Search Results (601)

Tomato yellow leaf curl virus (TYLCV) is a major plant pathogen that spreads worldwide through persistent circulative transmission by Bemisia tabaci. During transmission, TYLCV crosses several physiological barriers in the insect vector, evading immune defenses and altering host metabolic pathways to facilitate viral accumulation. Polyamines, essential for maintaining nucleic acid stability and promoting cellular processes, are known to play a critical role in viral accumulation. However, their role in TYLCV accumulation within B. tabaci is not well understood. Here, we demonstrate that TYLCV infection leads to significant alterations in polyamine levels in B. tabaci, with polyamine availability positively affecting viral DNA accumulation. Polyamine availability leads to higher viral loads and suppresses the expression of immune and MAPK signaling genes. These findings provide new insights into virus–vector and metabolic interactions underlying viral persistence in insect vectors. Full article

Verticillium wilt (VW), caused by the soil-borne fungus Verticillium dahliae, is a major disease that markedly compromises both the yield and fiber quality of cotton. In this study, we explored the function and underlying mechanism of the cotton expansin gene GhEXLB2 in response to VW infection. Expression profiling revealed that members of the GhEXL family exhibit distinct patterns across tissues and under various biotic and abiotic stresses. Notably, GhEXLB2, which encodes an extracellular protein, showed the strongest induction following V. dahliae challenge. Ectopic expression of GhEXLB2 in Arabidopsis thaliana promoted root elongation and root hair formation, and was associated with improved resistance to the pathogen. In contrast, silencing GhEXLB2 in cotton via virus-induced gene silencing (VIGS) led to pronounced vascular browning, increased pathogen recovery, and a lower level of disease resistance. In addition, RNA-seq profiling of GhEXLB2-silenced (VIGS) cotton plants revealed that most differentially expressed genes were enriched in pathways related to phytohormone signaling and plant–pathogen interactions, with salicylic acid (SA) signaling and WRKY transcription factors emerging as central regulatory components. Analysis of the GhEXLB2 promoter further identified multiple cis-acting elements associated with stress and hormone responsiveness. When integrated with protein–protein interaction (PPI) prediction data, these results suggest that GhEXLB2 may be modulated by a network of transcription factors and signaling pathways. Collectively, the evidence supports a positive association between GhEXLB2 and VW resistance. This study provides a framework for understanding expansin functions in cotton defense against VW. Full article

Plant viruses need to use many host factors to establish infection. During the viral cycle, intracellular transport is fundamental to reach the plasmodesmata to enable cell-to-cell transport. Cucumovirus CMV (cucumber mosaic virus, CMV) can infect plants from most economically important crops. To identify additional host proteins involved in CMV movement in melon, we used the MP as a bait to screen a Yeast two-hybrid cDNA library from CMV-infected plants and identified a Niemann-Pick C1 (NPC1) protein as a novel MP interactor. NPC1 is a transmembrane protein involved in cholesterol transport in animal cells, but also in the infection by several viruses of different families. The identified clone from the melon NPC1 gene spans from exons 25 to 28 and includes two introns. Notably, deletion of the two introns and exon 28 does not impair the interaction capacity of the remaining peptide. The identified CmNPC1 gene maps to chromosome 11. In addition, the melon genome encodes a second copy of NPC1 in chromosome 7 (CmNPC1-C7), highly similar. Functional assays revealed that the interaction domain of CmNPC1-C7 also interacts with CMV MP, suggesting that both genes could have a role in CMV infection. This study represents the first report linking NPC1 to the infection process of a plant virus, expanding our understanding of plant–virus interactions. Full article

