Search Results (67)

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

Tomato yellow leaf curl virus (TYLCV) is one of the most destructive viral diseases causing severe yield losses in tomato production worldwide. This study investigated the effects of TYLCV infection on plant growth, photosynthetic physiological responses, and yield formation in greenhouse-grown tomatoes and evaluated the applicability of physiological trait-based yield prediction models. Two large-fruited tomato cultivars widely cultivated in Korean protected horticulture systems, ‘Daphnis’ and ‘Pink Star’, were inoculated with TYLCV under greenhouse conditions, and their growth, physiological responses, and yield characteristics were compared under high- and low-temperature growing seasons. TYLCV infection significantly reduced leaf length, leaf width, and leaf area index (LAI), and decreased both flowering truss number and fruit-setting truss number, resulting in reduced total yield. Physiological analyses showed that infected plants exhibited decreases in the OJIP fluorescence rise curve and Fv/Fm values, indicating a reduced photochemical efficiency in photosystem II. In addition, A–Ci response curve analysis revealed a reduction in net photosynthetic rate, suggesting limited carbon assimilation capacity. Total yield showed significant positive correlations with maximum net photosynthetic rate (Amax), Fv/Fm, and Ci300. GGE and GT biplot analyses further indicated that yield was closely associated with photosynthetic performance and canopy development traits. A multiple regression model based on physiological traits and virus infection status explained a significant proportion of the variation in tomato yield (R² = 0.367), indicating that TYLCV infection acts as a key limiting factor for yield reduction. These findings demonstrate that TYLCV infection restricts tomato productivity through reduced photosynthetic efficiency and altered canopy structure. Moreover, physiological trait-based yield prediction approaches may provide a useful framework for evaluating productivity under viral infection conditions and for developing data-driven crop management strategies in greenhouse tomato production systems. Full article

Tomato is widely produced in Burkina Faso for its culinary, nutritional, and economic value. Tens of thousands of farmers are involved in its production throughout the country. However, they face significant biotic constraints that limit yields and income. In particular, tomato yellow leaf curl virus (TYLCV), a begomovirus transmitted by whiteflies (Bemisia tabaci), severely affects tomato production. This study evaluated the response of 13 tomato genotypes to tomato yellow leaf curl disease (TYLCD), including eight lines with different Ty resistance gene combinations; three local improved varieties, and two commercial varieties in western and central Burkina Faso. All genotypes developed TYLCD symptoms with considerable variability in genotypic responses. Four genotypes carrying a single gene, namely CLN4279O (Ty2), CLN4270I (Ty1/Ty3), CLN4270F (Ty1/Ty3), and CLN4018G (Ty2), exhibited the best field tolerance, with lower disease incidence and severity across sites. In contrast, genotype CLN4078A carrying two resistance genes (Ty1/Ty3 + Ty2), and the checks PETOMECH and ROMA VF were highly susceptible. Hierarchical clustering grouped the genotypes into four classes based on tolerance level and yield. These findings highlight the variability in resistance expression under field conditions and suggest possible interactions between host genotype, environmental factors, and virus populations. Broader multi-site evaluations, supported by molecular diagnostics to identify endemic TYLCV strains, are needed to refine the selection process. Full article

The rapid evolution of insecticide resistance in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) threatens effective pest management in key crops. This study characterized B. tabaci populations from cotton and tomato fields in Kashgar (September–October 2024) using mtCOI-RFLP for cryptic species identification, leaf-dip bioassays with 13 insecticides, and PCR detection of tomato yellow leaf curl virus (TYLCV). All analyzed individuals belonged to the Mediterranean (MED) cryptic species. Extreme resistance was observed to imidacloprid (RR = 320.65) and pyridaben (RR = 331.29), while nitenpyram (RR = 1.77) and the emamectin benzoate–chlorantraniliprole mixture (RR = 2.13) remained effective. TYLCV was detected in 97.5% of adults from tomato greenhouses. These findings provide a concise assessment of resistance status, species identification, and virus prevalence in B. tabaci, informing sustainable management strategies in cotton and tomato production. Full article

