Search Results (60)

Viral diseases pose a major threat to tomato cultivation, mainly due to the lack of effective antiviral control methods. Plant growth-promoting microorganisms (PGPMs) represent a promising and sustainable strategy for virus disease management, as, in addition to plant growth, they can promote resistance to pathogens. In this study, we examined the antiviral potential of selected PGPMs against three economically important and genetically distinct tomato viruses, tomato spotted wilt virus (TSWV, Orthotospovirus tomatomaculae), cucumber mosaic virus (CMV, Cucumovirus CMV), and tomato brown rugose fruit virus (ToBRFV, Tobamovirus fructirugosum) under controlled greenhouse conditions. The efficacy of each PGPM was assessed by monitoring disease development via visual scoring and DAS-ELISA. Our results indicate a significant TSWV symptom attenuation upon the application of Paraburkholderia eburnea EP3 and the yeast isolate SRL248, though, without a respective reduction in virus accumulation. However, no antiviral effect was observed by any PGPM tested against CMV or ToBRFV. A targeted gene expression analysis revealed a PGPM-specific induction of salicylic acid-dependent defense and RNA silencing markers, indicating priming of host immune responses. Overall, this work increases our knowledge on the antiviral potential of PGPMs showing a strain- and virus-specific effect primarily associated with enhanced symptom tolerance. Full article

As an important plant immune inducer, Dufulin has long been thought to enhance plant resistance to multiple plant viruses through activating the salicylic acid (SA) pathway. However, whether this immune inducer responds to tomato brown rugose fruit virus (ToBRFV) infection in the same way remains uncertain. In this study, we systematically analyzed the multiple effects of Dufulin treatment on the physiological, biochemical and gene expression patterns in tomato under ToBRFV infection. The results showed that the application of Dufulin could significantly increase the chlorophyll content; elevate the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT); reduce the ToBRFV viral load; and enhance plant growth. Moreover, we found that Dufulin treatment could increase both SA and abscisic acid (ABA) contents. However, SA-related genes were not strongly activated as the genes involved in ABA biosynthesis and signal transduction pathways. This suggested that ABA likely plays an unrecognized role in the formation of this induced resistance. Through weighted gene co-expression network analysis (WGCNA) and cis-element analysis of the target gene promoters, we identified that SlABI5-like and SlWRKY4 might be the key potential transcription factor genes for Dufulin-induced tomato resistance to ToBRFV, and constructed their molecular regulatory network. We also conducted qRT-PCR assay to verify the gene expression patterns involved in this study. These findings potentially provide new insights into the mechanism of Dufulin-induced antiviral resistance, and enlarge important molecular targets for ToBRFV prevention and control. Full article

Tomato brown rugose fruit virus (ToBRFV) has become a major threat to global tomato production due to its exceptional mechanical transmissibility and virion stability. Effective sanitation is essential for containment, yet the performance of commonly used disinfectants on greenhouse-relevant surfaces remains poorly characterized. This study evaluated multiple disinfectant formulations, applied by spraying or dipping, on polyethylene film, pruning shears, and human hands. After controlled inoculation with a standardized inoculum, treated surfaces were swabbed and extracts mechanically inoculated onto Nicotiana rustica L. Lesion number was visually quantified, and lesion area was measured using a computational image-analysis pipeline. Fifth-generation quaternary ammonium compounds (5°QAS) showed the highest virucidal activity on smooth, non-porous surfaces, reducing lesion numbers to fewer than 10 per leaf at 800–1000 ppm and maintaining infection severities below 1%. Glutaraldehyde at 500 ppm also performed strongly, achieving severities as low as 0.20% on plastic. Metallic pruning shears consistently retained infectious particles, with untreated controls exceeding 100 lesions per leaf and treated samples showing incomplete inactivation. Mechanical agents such as powdered milk and soap reduced infection but did not eliminate transmission. No clear dose–response trend was observed. The two most effective treatments, 5°QAS at 800–1000 ppm and glutaraldehyde at 500 ppm, significantly reduced or prevented systemic infection in tomato assays. These findings demonstrate that sanitation efficacy depends on formulation, surface type, and application method, providing operationally relevant guidelines for ToBRFV management. Full article

