Search Results (129)

Wheat dwarf virus (WDV) is a major constraint to global wheat production, causing severe yield losses and economic disruption. Understanding the molecular basis of wheat–WDV interactions is essential for developing resistant cultivars. Non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), are key regulators of gene expression and defence. This study identified ncRNAs involved in wheat responses to WDV, including host lncRNAs, miRNAs, and viral small interfering RNAs (siRNAs) targeting WDV genomic regions. High-throughput sequencing revealed extensive ncRNA reprogramming under WDV infection. A total of 437 differentially expressed lncRNAs (DElncRNAs) and 58 miRNAs (DEmiRNAs) were detected. Resistant genotypes displayed more DElncRNAs (204 in Svitava; 163 in Fengyou 3) than the susceptible Akteur (141). In Akteur, 66.7% of DElncRNAs were downregulated, whereas in Svitava, 56.9% were upregulated. Akteur also exhibited more DEmiRNAs (28) than resistant genotypes (15), with predominant downregulation. A co-expression network analysis revealed 391 significant DElncRNA–mRNA interactions mediated by 16 miRNAs. The lncRNA XLOC_058282 was linked to 298 transcripts in resistant genotypes, suggesting a central role in the host defence. Functional annotation showed enrichment in signalling, metabolic, and defence-related pathways. Small RNA profiling identified 1166 differentially expressed sRNAs targeting WDV, including conserved hotspots and 408 genotype-specific sites in Akteur versus Fengyou 3. Infected plants displayed longer sRNAs, a sense-strand bias, and a 5′ uridine preference, but lacked typical 21–24 nt phasing. These findings highlight the central roles of ncRNAs in orchestrating wheat antiviral defence and provide a molecular framework for breeding virus-resistant wheat. Full article

Plant viral diseases cause significant agricultural losses worldwide and are shaped by complex virus-host and virus-virus interactions. Unlike fungal or bacterial pathogens, viruses cannot be directly controlled with chemicals, and their management relies on insect vector control and the development of virus-resistant plant varieties. Plants deploy endogenous epigenetic (DNA/chromatin-based) and epitranscriptomic (RNA-based) mechanisms to limit viral infections. RNA silencing pathways, particularly post-transcriptional gene silencing (PTGS) mediated by small RNAs, restrict viral replication and shape viral populations. Additional layers, including RNA-directed DNA methylation (RdDM), N6-methyladenosine (m⁶A) RNA modifications, histone modifications and chromatin remodeling, further modulate host–virus interactions. DNA methylation can be inherited and may confer resistance to future generations, although its stability is partial and context-dependent. Virus-derived 24-nt small interfering RNAs (siRNAs) act as mobile signals, inducing systemic gene silencing and potentially influencing viral population dynamics. Understanding these epigenetic and epitranscriptomic mechanisms can improve virus diagnosis, pathogenesis studies and disease management, while also providing insights into viral diversity and co-infection dynamics. This review synthesizes current knowledge of these mechanisms and discusses their implications for developing sustainable antiviral strategies. 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

Brassica yellows virus (BrYV) mainly infects cruciferous crops and has been widely prevalent across China. To develop a rapid and highly sensitive method for detecting BrYV in oilseed rape, a reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assay was established. Four specific primers were designed to target the conserved gene of BrYV, with total RNA extracted from BrYV-infected oilseed rape leaves used as the template for the RT-LAMP assay. The optimal reaction conditions were determined, including a primer concentration ratio of 1:8, MgSO₄ concentration of 4 mM, reaction temperature of 64 °C, and a suitable reaction time of 60 min. Sensitivity analysis demonstrated that the RT-LAMP assay could detect total RNA at a concentration of 0.091 × 10⁻³ μg/μL, which was 100-fold more sensitive than conventional RT-PCR for BrYV detection. In addition to visualizing results by electrophoresis, the RT-LAMP assay could also be easily visualized using calcein-MnCl₂. These results indicate the potential of the established RT-LAMP assay for rapid BrYV detection in oilseed rape plants, which can provide better technical support for field diagnosis, disease forecasting, and the implementation of effective control strategies against the virus. Full article

