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Plant viral diseases cause great losses in agricultural production. Virus cross-protection is a strategy in which a mild virus is employed to shield plants against subsequent infections by severe viral strains. However, this approach is restricted to protection against the same viruses. In this study, we observed that pre-inoculation with apple geminivirus (AGV) reduced the accumulation of secondarily infected heterologous viruses, such as cucumber mosaic virus, potato virus X, and tobacco mosaic virus in Nicotiana benthamiana, tomato, and pepper plants. Transcriptional expression analysis showed that autophagy-related genes were transcriptionally up-regulated upon AGV inoculation at an early stage of infection. Accordingly, autophagic activity was observed to be elevated following AGV infection. Interestingly, AGV accumulation was reduced in autophagy-deficient plants, suggesting that autophagy activation promotes AGV infection in the plant. Moreover, pre-inoculation with AGV provided cross-protection against infection with a phytopathogenic bacterium (Pseudomonas syringae) and fungus (Botrytis cinerea) in Nicotiana species. In summary, our study showed that AGV, an asymptomatic virus, could protect plants against severe viral, fungal, and bacterial diseases to some extent through the activation of autophagy pathways, highlighting its potential as a biocontrol agent for managing a wide range of plant crop diseases in the field. [ABSTRACT FROM AUTHOR]

This article, published in Frontiers in Plant Science, discusses the mechanisms of plant virus cell-to-cell transport. The authors focus on complementation studies involving viral movement proteins (MPs) and movement-deficient plant viruses. They provide examples of complementation studies with different plant viruses and discuss the potential mechanisms behind these complementations. The article emphasizes the importance of viral MPs in facilitating the transport of viral genomes through plasmodesmata, the channels connecting neighboring plant cells. The document also explores the ability of certain proteins to complement the transport of RNA viruses, specifically geminivirus C5 and P3 of the fungal virus. These proteins modify plasmodesmata, leading to actin remodeling and inhibition of callose deposition. The document also covers the specificity of transport through plasmodesmata and the mechanisms by which viral movement proteins provide selective intercellular transport. Additionally, the document provides a list of references for various scientific articles related to virology and plant viruses, which can be valuable for researchers studying plant viruses and their interactions with host plants. [Extracted from the article]

Pear chlorotic leaf spot‐associated virus (PCLSaV) is a newly described emaravirus that infects pear trees. The virus genome consists of at least five single‐stranded, negative‐sense RNAs. The P5 encoded by RNA5 is unique to PCLSaV. In this study, the RNA silencing suppression (RSS) activity of P5 and its subcellular localization were determined in Nicotiana benthamiana plants by Agrobacterium tumefaciens‐mediated expression assays and green fluorescent protein RNA silencing induction. Protein P5 partially suppressed local RNA silencing, strongly suppressed systemic RNA silencing and triggered reactive oxygen species accumulation. The P5 self‐interacted and showed subcellular locations in plasmodesmata, endoplasmic reticulum and nucleus. Furthermore, P5 rescued the cell‐to‐cell movement of a movement defective mutant PVXΔP25 of potato virus X (PVX) and enhanced the pathogenicity of PVX. The N‐terminal 1–89 amino acids of the P5 were responsible for the self‐interaction ability and RSS activity, for which the signal peptide at positions 1–19 was indispensable. This study demonstrated the function of an emaravirus protein as a pathogenic factor suppressing plant RNA silencing to enhance virus infection and as an enhancer of virus movement. [ABSTRACT FROM AUTHOR]

The trans-replication system explores the concept of separating the viral RNA involved in the translation of the replicase protein from the replication of the viral genome and has been successfully used to study the replication mechanisms of alphaviruses. We tested the feasibility of this system with potato virus X (PVX), an alpha-like virus, in planta. A viral RNA template was designed which does not produce the replicase and prevents virion formation but remains recognizable by the replicase. The replicase construct encodes for the replicase protein, while lacking other virus-specific recognition sequences. Both the constructs were delivered into Nicotiana benthamiana leaves via Agrobacterium-mediated infiltration. Templates of various lengths were tested, with the longer templates not replicating at 4 and 6 days post inoculation, when the replicase protein was provided in trans. Co-expression of helper component proteinase with the short template led to its trans-replication. The cells where replication had been initiated were observed to be scattered across the leaf lamina. This study established that PVX is capable of trans-replicating and can likely be further optimized, and that the experimental freedom offered by the system can be utilized to delve deeper into understanding the replication mechanism of the virus. [ABSTRACT FROM AUTHOR]

