focus of many intensive studies because of their potential harm to higher organisms. The article focuses on high-resolution visualization of plant viruses. Tobacco mosaic virus, potato viruses X and B and others are not dangerous for the human being and are widely used in different applications such as vaccine preparation, construction of building units in nanotechnology and material science applications, nanoparticle production and delivery, and even metrology. The methods of virus's deposition, visualization, and consequent image processing and interpretation are described in details. Specific examples of viruses imaging are illustrated using the FemtoScan Online software, which has typical and all the necessary built-in functions for constructing three-dimensional images, their processing and analysis. Despite visible progress in visualizing the viruses using probe microscopy, many unresolved problems still remain. At present time the probe microscopy data on viruses is not systemized. There is no descriptive atlas of the images and morphology as revealed by this type of high resolution microscopy. It is worth emphasizing that new virus investigation methods will appear due to the progress of science. [ABSTRACT FROM AUTHOR]

Use of resistant germplasm is an effective, successful and eco-friendly approach to manage Tomato mosaic virus (ToMV) in tomato. Identity of ToMV in tomato was confirmed through reverse - transcriptase polymerase chain reaction (RT-PCR), an amplicon size of 300bp was obtained for coat protein gene of ToMV. Totally, 35 entries of tomato were screened for the identification of resistance source through mechanical inoculation under glasshouse condition. As per the severity scale, six were found resistant, 11 moderately resistant, 12 moderately susceptible, six were susceptible and none were immune to ToMV infection. The presence of Tm genes in the resistant once were identified using sequence characterized amplified region (SCAR) and allele specific (AS1) markers for Tm-1 and Tm-2 genes respectively. Both Tm-1 and Tm-2 genes were identified in hybrid Arka Rakshak and in lines such as LA 0887, TLB 503-3-2 and CK 12. However, Tm-2 alone was present in TLB-409 and TLB-504-1-1, similarly Tm-1 was detected in var. Sankranti which exhibited moderately resistant response. In case of susceptible hybrid Indus 1030, no amplification of Tm genes were noticed indicating Tm-1 and Tm-2 genes have shown to be responsible for resistance to ToMV infection in tomato germplasm. [ABSTRACT FROM AUTHOR]

Background: The antitoxin EndoAI is a TA system component that directly inhibits EndoA activity in vitro. The targeted activation of a TA system represents a potentially novel antimicrobial or antiviral strategy. However, whether the antitoxin functions alone and can induce plant disease resistance remain unknown. Results: An endoAI was previously identified in the genome of Paenibacillus terrae NK3-4. It underwent a bioinformatics analysis, cloned and expressed in Escherichia coli. Then the functions of EndoAI inducing plant resistance to diseases as an elicitor were evaluated. The results showed that, EndoAI is a stable, alkaline, and hydrophilic protein, with a J-shaped three-dimensional structure in the absence of a ligand. It was clustered on the same branch with an antitoxin from Paenibacillus polymyxa SC2. Ectopically expressed EndoAI triggered a reactive oxygen species burst and a positive hypersensitive response (HR) in tobacco leaves. Moreover, 2 μmol EndoAI induced HR activity in tomato leaf, and it remained active after a 15-min exposure at 4–50 °C, and pH 6–8. Additionally, EndoAI induced plant systemic resistance against Alternaria alternata and tobacco mosaic virus, and the up-regulated transcription of PR genes, including PR1a, PR1b, PR5, PDF1.2, COL1, NPR1, and PAL. Conclusions: These results imply that EndoAI may enhance the disease resistance of tobacco by promoting a series of early defense responses and up-regulating PR gene expression. These findings are relevant for future investigations on the mechanism underlying the EndoAI–plant interaction that leads to enhanced disease resistance. Furthermore, the endoAI may be useful for developing effective biocontrol agents to protect plants from diseases. [ABSTRACT FROM AUTHOR]

Systemic acquired resistance (SAR) is induced by pathogens and confers protection against a broad range of pathogens. Several SAR signals have been characterized, but the nature of the other unknown signalling by small metabolites in SAR remains unclear. Glutathione (GSH) has long been implicated in the defence reaction against biotic stress. However, the mechanism that GSH increases plant tolerance against virus infection is not entirely known. Here, a combination of a chemical, virus‐induced gene‐silencing‐based genetics approach, and transgenic technology was undertaken to investigate the role of GSH in plant viral resistance in Nicotiana benthamiana. Tobacco mosaic virus (TMV) infection results in increasing the expression of GSH biosynthesis genes NbECS and NbGS, and GSH content. Silencing of NbECS or NbGS accelerated oxidative damage, increased accumulation of reactive oxygen species (ROS), compromised plant resistance to TMV, and suppressed the salicylic acid (SA)‐mediated signalling pathway. Application of GSH or l‐2‐oxothiazolidine‐4‐carboxylic acid (a GSH activator) alleviated oxidative damage, decreased accumulation of ROS, elevated plant local and systemic resistance, enhanced the SA‐mediated signalling pathway, and increased the expression of ROS scavenging‐related genes. However, treatment with buthionine sulfoximine (a GSH inhibitor) accelerated oxidative damage, elevated ROS accumulation, compromised plant systemic resistance, suppressed the SA‐mediated signalling pathway, and reduced the expression of ROS‐regulating genes. Overexpression of NbECS reduced oxidative damage, decreased accumulation of ROS, increased resistance to TMV, activated the SA‐mediated signalling pathway, and increased the expression of the ROS scavenging‐related genes. We present molecular evidence suggesting GSH is essential for both local and systemic resistance of N. benthamiana to TMV through a differential modulation of SA and ROS. [ABSTRACT FROM AUTHOR]

