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Viruses infecting plants of the genus Rubus are among the pathogens that can cause significant economic losses to growers. As there is no effective treatment, it is necessary to plant healthy propagation material to prevent their spreading. To test plant material of the genus Rubus, real-time PCR-based multiplex detection systems have been developed for the diagnostics of known viruses: Black raspberry necrosis virus (BRNV), Raspberry ringspot virus (RpRSV), Raspberry bushy dwarf virus (RBDV), Strawberry latent ringspot virus (SLRSV), Rubus yellow net virus (RYNV); and the newly discovered Raspberry rubodvirus 1 (RaRV1) and Raspberry enamovirus 1 (RaEV1). The aim of the work was to verify the functionality of these systems on samples from living plants and to evaluate the presence of each virus in five categories corresponding to different origins of samples obtained in the Czech Republic. The results of the testing show that out of a total of 297 samples tested, 72 % of the plants were found to be infected with either a single virus or co-infected with multiple viruses. The most frequently occurring virus was RYNV, which was found in 51 % of the plants tested.

Advancements in understanding and engineering of virus-based nanomaterials (VBNs) for biomedical applications motivate a need to explore the interfaces between VBNs and other biomedically-relevant chemistries and materials. While several strategies have been used to investigate some of these interfaces with promising initial results, including VBN-containing slow-release implants and VBN-activated bioceramic bone scaffolds, there remains a need to establish VBN-immobilized three dimensional materials that exhibit improved stability and diffusion characteristics for biosensing and other analyte-capture applications. Silica sol-gel chemistries have been researched for biomedical applications over several decades and are well understood; various cellular organisms and biomolecules (e.g., bacteria, algae, enzymes) have been immobilized in silica sol-gels to improve viability, activity, and form factor (i.e., ease of use). Here we present the immobilization of an antibody-binding VBN in silica sol-gel by pore confinement. We have shown that the resulting system is sufficiently diffuse to allow antibodies to migrate in and out of the matrix. We also show that the immobilized VBN is capable of antibody binding and elution functionality under different buffer conditions for multiple use cycles. The promising results of the VBN and silica sol-gel interface indicate a general applicability for VBN-based bioseparations and biosensing applications.

Ilarviruses are a relatively understudied but important group of plant RNA viruses that includes a number of crop pathogens. Their genomes comprise three RNA segments encoding two replicase subunits, movement protein, coat protein (CP), and (in some ilarvirus subgroups) a protein that suppresses RNA silencing. Here we report that, in many ilarviruses, RNA3 encodes an additional protein (termed CP-RT) as a result of ribosomal readthrough of the CP stop codon into a short downstream readthrough (RT) ORF. Using asparagus virus 2 as a model, we find that CP-RT is expressed in planta where it functions as a weak suppressor of RNA silencing. CP-RT expression is essential for persistent systemic infection in leaves and shoot apical meristem. CP-RT function is dependent on a putative zinc-finger motif within RT. Replacing the asparagus virus 2 RT with the RT of an ilarvirus from a different subgroup restored the ability to establish persistent infection. These findings open up a new avenue for research on ilarvirus silencing suppression, persistent meristem invasion and vertical transmission. Author summary: Ilarviruses comprise a group of plant-infecting RNA viruses. Until now, ilarvirus genomes were thought to only encode two components of the viral replicase, a movement protein, the capsid protein, and the 2b suppressor of RNA silencing. Interestingly, whereas most plant viruses encode one or more proteins that suppress the host antiviral RNA silencing pathway, the gene encoding 2b is only present in some ilarviruses. Here, we identify an additional ilarvirus protein that is expressed via low efficiency ribosomal readthrough of the capsid protein (CP) stop codon. Readthrough ribosomes translate a short downstream readthrough (RT) domain to produce the capsid-readthrough fusion protein, CP-RT. We show that CP-RT is a second ilarvirus suppressor of silencing protein and is required for the model ilarvirus asparagus virus 2 to maintain persistent infection in the model plant Nicotiana benthamiana. These findings advance our understanding of ilarvirus molecular virology and virus-host interaction. Interestingly, there are substantial differences in the RT peptide between divergent groups of ilarviruses and, in at least two cases, a separate RT peptide appears to have evolved independently. Thus it will be of future interest to investigate the function of CP-RT in different ilarvirus lineages. [ABSTRACT FROM AUTHOR]

Most plants produce large amounts of seeds to disperse their progeny in the environment. Plant viruses have evolved to avoid plant resistance mechanisms and use seeds for their dispersal. The presence of plant pathogenic viruses in seeds and suppression of plant host defenses is a major worldwide concern for producers and seed companies because undetected viruses in the seed can represent a significant threat to yield in many economically important crops. The vertical transmission of plant viruses occurs directly through the embryo or indirectly by getting in pollen grains or ovules. Infection of plant viruses during the early development of the seed embryo can result in morphological or genetic changes that cause poor seed quality and, more importantly, low yields due to the partial or ubiquitous presence of the virus at the earliest stages of seedling development. Understanding transmission of plant viruses and the ability to avoid plant defense mechanisms during seed embryo development will help identify primary inoculum sources, reduce virus spread, decrease severity of negative effects on plant health and productivity, and facilitate the future of plant disease management during seed development in many crops. In this article, we provide an overview of the current knowledge and understanding of plant virus transmission during seed embryo development, including the context of hostvirus interaction. [ABSTRACT FROM AUTHOR]

Introduction: Tomato cultivation across the world is severely affected by emerging plant viruses. An effective method for protection of commercial crops against viral threats is the use of cultivars harboring resistance genes. Tomato brown rugose fruit virus (ToBRFV), a recently emerged tobamovirus, is able to overcome the dominant Tm-2² resistance that is present in the majority of commercial tomato cultivars. In an effort to alleviate the severe consequences of ToBRFV on tomato production, tomato breeding companies are developing new cultivars with varying levels of resistance against ToBRFV. Methods: In the present study, cultivars with a new resistant phenotype against ToBRFV were screened against a wild-type isolate of ToBRFV, and subsequently, their performance under commercial greenhouse conditions was monitored. Following the identification of ToBRFV symptoms in a commercial greenhouse--where both new resistant and susceptible cultivars were interplanted--these cultivars were more closely examined. Results: The presence of ToBRFV was molecularly confirmed on both cultivar types suggesting that the new resistance had been broken. High-throughput sequencing (HTS) was used to study the complete genomes of viral isolates present in the two cultivar types. The analysis revealed a single amino acid change at position 82 of the movement protein of ToBRFV in the isolate present in the new resistant cultivar compared with the isolate identified in the susceptible cultivar. Discussion: A screening bioassay, that was performed to compare the infectivity of the two ToBRFV isolates, confirmed that only the isolate with this specific amino acid change could successfully infect the resistant cultivar, overcoming the new resistance against ToBRFV. [ABSTRACT FROM AUTHOR]

Potyviridae, the largest family of plant RNA viruses, includes many important pathogens that significantly reduce the yields of many crops worldwide. In this study, we report that the 6-kilodalton peptide 1 (6K1), one of the least characterized potyviral proteins, is an endoplasmic reticulum-localized protein. AI-assisted structure modeling and biochemical assays suggest that 6K1 forms pentamers with a central hydrophobic tunnel, can increase the cell membrane permeability of Escherichia coli and Nicotiana benthamiana, and can conduct potassium in Saccharomyces cerevisiae. An infectivity assay showed that viral proliferation is inhibited by mutations that affect 6K1 multimerization. Moreover, the 6K1 or its homologous 7K proteins from other viruses of the Potyviridae family also have the ability to increase cell membrane permeability and transmembrane potassium conductance. Taken together, these data reveal that 6K1 and its homologous 7K proteins function as viroporins in viral infected cells. [ABSTRACT FROM AUTHOR]