Because virus vectors can spread systemically autonomously, they are powerful vehicles with which to deliver genome-editing tools into plant cells. Indeed, a vector based on a positive-strand RNA virus, potato virus X (PVX), harboring SpCas9 and its single guide RNA (sgRNA), achieved targeted mutagenesis in inoculated leaves of Nicotiana benthamiana. However, the large size of the SpCas9 gene makes it unstable in the PVX vector, hampering the introduction of mutations in systemic leaves. Smaller Cas variants are promising tools for virus vector-mediated genome editing; however, they exhibit far lower nuclease activity than SpCas9. Recently, AsCas12f, one of the smallest known Cas proteins so far (one-third the size of SpCas9), was engineered to improve genome-editing activity dramatically. Here, we first confirmed that engineered AsCas12f variants including I123Y/D195K/D208R/V232A exhibited enhanced genome-editing frequencies in rice. Then, a PVX vector harboring this AsCas12f variant was inoculated into N. benthamiana leaves by agroinfiltration. Remarkably, and unlike with PVX-SpCas9, highly efficient genome editing was achieved, not only in PVX-AsCas12f-inoculated leaves but also in leaves above the inoculated leaf (fourth to sixth upper leaves). Moreover, genome-edited shoots regenerated from systemic leaves were obtained at a rate of >60%, enabling foreign DNA-free genome editing. Taken together, our results demonstrate that AsCas12f is small enough to be maintained in the PVX vector during systemic infection in N. benthamiana and that engineered AsCas12f offers advantages over SpCas9 for plant genome editing using virus vectors. [ABSTRACT FROM AUTHOR]

Currently transient expression is one of the preferred plant-based technologies for recombinant protein manufacturing, particularly in respect to pharmaceutically relevant products. Modern hybrid transient expression systems combine the features of Agrobacterium tumefaciens and viral vectors. However, host plant reaction to Agrobacterium-mediated delivery of gene of interest can negatively affect foreign protein accumulation. In this study, we investigated whether the modulation of plant immune response through knockdown of the Nb-SABP2 and Nb-COI1 N. benthamiana genes could improve recombinant protein yield. In plants, the SABP2 and COI1 proteins are involved in the salicylic acid and jasmonic acid metabolism, respectively. We exemplified the utility of this approach with the green fluorescence (GFP) and b nerve growth factor (bNGF) proteins: compared to the tobacco mosaic virus (TMV)-based vector the Nb-SABP2 and Nb-COI1-suppressed plants provided an increased recombinant protein accumulation. We also show that this strategy is extendable to the expression systems utilizing potato virus X (PVX) as the vector backbone: the enhanced amounts of bNGF were detected in the Nb-SABP2 and Nb-COI1-depleted leaves co-infiltrated with the PVX-bNGF. These findings suggest that modulating host plant reaction to agrodelivery of expression vectors could be useful for improving transient foreign protein production in N. benthamiana. [ABSTRACT FROM AUTHOR]