Tomato brown rugose fruit virus (ToBRFV), a highly stable and mechanically transmissible tobamovirus, poses a significant threat to solanaceous crops worldwide, particularly tomato (Solanum lycopersicum). While its transmission via human activities and contaminated materials is well-documented, the role of common phytophagous insects in its epidemiology remains less understood. Henosepilachna vigintioctopunctata, the Hadda beetle, is a common pest of Solanaceae with a host range that overlaps extensively with that of ToBRFV. This study aimed to quantify the beetle’s capacity to act as a mechanical vector and to assess its potential epidemiological impact. Using reverse transcription quantitative PCR (RT-qPCR), we evaluated beetle-mediated transmission efficiency, the persistence of its virus-carrying capacity, and its ability to vector the virus to various solanaceous hosts. Our results demonstrate that H. vigintioctopunctata efficiently acquires and transmits ToBRFV to tomato and other key hosts, including black nightshade (S. nigrum), pepper (Capsicum annuum), and eggplant (Solanum melongena). The virus was retained and remained transmissible by beetles for up to 48 h post-acquisition, providing a significant window for dispersal. Viral particles were most abundant in the digestive tract, consistent with ingestion of infected tissue, and declined rapidly on external body parts, confirming a non-circulative, mechanical transmission mechanism. Furthermore, feeding wounds created by non-viruliferous beetles increased plant susceptibility to subsequent infection from environmental contamination. We conclude that H. vigintioctopunctata acts as a potential mechanical vector that might amplify ToBRFV spread at local and landscape levels. This highlights a synergistic interaction between a native pest and an invasive pathogen, underscoring the necessity of incorporating beetle management into integrated strategies for controlling ToBRFV. Full article

Plant viruses have detrimental effects on commercial tomato cultivation leading to severe economic consequences. Viral metagenomics studies provide the opportunity to examine in depth the virome composition of a sample set without any pre-existing knowledge of the viral species that are present. In the present study, 101 plant samples were collected from commercial greenhouses in 13 countries in Europe, Africa, Asia, and North America between 2017 and 2024. All samples were processed with the VLP enrichment protocol NetoVIR and the obtained data were analyzed with the ViPER pipeline. Forty-three eukaryotic viral species were identified, with a median identification of 2 species per sample. The most prevalent viral species were pepino mosaic virus (PepMV), tomato brown rugose fruit virus (ToBRFV), and southern tomato virus (STV). The obtained genome sequences were used to study the diversity and phylogeny of these viruses. The three genotypes identified for PepMV showed low diversity within each genotype (96.2–99.0% nucleotide identity). Low isolate diversity was also found for ToBRFV and STV. No significant association could be found between STV identification and the presence of symptoms, questioning the pathogenic potential of STV. Three other pathogenic viral species of particular interest due to their effects on tomato cultivation or recent emergence, namely tomato torrado virus (ToTV), tomato fruit blotch virus (ToFBV), and cucumber mosaic virus (CMV), were part of the virome with low prevalence. Our study provided a comprehensive overview of the analyzed samples’ virome, as well as the possibility to inspect the genetic diversity of the identified viral genomes and to look into their potential role in symptom development. 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

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

Tomato brown rugose fruit virus (ToBRFV) is an important emerging virus that poses a serious threat to the global agricultural economy. Ubiquitination is one of the key post-translational protein modification types in plant responses to biotic stress, but the extent to which ToBRFV infection alters the overall ubiquitination status has not been reported. This study conducted integrated ubiquitome and proteome analyses of Nicotiana benthamiana leaves infected with ToBRFV and identified differentially ubiquitinated proteins. A total of 346 lysine sites on 302 identified proteins were found to be affected, with 260 sites exhibiting upregulated ubiquitination levels in 224 proteins and 86 sites showing downregulated ubiquitination levels in 80 proteins. The differentially ubiquitinated proteins were primarily localized in the cytoplasm (29%), nucleus (18%), plasma membrane (8.9%), mitochondria (5.1%), and chloroplasts (4.6%). Fourteen conserved ubiquitination motifs, including ENNNK, ENNK, SK, and KNG, were identified. Furthermore, enrichment analysis indicated that ToBRFV infection induces an increase in the ubiquitination levels of proteins associated with ion transport, MAPK signaling pathways, and plant hormone signal transduction, while the ubiquitination levels of proteins related to carbon metabolism and secondary metabolite synthesis decreased. Functional analysis of the three differentially ubiquitinated proteins revealed that a RING/U-box superfamily protein negatively regulates ToBRFV infection. Our work provides the first systematic analysis of the ubiquitination profile in N. benthamiana leaves following ToBRFV infection, providing important resources for further studies on the regulatory mechanisms of ubiquitination in plant responses to ToBRFV. Full article