All biological forms of life rely on plants for many of their basic needs. Nonetheless, viruses can often infect plants. The ecosystem that depends on it could be destroyed as a result. An insect vector may be responsible for the virus's spread from plant to plant. A fractional order epidemic model is developed since it gives the more realistic solutions as the epidemics always persists in some or the other region and never becomes zero. The dynamics of the plant virus propagation model with effect from seasonality (PVP-S) and intraspecific competition among predators are investigated in terms of existence of solutions, boundedness, and uniqueness. Analysis of plant virus propagation with effect from seasonality and intraspecific competition among predators in terms of fractional order is the novelty of this model. Here, we observe that the infection almost becomes zero in case of integral value, whereas it always persists as the fractional order is introduced, which is more realistic in nature. The occurrence of transcritical bifurcation for the model has been investigated. The proposed nonlinear model is numerically studied by the Adams-Bashforth-Moulton method. This study reveals the effectiveness of the numerical technique as well as the effect of the fractional order derivative on PVP-S dynamics. [ABSTRACT FROM AUTHOR]

The plant cell wall is an actively reorganized network during plant growth and triggered immunity in response to biotic stress. While the molecular mechanisms managing perception, recognition, and signal transduction in response to pathogens are well studied in the context of damaging intruders, the current understanding of plant cell wall rebuilding and active defense strategies in response to plant virus infections remains poorly characterized. Pectins can act as major elements of the primary cell wall and are dynamic compounds in response to pathogens. Homogalacturonans (HGs), a main component of pectins, have been postulated as defensive molecules in plant–pathogen interactions and linked to resistance responses. This research focused on examining the regulation of selected pectin metabolism components in susceptible (rbohD-, Col-0-TuMV) and resistance (rbohF-, rbohD/F–TuMV) reactions. Regardless of the interaction type, ultrastructural results indicated dynamic cell wall rebuilding. In the susceptible reaction promoted by RbohF, there was upregulation of AtPME3 (pectin methylesterase) but not AtPME17, confirmed by induction of PME3 protein deposition. Moreover, the highest PME activity along with a decrease in cell wall methylesters compared to resistance interactions in rbohD–TuMV were noticed. Consequently, the susceptible reaction of rbohD and Col-0 to TuMV was characterized by a significant domination of low/non-methylesterificated HGs. In contrast, cell wall changes during the resistance response of rbohF and rbohD/F to TuMV were associated with dynamic induction of AtPMEI2, AtPMEI3, AtGAUT1, and AtGAUT7 genes, confirmed by significant induction of PMEI2, PMEI3, and GAUT1 protein deposition. In both resistance reactions, a dynamic decrease in PME activity was documented, which was most intense in rbohD/F–TuMV. This decrease was accompanied by an increase in cell wall methylesters, indicating that the domination of highly methylesterificated HGs was associated with cell wall rebuilding in rbohF and rbohD/F defense responses to TuMV. These findings suggest that selected PME with PMEI enzymes have a diverse impact on the demethylesterification of HGs and metabolism as a result of rboh–TuMV interactions, and are important factors in regulating cell wall changes depending on the type of interaction, especially in resistance responses. Therefore, PMEI2 and PMEI3 could potentially be important signaling resistance factors in the rboh–TuMV pathosystem. [ABSTRACT FROM AUTHOR]

Several species of Thysanoptera are considered agricultural pests, especially Frankliniella occidentalis (Western Flower Thrips, WFT). The damage WFT causes to plants can either be direct by feeding and oviposition activity or indirect by WFT serving as vectors for several plant viruses, bacteria, and fungi. Properties of WFT like polyphagy, cryptic lifestyle, fast reproduction and the ability to quickly develop insecticide resistance make them difficult to control. Alternative pest management tactics are thus in high demand. Potential targets are the facultative or obligate endosymbionts that affect the life history parameters of WFT. The known endosymbionts of WFT: BFo1/BFo2 (B = bacteria, Fo = Frankliniella occidentalis, number indicate different types) positively influence their fertility and development. Elimination of these endosymbionts could result in a decreased individual reproduction level and decreased population growth. Bacteriophages specific against BFo1/BFo2 were isolated and characterized and were applied in a nochoice feeding assay to female WFT. Antibiotic and sugar solutions served as controls. Phage-treated thrips showed no significant difference in survival, fecundity, oviposition rate or developmental time of the progeny compared to the control, whereas antibiotic treatment caused a decline in survival, fecundity, and oviposition rate, but not in the developmental time of offspring. The results showed a rapid decline of the bacteriophage concentration in the feed solution, which the WFT salivary gland products might cause. The complex relationship between thrips, endosymbionts and bacteriophages, needs further attention before bacteriophages could be used as potential management tools. [ABSTRACT FROM AUTHOR]

MicroRNA(miRNA) is a class of non‐coding small RNA that plays an important role in plant growth, development, and response to environmental stresses. Unlike most miRNAs, which usually target homologous genes across a variety of species, miR827 targets different types of genes in different species. Research on miR827 mainly focuses on its role in regulating phosphate (Pi) homeostasis of plants, however, little is known about its function in plant response to virus infection. In the present study, miR827 was significantly upregulated in the recovery tissue of virus‐infected Nicotiana tabacum. Overexpression of miR827 could improve plants resistance to the infection of chilli veinal mottle virus (ChiVMV) in Nicotiana benthamiana, whereas interference of miR827 increased the susceptibility of the virus‐infected plants. Further experiments indicated that the antiviral defence regulated by miR827 was associated with the reactive oxygen species and salicylic acid signalling pathways. Then, fructose‐1,6‐bisphosphatase (FBPase) was identified to be a target of miR827, and virus infection could affect the expression of FBPase. Finally, transient expression of FBPase increased the susceptibility to ChiVMV‐GFP infection in N. benthamiana. By contrast, silencing of FBPase increased plant resistance. Taken together, our results demonstrate that miR827 plays a positive role in tobacco response to virus infection, thus providing new insights into understanding the role of miR827 in plant‐virus interaction. [ABSTRACT FROM AUTHOR]

A cost-effective DNA extraction approach was developed and applied to PCR-based identification of yellow mosaic disease (YMD) causing viruses in individual whiteflies. Whiteflies were collected from urdbean and eggplant, representing host and non-host plants of target viruses, respectively. DNA from whiteflies was successfully extracted using the nuclease-free water boiling method and optimised template concentration for PCR assays. An average nucleic acid content of 3.844 ± 0.14 ng/µl was extracted from individual whiteflies in 50 µl nuclease-free water. PCR assays revealed Mungbean yellow mosaic India virus (MYMIV) presence in 90% of the whiteflies collected from urdbean. Conversely, YMD-causing viruses were not present in whiteflies collected from eggplant or in the eggplant plants themselves. The use of this low-cost approach for detecting YMD-causing viruses in whiteflies is very effective for the surveillance and monitoring of viruses. Early detection facilitates the deployment of appropriate management strategies, reducing both crop losses and the potential for outbreaks. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum) is a crucial vegetable globally, pivotal in securing the world's food supply. However, viral diseases pose a significant threat to tomato cultivation, resulting in considerable yield losses. Employing sensitive, rapid, and cost‐effective detection methods is imperative for mitigating such losses in agricultural production. In response, we developed a Taqman® probe‐based real‐time multiplex PCR method capable of concurrently detecting three major plant viruses: Tomato brown rugose fruit virus (ToBRFV), tomato spotted wilt orthotospovirus (TSWV), and pepino mosaic virus (PepMV), all of which are prominent viral pathogens affecting tomato production. Utilizing envelope protein encoding sequences of these pathogens, we designed primers and probes, assigning the FAM reporter for ToBRFV, the HEX reporter for TSWV, and the Cy5 reporter for PepMV detection. The multiplex RT‐qPCR experiment yielded successful results, with Ct values of 29.34, 25.93, and 27.47 for ToBRFV (at 10−6 dilution), TSWV (at 10−2 dilution), and PepMV (at 10−3 dilution), respectively. Developed primers facilitate the early detection of destructive pathogens ToBRFV, TSWV, and PepMV using both RT‐PCR and RT‐qPCR, offering a user‐friendly and cost‐effective approach. [ABSTRACT FROM AUTHOR]