Background: Viral diseases of sweet potatoes are causing severe crop losses worldwide. More than 30 viruses have been identified to infect sweet potatoes among which the sweet potato latent virus (SPLV), sweet potato mild speckling virus (SPMSV), sweet potato virus G (SPVG) and sweet potato virus 2 (SPV2) have been recognized as distinct species of the genus Potyvirus in the family Potyviridae. The sweet potato virus 2 (SPV2) is a primary pathogen affecting sweet potato crops. Methods: In this study, we detected an SPV2 isolate (named SPV2-LN) in Ipomoea nil in China. The complete genomic sequence of SPV2-LN was obtained using sequencing of small RNAs, RT-PCR, and RACE amplification. The codon usage, phylogeny, recombination analysis and selective pressure analysis were assessed on the SPV2-LN genome. Results: The complete genome of SPV2-LN consisted of 10,606 nt (GenBank No. OR842902), encoding 3425 amino acids. There were 28 codons in the SPV2-LN genome with a relative synonymous codon usage (RSCU) value greater than 1, of which 21 end in A/U. Among the 12 proteins of SPV2, P3 and P3N-PIPO exhibited the highest variability in their amino acid sequences, while P1 was the most conserved, with an amino acid sequence identity of 87-95.3%. The phylogenetic analysis showed that 21 SPV2 isolates were clustered into four groups, and SPV2-LN was clustered together with isolate yu-17-47 (MK778808) in group IV. Recombination analysis indicated no major recombination sites in SPV2-LN. Selective pressure analysis showed dN/dS of the 12 proteins of SPV2 were less than 1, indicating that all were undergoing negative selection, except for P1N-PISPO. Conclusion: This study identified a sweet potato virus, SPV2-LN, in Ipomoea nil. Sequence identities and genome analysis showed high similarity between our isolate and a Chinese isolate, yu-17-47, isolated from sweet potato. These results will provide a theoretical basis for understanding the genetic evolution and viral spread of SPV2. [ABSTRACT FROM AUTHOR]

Tomato fruit ripening is an elaborate genetic trait correlating with significant changes at physiological and biochemical levels. Sugar metabolism plays an important role in this highly orchestrated process and ultimately determines the quality and nutritional value of fruit. However, the mode of molecular regulation is not well understood. Galactinoal-sucrose galactosyltransferase (GSGT), a key enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs), can transfer the galactose unit from 1-α-D-galactosyl-myo-inositol to sucrose and yield raffinose, or catalyze the reverse reaction. In the present study, the expression of SlGSGT2 was decreased by Potato Virus X (PVX)-mediated gene silencing, which led to an unripe phenotype in tomato fruit. The physiological and biochemical changes induced by SlGSGT2 silencing suggested that the process of fruit ripening was delayed as well. SlGSGT2 silencing also led to significant changes in gene expression levels associated with ethylene production, pigment accumulation, and ripening-associated transcription factors (TFs). In addition, the interaction between SlGSGT2 and SlSPL-CNR indicated a possible regulatory mechanism via ripening-related TFs. These findings would contribute to illustrating the biological functions of GSGT2 in tomato fruit ripening and quality forming. [ABSTRACT FROM AUTHOR]

Information on the abundance and diversity of phytopathogenic viruses in Ukraine is very variable and limited. There is a high importance of a complex study of the species composition and ways of spreading crop viruses, as well as the development of epiphytotic forecasting systems, which will help to limit the ranges of these viruses and save crop yields. Consequently, the aim of our study was to explore the species composition and frequency of mono-and mixed virus infection of vegetable crops in Ukrainian agrocenoses and to identify the possible etiology of its occurrence. Methods. The samples were analyzed for the presence of viral antigens by enzyme-linked immunosorbent assay in sandwich and indirect modifications. For the detection of viral antigens in ELISA, test systems manufactured by Loewe were used. To identify the virus, the material was homogenized and purified, and then registered on a reader. Results. The frequency of vegetable crops damaged by diseases of viral etiology increased by 25-27% compared to the previous years of the study. Serological analysis showed that 59% of the studied samples of the Cucurbitaceae family and 54% of the Solanaceae family were affected by the main viral diseases most common in Ukraine. The seed way of transmission of vegetable viruses in Ukraine was demonstrated as one of the sources of viruses in agrocenoses. The presence of antigens to cucumber mosaic virus (CMV) in 14.3% of the studied seeds, zucchini yellow mosaic virus (ZYMV) - 11.2%, and tomato mosaic virus (ToMV) - 12.6% was shown. This allows us to suggest that sowing those seeds in the future will contribute to the spread of these viruses across Ukraine. Analysis of soil samples showed the presence of antigens of cucumber mosaic virus, tobacco mosaic virus, and potato virus X. The lowest level of antigens to CMV was detected in the soils of Vinnytsia region, to PVX - in the Kyiv and Cherkasy regions, and to TMV - in the Odesa region. Conclusions. Vegetable agrocenoses in Ukraine are more often affected by viruses belonging to the Tobamovirus, Cucumovirus, Potyvirus, and Tospovirus genera of the Bromoviridae, Potyviridae, and Bunyaviridae families. In addition to the increasing areas of viral monoinfection, there is an active spread of mixed infection, or «superinfection», in Ukrainian agrocenosis. Mixed infections are mainly formed during the growth and development of the tested vegetable crops. All of this leads to further signifi cant spread of not only mono-but also mixed virus infection of vegetable crops. [ABSTRACT FROM AUTHOR]