The Gretchen Hagen 3 (GH3) gene family, a key component of the early auxin-responsive gene family, plays a pivotal role in regulating plant growth, development, and stress responses. However, to date, a comprehensive genome-wide analysis of the GH3 gene family and its potential role in plant defense against viruses, such as tomato yellow leaf curl virus (TYLCV), has not been conducted in Nicotiana benthamiana. Here, the GH3 gene family was thoroughly examined in N. benthamiana using a comprehensive genome-wide bioinformatic approach. A total of 25 potential GH3 genes were discovered in N. benthamiana. Phylogenetic analysis classified these NbGH3s into three different clades. Chromosomal distribution and synteny analyses revealed that NbGH3s are unevenly distributed across 14 chromosomes, with 20 segmental and one tandem duplication pairs. Promoter analysis suggested their involvement in phytohormone signaling and stress responses. Quantitative PCR showed that several NbGH3s are transcriptionally responsive to TYLCV infection, with five of them significantly upregulated in infected leaves. Furthermore, virus-induced gene silencing revealed that the suppression of NbGH3-3 and NbGH3-9 markedly increased host susceptibility to TYLCV, underscoring their critical roles in plant antiviral defense mechanisms. This research establishes a framework for understanding the functions of NbGH3s in plant growth and their response to TYLCV infection. Full article

Phytopathogenic viruses severely impact major crops, leading to significant social and economic losses. Among them, begomoviruses pose a serious threat to key cultivars in subtropical and tropical regions despite ongoing efforts to limit their spread. Early detection of these pathogens in field crops and associated weeds is essential for the timely implementation of management strategies to mitigate viral disease outbreaks. In this study, we applied a sensitive loop-mediated isothermal amplification (LAMP) assay for the detection of tomato yellow leaf curl virus (TYLCV), tomato latent virus (TLV), and tomato mottle Taino virus (ToMoTV) in agro-inoculated Nicotiana benthamiana and Solanum lycopersicum. Importantly, LAMP assays also enabled the identification of these viruses in both symptomatic and asymptomatic field-grown tomato plants, detecting a higher number of infected plants than dot blot hybridization and PCR. Field surveys further revealed mixed infections of TYLCV, TLV, and ToMoTV within individual tomato plants, uncovering a complex epidemiological scenario. Full article

Tomato Yellow Leaf Curl Virus (TYLCV) has recently caused severe economic losses in global tomato production. According to the International Plant Protection Convention (IPPC), yield reductions of 50–60% have been reported in several regions, including the Caribbean, Central America, and South Asia, with losses in sensitive cultivars reaching up to 90–100%. In developing countries, TYLCV and mixed infections affect more than seven million hectares of tomato-growing land annually. In this study, we construct and analyze a nonlinear dynamic model describing the transmission of TYLCV, incorporating the Caputo fractional-order derivative operator. The existence and uniqueness of solutions to the proposed model are rigorously established. Equilibrium points are identified, and the Jacobian determinant approach is applied to compute the basic reproduction number, $R_0$. Suitable Lyapunov functions are formulated to analyze the global asymptotic stability of both the disease-free and endemic equilibria. The model is numerically solved using the Grünwald–Letnikov-based nonstandard finite difference method, and simulations assess how the memory index and preventive strategies influence disease propagation. The results reveal critical factors governing TYLCV transmission and suggest effective intervention measures to guide sustainable crop protection policies. Full article

