Search Results (252)

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

Sweetpotato (Ipomoea batatas) is a staple crop of strategic importance in West Africa, particularly in Côte d’Ivoire. However, its productivity is increasingly under threat due to viral diseases. Given the lack of updated epidemiological data over the past three decades, a nationwide survey was conducted in September 2023 across 94 fields in 83 locations covering seven agroecological zones of the country. A total of 221 symptomatic and asymptomatic leaf samples were analyzed using PCR for DNA viruses and RT-PCR for RNA viruses. The overall viral incidence rate calculated was 65.61%, with significant regional variations (35–97.18%, p < 0.001) and notable differences in the severity of symptoms (p = 0.0095). Agroecological zone I was the most affected, while agroecological zones IV and V were the least impacted. Four viruses were identified: cucumber mosaic virus (CMV), sweet potato leaf curl virus (SPLCV), sweet potato feathery mottle virus (SPFMV), and sweet potato chlorotic stunt virus (SPCSV). No badnaviruses were found. CMV was the most common virus found in single infections (43.44%), followed by SPLCV (5.43%). SPFMV and SPCSV were only observed in mixed infections, particularly CMV/SPLCV (14.03%) and CMV/SPFMV (1.81%). Two triple infections were also detected: SPFMV/SPCSV/CMV and SPFMV/SPLCV/CMV. In total, 34 partial coat protein sequences were obtained (28 SPLCV, 4 SPFMV, 1 CMV, 1 SPCSV). Phylogenetic analysis revealed a high similarity between SPLCV isolates characterized in Côte d’Ivoire and those from Burkina Faso, Europe (Spain, Italy), and the Americas (USA, Puerto Rico) with nucleotide identity values ranging from 98% to 100%. The Côte d’Ivoire SPCSV sequence showed 97.92% nucleotide identity with European isolates, whereas SPFMV sequences exhibited greater diversity (77–89% identity) but clustered within the West African lineage. Sweetpotato viral diseases were detected mostly in mixed-cropping fields (66.85%). This work provides the first epidemiological update on sweetpotato viral diseases since 1987 and the first molecular evidence of the nationwide presence of SPLCV and SPCSV in Côte d’Ivoire. 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

Cold stress is a critical factor restricting the cultivation of subtropical evergreen species such as Camellia sinensis and C. japonica in temperate climates. This study aimed to develop an integrated framework for evaluating cold tolerance by combining visual assessment, electrolyte leakage (EL), Evans blue staining, and nonlinear regression modeling. All experiments were conducted with n = 3 samples per treatment, and statistical analyses were performed at a significance level of α = 0.05. Under freezing treatment at −6 °C, C. japonica exhibited faster and more severe damage, including leaf curling and vein darkening, compared to C. sinensis. Electrolyte leakage and cell death increased rapidly in C. japonica, and a sharp rise in cell death occurred in both species when EL exceeded 55%. Logistic regression of EL data estimated LT₅₀ values of −10.96 °C for C. sinensis and −9.38 °C for C. japonica, while EL Temp₅₀ values were −9.59 °C and −8.97 °C, respectively, indicating higher membrane stability in C. sinensis. The difference in LT₅₀ between the two species was statistically significant (p < 0.05). Biochemical and heatmap analyses from 25 °C to −12 °C showed that C. sinensis maintained higher chlorophyll, antioxidant activity, and sugar levels, reflecting stronger cold tolerance. In contrast, C. japonica accumulated more proline and MDA, indicating higher stress sensitivity and membrane damage. This study presents a reproducible, quantitative framework for evaluating cold tolerance in Camellia species, offering valuable insights for breeding and expanding cultivation under climate change. 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

ASYMMETRIC LEAVES1 (AS1) and AS2 play essential roles in regulating leaf development in plants. However, their functional roles in soybean remain poorly understood. Here, we identified two members of the soybean AS1 gene family, GmAS1a and GmAS1c, which exhibit high expression levels in stem and leaf tissues. Using the CRISPR/Cas9 system, we targeted four GmAS1 and three GmAS2 genes, generating mutant lines with distinct leaf development phenotypes, including wrinkling (refers to fine lines and creases on the leaf surface, like aged skin texture), curling (describes the inward or outward rolling of leaf edges, deviating from the typical flat shape), and narrow. We found that functional redundancy exists among the four GmAS1 genes in soybean. GmAS1 and GmAS2 cooperatively regulate leaf curling, leaf crinkling phenotypes, and leaf width in soybean, with functional redundancy also observed between these two genes. Transcriptome sequencing analysis of w3 mutant (as1b as1c as1d as2a as2b as2c) identified 1801 differentially expressed genes (DEGs), including 192 transcription factors (TFs). Gene ontology enrichment analysis revealed significant enrichment of DEGs in pathways associated with plant hormone biosynthesis and signal transduction. A detailed examination of the DEGs showed several genes involved in the development of leaf lateral organs, such as KNOX (SHOOT MERISTEMLESS (STM), KNAT1, KNAT2, and KNAT6), LOB (LBD25, LBD30), and ARP5, were down-regulated in w3/WT (wild-type) comparison. CRISPR/Cas9-mediated targeted mutagenesis of the GmAS1/2 genes significantly impairs leaf development and polarity establishment in soybean, providing valuable germplasm resources and a theoretical framework for future studies on leaf morphogenesis. 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