Tomato brown rugose fruit virus (ToBRFV) is a recently emerged viral pathogen in the Tobamovirus genus first observed in 2014 in the Middle East that has since spread worldwide, causing significant losses in greenhouse tomato production. ToBRFV is easily mechanically transmitted and can escape the durable Tm-2² resistance gene, facilitating its global spread. Seed companies have identified novel sources of resistance and introduced these resistance traits into commercial cultivars. The identity, number, and mechanisms of these putative novel resistance genes are largely unknown but could be exerting selective pressures on ToBRFV. Here, we report 15 new ToBRFV genomic sequences from Canadian greenhouse production systems in susceptible and novel resistant or tolerant cultivars collected since 2023. We combined these sequences with five other Canadian ToBRFV genomes previously deposited in Genbank and a further five consensus sequences derived from metagenomic-based wastewater monitoring sequence data and conducted phylogenetic analysis. Most Canadian sequences grouped together when compared with 332 publicly available international sequences, but several isolates appeared distantly related, suggesting multiple introductions to Canadian production systems. High sequence identity between samples suggest movement of ToBRFV between independent greenhouses, highlighting areas where biosecurity can be improved. Several novel non-synonymous polymorphisms identified in the p126 and movement protein (MP) open reading frames (ORFs) were unique to Canadian sequences and associated with infection of novel resistant tomato cultivars. Many polymorphisms in the p126 ORF are located in a region of the protein associated with Tm-1 resistance-breaking isolates of tomato mosaic virus and ToBRFV, but have not been previously reported. Four novel polymorphisms in MP were also identified and do not appear to be associated with sites previously identified as interacting with Tm-2² and could be related to other unknown resistance genes. Together, these results confirm the difficulties in preventing the transmission of ToBRFV, identify putative adaptations to novel and existing resistance genes, and emphasize the urgent need for the cloning and characterization of these new sources of resistance to ToBRFV. Full article

Chili pepper (Capsicum annuum L.) is a very important vegetable crop, commonly used as a spice or seasoning in various dishes. With the growth of the global population, the demand for chili peppers has also increased exponentially. Tomato brown rugose fruit virus (ToBRFV) is an emerging tobamovirus that has spread to dozens of countries worldwide. Its infection in chili peppers can severely impact yield and quality, posing a significant threat to the chili pepper industry. However, the transcriptional response of chili peppers to ToBRFV infection has not been studied yet. This research utilized RNA-Seq technology to analyze the transcriptional profiles of chili pepper leaves (‘Haonong 11’) 13 days post-infection with ToBRFV or mock treatment, identifying a total of 1468 differentially expressed genes (DEGs), of which 1366 were upregulated and 102 were downregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that the DEGs were involved in biological processes such as defense response, response to reactive oxygen species, protein folding, and plant-pathogen interaction. Twelve DEGs were validated by RT-qPCR, with their expression trends consistent with the transcriptome data, indicating the reliability of the high-throughput data. Our systematic analysis provides a molecular basis for the response of chili pepper leaves to ToBRFV infection at the transcriptomic level and offers potential candidate genes for further research into the interaction mechanisms between ToBRFV and plant hosts. Full article

Flow virometry (FVM) offers a promising approach for monitoring viruses and virus-like particles (VLPs) in environmental samples. This study compares levels of non-specific VLPs across a wastewater treatment plant (WWTP) with levels of somatic coliphage, (F+) specific coliphage, Pepper Mild Mottle Virus (PMMoV), CrAssphage (CrAss), and Tomato Brown Rugose Fruit Virus (ToBRFV). All targets were quantified in influent, secondary-treated effluent, and tertiary-treated effluent at the University of California, Davis Wastewater Treatment Plant (UCDWWTP) over 11 weeks. We established an FVM-gating boundary for VLPs using bacteriophages T4 and ϕ6 as well as four phages isolated from wastewater. We then utilize T4 alongside three submicron beads as quality controls in the FVM assay. Coliphage was measured by standard plaque assays, and genome copies of PMMoV, CrAss, and ToBRFV were measured by digital droplet (dd)PCR. FVM results for wastewater revealed distinct microbial profiles at each treatment stage. However, correlations between VLPs and targeted viruses were poor. Trends for virus inactivation and removal, observed for targeted viruses during wastewater treatment, were consistent with expectations. Conversely, VLP counts were elevated in the WWTP effluent relative to the influent. Additional sampling revealed a decrease in VLP counts during the filtration treatment step following secondary treatment but a substantial increase in VLPs following ultraviolet disinfection. Defining application boundaries remain crucial to ensuring meaningful data interpretation as flow cytometry and virometry take on greater significance in water quality monitoring. Full article