Background/Objectives: Epigenetic regulation plays a fundamental role in controlling the spatiotemporal expression of genes in plants under stressful environmental conditions. While LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is known to be involved in histone modification, its function in regulating the biosynthesis of specialized metabolites, particularly monoterpenoid indole alkaloids (MIAs) in Catharanthus roseus, remains elusive. Methods: CrLHP1 was identified by mining the C. roseus proteome and characterized through sequence alignment, phylogenetic analysis, and conserved domain assessment. Virus-induced gene silencing (VIGS) was employed to suppress CrLHP1 expression, after which the transcript levels of jasmonic acid (JA)-responsive genes and key MIA biosynthetic genes, as well as the accumulation of vindoline and catharanthine, were analyzed. Furthermore, deep learning-based protein structure prediction (AlphaFold3) and yeast two-hybrid (Y2H) assays were conducted to explore protein-protein interactions. Results: CrLHP1 was confirmed as the ortholog of Arabidopsis thaliana LHP1 (AtLHP1). Exposure to 75 μM MeJA upregulated MIA upstream pathway genes while downregulating CrLHP1 transcription. Silencing CrLHP1 significantly upregulated JA-responsive and MIA biosynthetic genes, leading to enhanced catharanthine accumulation. Additionally, the structural prediction and Y2H assays revealed a physical interaction between CrLHP1 and CrJAZ1. Conclusions: These findings suggest that CrLHP1 negatively regulates MIA biosynthesis, potentially by modulating JA signal transduction through interaction with CrJAZ1. This study provides new insights into the possible epigenetic mechanisms governing alkaloid production in C. roseus. Full article

Geranyl diphosphate synthase (GPPS) is a key enzyme in the plant isoprenoid metabolic pathway and regulates the biosynthesis of volatile monoterpenes. It plays an important role in the biosynthesis of floral volatile terpenoids (FVTs) and inter-cultivar variation in snapdragon. Despite its importance in floral scent formation, the GPPS/GGPPS gene family in snapdragon (Antirrhinum majus L.) has not been systematically characterized. In this study, nine GPPS/GGPPS family members were identified at genome-wide level. These include six AmGPPS and three AmGGPPS genes. Phylogenetic analysis grouped them into distinct subfamilies. We further analyzed their chromosomal locations, gene structures, conserved protein motifs, and promoter cis-acting elements. These results revealed both conservation and functional divergence within the gene family. To explore their functional roles, we compared gene expression profiles at the full flowering stage. This comparison was performed between strongly scented cultivar (Am3) and the weakly scented cultivar (Am5). Among all candidates, AmGPPS6 showed the most significant differential expression. Further, functional validation was conducted using transient overexpression and virus-induced gene silencing (VIGS). Overexpression of AmGPPS6 significantly increased terpenoid production. Total floral volatile terpenoids (FVTs) increased by 1.4 fold. Both monoterpene and sesquiterpene emissions were enhanced. In contrast, silencing of AmGPPS6 markedly reduced the emission of key monoterpenes such as ocimene and its isomers. Sequence analysis showed that AmGPPS6 shares 67.04% identity with canonical GPPS small subunit (GPPS.SSU). However, it lacks the conserved catalytic DDx2-D motif. This suggests that AmGGPPS2 is not catalytically active. Instead, it likely functions through heterodimer with AmGGPPS2. This interaction is supported by coordinated transcriptional expression patterns. Additionally, natural sequence polymorphisms were identified in GPPS.SSU. These variations, rather than those in GPPS.LSU, appear to drive differences in monoterpense emission between cultivars. In conclusion, AmGPPS6 in a key regulator of floral scent biosynthesis in snapdragon. This study provides new insights into functional roles of GPPS/GGPPS genes. It also offers valuable gene targets for the molecular breeding of aromatic traits in ornamental plants. Full article

RNA viruses exhibit high mutation rates, necessitating antivirals targeting conserved infection mechanisms. In this study, viral hemorrhagic septicemia virus (VHSV), a non-human pathogenic negative-sense RNA virus, was used as a surrogate model to enable high-throughput antiviral screening under reduced biosafety conditions. A recombinant VHSV expressing enhanced green fluorescent protein was used to screen 17,265 compounds, 2000 plant extracts, and 100 marine extracts. Among the candidates, the leaf extract of Phellodendron amurense Rupr. (PL extract) exhibited antiviral activity with low cytotoxicity (selectivity index ≈ 10). The extract reduced viral infectivity in a dose-dependent manner and showed cross-activity against snakehead rhabdovirus. Mechanistic analyses indicated that the PL extract acts primarily at early stages of infection. Virucidal assays demonstrated direct, time-dependent inactivation of viral particles, while pre-treatment reduced host cell susceptibility. Time-of-addition experiments confirmed that antiviral activity was restricted to early infection, suggesting interference with viral attachment or entry rather than intracellular replication. Fractionation revealed that activity was associated with the non-polar n-hexane fraction, implicating lipophilic compounds that may disrupt viral envelope integrity or membrane interactions. These findings suggest that P. amurense leaf extract is a promising candidate for broad-spectrum antivirals targeting conserved entry processes in enveloped RNA viruses. Full article