To investigate the anti-TMV effects of Bunium persicum (BP) and Zataria multiflora (ZM), a set of experiments was conducted in a completely randomised design (n = 3) (p < 0.05). First, TMV particles were treated with different concentrations (0.5, 1.0, 2.5, and 5.0% (v/v)) of BP and ZM extracts. Nicotiana glutinosa and N. tabacum were mechanically inoculated with extract-treated TMV preparations at three intervals (24 h pre, simultaneous, and 24 h post-virus inoculation). Subsequently, local lesion number, inhibition rate, symptom index, and TMV accumulation were measured. Results showed that both extracts displayed significant anti-TMV effects. The highest inhibition percentages for BP and ZM extracts were 65.5% and 52.06%, respectively. 24 h pre-virus inoculation of both extracts at 5% was most efficient in reducing symptom index and ELISA extinction value. Therefore, ZM and BP can be considered as novel anti-TMV plants. Further studies are needed to find their mechanisms and evaluate their antiviral effects against other plant viruses. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) is a crucial hormone in plant antiviral immunity. Increasing evidence shows that viruses counter this host immune response by interfering with JA biosynthesis and signaling. However, the mechanism by which viruses affect JA biosynthesis is still largely unexplored. Here, we show that a highly conserved chloroplast protein cpSRP54 was downregulated in Nicotiana benthamiana infected by turnip mosaic virus (TuMV). Its silencing facilitated TuMV infection. Furthermore, cpSRP54 interacted with allene oxide cyclases (AOCs), key JA biosynthesis enzymes, and was responsible for delivering AOCs onto the thylakoid membrane (TM). Interestingly, TuMV P1 protein interacted with cpSRP54 and mediated its degradation via the 26S proteosome and autophagy pathways. The results suggest that TuMV has evolved a strategy, through the inhibition of cpSRP54 and its delivery of AOCs to the TM, to suppress JA biosynthesis and enhance viral infection. Interaction between cpSRP54 and AOCs was shown to be conserved in Arabidopsis and rice, while cpSRP54 also interacted with, and was degraded by, pepper mild mosaic virus (PMMoV) 126 kDa protein and potato virus X (PVX) p25 protein, indicating that suppression of cpSRP54 may be a common mechanism used by viruses to counter the antiviral JA pathway. Author summary: Jasmonic acid pathway has emerged as one of the predominant battlefields between plants and viruses. Several studies have indicated that, in addition to interfering with JA signaling, plant viruses can also affect JA biosynthesis, but the direct molecular links between them remain elusive. Here, we identify a highly conserved chloroplast protein cpSRP54 as a key positive regulator in JA biosynthesis and a common target for viruses belong to different genera. Through associating with cpSRP54 and inducing its degradation using the protein they encoded, the viruses can inhibit the cpSRP54-facilitated delivery of AOCs to the thylakoid membrane and manipulation of JA-mediated defense. This capability of viruses might define a novel and effective strategy against the antiviral JA pathway. [ABSTRACT FROM AUTHOR]

In this study, genotype analysis was conducted using the Fluidigm system with 13 SNP markers related to anthracnose, powdery mildew, phytophthora root rot, cucumber mosaic virus (CMV), potyvirus, and tobacco mosaic virus (TMV) resistance. A total of 25,350 data points were obtained, 8.2% of which indicated resistance genotypes. Resources having perfect resistance genotype to each disease-related molecular marker set were 58 accessions for anthracnose, 57 for powdery mildew, 246 for phytophthora root rot, and 765 for CMV. There was no resource having a perfect resistance genotype of all three potyvirus-related molecular SNP markers including pvr1, pvr2 (123457), and pvr2 (689). Thirty-seven accessions for pvr1, 349 accessions for pvr2 (123457), and 23 accessions for pvr2 (689) were identified as resources with resistance genotype. No resource with the TMV-resistance genotype was found in this study. The resources with complex resistance genotypes of anthracnose and powdery mildew were 55 accessions, and they were mainly Capsicum baccatum. Among these, seven accessions had a three-disease combined resistance genotype with phytophthora root rot. Thirty-six accessions, 16 accessions, and nine accessions each had resistance genotypes of the three potyvirus-related markers. These resources also had CMV and phytophthora root rot resistance genotypes, and they were mainly Capsicum chinense. The statistical analysis considering the evaluated resistance genotypes, revealed that the anthracnose resistance genotype showed a tendency to be linked with powdery mildew resistance genotype. The potyvirus-related marker pvr1 was positively correlated with Phytophthora root rot markers. [ABSTRACT FROM AUTHOR]

The structures of new crystal forms of Satellite tobacco mosaic virus (STMV) are described. These belong to space groups I2, P21212 (a low‐resolution form), R3 (H3) and P23. The R3 crystals are 50%/50% twinned, as are two instances of the P23 crystals. The I2 and P21212 crystals were grown from ammonium sulfate solutions, as was one crystal in space group P23, while the R3 and the other P23 crystals were grown from sodium chloride, sodium bromide and sodium nitrate. The monoclinic and orthorhombic crystals have half a virus particle as the asymmetric unit, while the rhombohedral and cubic crystals have one third of a virus particle. RNA segments organized about the icosahedral twofold axes were present in crystals grown from ammonium sulfate and sodium chloride, as in the canonical I222 crystals (PDB entry 4oq8), but were not observed in crystals grown from sodium bromide and sodium nitrate. Bromide and nitrate ions generally replaced the RNA phosphates present in the I222 crystals, including the phosphates seen on fivefold axes, and were also found at threefold vertices in both the rhombohedral and cubic forms. An additional anion was also found on the fivefold axis 5 Å from the first anion, and slightly outside the capsid in crystals grown from sodium chloride, sodium bromide and sodium nitrate, suggesting that the path along the symmetry axis might be an ion channel. The electron densities for RNA strands at individual icosahedral dyads, as well as at the amino‐terminal peptides of protein subunits, exhibited a diversity of orientations, in particular the residues at the ends. [ABSTRACT FROM AUTHOR]