Tobamovirus fructirugosum (ToBRFV) and Crinivirus tomatichlorosis (ToCV) are emerging viral threats to tomato production worldwide, with expanding global distribution. Both viruses exhibit distinct biological characteristics and transmission mechanisms that influence their spread. This study aimed to reconstruct the complete genomes of ToBRFV and ToCV from infected tomato plants and wastewater samples in Argentina to explore their global evolutionary dynamics. Additionally, it compared the genetic diversity of ToBRFV in plant tissue and sewage samples. Using metagenomic analysis, the complete genome sequences of two ToBRFV isolates and two ToCV isolates from co-infected tomatoes, along with four ToBRFV isolates from sewage, were obtained. The analysis showed that ToBRFV exhibited higher genetic diversity in environmental samples than in plant samples. Phylodynamic analysis indicated that both viruses had a recent, single introduction in Argentina but predicted different times for ancestral diversification. The evolutionary analysis estimated that ToBRFV began its global diversification in June 2013 in Israel, with rapid diversification and exponential growth until 2020, after which the effective population size declined. Moreover, ToCV’s global expansion was characterized by exponential growth from 1979 to 2010, with Turkey identified as the most probable location with the current data available. This study highlights how sequencing and monitoring plant viruses can enhance our understanding of their global spread and impact on agriculture. Full article

Tomato brown rugose fruit virus (ToBRFV) poses a significant threat to tomato production. Effective and accurate detection is critical for limiting the introduction and spread of ToBRFV. In this study, the impact of tomato planting patterns, growth stages, and cultivar variability on ToBRFV levels in tomatoes from distinct greenhouses and open fields were comprehensively analyzed. The results indicated that ToBRFV is detectable in asymptomatic tissues, regardless of artificial agroinoculation or natural infection. Additionally, higher viral levels were observed in newly emerging leaves and in fruits and sepals compared to old leaves. For tomato fruits infected with ToBRFV, the viral level in the mesocarp is higher than in the other interior parts, and no correlation was found between viral levels and the color of fruit lesions. Based on these results, it is recommended that new leaves and sepals should be given priority for testing of ToBRFV from tomato seedlings to the color turning stage, and that fruits and sepals are suggested to be collected at the full ripeness stage of tomato plants. This study underscores the importance of regular detection and optimal sampling beyond symptom observation in the surveillance of ToBRFV. Full article

Tomato brown rugose fruit virus (ToBRFV), being a mechanically transmitted disease, is usually difficult to control; therefore, an effective alternative to reduce transmission and replication in the crop is by spraying with chlorine dioxide (ClO₂) during routine crop management. In this research, the efficacy of chlorine dioxide (ClO₂) for ToBRFV management in a greenhouse and open field was determined. The phytotoxicity of ClO₂ and its effective concentration against ToBRFV in Nicotiana longiflora plants were evaluated. Subsequently, the effect of ClO₂ on ToBRFV was evaluated in tomato plants grown in an open field. Finally, the effectiveness of ClO₂ on plants inoculated with ToBRFV under greenhouse conditions was evaluated and the number of necrotic local lesions (NLLs) was quantified. The results revealed that ClO₂ at 760 mg L⁻¹ did not show phytotoxicity and reduced the number of NLLs in N. longiflora plants. It also decreased ToBRFV transmission and replication in field- and greenhouse-grown tomato plants, improving agronomic parameters. ClO₂ reduced replication in plants inoculated with different amounts of ToBRFV inoculum in a greenhouse. N. longiflora leaves expressed lower numbers of NLLs when inoculated with ClO₂-treated tomato plant extracts. Finally, the results demonstrate that ClO₂ represents an effective management alternative when used by direct application to plants. To our knowledge, this is the first study where the use of an antiviral compound is carried out under field and greenhouse conditions. Full article

Silica (SiO₂) particles are widely used in various industries due to their chemical inertness, thermal stability, and wear resistance. The present study describes the preparation and potential use of porous hydrophobic and hydrophilic SiO₂ microcapsules (MCs) of a narrow size distribution. First, various layers of SiO₂ micro/nano-particles (M/NPs) were grafted onto monodispersed polystyrene (PS) microspheres of a narrow size distribution. Hydrophobic and hydrophilic sintered SiO₂ MCs were then prepared by removing the core PS from the PS/SiO₂ core–shell microspheres by burning off under normal atmospheric conditions or organic solvent dissolution, respectively. We examined how the size and quantity of the SiO₂ M/NPs influence the MC’s properties. Additionally, we utilized two forms of hollow SiO₂ MC for different applications; one form was incorporated into polymer films, and the other was free-floating. The hydrophobic microcapsules filled with 6% hydrogen peroxide were effective in killing the tomato brown rugose fruit virus (ToBRFV). The hydrophilic microcapsules filled with thymol and thin coated onto polypropylene films were successfully used to prevent mold formation for hay protection. Full article