The study of herbivorous arthropod vectors of plant pathogens has been a subdiscipline within entomology for more than a century. It was recognized as a unique field with the establishment of a Subsection (Cc) in the Entomological Society of America (ESA) from 1953 through 2007. During that period, work in the field expanded from an initial emphasis on management of vector-borne plant pathogens to include biology of the pathosystems. Since 2007, when ESA reorganized the subsections within the society, work on herbivorous vectors of plant pathogens has continued to grow. This article briefly summarizes the work in this field prior to, during, and after the ESA Subsection Cc era. We identify and describe 4 research areas that have characterized the field since 2007: Molecular mechanisms of vector–plant interactions, managing vectors and pathogen transmission in agriculture, illuminating the ecology of vectors and pathogens outside of crops, and pathogen manipulation of host phenotypes and vector behavior. We then identify 10 frontiers and prospects for the field in the coming years that build on these 4 research areas, ranging from molecular and cellular aspects to ramifications for managed and natural ecosystems. We also examine trends in funding and professional opportunities for scientists working on herbivorous vectors and pathogens. Finally, we renew the call for greater integration of work addressing vector-borne plant, animal, and human pathogens due to fundamental similarities in their biology and importance for human well-being within an expanded understanding of the "One Health" paradigm, which currently emphasizes human and animal health. [ABSTRACT FROM AUTHOR]

Orius similis Zheng, a predatory bug that feeds on Frankliniella occidentalis (Pergande), a pest that damages vegetables and ornamental plants by feeding and transforming plant viruses. O. similis is an omnivorous predator on thrips, as well as pollen. Our study investigated the impact of five different amount densities of thrips and abundant loofah pollen on the survival, development, fecundity, and consumption of O. similis. The performance of O. similis nymphs and adults was significantly affected by the density of thrips and loofah pollen on which they fed. The highest survival and shortest development period of O. similis nymphs after feeding on 40 thrips/d, while the lowest survival rate and longest period were observed after feeding on only 5 thrips. Feeding on loofah pollen alone also significantly increased survival and decreased the nymph development period compared with feeding on 20 thrips/d. The highest prey consumption occurred at densities of 30 and 40 thrips/d, while the lowest prey consumption occurred at a thrips density of 5, regardless of whether the O. similis were nymphs or female adults. However, adding loofah pollen decreased prey consumption of nymphs and adult females. In addition, O. similis showed higher fecundity and longevity when feeding on 40 thrips/d compared to other thrips densities and adding loofah pollen. Adding loofah pollen also increased fecundity and longevity compared to feeding on thrips alone at the same density, regardless of the thrips' density. Therefore, a high thrips abundant density daily was beneficial for the development, fecundity, and longevity of O. similis, and adding loofah pollen can enhance their performance. [ABSTRACT FROM AUTHOR]

The best-characterized functional motifs of the potyviral Helper-Component protease (HC-Pro) responding for aphid transmission, RNA silencing suppression, movement, symptom development, and replication are gathered in this review. The potential cellular protein targets of plant virus proteases remain largely unknown despite their multifunctionality. The HC-Pro catalytic domain, as a cysteine protease, autoproteolytically cleaves the potyviral polyproteins in the sequence motif YXVG/G and is not expected to act on host targets; however, 146 plant proteins in the Viridiplantae clade containing this motif were searched in the UniProtKB database and are discussed. On the other hand, more than 20 interactions within the entire HC-Pro structure are known. Most of these interactions with host targets (such as the 20S proteasome, methyltransferase, transcription factor eIF4E, and microtubule-associated protein HIP2) modulate the cellular environments for the benefit of virus accumulation or contribute to symptom severity (interactions with MinD, Rubisco, ferredoxin) or participate in the suppression of RNA silencing (host protein VARICOSE, calmodulin-like protein). On the contrary, the interaction of HC-Pro with triacylglycerol lipase, calreticulin, and violaxanthin deepoxidase seems to be beneficial for the host plant. The strength of these interactions between HC-Pro and the corresponding host protein vary with the plant species. Therefore, these interactions may explain the species-specific sensitivity to potyviruses. [ABSTRACT FROM AUTHOR]

Aphid infestations are one of the primary causes of extensive damage to wheat and sorghum fields and are one of the most common vectors for plant viruses, resulting in significant agricultural yield losses. To address this problem, farmers often employ the inefficient use of harmful chemical pesticides that have negative health and environmental impacts. As a result, a large amount of pesticide is wasted on areas without significant pest infestation. This brings to attention the urgent need for an intelligent autonomous system that can locate and spray sufficiently large infestations selectively within the complex crop canopies. We have developed a large multi-scale dataset for aphid cluster detection and segmentation, collected from actual sorghum fields and meticulously annotated to include clusters of aphids. Our dataset comprises a total of 54,742 image patches, showcasing a variety of viewpoints, diverse lighting conditions, and multiple scales, highlighting its effectiveness for real-world applications. In this study, we trained and evaluated four real-time semantic segmentation models and three object detection models specifically for aphid cluster segmentation and detection. Considering the balance between accuracy and efficiency, Fast-SCNN delivered the most effective segmentation results, achieving 80.46% mean precision, 81.21% mean recall, and 91.66 frames per second (FPS). For object detection, RT-DETR exhibited the best overall performance with a 61.63% mean average precision (mAP), 92.6% mean recall, and 72.55 on an NVIDIA V100 GPU. Our experiments further indicate that aphid cluster segmentation is more suitable for assessing aphid infestations than using detection models. [ABSTRACT FROM AUTHOR]

The signature feature of all plant viruses is the encoding of movement proteins (MPs) that supports the movement of the viral genome into adjacent cells and through the vascular system. The recent discovery of umbravirus-like viruses (ULVs), some of which only encode replication-associated proteins, suggested that they, as with umbraviruses that lack encoded capsid proteins (CPs) and silencing suppressors, would require association with a helper virus to complete an infection cycle. We examined the infection properties of 2 ULVs: citrus yellow vein associated virus 1 (CY1), which only encodes replication proteins, and closely related CY2 from hemp, which encodes an additional protein (ORF5CY2) that was assumed to be an MP. We report that both CY1 and CY2 can independently infect the model plant Nicotiana benthamiana in a phloem-limited fashion when delivered by agroinfiltration. Unlike encoded MPs, ORF5CY2 was dispensable for infection of CY2, but was associated with faster symptom development. Examination of ORF5CY2 revealed features more similar to luteoviruses/poleroviruses/sobemovirus CPs than to 30K class MPs, which all share a similar single jelly-roll domain. In addition, only CY2-infected plants contained virus-like particles (VLPs) associated with CY2 RNA and ORF5CY2. CY1 RNA and a defective (D)-RNA that arises during infection interacted with host protein phloem protein 2 (PP2) in vitro and in vivo, and formed a high molecular weight complex with sap proteins in vitro that was partially resistant to RNase treatment. When CY1 was used as a virus-induced gene silencing (VIGS) vector to target PP2 transcripts, CY1 accumulation was reduced in systemic leaves, supporting the usage of PP2 for systemic movement. ULVs are therefore the first plant viruses encoding replication and CPs but no MPs, and whose systemic movement relies on a host MP. This explains the lack of discernable helper viruses in many ULV-infected plants and evokes comparisons with the initial viruses transferred into plants that must have similarly required host proteins for movement. The spread of viral genomes into adjacent cells and the plant vascular system is enabled by viral movement proteins. This study shows that umbravirus-like RNA viruses can spread systemically without encoding any, through the interaction of viral replication and capsid proteins with host protein PHLOEM PROTEIN 2. [ABSTRACT FROM AUTHOR]