Zhongshu Shan,1,2,* Hongtao Bi,3,* Angxiu Suonan,2 Yong Gu,1 Huan Zhou,4 Kun Xi,1 Rui Xiong,5 Hua Chen,2 Liang Chen1 1Department of Orthopedic Surgery, The 1st Affiliated Hospital of Soochow University, Suzhou, Jiangsu, People’s Republic of China; 2Department of Orthopedic Surgery, People’s Hospital of Qinghai Province, Xining, Qinghai, People’s Republic of China; 3Qinghai Provincial Key Laboratory of Tibetan Medicine Pharmacology and Safety Evaluation, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, People’s Republic of China; 4Department of Radiography, Rocket Army Specialty Medical Center, Beijing, People’s Republic of China; 5Nutrition Department, People’s Hospital of Qinghai Province, Xining, Qinghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Liang ChenDepartment of Orthopedic Surgery, The 1st Affiliated Hospital of Soochow University, 188 Shizi St. Suzhou, Jiangsu 215006, People’s Republic of ChinaEmail chenliangspine@163.comIntroduction: Tobacco mosaic virus-based nanoparticles (TMV VNPs) were previously shown to promote osteogenic differentiation in vitro. This study aims to investigate whether and how TMV VNPs impact on osteoclastogenesis in vitro and bone injury healing in vivo.Methods: Raw264.7 cells were cultured in osteoclastogenic medium in culture plates coated with or without TMV and TMV-RGD1 VNPs, followed by TRAP staining, RT-qPCR and WB assessing expression of osteoclastogenic marker genes, and immunofluorescence assessing NF-κB activation. TMV and TMV-RGD1-modified hyaluronic acid hydrogel were used to treat mouse tibial bone injury. Bone injury healing was checked by micro-CT and Masson staining.Results: TMV and TMV-RGD1 VNPs significantly inhibited osteoclast differentiation and downregulated the expression of osteoclastogenic marker genes Ctr, Ctsk, Mmp-9, Rank, and Trap. Moreover, TMV and TMV-RGD1 VNPs inhibited NF-κB p65 phosphorylation and nuclear translocation, as well as activation of mTOR/AKT signaling pathway. TMV and TMV-RGD1-modified HA hydrogel strongly promoted mouse tibial bone injury with increased bone mass compared to plain HA hydrogel. The amount of osteoclasts was significantly reduced in TMV and TMV-RGD1 treated mice. TMV-RGD1 was more effective than TMV in inhibiting osteoclast differentiation and promoting bone injury repair.Discussion: These data demonstrated the great potential of TMV VNPs to be developed into biomaterial for bone injury repair or replacement.Keywords: tobacco mosaic virus, viral nanoparticle, osteoclast, mTOR, tibial bone injury

The second half of the 20th century was marked by remarkable discoveries in the chemistry and biochemistry of proteins, in particular, in establishing the protein structure. James Sumner, John Northrop, and Wendell Stanley, the Nobel Laureates in chemistry in 1946, were the first to isolate individual enzymes and viruses in a pure crystalline form and prove their protein nature, thereby making an invaluable scientific contribution to the development of important biological disciplines such as biochemistry, enzymology, virology, and molecular biology. A significant contribution to understanding chemical bonding in the formation of the different levels of a protein structure was made by Linus Pauling – a prominent American scientist of the 20th century. He was awarded the Nobel Prize in Chemistry in 1954 “for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances”. Biochemists know him well as the author of the secondary structure of proteins – the α-helix and the β-sheet. Frederick Sanger, a two-time Nobel Prize winner (1958 and 1980), was the first among researchers who determined the primary amino acid sequence of a protein, for example, of two insulin polypeptide chains A and B. F. Sanger proved that the sequence nature of proteins’ structures is analogous to that of gene sequences in the DNA, and thus, the same principles may be applied. The difficult question of how a protein molecule is arranged in space was answered by the English biochemists Max F. Perutz and John C. Kendrew. They determined the three-dimensional structure of hemoglobin and myoglobin proteins by X-ray diffraction and were awarded the Nobel Prize in Chemistry in 1962 “for their studies of the structures of globular proteins”.

Abstract Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus. The 3′ end of TMV genome is consisted of an upstream pseudoknot domain (UPD) and a tRNA-like structure (TLS), both of which are important RNA elements to enhance TMV replication and translation. Deep-sequencing analysis revealed that TMV-specific viral small interfering RNAs (vsiRNAs) were generated in TMV-infected Nicotiana benthamiana plants. A vsiRNA derived from the juxtaposition between UPD and TLS, named TMV-vsiRNA 22 nt (6285–6306), possessed high sequence complementarity to a host gene which encodes a C2-domain abscisic acid (ABA)-related (CAR) 7-like protein. CAR proteins play a critical role in ABA signaling pathway. The CAR protein-encoding gene was amplified from N. benthamiana leaves and termed as Nb-CAR7. In TMV-infected plants, accumulation of Nb-CAR7 transcripts was significantly decreased, as compared with that of mock-inoculated and TMV-43A-infected plants. TMV-43A is a mutant without the UPD sequence in its genome. Overexpression of Nb-CAR7 led to decreased TMV RNA accumulation in the TMV-inoculated leaves. Silencing of Nb-CAR7 enhanced TMV replication and resulted in a higher viral RNA accumulation. In addition, the expression level of Nb-CAR7 was positively correlated to that of a low-temperature-induced ABA responsive gene (LTI65). The effect of Nb-CAR7 on TMV RNA accumulation in host plants was linked to ABA signaling pathway. In conclusion, a vsiRNA derived from the juxtaposition between UPD and TLS at the 3′UTR of TMV targets a host CAR7 gene.

Abstract A microbe-based silver nanoparticle could inhibit the tobacco mosaic virus. In the present study, AgNO3 reacts with Pseudomonas fluorescens CZ strain fermentative broth and formed silver nanoparticles. The crystallinity and purity of silver nanoparticles (AgNPs) were examined by an X-ray diffractometer. Number of Bragg reflection was indexed in the face-centered AgNPs to show a cubic structure. Observation of scan electron microscope (SEM) confirmed the formation of AgNPs. Antiviral effects determined by percentage inhibition of local lesion of tobacco mosaic virus (TMV). Spray of AgNPs and inoculation with TMV assayed analysis revealed percentage inhibition of local lesion 92.70. Effects of AgNPs on the morphology of TMV were observed by a transmission electron microscope (TEM). Micrograph images confirmed the significant effects on the morphology of TMV. Biogenic NP from AgNO3 and fermented broth from Pseudomonas fluorescens could be a potent approach to control the TMV.