Antiviral responses induced by double‐stranded RNA (dsRNA) include RNA interference (RNAi) and pattern‐triggered immunity (PTI), but their relative contributions to antiviral defence are not well understood. We aimed at testing the impact of exogenous applied dsRNA on both layers of defence against potato virus X expressing GFP (PVX‐GFP) in Nicotiana benthamiana. Co‐inoculation of PVX‐GFP with either sequence‐specific (RNAi) or nonspecific dsRNA (PTI) showed that nonspecific dsRNA reduced virus accumulation in both inoculated and systemic leaves. However, nonspecific dsRNA was a poor inducer of antiviral immunity compared to a sequence‐specific dsRNA capable of triggering the RNAi response, and plants became susceptible to systemic infection. Studies with a PVX mutant unable to move from cell to cell indicated that the interference with PVX‐GFP triggered by nonspecific dsRNA operated at the single‐cell level. Next, we performed RNA‐seq analysis to examine similarities and differences in the transcriptome triggered by dsRNA alone or in combination with viruses harbouring sequences targeted or not by dsRNA. Enrichment analysis showed an over‐representation of plant‐pathogen signalling pathways, such as calcium, ethylene and MAPK signalling, which are typical of antimicrobial PTI. Moreover, the transcriptomic response to the virus targeted by dsRNA had a greater impact on defence than the non‐targeted virus, highlighting qualitative differences between sequence‐specific RNAi and nonspecific PTI responses. Together, these results further our understanding of plant antiviral defence, particularly the contribution of nonspecific dsRNA‐mediated PTI. We envisage that both sequence‐specific RNAi and nonspecific PTI pathways may be triggered via topical application of dsRNA, contributing cumulatively to plant protection against viruses. [ABSTRACT FROM AUTHOR]

Virus diseases represent important economic threats to seed potato production worldwide, yet relatively little is known of their epidemiology at the landscape‐scale. In this study, data was compiled from the Scottish national seed potato classification scheme on the incidence of 10 different potato viruses for the years 2009–2022. A co‐occurrence analysis identified that 12 virus species pairs occurred together more often than expected by chance, and potato blackleg was positively associated with eight potato viruses. ArcGIS was used to investigate spatial and spatiotemporal variation in incidence rates of the three most prevalent viruses (potato virus Y, potato leaf roll virus and potato virus A), and this revealed prominent geographic differences in long‐term disease outcomes. Focusing on potato virus Y as the most commonly occurring single infection, interpretable machine‐learning techniques were used to investigate the influence of key crop, management and environmental factors on patterns of incidence in space and time. The results showed that health characteristics of seed stocks were among the most important predictors of incidence, along with blackleg infection, several management features, cultivar resistance, distance to the nearest seed and ware crop, temperature variables and several soil features. This approach provides a comprehensive overview of potato viruses in Scotland, a deeper understanding of epidemiological risk factors at the landscape‐scale and a forecast model that could serve as the basis of a decision support tool for improved management of potato virus Y. [ABSTRACT FROM AUTHOR]