Symbiosis between rhizobia and legumes can affect plant tolerance to abiotic and biotic stressors such as drought and herbivores. Yet few studies have assessed how soil rhizobia impact plants that face abiotic and biotic stress simultaneously. This is a major knowledge gap given that many aspects of plant growth and defense are affected by interacting stressors, and these interactions can affect legume–rhizobia symbiosis. Here we assessed rhizobia-mediated interactions between a legume host (Pisum sativum), a vector herbivore (pea aphid, Acyrthosiphon pisum), a plant virus (pea enation mosaic virus, PEMV), and soil water availability. We show that rhizobia promoted plant growth and mitigated osmotic stress caused by reduced soil water availability. Rhizobia also increased plant tolerance to PEMV under high soil moisture conditions but had no measurable effect on PEMV when plants were grown in soil with reduced water. To assess the mechanisms that mediated these complex interactions, we measured gene transcripts related to phytohormone signaling and found that salicylic acid, jasmonic acid, abscisic acid, and ethylene signaling were affected by interactions between rhizobia and water availability; each of these pathways affects PEMV transmission. Our study shows that beneficial effects of rhizobia on legumes are impacted by abiotic and biotic stress, and outcomes of symbiosis may be context-dependent in field settings. Full article

Changes in atmospheric CO₂ are known to influence plant physiology, subsequently affecting the nature of their interactions with their biotic environment. Barley yellow dwarf virus (BYDV), one of the most widespread and damaging viruses of small grains, is transmitted by cereal aphids and has a broad range of cultivated and uncultivated hosts from the Poaceae family. Here, we examined the effects of elevated CO₂ on plant physiology, Rhopalosiphum padi L. performance, and the accumulation of BYDV (strain BYDV-PAV) in winter wheat (Triticum aestivum L.), foxtail barley (Hordeum jubatum L.), and green foxtail (Setaria viridis (L.) Beauv.). A growth chamber experiment was conducted under ambient (420 ppm) and elevated CO₂ (700 ppm) with aphid-infested and uninfested plants. Elevated CO₂ significantly increased total plant biomass in all species but did not affect aphid survival or reproduction. The root biomass of winter wheat and foxtail barley, but not green foxtail, increased under elevated CO₂. However, no significant effect of aphids/BYDV was detected on total plant biomass. Transpiration rates varied with host plant and aphid presence but were not affected by CO₂ level. Total water-soluble carbohydrate concentration was unaffected by CO₂ or aphids. BYDV-PAV accumulation varied by host plant species, with winter wheat having the highest virus titer, followed by foxtail barley and green foxtail. Virus titers were increased under elevated CO₂ in all host plant species. We demonstrated that uncultivated grasses are important reservoirs for both BYDV-PAV and the R. padi vector and suggested that elevated CO₂ may enhance virus accumulation across the evaluated host plants. This underscores the need to consider the role of non-crop hosts in developing management plans and/or predicting BYDV dynamics in small grains. Full article

Citrus leprosis (CL) and citrus zonate chlorosis (ZC) were first described in Brazil in the 1930s. Both diseases, which caused non-systemic lesions primarily characterized by chlorotic and/or necrotic spots, were associated with the presence of Brevipalpus mites. While CL has since been well characterized as being caused by viruses of the genera Cilevirus (family Kitaviridae) and Dichorhavirus (family Rhabdoviridae) and transmitted by several species of Brevipalpus mites, the causal agent of ZC remained unknown. In this study, we analyzed Citrus spp. samples exhibiting typical ZC symptoms using high-throughput sequencing (HTS) to determine the etiology of ZC. We examined historical herbarium specimens collected between 1933 and 1965 alongside fresh samples collected from 2016 to 2022. Our results identified the higrevirus hibiscus green spot virus 2 (HGSV2, Higrevirus waimanalo) as the causal agent of ZC. In addition, we report for the first time the presence of a higrevirus in continental America, expand the diversity of known kitaviruses infecting citrus in Brazil, and demonstrate the transmission of an higrevirus by Brevipalpus yothersi and B. papayensis. Full article

Insect vectors play a pivotal role in the emergence and dissemination of plant viral diseases. Beyond their function in transmitting plant viruses, these insects harbor diverse insect-specific viruses (ISVs). Advances in high-throughput sequencing (HTS) have uncovered virus diversity and prevalence in insects that far exceed previous estimations. However, current knowledge of ISVs remains predominantly limited to genomic sequencing information. Investigating the fundamental biology of ISVs, their effects on insect physiology, and their modulation of vector competence is critical for deciphering complex virus–virus and virus–insect interactions. Such research holds substantial promise for developing innovative biocontrol strategies against plant viral pathogens. This review synthesizes current insights into the interplay between plant viruses and their insect vectors, explores the discovery and functional roles of ISVs, and discusses the potential application of ISVs in mitigating plant viral diseases. Understanding these dynamic relationships offers new avenues for sustainable plant disease management. Full article