A series of 1,3,4-oxadiazole contained sesquiterpene derivatives were synthesized, and the activity of the target compounds against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and tobacco mosaic virus (TMV) were evaluated. The biological activity results showed that the EC50 values of compounds H4, H8, H11, H12, H14, H16, and H19 for Xac inhibitory activity were 33.3, 42.7, 56.1, 74.5, 37.8, 43.8, and 38.4 μg/ml, respectively. Compounds H4, H8, H15, H19, H22, and H23 had inhibitory effects on Xoo, with EC50 values of 51.0, 43.3, 43.4, 50.5, 74.6, and 51.4 μg/ml, respectively. In particular, the curative and protective activities of compound H8 against Xoo in vivo were 51.9 and 49.3%, respectively. In addition, the EC50 values of the inactivation activity of compounds H4, H5, H9, H10, and H16 against TMV were 69.6, 58.9, 69.4, 43.9, and 60.5 μg/ml, respectively. The results of molecular docking indicated that compound H10 exhibited a strong affinity for TMV-coat protein, with a binding energy of −8.88 kcal/mol. It may inhibit the self-assembly and replication of TMV particles and have an anti-TMV effect, which supports its potential usefulness as an antiviral agent.

A recombinant vaccine candidate has been developed based on the major coronaviruses’ antigen (S protein) fragments and a novel adjuvant—spherical particles (SPs) formed during tobacco mosaic virus thermal remodeling. The receptor-binding domain and the highly conserved antigenic fragments of the S2 protein subunit were chosen for the design of recombinant coronavirus antigens. The set of three antigens (Co1, CoF, and PE) was developed and used to create a vaccine candidate composed of antigens and SPs (SPs + 3AG). Recognition of SPs + 3AG compositions by commercially available antibodies against spike proteins of SARS-CoV and SARS-CoV-2 was confirmed. The immunogenicity testing of these compositions in a mouse model showed that SPs improved immune response to the CoF and PE antigens. Total IgG titers against both proteins were 9–16 times higher than those to SPs. Neutralizing activity against SARS-CoV-2 in serum samples collected from hamsters immunized with the SPs + 3AG was demonstrated.

The present study focused on the impact of infection with the tobacco mosaic virus (TMV). Specifically, changes in phytochemicals and gene activity related to pathogenesis-related and phenylpropanoid pathway genes in tomato plants (Solanum lycopersicum L.) during a period of 2-14 days post-inoculation (dpi). According to TEM investigation and coat protein sequence analysis, the purified TMV Egyptian AM isolate (PP133743) has a rod-shaped structure with a diameter of around 110 nm. The RT-qPCR analysis revealed that PR-1 showed an initial increase after TMV infection, as seen in the time-course analysis. In contrast, PR-2 was consistently elevated throughout the infection, suggesting a stronger reaction to the virus and suppressing PAL expression at 6 to 14 dpi. The expression levels of HQT and CHS transcripts exhibited alternating patterns of up-regulation and down-regulation at different time intervals. The HPLC and GC-MS analysis of control- and TMV-infected tomato extracts revealed that different phenolic, flavonoid, and fatty acid compounds were increased (such as naringenin, rutin, flavone, ferulic acid, and pyrogallol) or significantly decreased (such as salicylic acid and chlorogenic acid) after TMV infection. The ability of TMV to inhibit most polyphenolic compounds could potentially accelerate the viral life cycle. Consequently, focusing on enhancing the levels of such suppressed compounds may be critical for developing plant viral infection management strategies., (© 2024. The Author(s).)

Natural products are a valuable resource for the discovery of novel crop protection agents. A series of γ-butyrolactone derivatives, derived from the simplification of podophyllotoxin's structure, were synthesized and assessed for their efficacy against tobacco mosaic virus (TMV). Several derivatives exhibited notable antiviral properties, with compound 3g demonstrating the most potent in vivo anti-TMV activity. At 500 μg/mL, compound 3g achieved an inactivation effect of 87.8%, a protective effect of 71.7%, and a curative effect of 67.7%, surpassing the effectiveness of the commercial plant virucides ningnanmycin and ribavirin . Notably, the syn -diastereomer ( syn - 3g ) exhibited superior antiviral activity compared to the anti -diastereomer ( anti - 3g ). Mechanistic studies revealed that syn - 3g could bind to the TMV coat protein and interfere with the self-assembly process of TMV particles. These findings indicate that compound 3g , with its simple chemical structure, could be a potential candidate for the development of novel antiviral agents for crop protection.

Strigolactones (SLs) are plant hormones that regulate diverse developmental processes and environmental responses in plants. It has been discovered that SLs play an important role in regulating plant immune resistance to pathogens but there are currently no reports on their role in the interaction between Nicotiana benthamiana and the tobacco mosaic virus (TMV). In this study, the exogenous application of SLs weakened the resistance of N. benthamiana to TMV, promoting TMV infection, whereas the exogenous application of Tis108, a SL inhibitor, resulted in the opposite effect. Virus-induced gene silencing (VIGS) inhibition of two key SL synthesis enzyme genes, NtCCD7 and NtCCD8 , enhanced the resistance of N. benthamiana to TMV. Additionally, we conducted a screening of N. benthamiana related to TMV infection. TMV-infected plants treated with SLs were compared to the control by using RNA-seq. The KEGG enrichment analysis and weighted gene co-expression network analysis (WGCNA) of differentially expressed genes (DEGs) suggested that plant hormone signaling transduction may play a significant role in the SL-TMV- N. benthamiana interactions. This study reveals new functions of SLs in regulating plant immunity and provides a reference for controlling TMV diseases in production.