Summary: Nucleotide‐binding domain and leucine‐rich repeat (NLR) proteins with pathogen sensor activities have evolved to initiate immune signaling by activating helper NLRs. However, the mechanisms underpinning helper NLR activation by sensor NLRs remain poorly understood. Although coiled coil (CC) type sensor NLRs such as the Potato virus X disease resistance protein Rx have been shown to activate the oligomerization of their downstream helpers NRC2, NRC3 and NRC4, the domains involved in sensor–helper signaling are not known.Here, we used Agrobacterium tumefaciens‐mediated transient expression in Nicotiana benthamiana to show that the nucleotide‐binding (NB) domain within the NB‐ARC of Rx is necessary and sufficient for oligomerization and immune signaling of downstream helper NLRs. In addition, the NB domains of the disease resistance proteins Gpa2 (cyst nematode resistance), Rpi‐amr1, Rpi‐amr3 (oomycete resistance) and Sw‐5b (virus resistance) are also sufficient to activate their respective downstream NRC helpers.Using transient expression in the lettuce (Lactuca sativa), we show that Rx (both as full length or as NB domain truncation) and its helper NRC2 form a minimal functional unit that can be transferred from solanaceous plants (lamiids) to Campanulid species.Our results challenge the prevailing paradigm that NLR proteins exclusively signal via their N‐terminal domains and reveal a signaling activity for the NB domain of NRC‐dependent sensor NLRs. We propose a model in which helper NLRs can perceive the status of the NB domain of their upstream sensors. [ABSTRACT FROM AUTHOR]

A wide range of virus-like particles (VLPs) is extensively employed as carriers to display various antigens for vaccine development to fight against different infections. The plant-produced truncated variant of the hepatitis E virus (HEV) coat protein is capable of forming VLPs. In this study, we demonstrated that recombinant fusion proteins comprising truncated HEV coat protein with green fluorescent protein (GFP) or four tandem copies of the extracellular domain of matrix protein 2 (M2e) of influenza A virus inserted at the Tyr485 position could be efficiently expressed in Nicotiana benthamiana plants using self-replicating vector based on the potato virus X genome. The plant-produced fusion proteins in vivo formed VLPs displaying GFP and 4M2e. Therefore, HEV coat protein can be used as a VLP carrier platform for the presentation of relatively large antigens comprising dozens to hundreds of amino acids. Furthermore, plant-produced HEV particles could be useful research tools for the development of recombinant vaccines against influenza. [ABSTRACT FROM AUTHOR]

Plant viruses cause substantial losses in crop yield and quality; therefore, devising new, robust strategies to counter viral infections has important implications for agriculture. Virus inhibitory protein endoplasmic reticulum-associated interferoninducible (Viperin) proteins are conserved antiviral proteins. Here, we identified a set of Viperin and Viperin-like proteins from multiple species and tested whether they could interfere with RNA viruses in planta. Our data from transient and stable overexpression of these proteins in Nicotiana benthamiana reveal varying levels of interference against the RNA viruses tobacco mosaic virus (TMV), turnip mosaic virus (TuMV), and potato virus x (PVX). Harnessing the potential of these proteins represents a novel avenue in plant antiviral approaches, offering a broader and more effective spectrum for application in plant biotechnology and agriculture. Identifying these proteins opens new avenues for engineering a broad range of resistance to protect crop plants against viral pathogens. [ABSTRACT FROM AUTHOR]

Transcription factors belonging to the family of ethylene response factors (ERFs) in plants function in disease resistance to pathogens. One of the tobacco ERF genes, NtERF5, inhibits the accumulation of tobacco mosaic virus (genus Tobamovirus) when overexpressed in tobacco carrying the resistance gene N. Here, we report that NtERF5 can function as a transcriptional activator through binding of the GCC-box in planta. We then determined whether overexpression of NtERF5 in tobacco lacking the N gene (nn tobacco) inhibited infection by potato virus X (PVX: genus Potexvirus). Transient overexpression of NtERF5 inhibited the accumulation of PVX without affecting virus spread and increased the transcript levels of NtPRB-1b and NtPR6, which are jasmonic acid/ethylene-signaling marker genes encoding pathogenesis-related (PR) proteins. Stable overexpression of NtERF5 in nn tobacco also resulted in decreased PVX accumulation and the induction of the expression of NtPRB-1b and NtPR6. Our results revealed that overexpression of NtERF5 limited successful infection and accumulation of PVX, suggesting the role of NtERF5 as a positive regulator of basal defense against virus infection. [ABSTRACT FROM AUTHOR]