Chili (Capsicum annuum L.) production is threatened by the pepper yellow leaf curl virus (PepLCV), transmitted by whiteflies, leading to reduced yields. This study investigated the biochemical changes in two chili genotypes, PEP6 (tolerant to PepLCV) and Homsuphan (susceptible to PepLCV), following inoculation with the Thailand strain of PepLCV (known as Pepper Yellow Leaf Curl Thailand Virus, PepYLCTHV). Inoculation was performed using whitefly transmission (WF) and graft transmission (GT) methods, and disease severity was evaluated using a standardized index. The level of total phenolic compounds and the activities of peroxidase (POD) and polyphenol oxidase (PPO) enzymes were analyzed in virus-infected plants and compared with those in uninoculated controls. Both chili genotypes exhibited a more rapid increase in disease severity when inoculated with WF than with GT. In PEP6, disease severity was lower than Homsuphan in both WF and GT inoculations. Disease severity in WT-inoculated PEP6 plants increased gradually, reaching 100% by day 36, whereas Homsuphan plants had a more rapid progression, attaining 100% by day 21. The GT method led to slower disease severity progression in both genotypes, reaching 80–85% by day 36. In PEP6 plants, total phenolic compound content increased significantly following WF, indicating an active defense response, whereas levels remained stable in GT plants. Phenolic content in the tolerant genotype Homsuphan remained stable across all conditions. Notably, peroxidase (POD) activity was elevated in GT plants of both genotypes, which correlated with reduced disease severity. Polyphenol oxidase (PPO) activity was lowest in control plants, but WT and GT increased the PPO level. Among the treatments, GT induced the highest PPO activity, which was associated with the lowest disease severity. These findings suggest that GT may enhance disease resistance by modulating phenolic compound accumulation and increasing POD and PPO activity. Full article

Sweetpotato is a key staple crop in tropical and subtropical regions. Its vegetative propagation makes it a persistent reservoir, facilitating the emergence and spread of complex infections. Understanding its virome is crucial for disease management and food security. We investigated the sweetpotato virome in Burkina Faso using rolling circle amplification and Oxford Nanopore sequencing. Eight symptomatic leaf samples, previously undiagnosed using conventional methods, were analysed. Bioinformatic pipelines were employed followed by phylogenetic comparisons. Two viruses known to infect sweetpotato, namely sweet potato leaf curl virus (SPLCV) and sweet potato leaf curl deltasatellite 3 (SPLCD3), were consistently detected in all samples. Additionally, pepper yellow vein Mali virus (PepYVMV), cotton leaf curl Gezira alphasatellite (CLCuGeA) and cotton leaf curl Gezira betasatellite (CLCuGeB) were identified for the first time in this crop. Phylogenetic analysis confirmed their genetic proximity to isolates from tomato, okra and pepper. Their co-occurrence with SPLCV and SPLCD3 indicates a complex viral landscape that could influence disease severity. This study highlights the underestimated role of sweetpotato as a viral reservoir, influencing virus evolution and transmission. Further studies should assess their pathogenicity, co-infection dynamics and vector-mediated transmission to improve crop productivity. Full article

The GRAS gene family not only performs a variety of regulatory functions in plant growth and development but also plays a key role in the defense mechanisms of plants in response to environmental stresses. Although GRASs have been identified in many species, research on them in Nicotiana benthamiana remains relatively limited until now. In this study, we comprehensively analyzed the GRAS gene family in N. benthamiana plants. Phylogenetic analysis displayed that all identified NbGRASs were classified into eight different subfamilies. Gene duplication analysis revealed that segmental duplication was the main driving force for the expansion of the NbGRAS gene family, with a total of 40 segmental duplication pairs identified. NbGRASs were unevenly distributed across the 19 chromosomes. Additionally, both gene families exhibited a relatively weak codon usage bias, a pattern shaped by mutational and selective pressures. Expression analysis showed that NbGRASs had tissue-specific expression patterns, with relatively high expression levels being observed in leaves and roots. The expression of NbGRASs was significantly changed under tomato yellow leaf curl virus or bamboo mosaic virus infection, suggesting that these NbGRASs can be involved in the plant’s antiviral response. These findings provide new perspectives for in-depth understanding of the evolution and functions of the GRAS gene family in N. benthamiana. Full article

To ensure the normal water status of apple rootstock softwood cuttings during the initial stage of cutting, a drought stress monitoring model was designed. The model is optimized based on the YOLOv11n-seg instance segmentation model, using the leaf curl degree of cuttings as the classification basis for drought-stress grades. The backbone structure of the IMYOLOv11n-seg model is improved by the C3K2_CMUNeXt module and the multi-head self-attention (MHSA) mechanism module. The neck part is optimized by the KFHA module (Kalman filter and Hungarian algorithm model), and the head part enhances post-processing effects through HIoU-SD (hierarchical IoU–spatial distance filtering algorithm). The IMYOLOv11-seg model achieves an average inference speed of 33.53 FPS (frames per second) and the mean intersection over union (MIoU) value of 0.927. The average recognition accuracies for cuttings under normal water status, mild drought stress, moderate drought stress, and severe drought stress are 94.39%, 93.27%, 94.31%, and 94.71%, respectively. The IMYOLOv11n-seg model demonstrates the best comprehensive performance in ablation and comparative experiments. The automatic humidification system equipped with the IMYOLOv11n-seg model saves 6.14% more water than the labor group. This study provides a design approach for an automatic humidification system in protected agriculture during apple rootstock cutting propagation. 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