A series of indole derivatives containing quinoline structures were designed and synthesized. The synthesized compounds were characterized by NMR and HRMS. And W14 was performed by single crystal X-ray diffraction experiments. The antiviral activity studies showed that some of the target compounds possessed significant activity against tobacco mosaic virus (TMV). In particular, W20 had significant activity. The results of in vivo anti-TMV activity assay showed that W20 possessed the best curative and protective activities with EC 50 values of 84.4 and 65.7 μg/mL, which were better than ningnanmycin (NNM) 205.1 and 162.0 μg/mL, respectively. The results of Microscale thermophoresis (MST) showed that W20 had a strong binding affinity for the tobacco mosaic virus coat protein (TMV-CP) with a dissociation constant (K d ) of 0.00519 μmol/L, which was superior to that of NNM (1. 65320 μmol/L). The molecular docking studies were in accordance with the experimental results. In addition, the determination of malondialdehyde (MDA) content in tobacco leaves showed that W20 improved the disease resistance of tobacco. Overall, this study shows that indole derivatives containing quinoline can be used as new antiviral agents for plant viruses for further research., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Protein cages are promising tools for the controlled delivery of therapeutics and imaging agents when endowed with programmable disassembly strategies. Here, we produced hybrid nanocomposites made of tobacco mosaic virus (TMV) and magnetic iron oxide nanoparticles (IONPs), designed to disrupt the viral protein cages using magnetically induced release of heat. We studied the effects of this magnetic hyperthermia on the programmable viral protein capsid disassembly using (1) elongated nanocomposites of TMV coated heterogeneously with magnetic iron oxide nanoparticles (TMV@IONPs) and (2) spherical nanocomposites of polystyrene (PS) on which we deposited presynthesized IONPs and TMV via layer-by-layer self-assembly (PS@IONPs/TMV). Notably, we found that the extent of the disassembly of the protein cages is contingent upon the specific absorption rate (SAR) of the magnetic nanoparticles, that is, the heating efficiency, and the relative position of the protein cage within the nanocomposite concerning the heating sources. This implies that the spatial arrangement of components within the hybrid nanostructure has a significant impact on the disassembly process. Understanding and optimizing this relationship will contribute to the critical spatiotemporal control for targeted drug and gene delivery using protein cages.

Since the discovery of the tobacco mosaic virus in the 1890s, awareness has grown in regard to how viruses affect the environment. Viral infections are now known to cause various effects besides pathogenicity, with some viruses in fact having a beneficial impact on plants. Although research has focused on disease-causing viruses that can infect plants, many wild plants are also infected with non-pathogenic viral agents. Traditionally, abiotic, and biotic stresses have been studied as isolated stimuli that trigger signaling pathways within the plant. However, both biotic and abiotic stress can trigger complex molecular interactions within plants, which in turn drive interconnected response pathways. Here, we demonstrate that heat-killed tobacco mosaic virus (TMV) can increase abiotic stress tolerance in plants, an effect that could potentially be implemented in challenging growth environments. To our knowledge, this is the first report of plant abiotic stress tolerance following treatment with heat-killed viral particles.

Plant nucleotide-binding, leucine-rich, repeat-containing proteins (NLRs) play important roles in plant immunity. NLR expression and function are tightly regulated by multiple mechanisms. In this study, a conserved serine/arginine-rich protein (SR protein) was identified through the yeast one-hybrid screening of a tobacco cDNA library using DNA fragments from the N gene, an NLR that confers immunity to tobacco mosaic virus (TMV). This SR protein showed an interaction with a 3′ genomic regulatory sequence (GRS) and has a potential role in regulating the alternative splicing of N. Thus, it was named SR regulator for N, abbreviated SR4N. Further study showed that SR4N plays a positive role in N-mediated cell death but a negative role in N protein accumulation. SR4N also promotes multiple virus replications in co-expression experiments, and this enhancement may not function through RNA silencing suppression, as it did not enhance 35S-GFP expression in co-infiltration experiments. Bioinformatic and molecular studies revealed that SR4N belongs to the SR2Z subtype of the SR protein family, which was conserved in both dicots and monocots, and its roles in repressing viral immunity and triggering cell death were also conserved. Our study revealed new roles for SR2Z family proteins in plant immunity against viruses.

Early and sensitive detection of tobacco mosaic virus (TMV) is of great significance for improving crop yield and protecting germplasm resources. Herein, we constructed a novel fluorescence sensor to detect TMV RNA (tRNA) through double strand specific nuclease (DSN) cycle and activator regenerative electron transfer atom transfer radical polymerization (ARGET ATRP) dual signal amplification strategy. The hairpin DNA complementarily paired with tRNA was used as a recognition unit to specifically capture tRNA. By the double-stranded DNA hydrolyzed with DSN, tRNA is released to open more hairpin DNA, and more complementary DNA (cDNA) is bound to the surface of the magnetic beads (MBs) to achieve the first amplification. After binding with the initiator, the cDNA employed ARGET ATRP to attach more fluorescent signal molecules to the surface of MBs, thus achieving the second signal amplification. Under the optimal experimental conditions, the logarithm of fluorescence intensity versus tRNA concentration showed a good linear relationship in the range of 0.01-100 pM, with a detection limit of 1.03 fM. The limit of detection (LOD) was calculated according to LOD = 3 N/S. Besides, the sensor showed good reproducibility and stability, which present provided new method for early and highly sensitive detection for plant viruses., (© 2024 John Wiley & Sons Ltd.)

The objective of this study was to investigate the mechanism underlying LW-1-induced resistance to TMV in wild-type and salicylic acid (SA)-deficient NahG transgenic tobacco plants. Our findings revealed that LW-1 failed to induce antivirus infection activity and increase SA content in NahG tobacco, indicating the crucial role of SA in these processes. Meanwhile, LW-1 triggered defense-related early-signaling nitric oxide (NO) generation, as evidenced by the emergence of NO fluorescence in both types of tobacco upon treatment with LW-1, however, NO fluorescence was stronger in NahG compared to wild-type tobacco. Notably, both of them were eliminated by the NO scavenger cPTIO, which also reversed LW-1-induced antivirus activity and the increase of SA content, suggesting that NO participates in LW-1-induced resistance to TMV, and may act upstream of the SA pathway. Defense-related enzymes and genes were detected in tobacco with or without TMV inoculation, and the results showed that LW-1 regulated both enzyme activity (β-1,3-glucanase [GLU], catalase [CAT] and phenylalanine ammonia-lyase [PAL]) and gene expression (PR1, PAL, WYKY4) through NO signaling in both SA-dependent and SA-independent pathways., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