The document discusses the current state of plant virus research in China, highlighting advancements in areas such as virus discovery, plant-virus interactions, and virus detection technology. Various studies are presented, including the identification of novel viruses in rice plants, the development of detection methods, and the role of translation initiation factors in viral resistance. The document aims to provide an updated understanding of plant-virus interactions and to support further research in virology and related fields. [Extracted from the article]

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]

Potato is the most predominant non-grain food crop across the world. Plant viruses have a considerable impact on potato yield, which is now a serious danger to the sustainability of the global food supply. Therefore, a highly sensitive, specific and accurate detection of potato plant viruses is crucial for early monitoring of plant health due to the rapid spread of viruses. Potato aucuba mosaic virus (PAMV) is one of the economically important viruses causing potatoes diseases. Hence, a highly sensitive PAMV electrochemical immunosensor was developed using an effective antibody immobilization strategy with shape-dependent nanomatrix support. The limits of detection of spherical gold nanoparticle (AuNP) and reduced graphene oxide (rGO) nanosheets based immunoelectrodes were found at concentrations of 0.96 × 10−12 M and 0.065 × 10−12 M, respectively. Our proposed immunosensor was evaluated and validated with PAMV-positive control spiked with potato leaf samples as well as real potato leaf samples. The immunosensor exhibits potential as a nano-diagnostic platform for on-site plant virus detection. [ABSTRACT FROM AUTHOR]

Human interferon (hINF) alpha 2b is clinically important pharmaceutical product included in combinatory therapy against chronic hepatitis C and B and complex therapy against several cancer diseases. Here, we created the genetic constructions, based on genome elements of potato virus X (PVX), carrying the infα2b gene for transient expression in plant cells. The created plasmid vector constructions were tested through Agrobacterium-mediated transient gene expression method in two plant species—Nicotiana benthamiana and Ocimum basilicum (sweet basil). Production of recombinant hINF alpha 2b was more efficient in N. benthamiana than that in O. basilicum plants. The average yield of hINF alpha 2b produced in N. benthamiana plants was 0.56 mg/g of fresh leaf weight (FW) or 6% of the total soluble cell proteins (TSP). The maximal level reached up to 1.2 mg/g FW or 9% TSP. We estimated that about 0.67 mg of hINF can be obtained from one N. benthamiana plant. The yield of hINF alpha 2b obtained with the PVX-based expression cassette was about 80 times higher than the yield of hINF alpha 2b obtained with a simple expression cassette in which the infα2b gene was controlled by the 35S promoter of cauliflower mosaic virus. Key points: • PVX-based expression vectors provide efficient transient expression of infα2b gene • N. benthamiana plants can produce human interferon alpha 2b at high levels • The yield of the hINF α2b reached up to 1.2 mg/g of fresh leaf weight [ABSTRACT FROM AUTHOR]

Substrate channeling could be very useful for plant metabolic engineering; hence, we propose that functionalized supramolecular self-assembly scaffolds can act as enzymatic hubs able to perform reactions in close contiguity. Virus nanoparticles (VNPs) offer an opportunity in this context, and we present a functionalization strategy to display different enzymes on the outer surface of three different VNPs produced in plants. Tomato bushy stunt virus (TBSV) and Potato virus X (PVX) plant viruses were functionalized by the genetic fusion of the E-coil peptide coding sequence to their respective coat proteins genes, while the enzyme lichenase was tagged with the K-coil peptide. Immobilized E-coil VNPs were able to interact in vitro with the plant-produced functionalized lichenase, and catalysis was demonstrated by employing a lichenase assay. To prove this concept in planta, the Hepatitis B core (HBc) virus-like particles (VLPs) were similarly functionalized by genetic fusion with the E-coil sequence, while acyl-activating enzyme 1, olivetolic acid synthase, and olivetolic acid cyclase enzymes were tagged with the K-coil. The transient co-expression of the K-coil-enzymes together with E-coil-VLPs allowed the establishment of the heterologous cannabinoid precursor biosynthetic pathway. Noteworthy, a significantly higher yield of olivetolic acid glucoside was achieved when the scaffold E-coil-VLPs were employed. [ABSTRACT FROM AUTHOR]