Background: Since the 2000's, plants have been used as bioreactors for the transient production of molecules of interest such as vaccines. To improve protein yield, "amplicon" vectors based on plant viruses are used. These viral constructs, engineered to carry the gene of interest replicate strongly once introduced into the plant cell, allowing significant accumulation of the protein. Here, we evaluated the suitability of the monocot-infecting RNA virus Rice yellow mottle virus (RYMV) as an amplicon vector. The promastigote surface antigen (PSA) of the protozoan Leishmania was considered as a protein of interest due to its vaccine properties against canine leishmaniasis. Results: Since P1 (ORF1) and CP (ORF3) proteins are not strictly necessary for viral replication, ORF1 was deleted and the PSA gene was substituted to ORF3 in the RYMV-based vector. We evaluated its expression in the best described plant bioreactor system, Nicotiana benthamiana which, unlike rice, allows transient transformation by Agrobacterium. Despite not being its natural host, we demonstrated a low level of RYMV-based vector replication in N. benthamiana leaves. Under optimized ratio, we showed that the P19 silencing suppressor in combination with the missing viral CP ORF significantly enhanced RYMV amplicon replication in N. benthamiana. Under these optimized CP/P19 conditions, we showed that the RYMV amplicon replicated autonomously in the infiltrated N. benthamiana cells, but was unable to move out of the infiltrated zones. Finally, we showed that when the RYMV amplicon was expressed under the optimized conditions we set up, it allowed enhanced PSA protein accumulation in N. benthamiana compared to the PSA coding sequence driven by the 35S promoter without amplicon background. Conclusion: This work demonstrates that a non-dicot-infecting virus can be used as an amplicon vector for the efficient production of proteins of interest such as PSA in N. benthamiana leaves. [ABSTRACT FROM AUTHOR]

Background: Lablab (Lablab purpureus) is a potential vegetable crop cultivated throughout India. It is a tropical and subtropical vegetable adaptive to different climatic conditions and grown in all seasons. Thrips are one of the important pests of lablab as they affect all stages of the crop and transmit plant viruses. The current study aimed at identifying the thrips diversity present in lablab as a base for monitoring and management purposes. Methods: An exploratory survey was conducted to identify the diversity of thrips on lablab in its growing areas of Coimbatore. Furthermore, continuous monitoring of the lablab crops in TNAU orchard, Coimbatore, was done to explore all the life stages of thrips species and their diversity. Morphological and molecular characterization of the collected species was done using taxonomic keys and mtCOI DNA sequencing approach. Result: Thrips palmi and Thrips tabaci were observed during the crop's early stages before blossoming. Frankliniella schultzei is a polyphagous pest species that has been found infesting all phases of crop development, from early leaf through pod formation. During and after blooming, the four species Megalurothrips usitatus, Thrips parvispinus, Chaetanaphothrips orchidii and Haplothrips gowdeyi began to infest. Shannon and Simpson diversity indices were determined to be -1.739 and -0.1979. According to Shannon index, C. orchidii and T. parvispinus were the first and second predominant species after flowering. Taxonomic investigations of the collected species were done and substantiated with molecular identification of those analyzed species. A phylogenetic tree of the analyzed sequences was constructed to denote species divergence based on their specific sequences. [ABSTRACT FROM AUTHOR]

Tobamoviruses are a group of plant viruses that pose a significant threat to agricultural crops worldwide. In this review, we focus on plant immunity against tobamoviruses, including pattern-triggered immunity (PTI), effector-triggered immunity (ETI), the RNA-targeting pathway, phytohormones, reactive oxygen species (ROS), and autophagy. Further, we highlight the genetic resources for resistance against tobamoviruses in plant breeding and discuss future directions on plant protection against tobamoviruses. [ABSTRACT FROM AUTHOR]

In 1929, it was reported that yellowing symptoms caused by a tobacco mosaic virus (TMV) yellow mosaic isolate were suppressed in tobacco plants that were systemically infected with a TMV light green isolate. Similar to vaccination, the phenomenon of cross-protection involves a whole plant being infected with an attenuated virus and involves the same or a closely related virus species. Therefore, attenuated viruses function as biological control agents. In Japan, many studies have been performed on cross-protection. For example, the tomato mosaic virus (ToMV)-L11A strain is an attenuated isolate developed by researchers and shows high control efficiency against wild-type ToMV in commercial tomato crops. Recently, an attenuated isolate of zucchini yellow mosaic virus (ZYMV)-2002 was developed and registered as a biological pesticide to control cucumber mosaic disease. In addition, attenuated isolates of pepper mild mottle virus (PMMoV), cucumber mosaic virus (CMV), tobacco mild green mosaic virus (TMGMV), melon yellow spot virus (MYSV), and watermelon mosaic virus (WMV) have been developed in Japan. These attenuated viruses, sometimes called plant vaccines, can be used not only as single vaccines but also as multiple vaccines. In this review, we provide an overview of studies on attenuated plant viruses developed in Japan. We also discuss the application of the attenuated strains, including the production of vaccinated seedlings. [ABSTRACT FROM AUTHOR]

In Australia, Soldier flies (Inopus spp.) are economically significant pests of sugarcane that currently lack a viable management strategy. Despite various research efforts, the mechanisms underlying the damage caused by soldier fly larvae remain poorly understood. Our study aims to explore whether this damage is associated with the transmission of plant viruses during larval feeding. We also explore the larval transcriptome to identify any entomopathogenic viruses with the potential to be used as biocontrol agents in future pest management programs. Seven novel virus sequences are identified and characterised using de novo assembly of RNA-Seq data obtained from salivary glands of larvae. The novel virus sequences belong to different virus families and are tentatively named SF-associated anphevirus (SFaAV), SF-associated orthomyxo-like virus (SFaOV), SF-associated narna-like virus (SFaNV), SF-associated partiti-like virus (SFaPV), SF-associated toti-like virus (SFaTV-1 and SFaTV-2) and SF-associated densovirus (SFaDV). These newly identified viruses are more likely insect-associated viruses, as phylogenetic analyses show that they cluster with other insect-specific viruses. Small RNA analysis indicates prominent peaks at both 21 nt and 26–29 nt, suggesting the activation of host siRNA and piwiRNA pathways. Our study helps to improve understanding of the virome of soldier flies and could identify insect viruses for deployment in novel pest management strategies. [ABSTRACT FROM AUTHOR]

Glycosylation, a dynamic modification prevalent in viruses and higher eukaryotes, is principally regulated by uridine diphosphate (UDP)-glycosyltransferases (UGTs) in plants. Although UGTs are involved in plant defense responses, their responses to most pathogens, especially plant viruses, remain unclear. Here, we aimed to identify UGTs in the whole genome of Nicotiana benthamiana (N. benthamiana) and to analyze their function in Chinese wheat mosaic virus (CWMV) infection. A total of 147 NbUGTs were identified in N. benthamiana. To conduct a phylogenetic analysis, the UGT protein sequences of N. benthamiana and Arabidopsis thaliana were aligned. The gene structure and conserved motifs of the UGTs were also analyzed. Additionally, the physicochemical properties and predictable subcellular localization were examined in detail. Analysis of cis-acting elements in the putative promoter revealed that NbUGTs were involved in temperature, defense, and hormone responses. The expression levels of 20 NbUGTs containing defense-related cis-acting elements were assessed in CWMV-infected N. benthamiana, revealing a significant upregulation of 8 NbUGTs. Subcellular localization analysis of three NbUGTs (NbUGT12, NbUGT16 and NbUGT17) revealed their predominant localization in the cytoplasm of N. benthamiana leaves, and NbUGT12 was also distributed in the chloroplasts. CWMV infection did not alter the subcellular localization of NbUGT12, NbUGT16, and NbUGT17. Transient overexpression of NbUGT12, NbUGT16, and NbUGT17 enhanced CWMV infection, whereas the knockdown of NbUGT12, NbUGT16 and NbUGT17 inhibited CWMV infection in N. benthamiana. These NbUGTs could serve as potential susceptibility genes to facilitate CWMV infection. Overall, the findings throw light on the evolution and function of NbUGTs. [ABSTRACT FROM AUTHOR]