[Display omitted] The interaction of the tobacco mosaic virus with the active surface of an iron-containing adsorbent obtained from lignin by the plasma-catalytic method was studied by IR spectroscopy. The results revealed decomposition of the virus into protein molecules and RNA reacting with the lignin surface via oxygen atoms during the binding of the virus to the sorbent surface. It was assumed that oxygen carboxylate groups interrelate with nanosized iron clusters incorporated into the adsorbent surface structure. [ABSTRACT FROM AUTHOR]

Tomato cultivars containing the Tm‐22 resistance gene have been widely known to resist tobacco mosaic virus (TMV) and tomato mosaic virus. Tomato brown rugose fruit virus (ToBRFV), a new emerging tobamovirus, can infect tomato plants carrying the Tm‐22 gene. However, the virulence determinant of ToBRFV that overcomes the resistance conferred by the Tm‐22 gene remains unclear. In this study, we substituted the movement protein (MP) encoding sequences between ToBRFV and TMV infectious clones and conducted infectivity assays. The results showed that MP was the virulence determinant for ToBRFV to infect Tm‐22 transgenic Nicotiana benthamiana plants and Tm‐22‐carrying tomato plants. A TMV MP chimera with amino acid residues 60–186 of ToBRFV MP failed to induce hypersensitive cell death in the leaves of Tm‐22 transgenic N. benthamiana plants. Chimeric TMV containing residues 60–186 of ToBRFV MP could, but chimeric ToBRFV containing 61–187 residues of TMV MP failed to infect Tm‐22 transgenic N. benthamiana plants, indicating that 60–186 residues of MP were important for ToBRFV to overcome Tm‐22 gene‐mediated resistance. Further analysis showed that six amino acid residues, H67, N125, K129, A134, I147, and I168 of ToBRFV MP, were critical in overcoming Tm‐22‐mediated resistance in transgenic N. benthamiana plants and tomato plants. These results increase our understanding of the mechanism by which ToBRFV overcomes Tm‐22‐mediated resistance. [ABSTRACT FROM AUTHOR]

The pepino (Solanum muricatum) is an Andean vegetable crop closely related to tomato. In the last decades, it has been introduced in the Mediterranean region and other parts of the world as a potential new crop. However, several tomato major pathogens may threaten the expansion of pepino cultivation. We identified Fusarium oxysporum f. sp. lycopersici (FOL), Verticillium dahliae (VE), pepino mosaic virus (PepMV) and tomato mosaic virus (ToMV) as four of the most likely pathogens to cause damage to pepino crops in Mediterranean climates. In order to evaluate the response of the pepino genepool against these pathogens, as well as to identify sources of tolerance, we inoculated six accessions of cultivated pepino, nine accessions of seven pepino wild relatives, and one interspecific hybrid with FOL, VE, PepMV and ToMV and followed its symptomatology for 30 days (FOL and VE) or 60 days (PepMV and ToMV). ELISA tests were also performed for PepMV and ToMV. Susceptible tomato materials were used as controls. The pepino genepool displayed fewer symptoms than susceptible tomato controls after inoculation with FOL, with most accessions being tolerant or resistant. Regarding VE, a wide variation of values for the symptoms index (SI) was observed, with three cultivated pepino accessions displaying tolerance. For PepMV a wide variation for SI was also observed, with one accession of S. caripense being resistant, and several accessions of pepino and other wild relatives displaying different degrees of tolerance. PepMV absorbance values obtained by ELISA tests followed a pattern similar to that of SI. For ToMV no resistances were found, although two wild accessions and the interspecific hybrid displayed low values for the SI and were considered as moderately tolerant. ELISA tests against ToMV revealed that the virus replicated well in all materials. None of the accessions evaluated displayed resistance or high levels of tolerance to the four pathogens, but some of them were complementary for resistance or high levels of tolerance. Although the interspecific hybrid tested was not resistant to any of the pathogens, it was tolerant to FOL and PepMV and moderately tolerant to VE and ToMV. A multivariate hierarchical clustering revealed similar patterns among accessions in the response to the two fungal diseases (FOL and VE) on one side and to the two viral ones (PepMV and ToMV) on the other. The information generated in this study has allowed identifying materials within the pepino genepool for the development of multi‐resistant pepino cultivars to major diseases threatening its expansion in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Two-dimensional ultrastructural changes of Tobacco mosaic virus (TMV) and Zucchini yellow mosaic virus (ZYMV) in tobacco and pumpkin plants, respectively, are well studied. To provide 3D data, representative control and infected cells were reconstructed using serial sectioning and transmission electron microscopy. Quantitative data of 3D ultrastructural changes were then extracted from the cytosol and organelles by image analysis. While TMV induced the accumulation of an average of 40 virus inclusion bodies in the cytosol, which covered about 13% of the cell volume, ZYMV caused the accumulation of an average of 1752 cylindrical inclusions in the cytosol, which covered about 2.7% of the total volume of the cell. TMV infection significantly decreased the number and size of mitochondria (− 49 and − 20%) and peroxisomes (− 62 and − 28%) of the reconstructed cell. The reconstructed ZYMV-infected cell contained more (105%) and larger (109%) mitochondria when compared to the control cell. While the reconstructed TMV-infected cell contained larger (20%) and the ZYMV-infected smaller (19%) chloroplasts, both contained less chloroplasts (− 40% for TMV and − 23% for ZYMV). In chloroplasts, the volume of starch and plastoglobules increased (664% and 150% for TMV and 1324% and 1300% for ZYMV) when compared to the control. The latter was correlated with a decrease in the volume of thylakoids in the reconstructed ZYMV-infected cell (− 31%) indicating that degradation products from thylakoids are transported and stored in plastoglobules. Summing up, the data collected in this study give a comprehensive overview of 3D changes induced by TMV and ZYMV in plants. [ABSTRACT FROM AUTHOR]

