Search Results (194)

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

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

Determining mechanisms to establish an initial infection and form intracellular complexes for accumulation and movement of RNA plant viruses are important areas of study in plant virology. The impact of these findings on the basic understanding of plant molecular virology and its application in agriculture is significant. Studies with tobacco mosaic virus (TMV) and related tobamoviruses often provide important foundational knowledge for studies involving other viruses. Topics discussed here include capsid disassembly, establishment of a virus replication complex (VRC), and transport of the VRCs or virus components within the cell to locations at the plasmodesmata for intercellular virus RNA (vRNA) movement. Seminal findings with TMV and related tobamoviruses include detecting co-translational disassembly of the vRNA from the virus rod, full sequencing of genomic vRNA and production of infectious transcript for genetic studies determining virus components necessary for intercellular movement, and biochemical and cell biological studies determining the host factors, protein and membrane, needed for replication and movement. This review highlights many of the studies through the years on TMV and selected tobamoviruses that have impacted not only our understanding of tobamovirus accumulation and movement but also that of other plant viruses. Full article

Plant viral diseases cause great harm to crops in terms of yield and quality. Natural products have been providing an excellent source of novel chemistry, inspiring the development of novel synthetic pesticides. The Amaryllidaceae alkaloids crinasiadine (3a), trisphaeridine (4a), and bicolorine (5a) were selected as parent structures, and a series of their derivatives were designed, synthesized, and investigated for their anti-plant virus effects for the first time. Compounds 13b and 18 exhibited comparable inhibitory activities to ningnanmycin against tobacco mosaic virus (TMV). Preliminary research into the mechanism, involving transmission electron microscopy and molecular docking studies, suggests that compound 18 may interfere with the elongation phase of the TMV assembly process. This study provides some important information for the research and development of agrochemicals with phenanthridine structures. Full article

The size of viral genomes is limited, thus the majority of encoded proteins possess multiple functions. The main function of tobamoviral movement protein (MP) is to perform plasmodesmata gating and mediate intercellular transport of the viral RNA. MP is a remarkable example of a protein that, in addition to the initially discovered and most obvious function, carries out numerous activities that are important both for the manifestation of its key function and for successful and productive infection in general. Briefly, MP binds the viral genome, delivers it to the plasmodesmata (PD) and mediates its intercellular transfer. To implement the transport function, MP interacts with diverse cellular factors. Each of these cellular proteins has its own function, which could be different under normal conditions and upon viral infection. Here, we summarize the data available at present on the plethora of cellular factors that were identified as tobamoviral MP partners and analyze the role of these interactions in infection development. Full article

Potyviral P3 is involved in viral replication, movement, and pathogenicity; however, its biochemical function is unknown. In this study, the P3 of the zucchini yellow mosaic virus (ZYMV) interacted with ClBBD, a protein with high ortholog bifunctional nuclease activity, in watermelon. The binding site was shown via yeast two-hybrid screening and BiFC assay to be located at the N-terminus of P3 rather than P3N-PIPO. ClBBD localized predominantly to the chloroplast and plasma membrane. ZYMV P3 was also present in the nucleus and cytoplasm as aggregates. When co-expressed with P3 in tobacco, ClBBD formed aggregates with P3 in the cytoplasm. The knockdown of ClBBD using the VIGS vector pV190 and challenge with ZYMV revealed a positive correlation between viral accumulation and ClBBD expression, indicating that ClBBD reduces the resistance of watermelon to ZYMV. Furtherly, we found that when P3 and ClBBD were transiently co-expressed in tobacco, the level of P3 was significantly higher than that when it was expressed alone or co-expressed with GUS. It inferred that ClBBD may be able to stabilize the expression of P3. Overall, the results suggest that the interaction of P3 with ClBBD promotes virus infection, and ClBBD may be involved in stabilizing the expression level of P3. Full article

This study presents a one-step multiplex reverse transcription polymerase chain reaction (RT-PCR) method for the simultaneous detection of multiple viruses affecting melon crops. Viruses such as Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV), Squash mosaic virus (SqMV), Tobacco mosaic virus (TMV), Papaya ring spot virus (PRSV), and Melon yellow spot virus (MYSV) pose a great threat to melons. The mixed infection of these viruses is the most common observation in the melon-growing fields. In this study, we surveyed northern Xingjiang (Altay, Changji, Wujiaqu, Urumqi, Turpan, and Hami) and southern Xingjiang (Aksu, Bayingolin, Kashgar, and Hotan) locations in Xinjiang province and developed a one-step multiplex RT-PCR to detect these melon viruses. The detection limits of this multiplex PCR were 10³ copies/μL for ZYMV and MYSV and 10² copies/μL for WMV, SqMV, PRSV, CMV, and TMV. The detection results in the field showed 242 samples were infected by one or more viruses. The multiplex RT-PCR protocol demonstrated rapid, simultaneous, and relatively effective detection of viruses such as WMV, CMV, ZYMV, SqMV, TMV, PRSV, and MYSV. The technique is designed to identify these melon viruses in a single reaction, enhancing diagnostic efficiency and reducing costs, thus serving as a reference for muskmelon anti-virus breeding in Xinjiang. Full article