The sweet potato whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is responsible for significant crop losses and presents one of the greatest challenges for global agricultural pest management. Management of whitefly populations and associated plant viral diseases is hindered by widespread whitefly resistance to chemical insecticides. An alternative control approach involves the use of insect‐specific neurotoxins, but these require delivery from the whitefly gut into the haemocoel. Here we demonstrate that the coat protein (CP) of a begomovirus, Tomato yellow leaf curl virus, is sufficient for delivery of fused proteins into the whitefly haemocoel without virion assembly. Following feeding on the recombinant CP‐P‐mCherry fusion (where ‐P‐ is a proline‐rich linker), mCherry fluorescence was detected in the dorsal aorta and pericardial cells of the whitefly, but not in those of whitefly fed on negative control treatments, indicating effective CP‐mediated delivery of mCherry into the whitefly haemocoel. Significant mortality was observed in whiteflies fed on a fusion of CP‐P to the insect‐specific neurotoxin Hv1a, but not in whiteflies fed on CP‐P fused to a disarmed Hv1a mutant. Begomovirus coat protein – insect neurotoxin fusions hold considerable potential for transgenic resistance to whitefly providing valuable tools for whitefly management. [ABSTRACT FROM AUTHOR]

Maize lethal necrosis (MLN) is a viral disease caused by co-infection of Maize chlorotic mottle virus (MCMV) and a potyvirus mostly Sugarcane mosaic virus (SCMV). MLN is one of the most important maize production constraints in East Africa including Ethiopia. In this study molecular characterization was used to determine potential insect vectors that transmit MLN causing viruses in Ethiopia. Suspected insect vectors of MLN causing viruses collected from maize fields were initially identified to a genus/species level based on the morphological features. Further taxonomic determination was carried out using DNA sequencing from cytochrome oxidase primers. Pre-identified insect vectors of MLN-causing viruses were separately tested in the greenhouse for potential transmission of MCMV and SCMV. Accordingly, maize thrips, Franklinella sp. (Thysanoptera: Thripidae) and cereal leaf beetle, Oulema sp. (Coleoptera: Chrysomelidae) transmitted MCMV, whereas corn leaf aphids, Rhopalosiphum maidis Fich (Hemiptera: Aphididae) transmitted SCMV. Out of 86 maize fields surveyed, Franklinella sp. were widely distributed in 22 (25.6%) fields, mostly in Arsi and West Shewa zones of Oromia region. R. maidis was abundant in all the areas assessed, suggesting that this insect spp. is a vector for SCMV in Ethiopia. The presence of insects as vectors of MLN causing viruses on maize plants is believed to contribute to the widespread of MLN viruses from plant to plant, field to field and to new geographical areas. Thus, managing these vectors through appropriate control measures can reduce maize yield losses caused by MLN disease. [ABSTRACT FROM AUTHOR]

Summary: Viral nanoparticles (VNPs) are a new class of virus‐based formulations that can be used as building blocks to implement a variety of functions of potential interest in biotechnology and nanomedicine. Viral coat proteins (CP) that exhibit self‐assembly properties are particularly appropriate for displaying antigens and antibodies, by generating multivalent VNPs with therapeutic and diagnostic potential. Here, we developed genetically encoded multivalent VNPs derived from two filamentous plant viruses, potato virus X (PVX) and tobacco etch virus (TEV), which were efficiently and inexpensively produced in the biofactory Nicotiana benthamiana plant. PVX and TEV‐derived VNPs were decorated with two different nanobodies recognizing two different regions of the receptor‐binding domain (RBD) of the SARS‐CoV‐2 Spike protein. The addition of different picornavirus 2A ribosomal skipping peptides between the nanobody and the CP allowed for modulating the degree of VNP decoration. Nanobody‐decorated VNPs purified from N. benthamiana tissues successfully recognized the RBD antigen in enzyme‐linked immunosorbent assays and showed efficient neutralization activity against pseudoviruses carrying the Spike protein. Interestingly, multivalent PVX and TEV‐derived VNPs exhibited a neutralizing activity approximately one order of magnitude higher than the corresponding nanobody in a dimeric format. These properties, combined with the ability to produce VNP cocktails in the same N. benthamiana plant based on synergistic infection of the parent PVX and TEV, make these green nanomaterials an attractive alternative to standard antibodies for multiple applications in diagnosis and therapeutics. [ABSTRACT FROM AUTHOR]

Plant viruses produce particular suppressors to antagonize the host defense response of RNA silencing to establish infection. Cucurbit chlorotic yellows virus (CCYV), a member of the genus Crinivirus of the family Closteroviridae, severely damages the production of economically essential cucurbits worldwide. Here, we used the attenuated zucchini yellow mosaic virus (ZYMV) vector ZAC to express individual coding sequences, including CP, CPm, P25, and P22, of a Taiwan CCYV isolate (CCYV-TW) to identify their possible roles as pathogenicity determinants. ZAC is an HC-Pro function mutant that lacks the ability of local lesion induction on Chenopodium quinoa leaves and induces mild mottling followed by recovery on its natural host zucchini squash plants. Only the recombinant expressing CCYV-TW P22 complemented the effect of ZAC HC-Pro dysfunction, causing more severe symptoms on zucchini squash plants and restoring lesion formation on C. quinoa leaves, with lesions forming faster than those generated by the wild-type ZYMV. This suggests that CCYV-TW P22 is a virulence enhancer. Sequence analysis of criniviral P22s revealed the presence of four conserved leucine residues (L10, L17, L84, and L127) and one conserved lysine residue (K185). The five P22 residues conserved among the CCYV isolates and the P22 orthologs of two other criniviruses were each substituted with alanine in CCYV-TW P22 to investigate its ability to suppress RNA silencing and pathogenicity. The results provide new insights into CCYV-P22, showing that the L127 residue of P22 is indispensable for maintaining its stability in RNA silencing suppression and essential for virulence enhancement. [ABSTRACT FROM AUTHOR]

Chronic obstructive pulmonary disease is a chronic inflammatory lung disease that causes airflow obstruction in the lungs. In fact, it is a lung disease that can cause involvement of respiratory tracts, lung tissue or blood vessels. There is still no accurate diagnostic tool for COPD. Among various biomarkers, the current review focuses on different types of miRNAs in COPD which have been studied. Many target cells and molecules, microRNAs are involved in the pathogenesis of COPD. MicroRNAs are a group of protected short single-stranded RNAs between 19 and 23 nucleotides and non-coding, which act as post-transcriptional regulators in animals, plants and viruses. In this article, the aim is to collect and categorize the studies conducted in the field of microRNA as biomarkers in COPD patients. [ABSTRACT FROM AUTHOR]

The prevalence of cotton leaf curl disease (CLCuD) has significantly hampered chili (Capsicum spp.) production, presenting a formidable challenge in Pakistan. During a chili field survey in 2018, distinct symptoms, including stunted growth, yellowing, and severe leaf curling, were observed on several plants. Subsequently, a comprehensive sampling effort was undertaken, collecting a total of 39 symptomatic samples from diverse locations across Multan, Punjab. The DNA extraction from these samples was conducted at the plant virology laboratory at Bahauddin Zakariya University, Multan, marking a crucial step in the investigation of this debilitating disease and its impact on chili production in the region. Molecular analysis with PCR using Av/Ac Core, Beta 01/02, and CLCuMuBF11/R33 primers confirmed begomovirus infection in chili plants. Positive amplification demonstrated a 71.79% infection rate, with 579 bp, 1.4 kb, and 481 bp amplicons for Av/Ac Core, Beta 01/02, and CLCuMuBF11/R33, respectively. Sequencing identified cotton leaf curl Multan beta-satellite (MT668934) infecting the chili plant. Effectively managing these begomoviruses is crucial to curbing their multiplication and protecting vital crops like chili. Addressing the distributions of beta-satellites in agricultural fields, particularly chili, is imperative to prevent further viral spread. [ABSTRACT FROM AUTHOR]