Using a virus as a template to synthesize nanomaterial is a simple, green, and controllable method to acquire unique structure nanoparticles. In this study, CdS nanowires were synthesized using the tobacco mosaic virus (TMV) as a template and for deposition in the inner center channel of TMV. TMV/CdS was successfully characterized, with the results showing a diameter of 4.0 nm, a cubic-phase composition, and strong fluorescence emission peaks, with an absorption edge of 566 nm and bandgap energy of 2.28 eV. The bandgap energy is narrower than that of template-free CdS. Furthermore, TMV/CdS exhibited an increased transient photocurrent, which was attributed to the effective separation of electron-hole pairs. The photoactivities of TMV/CdS and template-free CdS were tested; the results showed that the TMV/CdS had a better performance in methylene blue (MB) photodegradation, indicating that the photoactivity of TMV/CdS was higher than that of the template-free CdS. Further research on TMV/CdS regarding the photocatalytic mechanism showed that O2•− and •OH were the major species involved in photocatalysis, rather than holes (h+). Therefore, TMV/CdS might have applications as a novel visible-light-responsive photocatalyst. Key points: • CdS nanowires were firstly synthesized in the inner center channel of TMV • TMV/CdS presented higher photocatalytic efficiency compared with template-free CdS • The O2•−and•OH were responsible for the photocatalytic reaction of TMV/CdS [ABSTRACT FROM AUTHOR]

Poaceae plant species, such as silver grass, are commonly used in mulching activities Japan. In contrast, local farmers have traditionally used Japanese knotweed (Fallopia japonica) mulch in the cultivation of solanaceous crops in the Nishi-Awa area of Japan, which is a Globally Important Agricultural Heritage Systems site. We have previously evaluated the positive effects of Japanese knotweed mulching on solanaceous crops, such as eggplants, tomato, and potato. In the present study, we observed that the naturally occurring diseases in the solanaceous crops tended to decrease when the knotweed mulching system was adopted, in comparison to when Poaceae mulch was adopted. In eggplants, leaf mold and powdery mildew decreased under Japanese knotweed mulching. We further evaluated the effects of Japanese knotweed mulching by inoculating test plants with Pseudomonas cichorii. We observed suppression of bacterial disease and tomato mosaic virus under Japanese knotweed mulching and following spraying with Japanese knotweed extracts. In addition, disease-resistance genes were expressed at high levels in Arabidopsis thaliana, a model plant, following treatment with Japanese knotweed extracts. The results suggest that Japanese knotweed has potential applications in future sustainable agriculture activities. [ABSTRACT FROM AUTHOR]

BACKGROUND Tobacco mosaic virus (TMV) is a disreputable plant pathogen that causes a decline in the quality and yield of various economic crops. Natural products are important potential sources of biopesticides to control TMV. This study focuses on the discovery of anti‐TMV active flavonoid glycosides and their mode of action on TMV particles from Clematis lasiandra Maxim. RESULTS: A new benzoyl acylated flavonoid glycoside, kaempferol 3‐O‐(2′′‐benzoyl)‐β‐d‐glucopyranosyl‐7‐O‐α‐l‐rhamnopyranoside (1), and nine known flavonoids (2–10) were identified first from C. lasiandra. The hydroxyl group at C‐7, E‐p‐coumarate at C‐6′′ in the Glc of C‐6, and the glucuronic acid at C‐3 were functional groups for the antiviral flavonoid glycosides. Flavonoids 2, 5, and 6 showed higher inactivation efficacies of 64.62% to 82.54% compared with ningnanmycin at 500 μg ml−1. The protective and curative efficacies for 2 and 5 were 57.44–59.00% and 41.17–43.92% at 500 μg ml−1, respectively. Compound 5 showed higher TMV systemic resistance with control efficacies of 41.64%, 36.56% and 27.62% at concentrations of 500, 250 and 125 μg ml−1 compared with ningnanmycin in K326 tobaccos, respectively. Compound 5 can directly fracture TMV particles into small fragments combining with the fusion phenomena, and TMV‐CP was an important target for 5 to break TMV particles. CONCLUSION: Flavonoid glycosides from C. lasiandra showed potent antiviral activities against TMV with multiple modes of action including inactivation, protective and curative effects, and inducing systemic resistance. TMV‐CP was an important target for active flavonoid glycosides to fracture TMV particles. The results provided evidence that flavonoid glycosides from C. lasiandra have the potential to control TMV. [ABSTRACT FROM AUTHOR]

Two aphid-transmitted RNA viruses, broad bean wilt virus 2 (BBWV2) and cucumber mosaic virus (CMV), are the most prevalent viruses in Korean pepper fields and cause chronic damage in pepper production. In this study, we employed a screening system for pathotype-specific resistance of pepper germplasm to BBWV2 and CMV by utilizing infectious cDNA clones of different pathotypes of the viruses (two BBWV2 strains and three CMV strains). We first examined pathogenic characteristics of the BBWV2 and CMV strains in various plant species and their phylogenetic positions in the virus population structures. We then screened 34 commercial pepper cultivars and seven accessions for resistance. While 21 pepper cultivars were resistant to CMV Fny strain, only two cultivars were resistant to CMV P1 strain. We also found only one cultivar partially resistant to BBWV2 RP1 strain. However, all tested commercial pepper cultivars were susceptible to the resistance-breaking CMV strain GTN (CMV-GTN) and BBWV2 severe strain PAP1 (BBWV2-PAP1), suggesting that breeding new cultivars resistant to these virus strains is necessary. Fortunately, we identified several pepper accessions that were resistant or partially resistant to CMV-GTN and one symptomless accession despite systemic infection with BBWV2-PAP1. These genetic resources will be useful in pepper breeding programs to deploy resistance to BBWV2 and CMV. [ABSTRACT FROM AUTHOR]