Nanoviruses have multipartite, circular, single‐stranded DNA genomes and cause huge production losses in legumes and other crops. No viral suppressor of RNA silencing (VSR) has yet been reported from a member of the genus Nanovirus. Here, we demonstrate that the nanovirus U2 protein is a VSR. The U2 protein of milk vetch dwarf virus (MDV) suppressed the silencing of the green fluorescent protein (GFP) gene induced by single‐stranded and double‐stranded RNA, and the systemic spread of the GFP silencing signal. An electrophoretic mobility shift assay showed that the U2 protein was able to bind double‐stranded 21‐nucleotide small interfering RNA (siRNA). The cysteine residues at positions 43, 79 and 82 in the MDV U2 protein are critical to its nuclear localization, self‐interaction and siRNA‐binding ability, and were essential for its VSR activity. In addition, expression of the U2 protein via a potato virus X vector induced more severe necrosis symptoms in Nicotiana benthamiana leaves. The U2 proteins of other nanoviruses also acted as VSRs, and the three conserved cysteine residues were indispensable for their VSR activity. [ABSTRACT FROM AUTHOR]

The article discusses the use of virus-induced flowering (VIF) as a method to control the flowering time of tomato plants. VIF involves delivering a transmissible molecule called florigen, which promotes the change to the reproductive phase, using a viral vector. The study successfully optimized the VIF method for tomato plants using a potato virus X (PVX)-based vector. Treated tomato plants flowered earlier and produced more flowers and ripe fruits compared to untreated controls. The use of VIF has been demonstrated in various crops, but customization is required for different plant species. The article highlights the importance of past discoveries, such as the discovery of florigen, in advancing plant breeding techniques. [Extracted from the article]

Potato virus X (PVX) vectors expressing the Arabidopsis thaliana FLOWERING LOCUS T (FT) or tomato FT ortholog SINGLE-FLOWER TRUSS (SFT) shortened the generation time in tomato due to accelerated tomato flowering and ripening by 14–21 d, and caused a 2–3-fold increase in the number of flowers and fruits, compared with non-infected or empty vector-infected plants. The Arabidopsis FT was more effective than the tomato orthologue SFT and there was no alteration of the flower or fruit morphology. The virus was not transmitted to the next generation; therefore viral vectors with expression of a heterologous FT will be a useful approach to speed breeding in tomato and other species. [ABSTRACT FROM AUTHOR]

Recently, as a result of the development of agriculture, and the expansion of the international export of seeds and seedlings, pathogenic viruses that infect potatoes have spread to other regions, and changes in viruses under the influence of various climatic factors have led to the emergence of strong pathogenic isolates. The preservation of potato viruses in potato nodules and other plant organs creates several difficulties in their diagnosis. For this, it is advisable to use highly sensitive diagnostic methods. In this work, the results of the research on the preparation of polyclonal serum, which is the basis for obtaining antibodies necessary for the immunodiagnosis of potato X virus (PXV), are given. In this case, an isotonic solution of NaCl or cycloferon together with a purified virus antigen was injected between the muscles of the biceps and hind legs of rabbits. The delivered antigen dose was increased by the same amount for both rabbits. Before reimmunization, the titer of sera from the rabbit injected with cyclotron was 1:64, the titer from the rabbit injected with an isotonic solution of sodium chloride was 1:32, and after reimmunization, the titer of the serum isolated from the first rabbit decreased to 1:32, and from the rabbit injected with NaCl the resulting serum was found to be elevated to a titer of 1:256. The prepared serum was used in the diagnosis of PXV and its amount in plant tissue was determined. [ABSTRACT FROM AUTHOR]