Plant viruses can significantly influence the behavior and performance of their insect vectors, with profound implications for viral epidemiology. However, studies on the effects of co-infection with multiple plant viruses on vector feeding behavior remain scarce, despite its frequent occurrence in nature and potential for altered transmission outcomes. Bemisia tabaci MED, a key vector insect, is closely linked to the rapid spread of tomato chlorosis virus (ToCV) and tomato yellow leaf curl virus (TYLCV) in China. In this study, the electrical penetration graph (EPG) technique was employed to investigate and compare the indirect (via infected plants) and direct (via viruliferous insects) effects of ToCV alone and ToCV and TYLCV co-infection on the feeding behaviors of B. tabaci MED. The results revealed that whiteflies on ToCV-infected or ToCV&TYLCV co-infected plants exhibited significantly longer non-probing durations compared to those on un-infected plants. The intracellular puncture activity of whiteflies was markedly reduced on virus-infected plants, and ToCV infection particularly shortened the duration of phloem sap ingestion. Moreover, viruliferous whiteflies (carrying ToCV or both viruses) spent less time in the intercellular pathway phase. Specifically, ToCV-viruliferous whiteflies had a shorter first-probe duration than non-viruliferous ones. The time from the first probe to the first E phase was also shorter in viruliferous whiteflies, especially in those carrying both ToCV and TYLCV. Furthermore, a significant difference was observed in the total duration of phloem sap ingestion between ToCV-viruliferous and ToCV&TYLCV-viruliferous whiteflies. These findings indicate that both ToCV infection and ToCV&TYLCV co-infection can modulate whitefly feeding behaviors through indirect and direct manners, with co-infection eliciting unique behavioral changes. These insights are valuable for elucidating the negative impact of ToCV-infected and ToCV&TYLCV co-infected tomato plants on whitefly performance, and for uncovering the mechanisms underlying the epidemics of these viruses. Full article

Pepper (Capsicum spp.) is an economically valuable crop worldwide including in the United States due to its nutritional benefits in human health and widespread use as a spice or vegetable. Although numerous viruses have been reported infecting peppers in the USA, little is known about the diversity and distribution of pepper-infecting viruses in Oklahoma. To address this knowledge gap, we conducted a comprehensive pepper virome study to identify viruses infecting pepper and their incidence across six different counties in Oklahoma. A total of 310 plant samples including pepper and other potential hosts were collected during the 2021 and 2022 growing seasons. Samples were analyzed using high-throughput sequencing (HTS) and/or reverse transcription-polymerase chain reaction (RT-PCR) assays. Viral contigs identified via HTS were further validated through RT-PCR or PCR assays followed by Sanger sequencing. In total, 17 distinct viruses were detected, including 15 RNA and two DNA viruses, with several representing putatively novel findings. The most prevalent virus was beet curly top virus (BCTV), followed by tomato yellow leaf curl virus (TYLCV), potato yellow dwarf virus/constricta yellow dwarf virus (PYDV/CYDV), and pepper mild mottle virus (PMMoV). Virus incidence varied by season and location, with some surveys showing infection rates exceeding 80%. This study provides the first in-depth characterization of the pepper virome in Oklahoma and valuable insights into the prevalence and distribution of pepper-infecting viruses. These findings will support the development of informed, targeted strategies for virus detection and management in pepper production systems. Full article

Background: The ubiquitin–proteasome system plays a critical role in plant antiviral defense, with HECT-type E3 ubiquitin ligases serving as key regulators of protein turnover. To explore the potential involvement of the HECT gene family in host resistance against tomato yellow leaf curl virus (TYLCV), a comprehensive analysis was conducted in Nicotiana benthamiana. Methods: In this study, the HECT gene family in N. benthamiana was systematically investigated using a genome-wide bioinformatic analysis. The potential roles of these genes in the response to TYLCV infection were further examined using a virus-induced gene silencing (VIGS) technique. Results: Using a Hidden Markov Model approach, 18 NbHECT genes were identified that phylogenetically clustered into four subfamilies with distinct structural features. Chromosomal location and synteny analyses indicated that these genes were unevenly distributed across 11 chromosomes, with 10 instances of segmental duplication identified. Tissue-specific expression profiling demonstrated that 17 NbHECTs were constitutively expressed, with Group III members showing the highest expression in reproductive tissues. Following TYLCV infection, NbHECT6 was significantly downregulated while NbHECT13 was upregulated in both inoculated and systemic leaves. Functional validation through the VIGS approach revealed that suppression of NbHECT6 and NbHECT13 increased host susceptibility, as evidenced by exacerbated symptom severity and enhanced viral DNA accumulation compared to controls. Conclusions: These findings establish NbHECT6 and NbHECT13 as critical components of the plant antiviral response, providing new insights into ubiquitin-mediated defense mechanisms against geminiviruses. Full article