Soil salinity limits ginger productivity, but the underlying molecular mechanisms remain largely unclear. The 14-3-3 proteins are conserved regulators in stress signaling. Here, we genome-wide characterized the 14-3-3 family in Zingiber officinale and examined the possible involvement of Zo14-3-3-03 in salt response. A total of 21 Zo14-3-3 genes were identified and classified into four groups with uneven chromosomal distribution. Among them, Zo14-3-3-03 was strongly salt-responsive: transcript levels increased 9.91- to 33.82-fold during 1–7 days of treatment and reached 62.47-fold in leaves at day 14. NaCl treatment elevated GUS expression driven by the Zo14-3-3-03 promoter. Virus-induced gene silencing (VIGS) of Zo14-3-3-03 resulted in silenced plants exhibiting higher malondialdehyde (up to 73.6%), lower antioxidant enzyme activities (SOD, POD, CAT, and APX: 18.9–31.9% reduction), reduced osmolytes (proline, soluble protein, sugars, and ascorbic acid: 23.2–36.2% reduction), excessive reactive oxygen species, and decreased relative water content. Several antioxidant-related genes were significantly downregulated. Protein interaction assays suggested a possible interaction with ZoSOS2, and the expression of SOS2 pathway genes was altered in silenced plants, indicating a potential link to calcium signaling and ion homeostasis. Taken together, these results suggest that Zo14-3-3-03 participates in ginger salt stress response possibly through redox balance, osmotic adjustment, and calcium-mediated pathways which would provide a basis for understanding 14-3-3-mediated stress responses and nominates Zo14-3-3-03 as a candidate requiring deeper validation for salt tolerance improvement in ginger. Nevertheless, due to limited functional validation, its role as a positive regulator and breeding target remains preliminary. Further genetic and mechanistic studies are needed to confirm causality and assess field-level applicability. Full article

Background: A major challenge in antiviral development is the identification of novel virus–host interactions while ensuring therapeutic efficacy and safety. These challenges have renewed interest in phytochemicals derived from medicinal plants as alternative antiviral agents. Objectives: In this study, we investigated the antioxidant, antiviral, and immunomodulatory properties of a Mediterranean Urtica dioica extract (UdE) against SARS-CoV-2 using chemical, biochemical, and in vitro approaches. Methods: The physicochemical properties of UdE were characterized using microtiter assays and HPLC analysis. Cytocompatibility was evaluated in HEK293T, Vero E6, Caco-2, and Calu-3 cell lines while antioxidant activity was assessed using both chemical and cell-based assays. Antiviral activity was evaluated by assessing inhibition of SARS-CoV-2 receptor binding domain (RBD)–ACE2 interaction using ELISA, inhibition of SARS-CoV-2 main protease (Mpro) activity via FRET assay and inhibition of viral entry using SARS-CoV-2 S1 pseudovirus neutralization assay. Results: UdE (100 µg/mL) inhibited RBD–ACE2 binding by 94% and suppressed Mpro activity by 74%, while reducing moderate but significant inhibition of pseudovirus entry (33.6%) at 300 µg/mL dose level in ACE2 expressing HEK293T cells. Immunomodulatory analysis revealed significant suppression of IL-1β and IL-6 production, accompanied by increased TNF-α and IL-8 levels. Conclusions: Collectively, these findings highlight that UdE exhibits multi-target in vitro antioxidant, antiviral, and immunomodulatory activity against SARS-CoV-2; therefore, UdE represents a promising bioactive extract for the management of SARS-CoV-2 infection. Full article