The interaction of viral proteins with host factors represents a crucial aspect of the infection process in plants. In this work, we developed a strategy to identify host factors in Nicotiana tabacum that interact with movement proteins (MPs) of the 30K family, a group of viral proteins around 30 kDa related to the MP of tobacco mosaic virus, which enables virus movement between plant cells. Using the alfalfa mosaic virus (AMV) MP as a model, we incorporated tags into its coding sequence, without affecting its functionality, enabling the identification of 121 potential interactors through in vivo immunoprecipitation of the tagged MP. Further analysis of five selected candidates (histone 2B (H2B), actin, 14-3-3A protein, eukaryotic initiation factor 4A (elF4A), and a peroxidase-POX-) were conducted using bimolecular fluorescence complementation (BiFC). The interactions between these factors were also studied, revealing that some form part of protein complexes associated with AMV MP. Moreover, H2B, actin, 14-3-3, and eIF4A interacted with other MPs of the 30K family. This observation suggests that, beyond functional and structural features, 30K family MPs may share common interactors. Our results demonstrate that tagging 30K family MPs is an effective strategy to identify host factors associated with these proteins during viral infection. Full article

This article reviews the literature concerning the largely forgotten tobamovirus gene products for which no functions have been ascribed. One of these gene products is the 54 kDa protein, representing the RNA-dependent RNA polymerase segment of the 183 kDa protein translated from the I₁-subgenomic mRNA, but which has been found only by in vitro translation and not in plants. The other is a collection of small proteins, expressed from alternative reading frames (likely from internal ribosome entry sites) in either or both the movement protein gene or the capsid protein gene. Previously, two small proteins were referred to as the 4–6 kDa proteins, since only single proteins of such size had been characterized from tobacco mosaic virus and tomato mosaic virus genomes. Such putative proteins will be referred to here as P6 proteins, since many new proposed P6 open reading frames could be discerned, from an analysis of 45 of 47 tobamovirus genomes, with a coding capacity of >15 amino acids up to 94 amino acids, whereas other peptides with ≤15 amino acids were not considered here. The distribution of the putative P6 proteins among these tobamoviruses is described, as well as the various classes they fall into, based on their distribution with regard to the organization of other genes in the viral genomes. Models also are presented for possible functions of the 54 kDa protein and the P6 proteins, based on data in the literature. Full article

The majority of plant viruses rely on insect vectors for inter-plant transmission. Amid virus transmission, vector-borne viruses such as begomoviruses may significantly modulate host plants in various ways and, in turn, plant palatability to insect vectors. While many case studies on monopartite begomoviruses are available, bipartite begomoviruses are understudied. More importantly, detailed elucidation of the molecular mechanisms involved is limited. Here, we report the mechanisms by which an emerging bipartite begomovirus, the Sri Lankan cassava mosaic virus (SLCMV), modulates plant defenses against whitefly. SLCMV infection of tobacco (Nicotiana tabacum) plants significantly downregulated defenses against whitefly, as whitefly survival and fecundity increased significantly on virus-infected plants when compared to the controls. We then profiled SLCMV-induced transcriptomic changes in plants and identified a repertoire of differentially expressed genes (DEGs). GO enrichment analysis of DEGs demonstrated that the term defense response was significantly enriched. Functional analysis of DEGs associated with defense response revealed that four downregulated DEGs, including putative late blight resistance protein homolog R1B-17 (R1B-17), polygalacturonase inhibitor-like (PGI), serine/threonine protein kinase CDL1-like (CDL1), and Systemin B, directly contributed to plant defenses against whitefly. Taken together, our findings elucidate the role of novel plant factors involved in the modulation of plant defenses against whitefly by a bipartite begomovirus and shed new light on insect vector–virus–host plant tripartite interactions. Full article