Tomato yellow leaf curl virus (TYLCV) is a highly destructive pathogen of global tomato crops. The open reading frame (ORF) of TYLCV V2 contains two initiation codons (ATG1/V2-1 and ATG2/V2-2), producing distinct protein isoforms. Using custom antibodies, we confirmed V2-1 and V2-2 expression in infected Nicotiana benthamiana and tomato plants. Deletion mutants revealed their specialized roles: V2-1 was indispensable for viral replication and systemic spread—its loss severely reduced pathogenicity and genome accumulation. V2-2 acted as an auxiliary factor, and its deletion attenuated symptoms but kept the virus infection. Host-specific effects were observed—V2-1 deletion led to lower viral DNA/coat protein levels in N. benthamiana than in tomato, suggesting host-dependent regulation. Mutant viruses declined progressively in tomato, indicating host defense clearance. Heterologous co-expression of both isoforms via potato virus X induced systemic necrosis in N. benthamiana, demonstrating functional synergy between isoforms. Both initiation codons were essential for V2-mediated suppression of transcriptional gene silencing (TGS) and post-transcriptional gene silencing (PTGS). This study uncovers the mechanistic divergence of V2 isoforms in TYLCV infection, highlighting their collaborative roles in virulence and host manipulation. The findings advance understanding of geminivirus coding complexity and offer potential targets for resistance strategies. Full article

Tomato yellow leaf curl disease (TYLCD) significantly affects tomato yield. The jasmonic acid (JA) pathway is crucial in the defence response of plants; however, its role in plant resistance to TYLCD remains undefined. In production, CCC (chlorocholine chloride) is often used to cultivate strong seedlings to enhance seedling vitality and improve stress resistance. However, the mechanism through which CCC enhances disease resistance in tomatoes remains unclear. In this study, tomato seedlings were exogenously sprayed with 300 mg/L CCC before and after inoculation with tomato yellow leaf curl virus (TYLCV). The results indicated that no significant tomato yellow virus disease phenotype was observed in tomato seedlings after spraying with CCC and subsequent inoculation with the virus. Spraying CCC on seedlings inoculated with the virus and exhibiting typical phenotypes can significantly alleviate the yellowing and curling symptoms of new leaves and improve photosynthesis-related indicators in tomato plants. The detection of virus copy numbers within the plants revealed that the virus copy numbers in plants treated with CCC were significantly lower than those in the control group. Transcriptomic analysis revealed that, after spraying CCC, the key enzyme genes AOS2 and AOC in the JA synthesis pathway in tomatoes were significantly upregulated, whereas the expressions of JAZ2 and MYC2 genes, which negatively regulate JA synthesis, were significantly downregulated. In the stable state, JAZ proteins interact with MYC2 and inhibit its transcriptional activity of MYC2. Tomatoes overexpressing MYC2 and JAZ2 exhibit a significant decrease in TYLCD resistance. These results indicated that exogenous spraying CCC affected the expression of genes such as MYC2 and JAZ2, and then regulated JA pathway, increased the endogenous JA content in plants, and enhanced the disease resistance of tomato plants to TYLCD. This study provides a scientific reference for effectively preventing and controlling TYLCD in tomato production and reducing the influence of TYLCD on tomato yield and quality. Full article