Vitellaria paradoxa (shea tree) is an economically and medicinally important species indigenous to sub-Saharan Africa. Although the species holds substantial value, domestication efforts have been constrained, primarily due to the absence of efficient propagation alternatives, especially for the East African subspecies (V. paradoxa subsp. nilotica) which remains understudied in tissue culture research. This study investigated the influence of leaf explant developmental stage and media composition on callogenesis and embryogenic potential in V. paradoxa subsp. nilotica. Thus, leaf explants from six distinct growth stages were cultured on Murashige and Skoog (MS) media supplemented with various concentrations of 2,4-D, TDZ, NAA, and BAP. Callogenesis was significantly influenced by explant age, media strength, and specific PGR combinations. Results revealed that explants from Stage III (11–15 days) and Stage IV (16–20 days) exhibited the highest callus induction rates (up to 100%), particularly on half-strength MS media containing 2.0 mg/L 2,4-D and 0.5–1.0 mg/L TDZ. Histological analysis suggests that varying responses at the different stages relate to chloroplast distribution, trichome density/orientation, and vascular tissue maturity. Pro-embryogenic structures were successfully induced, representing a developmental milestone with strong prospects for advanced stages of differentiation. The findings also emphasize the importance of explant physiology and media formulation in developing regeneration protocols for V. paradoxa from leaf explants. Full article

The construction of infectious clones (ICs) is essential for studying viral replication, pathogenesis, and host interactions. Milk vetch dwarf virus (MDV), a nanovirus with a multipartite, single-stranded DNA genome, presents unique challenges for IC development due to its segmented genome organization. To enable functional analysis of its genome, we constructed full-length tandem-dimer-based ICs for all eight MDV genomic segments. Each segment was cloned into a binary vector and co-delivered into Nicotiana benthamiana, Nicotiana tabacum, Vicia faba, and Vigna unguiculata plants via Agrobacterium-mediated inoculation. Systemic infection was successfully reconstituted in all host plants, with PCR-based detection confirming the presence of all viral segments in the infected leaves of nearly all tested plants. Segmental accumulation in infected plants was quantified using qPCR, revealing non-equimolar distribution across hosts. This study establishes the first complete IC system for MDV, enabling reproducible infection, replication analysis, and quantitative segment profiling. It provides a foundational tool for future molecular investigations into MDV replication, host interactions, and viral movement, advancing our understanding of nanovirus biology and transmission dynamics. Full article

Plant viruses have been traditionally considered pathogens restricted to plant hosts. However, recent studies have shown that some plant viruses can infect and replicate in filamentous fungi and oomycetes, suggesting that their host range is broader than previously thought, and that their ecological interactions are more complex. In this study, we investigated the ability of the well-characterized positive-sense RNA plant virus Tobacco mosaic virus (TMV) to replicate in four major phytopathogenic fungi from different taxonomic groups: Botrytis cinerea, Fusarium oxysporum f. sp. lycopersici, Verticillium dahliae, and Monilinia fructicola. Using a recombinant TMV-based vector expressing a green fluorescent protein (TMV-GFP-1056) as reporter, we demonstrated that TMV can enter, replicate, and persist within the mycelia of B. cinerea and V. dahliae—at least through the first subculture. However, it cannot replicate in F. oxysporum f. sp. lycopersici and M. fructicola. RNA interference (RNAi) is a conserved eukaryotic epigenetic mechanism that provides an efficient defence against viruses. We explored the role of RNAi in the interaction between TMV and the mycelia of V. dahliae and B. cinerea. Our results revealed a strong induction of the Dicer-like 1 and Argonaute 1 genes, which are key compounds of the RNA silencing pathway. This RNAi-based response impaired TMV-GFP replication in both fungi. Notably, despite viral replication and RNAi activation, the virulence of V. dahliae and B. cinerea on their respective host plants remained unaffected. These findings reinforce the emerging recognition of cross-kingdom virus transmission and interactions, which likely play a crucial role in pathogen ecology and viral evolution. Understanding these virus–fungus interactions not only sheds light on RNAi interference silencing mechanisms but also suggests that plant viruses like TMV could serve as simple and effective tools for functional genomic studies in fungi, such as in V. dahliae and B. cinerea. Full article