In recent years, nanotechnology has made remarkable progress in the fight against infectious diseases. However, the development of safe and effective antiviral drugs remains a challenge, as viruses rely on host cells for replication. Plant-derived, environmentally friendly nanoparticles have gained significant attention due to their low toxicity, which enables them to target viruses without damaging host cells. In this study, we describe the synthesis of silver nanoparticles (AgNPs) using Arctostaphylos uva-ursi leaf extract and explore their potential antiviral activity. The uva-ursi AgNPs were initially characterized using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). We then optimized two different gellan gum/alginate film formulations (1.6:0.4 and 1.2:0.8) as delivery matrices for the AgNPs and assessed Ag⁺ skin permeation using a Franz diffusion cell system. The antiviral potential of the uva-ursi AgNPs—both alone and incorporated into the films—was tested against herpes simplex virus type 1 (HSV-1). Our findings indicate that uva-ursi AgNPs may directly interact with the viral envelope, disrupting the lipid membrane and/or interfering with viral surface proteins. Overall, green-synthesized uva-ursi AgNPs may represent a natural, cost-effective, and safe alternative strategy for managing herpetic infections. Full article

Wheat streak mosaic (WSM), historically attributed to wheat streak mosaic virus (WSMV) and transmitted by the wheat curl mite (WCM; Aceria tosichella), remains a major cause of yield loss in the Texas High Plains. In recent years, Triticum mosaic virus (TriMV), also transmitted by WCM, has emerged as an increasingly important component of the WSM disease complex. Under field conditions, TriMV is most frequently detected in mixed infections with WSMV. Management of WSM relies primarily on resistant cultivars carrying genes such as Wsm1 or Wsm2. Although synergistic interactions between WSMV and TriMV have been documented under controlled conditions, their dynamics during natural field infections—particularly during the latent phase between initial infection and symptom development—remain poorly understood. Moreover, the extent to which host genotype influences virus–virus interactions and vector acquisition dynamics in the field has not been fully resolved. Replicated field trials conducted over two growing seasons were used to quantify temporal accumulation patterns and relative ratios of WSMV and TriMV in susceptible (TAM 304) and resistant cultivars differing in resistance source (BT [Wsm1] and Joe [Wsm2]) under natural disease spread. WSMV remained the predominant virus in mixed infections across cultivars, sampling times, and disease stages. However, as plants aged and entered senescence, WSMV titers declined more rapidly than TriMV titers, resulting in a progressive reduction in the WSMV-to-TriMV ratio. From early infection through disease development, the Wsm1 cultivar (BT) consistently supported significantly lower TriMV accumulation than the Wsm2 cultivar (Joe), providing a mechanistic explanation for the comparatively stronger disease suppression associated with WSM. Mites feeding on BT also acquired lower TriMV titers. Although viral concentrations in wheat tissue were strongly correlated with those detected in feeding mites, substantial differences in plant-level WSMV-to-TriMV ratios among cultivars were not mirrored within the vector. These findings indicate that while host resistance regulates absolute virus accumulation, vector-associated factors may influence the relative proportions of viruses detected following acquisition, with important implications for WSM epidemiology and resistance deployment in field systems. Full article

The chloroplast, a key organelle for plant immunity, is frequently targeted by viral proteins to suppress host defense. Here, we demonstrate that NSvc4, the movement protein of rice stripe virus (Tenuivirus oryzaclavatae; genus Tenuivirus), functions as a chloroplast-localized virulence effector. We show that NSvc4 enters chloroplasts and directly associates with NbPsbQ, a subunit of the oxygen-evolving complex (OEC) of Photosystem II. This interaction competitively disrupts the binding of NbPsbQ to its native partners NbPsbO and NbPsbP, thereby dampening the accumulation of chloroplast-derived reactive oxygen species (cROS) and attenuating pathogen-triggered immune signaling. Genetic knockout of NbPsbQ enhanced plant susceptibility to RSV, confirming its role as a positive regulator of antiviral defense. Our study uncovers a distinct strategy whereby a viral movement protein inhibits chloroplast-mediated immunity by targeting extrinsic subunits of the OEC. These findings expand the functional scope of viral movement proteins and highlight the OEC as a critical battleground in plant–virus interactions. Full article

Plant defences are assumed to evolve in response to the negative effects of virus infection on plant fitness (virulence), and to drive plant–virus coevolution. However, viruses are not always antagonistic symbionts of plants, and the expression of defence traits is environment-dependent. Thus, understanding plant–virus interactions requires analysing the expression of defence traits in the host’s native habitat. Here we analyse the effect of cucumber mosaic virus (CMV) infection, and the expression of resistance and tolerance in the native habitat of a wild Arabidopsis thaliana population. Plants from ten genotypes from that population, which have been shown to differ in resistance and tolerance to CMV in a greenhouse, were inoculated with an Arabidopsis isolate of CMV and transplanted to their habitat. Resistance was rated based on virus accumulation in leaves, and tolerance was rated based on the effect of infection on plant fecundity relative to virus accumulation. Consistent with the greenhouse assays, virulence depended on the host genotype, and polymorphisms for resistance and tolerance were expressed in the field, supporting the validity of the conclusions from the greenhouse assays. Our results also support theoretical predictions on the relationships between pathogen multiplication and virulence and between resistance and tolerance. Full article