Viral diseases pose a threat to fruit tree growth. In this study, we observed some pimple-shaped 'Yali' pears (Pyrus bretschneideri Rehd.) and investigated their viral components. We used virome analysis to elucidate the viral composition within the pimple-shaped fruit. RT-PCR was applied to detect the plant viruses of fruits, leaves, and branches in 'Yali' pear. We also constructed a phylogenetic tree based on the amino acid sequences of the movement proteins of 6 apple stem grooving virus (ASGV) isolates and 44 ASGVs from the NCBI database. We detected ASGV and apple stem pitting virus (ASPV) in the pimple-shaped pear fruits, which is the first report of these viruses existing in 'Yali' pear fruits. ASGV was present in all pimple-shaped fruit samples from six 'Yali' pear-producing regions. The phylogenetic tree showed that ASGVs from pears, apples, and citrus plants were separated into different branches, suggesting that hosts influence the genetic diversity of ASGV. Our study revealed the viral components and genetic variation of ASGV in pimple-shaped pear fruit, providing new insights into the epidemiology of this virus. [ABSTRACT FROM AUTHOR]

Currently, there are approximately 6500 species of viruses known in the world, among which more than 1500 are plant viruses. Most of them are capable of causing epiphytoties, which lead to decreased yields, reduced product quality, and sometimes put valuable commercial varieties or even entire plant species at risk of extinction. The global spread of viruses leads to the need to strengthen phytosanitary and quarantine restrictions, which requires additional financial costs. Understanding of viral biology and the principles of its propagation is a key factor in the formation of strategies and methods for combating these pathogens. Among the newest approaches are the genetic engineering technologies. Their use made it possible to create a number of plant varieties with increased resistance to viruses. However, the problem of creating virus-resistant plants still remains one of the most urgent since viruses acquire the ability to bypass defense mechanisms with time and there is a need to obtain new resistant varieties. There are several main approaches for obtaining of transgenic plants with increased resistance to viruses. They are based on RNA interference, resistance associated with viral capsid proteins, RNA-satellites, antisense RNAs, replicases, RNA-dependent RNA polymerase, the action of ribonucleases, ribosome-inactivating proteins, hammerhead ribozymes, miRNAs, plant antibodies, etc. One of the approaches to creating virus-resistant plants is the use of ribonuclease genes. The genes encoding ribonucleases have different origin and belong to a wide range of hosts: bacteria, fungi, plants, and animals. In particular, extracellular ribonucleases are able to cut nonspecifically molecules of viral RNA in apoplast that allows for creating plants with increased resistance to various plant viruses. This review is focused on the study of various genetic engineering approaches and the prospects of their use for the creation of virus-resistant plants. Emphasis is placed on the study of heterologous ribonuclease genes influence. [ABSTRACT FROM AUTHOR]

Chemical pesticide delivery is a fundamental aspect of agriculture. However, the extensive use of pesticides severely endangers the ecosystem because they accumulate on crops, in soil, as well as in drinking and groundwater. New frontiers in nano-engineering have opened the door for precision agriculture. We introduced Tobacco mild green mosaic virus (TMGMV) as a viable delivery platform with a high aspect ratio and favorable soil mobility. In this work, we assess the use of TMGMV as a chemical nanocarrier for agriculturally relevant cargo. While plant viruses are usually portrayed as rigid/solid structures, these are "dynamic materials," and they "breathe" in solution in response to careful adjustment of pH or bathing media [e.g., addition of solvent such as dimethyl sulfoxide (DMSO)]. Through this process, coat proteins (CPs) partially dissociate leading to swelling of the nucleoprotein complexes—allowing for the infusion of active ingredients (AI), such as pesticides [e.g., fluopyram (FLP), clothianidin (CTD), rifampicin (RIF), and ivermectin (IVM)] into the macromolecular structure. We developed a "breathing" method that facilitates inter-coat protein cargo loading, resulting in up to ~ 1000 AIs per virion. This is of significance since in the agricultural setting, there is a need to develop nanoparticle delivery strategies where the AI is not chemically altered, consequently avoiding the need for regulatory and registration processes of new compounds. This work highlights the potential of TMGMV as a pesticide nanocarrier in precision farming applications; the developed methods likely would be applicable to other protein-based nanoparticle systems. [ABSTRACT FROM AUTHOR]

The presence of viruses that spread to both plant and fungal populations in nature has posed intriguingly scientific question. We found a negative-strand RNA virus related to members of the family Phenuiviridae, named Valsa mali negative-strand RNA virus 1 (VmNSRV1), which induced strong hypovirulence and was prevalent in a population of the phytopathogenic fungus of apple Valsa canker (Valsa mali) infecting apple orchards in the Shaanxi Province of China. Intriguingly, VmNSRV1 encodes a protein with a viral cell-to-cell movement function in plant tissue. Mechanical leaf inoculation showed that VmNSRV1 could systemically infect plants. Moreover, VmNSRV1 was detected in 24 out of 139 apple trees tested in orchards in Shaanxi Province. Fungal inoculation experiments showed that VmNSRV1 could be bidirectionally transmitted between apple plants and V. mali, and VmNSRV1 infection in plants reduced the development of fungal lesions on leaves. Additionally, the nucleocapsid protein encoded by VmNSRV1 is associated with and rearranged lipid droplets in both fungal and plant cells. VmNSRV1 represents a virus that has adapted and spread to both plant and fungal hosts and shuttles between these two organisms in nature (phyto-mycovirus) and is potential to be utilized for the biocontrol method against plant fungal diseases. This finding presents further insights into the virus evolution and adaptation encompassing both plant and fungal hosts. [ABSTRACT FROM AUTHOR]

Lisianthus (Eustoma russellianum) is one of the emerging cut flower crops in international flower market quickly ranked in top ten cut flowers worldwide. Despite its rising popularity, studies relating to the identification and characterization of viral diseases affecting it are lacking from India. Thus, the present study was focused on identification and characterization of virus in lisianthus plants samples collected from Vensai Floritech, Narasihmanahalli village, Tubagere hobli, Doddaballapur taluk, Bengaluru rural district, Karnataka state, India exhibiting symptoms similar to begomoviruses infections. Association of the begomovirus with sample was confirmed by PCR using begomovirus specific primers which resulted in the expected amplicon (~ 1.2 kb). Further, whole-genome amplification was done by rolling circle amplification (RCA) for one representative sample (LIS-1). The amplified RCA product was cloned, sequenced and analyzed. The phylogenetic and nucleotide (nt) sequence analysis revealed that the begomovirus associated with lisianthus plants showed the maximum nt identity of 91.0% with sida yellow vein Madurai virus (SIYVMV-TN:OM141480) infecting a weed, Sida cordata, reported from Tamil Nadu, India, which is geographically close to Karnataka. Based on species demarcation criteria for begomoviruses, the collected isolate is identified as a strain of sida yellow vein Madurai virus associated with leaf curl of lisianthus from India and proposed the name "Sida yellow vein Madurai virus -[India:Karnataka:Doddaballapura:Lisianthus:2023]" and designated as SIYVMV-[IN:Kar:Dod:Lis:23]. Further, recombination analysis revealed a single intra-specific recombination event in the genomic region. Hence, this study provides a one more evidence of expanding host range for begomoviruses in India. [ABSTRACT FROM AUTHOR]

The flower thrips Frankliniella intonsa (Thysanoptera: Thripidae) is a common insect found in flowers of many plants. Sometimes, F. intonsa causes damage to crops through direct feeding and transmission of plant viruses. Here, we assembled a chromosomal level genome of F. intonsa using the Illumina, Oxford Nanopore (ONT), and Hi-C technologies. The assembled genome had a size of 209.09 Mb, with a contig N50 of 997 bp, scaffold N50 of 13.415 Mb, and BUSCO completeness of 92.5%. The assembled contigs were anchored on 15 chromosomes. A set of 14,109 protein-coding genes were annotated in the genome with a BUSCO completeness of 95.0%. The genome contained 491 non-coding RNA and 0.57% of interspersed repeats. This high-quality genome provides a valuable resource for understanding the ecology, genetics, and evolution of F. intonsa, as well as for controlling thrips pests. [ABSTRACT FROM AUTHOR]