The Asian citrus psyllid (Diaphorina citri) is an economically important pest of citrus as it is a vector of the bacterium (Candidatus Liberibacter asiaticus, CLas) that causes huanglongbing disease (HLB). Understanding the virome of D. citri is important for uncovering factors that influence vector competence, to support biosecurity surveillance, and to identify candidate agents for biological control. Previous studies have identified several D. citri-associated viruses from various geographical populations of this pest. To further investigate virus diversity in this pest, high-throughput sequencing was used to analyse D. citri populations from the Samoan islands of Upolu and Savai’i. Eleven novel viruses from the Yadokariviridae, Botourmiaviridae, Nodaviridae, Mymonaviridae, Partitiviridae, Totiviridae, and Polymycoviridae were identified as well as some that corresponded to unclassified groups. In addition, microbiome analysis revealed the presence of several endosymbiotic microorganisms, including Wolbachia, as well as some plant pathogenic fungi, including Botrytis cinerea. However, the causative agent of HLB disease (CLas) was not detected in the RNA-Seq data. These findings highlight the complex and diverse microbiota associated with D. citri and suggest potential interactions and dynamics between microorganisms and psyllid-associated viruses. Further research is needed to understand the ecological significance of these discoveries, and whether the novel viruses play a role in regulating field populations of the psyllid. Full article

Viral infections and their vector dynamics pose a major threat to potatoes (Solanum tuberosum L.) worldwide, urgently needing an integrated understanding of the molecular and ecological interactions in this tripartite system. This review describes the major potato viruses, namely potato virus Y (PVY), the potato leafroll virus (PLRV), and potato virus X (PVX), with an emphasis on their infection and replication strategies in plants, as well as their movement within them. It also discusses plant responses to these viruses by uncovering RNA silencing, resistance (R) genes, and hormonal signaling. The complex dynamics of virus–vector interactions are discussed, considering the modes of transmission-persistent, non-persistent and semi-persistent—the role of viral proteins such as HC-Pro in determining vector specificity and adaptations in vectors that facilitate virus dissemination. This article discusses how vectors select potato plants, with an emphasis on the role played by plant-excreted volatiles and vector-applied saliva in plant defense. It also discusses host genes that contribute to vector resistance. This review provides an overview of the interactions between potato plants, viruses, and vectors and shows how viruses influence plant–vector interactions, the molecular pathways shared, and the altered gene expression profiles due to these interactions. The review offers an integrated perspective essential for developing sustainable and precise control strategies against potato viral pathogens under changing climatic conditions. Full article

Whiteflies of the Bemisia tabaci complex, along with the plant viruses they transmit, pose significant challenges to crop production worldwide. Upon infestation or infection, intimate interactions occur between plant hosts and these pests, influencing the spread and severity of pest-related epidemics in natural and agricultural ecosystems. This review explores the role of the salicylic acid (SA) signaling pathway, an essential component of plant defense, in modulating plant interactions with whiteflies and whitefly-borne viruses. We first outline the biosynthesis and signal transduction of SA. We then analyze how whitefly infestation activates the SA signaling pathway and how this defense response affects whitefly performance and preference. Next, we explore the interactions between the SA signaling pathway and whitefly-borne plant viruses, especially begomoviruses, which often activate and manipulate this pathway. We also examine how the SA signaling pathway influences plant–whitefly–virus tripartite interactions, highlighting the significant role of this defense pathway in whitefly-induced changes in plant–virus interactions and virus-induced changes in plant–whitefly interactions. Finally, we identify key areas for future research to further unravel the complexities of plant interactions with whiteflies and whitefly-borne viruses. Full article

Tomato yellow leaf curl disease poses one of the most severe threats to tomato production worldwide. This disease is associated with a group of closely related tomato yellow leaf curl viruses. These viruses can be transmitted by the sweet potato whitefly (Bemisia tabaci) in a persistent-circulative mode. Virus particles can infect the midgut and filter chamber of whiteflies feeding on infected plants, circulate in the hemolymph, and eventually infect the primary salivary gland (PSG) of whiteflies. Later, the whiteflies feed on healthy plants, and viral particles are introduced into the plants through their saliva. Virus–vector interactions play a crucial role in the efficiency and dynamics of virus transmission. In this study, we assessed the effects of the acquisition time and viral load of source plants on infections of two tomato begomoviruses, tomato yellow leaf curl Thailand virus (TYLCTHV) and tomato leaf curl Taiwan virus (ToLCTV), in B. tabaci Middle East–Asia Minor 1. We found that more viruses were acquired and accumulated in the whitefly midgut and PSG before reaching a plateau when the acquisition time increased and when the source plant had a higher viral load. The midgut and PSG acquired and accumulated more TYLCTHV than ToLCTV with the same acquisition time and regardless of the viral loads in coinfected source plants. These results not only help us to understand virus–vector interactions but also help in developing integrated disease management strategies. Full article