Background/Objectives: Until now, there have been no suitable medicines to treat infections caused by the Ebola virus. Cistus incanus, a traditional medicinal plant, contains several phytocompounds exhibiting antioxidant and anti-inflammatory properties. Methods: In this research, the molecular level interactions of the phytocompounds of Cistus incanus were investigated for their antiviral potential against the active site of VP40 protein of Ebola virus using in silico molecular docking. Further, the potential compounds were assessed for their stability in the protein using molecular dynamics (MD) simulations. Results: Methyl gallate, catechin, and quercetin showed excellent docking scores of −9.8, −8.8, and −7.7 kcal/mol, respectively, and favorable interactions with the target protein. These complexes showed good stability over the 100 ns MD simulation time. In addition, the phytocompounds displayed favorable pharmacokinetics and drug-like properties. Conclusions: Our study offers the antiviral potential of phytocompounds (methyl gallate, catechin, and quercetin) of Cistus incanus, suggesting their suitability as lead candidates for the treatment of Ebola viral infection. Full article

RipP1 is a well-characterized avirulence effector that induces a hypersensitive response (HR) in three tobacco species. However, the molecular mechanisms by which host proteins recognize RipP1 to activate a defense response and modulate host–pathogen interactions remain largely unknown. In this study, we screened a Nicotiana benthamiana cDNA library via yeast two-hybrid assay and identified FRIGIDA-like protein 4a (FRL4a) as a host protein interacting with RipP1. Secondary structure analysis of FRL4a and construction of serial mutants revealed that the ClyA-like domain of FRL4a is the key region mediating its interaction with RipP1. Using virus-induced gene silencing (VIGS) and quantitative real-time PCR (qPCR) analysis, we found that the ability of RipP1 to induce HR was significantly attenuated in FRL4a-silenced plants, and RipP1 no longer suppressed the ethylene signaling pathway. Pathogenicity tests by inoculating R. solanacearum on N. benthamiana with different FRL4a expression levels showed enhanced bacterial wilt resistance in FRL4a-silenced plants but increased susceptibility in FRL4a-overexpressing plants. Collectively, these findings demonstrate that RipP1 suppresses the ethylene pathway through its interaction with FRL4a, and FRL4a acts as a negative regulator of tobacco resistance to bacterial wilt. Full article

Soybean mosaic virus (SMV) is a major constraint on global soybean (Glycine max (L.) Merr.) production, causing substantial economic losses worldwide. Despite these losses, the potential of resistance genes as a solution remains largely unexplored. In this study, the COPPER CHAPERONE FOR SUPEROXIDE DISMUTASE (GmCCS) was initially employed as a bait to screen the soybean cDNA library, leading to the identification of a protein homologous to Arabidopsis thaliana COP9 signalosome complex subunit 5B (AtCSN5B), designated as GmCSN5B. Quantitative real-time PCR (qRT-PCR) analysis revealed differential expression of GmCSN5B in the SMV-resistant (Qihuang No.1, QH) and susceptible (Nannong 1138-2, NN) variety following SMV-SC3 strain inoculation. Knockdown of GmCSN5B via Bean pod mottle virus (BPMV)-induced gene silencing (VIGS) significantly enhanced SMV resistance compared to control plants. This work further demonstrated that GmCSN5B can interact with the downstream GmVTC1 protein, which was potentially associated with ascorbic acid (AsA; Vitamin C) synthesis. Moreover, GmVTC1 also responded to SMV infection, and its knockdown led to a reduction in endogenous AsA levels within the host, thereby compromising the plant’s resistance to SMV. Together, these findings suggest that the GmCCS-GmCSN5B-GmVTC1 pathway in soybean modulates host resistance to SMV through the regulation of AsA synthesis. Full article