Biochar soil amendment was applied as an eco-friendly approach to control Tomato mosaic virus (ToMV) and improve tomato growth and nutritional status. Three concentrations of biochar, 0.5, 1.0 and 1.5% were used as soil amendments. Using biochar at the rate of 1 and 1.5% reduced the ToMV incidence and delayed symptoms appearance as compared with plants grown in nonamended soil. Infection percentage and disease severity of ToMV were reduced by 33.3 and 50%, respectively, 15 days after inoculation of plants of soil amended with 1.5% biochar. ToMV relative concentration, using indirect ELISA was significantly reduced in plants of biochar 1% and 1.5% treatments. The lowest virus concentration was recorded at 21 days after inoculation in plants of 1.5% biochar amended soil. The shoot fresh weight was increased at biochar rates of 1.5 and 0.5% in non-infected and ToMV infected tomato, respectively. Significant increase was obtained in shoot K content amended with 1.0 and 1.5% biochar treatments of healthy and ToMVinfected tomato plants, respectively. Whereas, shoot Na content was diminished in infected plants grown in biochar amended soil at all tested biochar concentrations. Overall, the biochar application to soil enhanced resistance to ToMV infection, stimulated growth and K content increment and Na content decrement in tomato plants. In conclusion, application of biochar to agricultural soil could be considered a practical tool for minimizing the change effects of climate through carbon sequestration, improve plant productivity and increase diseases tolerance for sustainable agriculture. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tobacco mosaic virus (TMV) is one of destructive plant viruses, causing serious economic losses in the world. Using antiviral proteins or elicitors to inhibit viral infection or promote plant immunity is one of the efficient strategies against TMV. Our previous study identified that the fermentation broth of Brevibacillus laterosporus strain B8 showed strong antiviral activity against TMV. However, the active antiviral ingredient is still unclear. RESULTS: Here, BLB8 (B. laterosporus strain B8 protein, BLB8), an antiviral protein from B. laterosporus strain B8 was isolated and characterized. BLB8 showed protective, inactive and curative effects against TMV, and the inhibition rate reached up to 63%, 83% and 55%, respectively. BLB8 infiltrated around the infection site of the recombinant virus TMV‐GFP inhibited the systemic extend and movement of TMV. Pretreatment of the bottom leaves with BLB8 inhibited the spread and accumulation of TMV in upper systemic leaves. Furthermore, BLB8 caused hypersensitive response (HR) in a dose‐dependent way, promoted H2O2 accumulation, and induced the expression of defense‐relative genes in Nicotiana benthamiana. CONCLUSION: The antiviral protein BLB8 from B. laterosporus strain B8 effectively inhibits TMV infection in inactivation, protective and curative effects through triggering plant immunity in tobacco. Therefore, the present study provides a new antiviral agent for prevention and control of viral disease. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plant viruses are major contributors to crop losses and induce high economic costs worldwide. For reliable, on-site and early detection of plant viral diseases, portable biosensors are of great interest. In this study, a field-effect SiO2-gate electrolyte-insulator-semiconductor (EIS) sensor was utilized for the label-free electrostatic detection of tobacco mosaic virus (TMV) particles as a model plant pathogen. The capacitive EIS sensor has been characterized regarding its TMV sensitivity by means of constant-capacitance method. The EIS sensor was able to detect biotinylated TMV particles from a solution with a TMV concentration as low as 0.025 nM. A good correlation between the registered EIS sensor signal and the density of adsorbed TMV particles assessed from scanning electron microscopy images of the SiO2-gate chip surface was observed. Additionally, the isoelectric point of the biotinylated TMV particles was determined via zeta potential measurements and the influence of ionic strength of the measurement solution on the TMV-modified EIS sensor signal has been studied. [ABSTRACT FROM AUTHOR]

A highly sensitive fluorescence detection method for tobacco mosaic virus (TMV) RNA based on in situ reaction of disodium 4,4′-diazidostilbene-2,2′-disulfonate tetrahydrate (DES) was developed for the first time. Specifically, cDNA-1 (probe 1) was fixed on carboxylated Fe3O4 magnetic beads (MBs), and hybridized with the TMV RNA (tRNA) in the next step. Then, cDNA-2 (probe 2) that was hybridized with tRNA was linked to alkaline phosphatase-conjugated streptavidin (SA-ALP) via the binding of biotin and SA. Next, L -ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AAPi) was dephosphorylated and hydrolyzed by alkaline phosphatase (ALP), producing ascorbic acid (AA). The subsequently added DES was reduced by AA, producing reduced DES, which successfully resulted in 'turn-on' of the fluorescent signal. Under optimal conditions, a good linear relationship between the fluorescence intensity and the logarithm of the tRNA concentration was obtained in the range from 1 pM to 10 nM, with a detection limit of 0.101 pM. Meanwhile, the method exhibited excellent selectivity and reproducibility. These results showed that the fluorescence detection strategy can be effectively employed for the qualitative and quantitative analysis of tRNA and has a potential application in the actual detection of tRNA. [ABSTRACT FROM AUTHOR]

Parietaria mottle virus (PMoV) is considered an emerging virus in many countries of the Mediterranean basin, especially on tomato and pepper crops. Symptoms on tomato leaves and fruits can be easily confused with those induced by cucumber mosaic virus (CMV) with necrogenic satellite RNA (CMV-satRNA), tomato spotted wilt virus (TSWV) or tomato mosaic virus (ToMV). Mixed infection of these viruses has been also reported in some tomato cultivars, with an increase in the complexity of the symptoms and severity of the disease. Although a specific serum and riboprobes have been produced, nowadays no sensitive diagnostic methods are available for the rapid PMoV detection. Here, we have developed a RT-qPCR assay with the aim to establish a more sensitive and specific method for PMoV detection. Specific primers and TaqMan probe were designed and in silico tested with all PMoV isolates available in GenBank. Moreover, this method was evaluated on tomato naturally infected samples from Sicily region (Italy). Results obtained showed that the RT-qPCR assay developed in this work is extremely sensitive, in fact, it is able to detect as few as 10 PMoV RNA copies in tomato total RNA; moreover, it will be a particularly valuable tool for early detection of PMoV. Furthermore, the analyzes on field samples show how this pathogen is increasingly present in tomato crops in the last years, helping to undermine the Italian horticultural sector. [ABSTRACT FROM AUTHOR]