The virions of plant viruses and their structurally modified particles (SP) represent valuable platforms for recombinant vaccine epitopes and antitumor agents. The possibility of modifying their surface with biological compounds makes them a tool for developing medical biotechnology applications. Here, we applied a new type of SP derived from virions and virus-like particles (VLP) of Alternanthera mosaic virus (AltMV) and well-studied SP from Tobacco mosaic virus (TMV). We have tested the ability of SP from AltMV (AltMV SP_V) and TMV virions also as AltMV VLP to bind to and penetrate Ewing sarcoma cells. The adsorption properties of AltMV SP_V and TMV SP are greater than those of the SP from AltMV VLP. Compared to normal cells, AltMV SP_V adsorbed more effectively on patient-derived sarcoma cells, whereas TMV SP were more effective on the established sarcoma cells. The AltMV SP_V and TMV SP were captured by all sarcoma cell lines. In the established Ewing sarcoma cell line, the effectiveness of AltMV SP_V penetration was greater than that of TMV SP. The usage of structurally modified plant virus particles as a platform for drugs and delivery systems has significant potential in the development of anticancer agents. Full article

Background: The rapid production of influenza vaccines is crucial to meet increasing pandemic response demands. Here, we developed plant-made vaccines comprising centralized consensus influenza hemagglutinin (HA-con) proteins (H1 and H3 subtypes) conjugated to a modified plant virus, tobacco mosaic virus (TMV) nanoparticle (TMV-HA-con). Methods: We compared immune responses and protective efficacy against historical H1 or H3 influenza A virus infections among TMV-HA-con, HA-con protein combined with AddaVax™ adjuvant, and whole-inactivated virus vaccine (Fluzone^®). Results: Immunogenicity studies demonstrated robust IgG, IgM, and IgA responses in the TMV-HA-con and HA-con protein vaccinated groups, with relatively low induction of interferon (IFN)-γ⁺ T-cell responses across all vaccinated groups. The TMV-HA-con and HA-con protein groups displayed partial protection (100% and 80% survival) with minimal weight loss following challenge with two H1N1 strains. The HA-con protein group exhibited 80% and 100% survival against two H3 strains, whereas the TMV-HA-con groups showed reduced protection (20% survival). The Fluzone^® group conferred 20–100% survival against two H1N1 strains and one H3N1 strain, but did not protect against H3N2 infection. Conclusions: Our findings indicate that TMV-HA and HA-con protein vaccines with adjuvant induce protective immune responses against influenza A virus infections. Furthermore, our results underscore the potential of plant-based production using TMV-like nanoparticles for developing influenza A virus candidate vaccines. Full article

This study used the DNA of Bacillus amyloliquefaciens Ba168 as a template to amplify the flagellin BP8-2 gene and ligate it into the fusion expression vector pCAMBIA1300-35S-EGFP after digestion for the construction of the expression vector pCAMBIA1300-EGFP-BP8-2. Next, using Nicotiana benthamiana as receptor material, transient expression was carried out under the mediation of Agrobacterium tumefaciens C58C1. Finally, the transient expression and subcellular localisation of flagellin BP8-2 protein were analysed using the imaging of co-transformed GFP under laser confocal microscopy. The results showed that flagellin BP8-2 was localised in the cell membrane and nucleus, and the RT-PCR results showed that the BP8-2 gene could be stably expressed in tobacco leaf cells. Furthermore, there was stronger antiviral activity against tobacco mosaic virus (TMV) infection in Nicotiana glutinosa than in BP8-2 and ningnanmycin, with an inhibitory effect of 75.91%, protective effect of 77.45%, and curative effect of 68.15%. TMV movement and coat protein expression were suppressed, and there was a high expression of PR-1a, PAL, and NPR1 in BP8-2-treated tobacco leaf. These results suggest that flagellin BP8-2 inhibits TMV by inducing resistance. Moreover, BP8-2 has low toxicity and is easily biodegradable and eco-friendly. These results further enrich our understanding of the antiviral mechanisms of proteins and provide alternatives for controlling viral diseases in agriculture. Full article

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. Full article

Tobacco mosaic virus (TMV) is one of the most persistent and infectious plant viruses. The substantial economic losses caused by TMV in the production of tobacco and vegetables (especially in the Solanaceae family) are prompting the introduction of innovative solutions that effectively inhibit infection by this pathogen. Biological control agents based on bacteria of the genera Pseudomonas, Bacillus, Pantoea and actinomycetes are becoming increasingly popular in the fight against TMV. Some fungi, including Fusarium spp., Trichoderma spp., Alternaria spp. and Sepedonium spp., as well as wood-rotting fungi, also exhibit high anti-TMV activity. This article presents a comprehensive review of recent scientific advances in the bioprotection of selected solanaceous crops against TMV. It provides information on the structure of the virus, its host range, pathogenicity and the severity of losses caused in pepper, tomato and tobacco production. The review characterises environmentally safe techniques involving biological control agents naturally occurring in the environment and the bioactive compounds extracted from them. It also identifies their effects on crops at the morphological, physiological and molecular levels. In addition, the manuscript outlines prospects for the future applications of beneficial micro-organisms and active compounds derived from them in the protection against TMV. Full article