Wastewater surveillance has proven a cost-effective key public health tool to understand a wide range of community health diseases and has been a strong source of information on community levels and spread for health departments throughout the SARS- CoV-2 pandemic. Studies spanning the globe demonstrate the strong association between virus levels observed in wastewater and quality clinical case information of the population served by the sewershed. Few of these studies incorporate the temporal dependence present in sampling over time, which can lead to estimation issues which in turn impact conclusions. We contribute to the literature for this important public health science by putting forward time series methods coupled with statistical process control that (1) capture the evolving trend of a disease in the population; (2) separate the uncertainty in the population disease trend from the uncertainty due to sampling and measurement; and (3) support comparison of sub-sewershed population disease dynamics with those of the population represented by the larger downstream treatment plant. Our statistical methods incorporate the fact that measurements are over time, ensuring correct statistical conclusions. We provide a retrospective example of how sub-sewersheds virus levels compare to the upstream wastewater treatment plant virus levels. An on-line algorithm supports real-time statistical assessment of deviations of virus level in a population represented by a sub-sewershed to the virus level in the corresponding larger downstream wastewater treatment plant. This information supports public health decisions by spotlighting segments of the population where outbreaks may be occurring. [ABSTRACT FROM AUTHOR]

Introduction: Honey bee (Apis mellifera) pollination is widely used in tree fruit production systems to improve fruit set and yield. Many plant viruses can be associated with pollen or transmitted through pollination, and can be detected through bee pollination activities. Honey bees visit multiple plants and flowers in one foraging trip, essentially sampling small amounts of pollen from a wide area. Here we report metagenomics-based area-wide monitoring of plant viruses in cherry (Prunus avium) and apple (Malus domestica) orchards in Creston Valley, British Columbia, Canada, through bee-mediated pollen sampling. Methods: Plant viruses were identified in total RNA extracted from bee and pollen samples, and compared with profiles from double stranded RNA extracted from leaf and flower tissues. CVA, PDV, PNRSV, and PVF coat protein nucleotide sequences were aligned and compared for phylogenetic analysis. Results: A wide array of plant viruses were identified in both systems, with cherry virus A (CVA), prune dwarf virus (PDV), prunus necrotic ringspot virus (PNRSV), and prunus virus F (PVF) most commonly detected. Citrus concave gum associated virus and apple stem grooving virus were only identified in samples collected during apple bloom, demonstrating changing viral profiles from the same site over time. Different profiles of viruses were identified in bee and pollen samples compared to leaf and flower samples reflective of pollen transmission affinity of individual viruses. Phylogenetic and pairwise analysis of the coat protein regions of the four most commonly detected viruses showed unique patterns of nucleotide sequence diversity, which could have implications in their evolution and management approaches. Coat protein sequences of CVA and PVF were broadly diverse with multiple distinct phylogroups identified, while PNRSV and PDV were more conserved. Conclusion: The pollen virome in fruit production systems is incredibly diverse, with CVA, PDV, PNRSV, and PVF widely prevalent in this region. Bee-mediated monitoring in agricultural systems is a powerful approach to study viral diversity and can be used to guide more targeted management approaches. [ABSTRACT FROM AUTHOR]

Summary: Plant‐derived volatiles mediate interactions among plants, pathogenic viruses, and viral vectors. These volatile‐dependent mechanisms have not been previously demonstrated belowground, despite their likely significant role in soil ecology and agricultural pest impacts. We investigated how the plant virus, tobacco rattle virus (TRV), attracts soil nematode vectors to infected plants.We infected Nicotiana benthamiana with TRV and compared root growth relative to that of uninfected plants. We tested whether TRV‐infected N. benthamiana was more attractive to nematodes 7 d post infection and identified a compound critical to attraction. We also infected N. benthamiana with mutated TRV strains to identify virus genes involved in vector nematode attraction.Virus titre and associated impacts on root morphology were greatest 7 d post infection. Tobacco rattle virus infection enhanced 2‐ethyl‐1‐hexanol production. Nematode chemotaxis and 2‐ethyl‐1‐hexanol production correlated strongly with viral load. Uninfected plants were more attractive to nematodes after the addition of 2‐ethyl‐1‐hexanol than were untreated plants. Mutation of TRV RNA2‐encoded genes reduced the production of 2‐ethyl‐1‐hexanol and nematode attraction.For the first time, this demonstrates that virus‐driven alterations in root volatile emissions lead to increased chemotaxis of the virus's nematode vector, a finding with implications for sustainable management of both nematodes and viral pathogens in agricultural systems. [ABSTRACT FROM AUTHOR]

Rotavirus infection is a leading cause of severe dehydrating gastroenteritis in children under 5 years of age. Although rotavirus-associated mortality has decreased considerably because of the introduction of the worldwide rotavirus vaccination, the global burden of rotavirus-associated gastroenteritis remains high. Current vaccines have a number of disadvantages; therefore, there is a need for innovative approaches in rotavirus vaccine development. In the current study, a universal recombinant rotavirus antigen (URRA) for a novel recombinant vaccine candidate against rotavirus A was obtained and characterised. This antigen included sequences of the VP8* subunit of rotavirus spike protein VP4. For the URRA, for the first time, two approaches were implemented simultaneously—the application of a highly conserved neutralising epitope and the use of the consensus of the extended protein's fragment. The recognition of URRA by antisera to patient-derived field rotavirus isolates was proven. Plant virus-based spherical particles (SPs), a novel, effective and safe adjuvant, considerably enhanced the immunogenicity of the URRA in a mouse model. Given these facts, a URRA + SPs vaccine candidate is regarded as a prospective basis for a universal vaccine against rotavirus. [ABSTRACT FROM AUTHOR]

The structural study of plant viruses is of great importance to reduce the damage caused by these agricultural pathogens and to support their biotechnological applications. Nowadays, X-ray crystallography, NMR spectroscopy and cryo-electron microscopy are well accepted methods to obtain the 3D protein structure with the best resolution. However, for large and complex supramolecular structures such as plant viruses, especially flexible filamentous ones, there are a number of technical limitations to resolving their native structure in solution. In addition, they do not allow us to obtain structural information about dynamics and interactions with physiological partners. For these purposes, small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are well established. In this review, we have outlined the main principles of these two methods and demonstrated their advantages for structural studies of plant viruses of different shapes with relatively high spatial resolution. In addition, we have demonstrated the ability of AFM to obtain information on the mechanical properties of the virus particles that are inaccessible to other experimental techniques. We believe that these under-appreciated approaches, especially when used in combination, are valuable tools for studying a wide variety of helical plant viruses, many of which cannot be resolved by classical structural methods. [ABSTRACT FROM AUTHOR]

Theodor ("Ted") Otto Diener (* 28 February 1921 in Zürich, Switzerland; † 28 March 2023 in Beltsville, MD, USA) pioneered research on viroids while working at the Plant Virology Laboratory, Agricultural Research Service, USDA, in Beltsville. He coined the name viroid and defined viroids' important features like the infectivity of naked single-stranded RNA without protein-coding capacity. During scientific meetings in the 1970s and 1980s, viroids were often discussed at conferences together with other "subviral pathogens". This term includes what are now called satellite RNAs and prions. Satellite RNAs depend on a helper virus and have linear or, in the case of virusoids, circular RNA genomes. Prions, proteinaceous infectious particles, are the agents of scrapie, kuru and some other diseases. Many satellite RNAs, like viroids, are non-coding and exert their function by thermodynamically or kinetically controlled folding, while prions are solely host-encoded proteins that cause disease by misfolding, aggregation and transmission of their conformations into infectious prion isoforms. In this memorial, we will recall the work of Ted Diener on subviral pathogens. [ABSTRACT FROM AUTHOR]

This study focused on the viruses of the Tymoviridae family that infect grapevines in the Czech Republic. Complete sequences of GFkV (grapevine fleck virus) and GRGV (grapevine red globe virus) from the genus Maculavirus and GRVFV (grapevine rupestris vein feathering virus) and GSyV-1 (grapevine Syrah virus 1) from the genus Marafivirus were obtained using high-throughput sequencing of small RNAs and total RNAs. Mixed infections with these viruses were observed, as well as several variants of these viruses in the same plant. Phylogenetic analysis showed the position of the newly obtained virus isolates within the Tymoviridae family. Recombinant analysis provided evidence of single and multiple intraspecific recombinations in GRGV, GSyV-1, and GRVFV. Additionally, GAMaV, a grapevine virus from the genus Marafivirus, was reported for the first time in the Czech Republic. [ABSTRACT FROM AUTHOR]