Tomato yellow leaf curl virus (TYLCV), tomato leaf curl New Delhi virus (ToLCNDV), and tomato chlorosis virus (ToCV) are emerging viruses that cause significant damage to tomato (Solanum lycopersicum). TYLCV and ToLCNDV are single-stranded DNA viruses from the genus Begomovirus, family Geminiviridae, while ToCV is an RNA virus from the genus Crinivirus (family Closteroviridae). These viruses share overlapping geographic ranges, vectors (the whitefly Bemisia tabaci), and host plants, making mixed infections common. This study investigated interactions between TYLCV and ToLCNDV and between ToLCNDV and ToCV in mixed infections of susceptible and TYLCV-resistant tomato genotypes. We evaluated infection, disease development, trans-replication of genome components, and genetic exchange. Our results showed no significant synergistic or antagonistic interactions, complementation, or interference between the viruses. TYLCV resistance in tomato genotypes remained stable. The DNA-B component of ToLCNDV exhibited impaired functionality and was not complemented by TYLCV. No evidence was found that the crinivirus tomato chlorosis virus (ToCV) enhances ToLCNDV infection, suggesting limited interactions despite shared vectors. Genetic exchange was detected in defective DNA (def-DNA) molecules using high-throughput sequencing (HTS), indicating potential genetic interactions between these viruses. These findings suggest that mixed infections do not pose immediate concerns for increased pathogenicity but highlight the ecological implications of genetic exchange, warranting further study of the evolutionary consequences of such interactions in mixed-virus environments. Full article

Tomato leaf curl New Delhi virus (ToLCNDV) and tomato yellow leaf curl virus (TYLCV) are two important viral pathogens that severely affect Solanaceae and Cucurbitaceae plants. In order to reduce the further spread of these viruses, it is crucial to establish an efficient and reliable method to accurately detect the viruses. In this study, a multiplex PCR assay for the simultaneous detection of TYLCV and ToLCNDV was established. Three primer pairs designed from conserved regions within the coat protein or movement protein-encoding regions of the respective viruses were employed in the assay. The optimization of parameters such as primer concentration was set at 0.15 μM/0.15 μM, 0.25 μM/0.25 μM, and 0.50 μM/0.50 μM for ToLCNDV-DNA-A-F/R, TYLCV-F/R, and ToLCNDV-DNA-B-F/R primer pairs. At optimal primer concentrations, the multiplex PCR method demonstrates effective performance with an annealing temperature ranging from 51 °C to 66 °C. The specificity of the assay evaluated by testing against other begomoviruses showed no evidence of cross-amplification. Further sensitivity analysis performed using a serially diluted plasmid containing viral targets as templates demonstrated high sensitivity with a detection limit of 10³ copies/μL. Field surveys utilizing the multiplex PCR assay successfully identified the infection of TYLCV and ToLCNDV in field-collected samples. Full article

Tomato yellow leaf curl virus (TYLCV) poses a significant threat to tomato production, leading to severe yield losses. The current control strategies primarily rely on the use of pesticides, which are often nonselective and costly. Therefore, there is an urgent need to identify more environmentally friendly alternatives. Dufulin, a novel compound that has been effective in controlling viral diseases in tobacco and rice, has not yet been tested against TYLCV. This study assessed the efficacy of dufulin in controlling TYLCV over a three-year span from 2021 to 2023 through field trials, by monitoring disease symptoms and viral titers. Additionally, this study assessed the expression levels of genes associated with systemic acquired resistance (SAR), specifically proteinase inhibitor II (PI II) and non-expressor of pathogenesis-related genes 1 (NPR1), using real-time qRT-PCR. The chlorophyll and nitrogen content in the leaves were also measured. Plants treated with dufulin showed reduced symptomatology and lower viral titers compared to the controls. Analysis of gene expression revealed that NPR1 was upregulated in the dufulin-treated plants, whereas PI II expression was consistently downregulated in the TYLCV-infected plants. Interestingly, PI II expression increased in the healthy plants following a seven-day post-treatment with dufulin. Moreover, the treated plants exhibited a higher chlorophyll content than the controls, though no significant differences in the nitrogen levels were observed between the dufulin-treated and water-treated plants. Overall, the application of dufulin significantly bolstered the plant’s defense response, effectively reducing TYLCV symptoms and enhancing resistance. Full article