Whiteflies cause significant crop losses through direct sap feeding, inducing plant physiological disorders and promoting the growth of sooty mold. Moreover, whiteflies can indirectly harm plants by transmitting plant viruses, particularly begomoviruses and criniviruses, resulting in severe viral disease epidemics. This study aimed to evaluate the physiological characteristics of susceptible and resistant soybean cultivars to B. tabaci. The experiments were conducted in a greenhouse. Eleven soybean cultivars were selected and infested with 100 adults of B. tabaci at the V3 stage. The evaluation of photosynthetic parameters, such as photosynthetic rate, leaf transpiration, stomatal conductance, and internal CO2 concentration, revealed that B. tabaci infestation influenced gas exchange in soybean plants. The photosynthetic rate was higher in cultivars AS3810 and M8349 during the V6 stage. Infestations caused alterations in photosynthetic parameters, suggesting increased energy demand to maintain photosynthetic activity. However, the response to infestation varied among the different cultivars, indicating varying levels of resistance and tolerance to the whitefly's damage. Furthermore, the infestation had a more notable impact during the vegetative phenological stage. In summary, infestation by B. tabaci has a discernible impact on the physiology of soybean plants, resulting in alterations in gas exchange parameters and water use efficiency. The reaction to infestation exhibited variations among different soybean cultivars, indicating potential differences in resistance to the pest. This study underscores the significance of assessing the physiological consequences of whitefly infestations on soybean crops. [ABSTRACT FROM AUTHOR]

Phalaenopsis orchids are one of the most popular ornamental plants. More than thirty orchid viruses have been reported, and virus-infected Phalaenopsis orchids significantly lose their commercial value. Therefore, the development of improved viral disease detection methods could be useful for quality control in orchid cultivation. In this study, we first utilized the MinION, a portable sequencing device based on Oxford Nanopore Technologies (ONT) to rapidly detect plant viruses in Phalaenopsis orchids. Nanopore sequencing revealed the presence of three plant viruses in Phalaenopsis orchids: odontoglossum ringspot virus, cymbidium mosaic virus, and nerine latent virus (NeLV). Furthermore, for the first time, we detected NeLV infection in Phalaenopsis orchids using nanopore sequencing and developed the reverse transcription–recombinase polymerase amplification (RT-RPA)-CRISPR/Cas12a method for rapid, instrument-flexible, and accurate diagnosis. The developed RT-RPA-CRISPR/Cas12a technique can confirm NeLV infection in less than 20 min and exhibits no cross-reactivity with other viruses. To determine the sensitivity of RT-RPA-CRISPR/Cas12a for NeLV, we compared it with RT-PCR using serially diluted transcripts and found a detection limit of 10 zg/μL, which is approximately 1000-fold more sensitive. Taken together, the ONT platform offers an efficient strategy for monitoring plant viral pathogens, and the RT-RPA-CRISPR/Cas12a method has great potential as a useful tool for the rapid and sensitive diagnosis of NeLV. [ABSTRACT FROM AUTHOR]

The citrus whitefly, Dialeurodes citri, is a destructive pest that infests citrus plants. It is a major vector in transmitting plant viruses such as citrus yellow vein clearing virus (CYVCV), which has caused severe economic losses worldwide, and therefore efficient control of this pest is economically important. However, the scope of genetic studies primarily focused on D. citri is restricted, something that has potentially limited further study of efficient control options. To explore the functionalities of D. citri target genes, screening for specific reference genes using RT-qPCR under different experimental conditions is essential for the furtherance of biological studies concerning D. citri. The eight candidate reference genes were evaluated by dedicated algorithms (geNorm, Normfinder, BestKeeper and ΔCt method) under five specific experimental conditions (developmental stage, sex, tissue, population and temperature). In addition, the RefFinder software, a comprehensive evaluation platform integrating all of the above algorithms, ranked the expression stability of eight candidate reference genes. The results showed that the best reference genes under different experimental settings were V-ATP-A and RPS18 at different developmental stages; α-tubulin, 18S and V-ATP-A in both sexes; EF1A and α-tubulin in different tissues; Actin and Argk under different populations; and RPS18 and RPL13 in different temperatures. The validation of selected reference genes was further identified using heat shock protein (Hsp) 70 as a reporter gene. Our study, for the first time, provides a detailed compilation of internal reference genes for D. citri that are suitable for RT-qPCR analysis, which is robust groundwork for comprehensive investigation of the functional target genes of D. citri. [ABSTRACT FROM AUTHOR]

A series of novel thiazine derivatives featuring axial chirality in both (R) and (S) configurations were successfully synthesized by N‐heterocyclic carbene (NHC)‐catalyzed enantioselective [3 + 3] annulations, and their potential as anti‐plant virus agents against potato virus Y (PVY) was evaluated. Biological activity results demonstrated that most of these chiral thiazine derivatives exhibited significant activities against PVY. Notably, compound (S)‐3g displayed a remarkable 58% inactivation effect against PVY at a concentration of 500 μg/mL, slightly surpassing the effectiveness of Ningnanmycin (NNM) at 57%. Additionally, (S)‐3g exhibited curative activity of 57%, which is superior to NNM (53%). Molecular docking studies revealed preliminary insights into the distinct biological properties of the two different enantiomers, (R) or (S)‐3g against PVY, wherein single enantiomer (S)‐3g formed a more stable interaction with PVY‐CP, as indicated by its lower binding free energy (−41.18 kcal/mol) compared to (R)‐3g (−36.9 kcal/mol). The findings in this study with a new class of axially chiral thiazine derivatives shall inspire further development of chiral heterocycles as potential drug candidates for the protection of plant virus infections. [ABSTRACT FROM AUTHOR]

Cotton leaf curl Kokhran virus (CLCuKoV) (genus, Begomovirus; family, Geminiviridae) is one of several plant virus pathogens of cotton (Gossypium hirsutum L.) that cause cotton leaf curl disease in Pakistan. Begomoviruses are transmitted by the whitefly Bemisia tabaci cryptic species group and cause economic losses in cotton and other crops worldwide. The CLCuKoV strain, referred to as CLCuKoV-Bur, emerged in the vicinity of Burewala, Pakistan, and was the primary causal virus associated with the second CLCuD epidemic in Pakistan. The monopartite ssDNA genome of (2.7 Kb) contains six open reading frames that encode four predicted proteins. RNA interference (RNAi)-mediated antiviral immunity is a sequence-specific biological process in plants and animals that has evolved to combat virus infection. The objective of this study was to design cotton locus-derived microRNA (ghr-miRNA) molecules to target strains of CLCuKoV, with CLCuKoV-Lu, as a typical CLCuD-begomovirus genome, predicted by four algorithms, miRanda, RNA22, psRNATarget, and RNA hybrid. Mature ghr-miRNA sequences (n = 80) from upland cotton (2n = 4x = 52) were selected from miRBase and aligned with available CLCuKoV-Lu genome sequences. Among the 80 cotton locus-derived ghr-miRNAs analyzed, ghr-miR2950 was identified as the most optimal, effective ghr-miRNA for targeting the CLCuKoV-Lu genome (nucleotide 82 onward), respectively, based on stringent criteria. The miRNA targeting relies on the base pairing of miRNA–mRNA targets. Conservation and potential base pairing of binding sites with the ghr-miR2950 were validated by multiple sequence alignment with all available CLCuKoV sequences. A regulatory interaction network was constructed to evaluate potential miRNA–mRNA interactions with the predicted targets. The efficacy of miRNA targeting of CLCuKoV was evaluated in silico by RNAi-mediated mRNA cleavage. This predicted targets for the development of CLCuD-resistant cotton plants. [ABSTRACT FROM AUTHOR]