This research studied ten isolates of potato virus X (PVX) isolated from potato cultivars growing in Kazakhstan (KZ), Belarus (BY) and China (CN). Additionally, the potato samples were screened for Potato virus Y (PVY), Potato virus S (PVS), and Potato leafroll virus (PLRV) using multiplex reverse transcription-polymerase chain reaction (RT-PCR). PVX was isolated from the potato varieties 'Tamasha', 'Red Scarlet', 'Gala variety', 'Krone', 'Juwel', 'Gala', and 'b2-7'. The identified isolates of PVX were sequenced and used to construct a phylogenetic tree, which demonstrated that KZ and BY isolates form clusters closely related to isolates from Asia and Europe, however, CN isolate formed a separate clade. KZ5 and KZ7 PVX isolates showed local symptoms of mosaic and light green speckled spots on the upper leaves of Datura stramonium in pathogenicity test. [ABSTRACT FROM AUTHOR]

Early detection of pathogens can significantly reduce yield losses and improve the quality of agricultural products. This study compares the efficiency of hyperspectral (HS) imaging and pulse amplitude modulation (PAM) fluorometry to detect pathogens in plants. Reflectance spectra, normalized indices, and fluorescence parameters were studied in healthy and infected areas of leaves. Potato virus X with GFP fluorescent protein was used to assess the spread of infection throughout the plant. The study found that infection increased the reflectance of leaves in certain wavelength ranges. Analysis of the normalized reflectance indices (NRIs) revealed indices that were sensitive and insensitive to infection. NRI700/850 was optimal for virus detection; significant differences were detected on the 4th day after the virus arrived in the leaf. Maximum (Fv/Fm) and effective quantum yields of photosystem II (ΦPSII) and non-photochemical fluorescence quenching (NPQ) were almost unchanged at the early stage of infection. ΦPSII and NPQ in the transition state (a short time after actinic light was switched on) showed high sensitivity to infection. The higher sensitivity of PAM compared to HS imaging may be due to the possibility of assessing the physiological changes earlier than changes in leaf structure. [ABSTRACT FROM AUTHOR]

The problem of increasing the yield of cultivated plants attracts the attention of specialists and prompts scientists to study viral plant diseases as one of the causes of significant crop losses. A virus is an endogenous parasite that, having entered plant cells, uses the functions of cell organoids and biosystems for its reproduction, which leads to plant disease and a decrease in their productivity. One of the promising approaches to reducing viral damage to plants is the use of microbial antiviral preparations. The complex bacterial preparation Azogran, developed at the Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine, is based on the interaction of phosphate-mobilizing bacteria Bacillus subtilis IMV B-7023, nitrogen-fixing bacteria Azotobacter vinelandii IMV B-7076, and clay mineral -- bentonite. Phosphate-mobilizing bacteria and nitrogen-fixing bacteria significantly improve the growth and development of plants, essentially increasing the yield of agricultural crops. However, the effect of Azogran on the development and yield of potato plants infected with the X-virus has not been sufficiently studied. Taking this into account, the aim of the work was to study the effect of the complex bacterial preparation Azogran on the growth, some physiological and biochemical properties, and productivity of potato plants, uninfected and infected by the potato virus X. Methods. Microbiological (obtaining the bacterial preparation Azogran, used in granular form (0.25 g)), virological (isolation of potato virus X, inoculation of plants with potato virus X), serological (testing for the presence or absence of the virus), biochemical (determination of chlorophylls a, b and carotenoids), spectrophotometric, and statistical analysis. Results. In the conducted experiments, the Azogran was used in granular form in the amount of one and two granules. The effectiveness of the use of the preparation, which stimulates the intensive growth of plants of two varieties of potatoes (early variety Spokusa and medium variety Diva), which leads to an increase in their yield, is shown. The positive effect of Azogran was observed on the development of both infected and non-infected plants. It was found that when two granules of the preparation were applied, the yield of potatoes of the Diva variety increased by 27.02%, and the yield of potatoes of the Spokusa variety under the same conditions increased by 29.46%. A similar effect of Azogran was observed on plants infected with the estabpotato virus X, only to a lesser extent: in the Diva variety, the yield was 16.3% higher compared to the control (control -- plants not infected by the virus), and in the Spokusa variety it was higher by 22.59%. When studying the content of chlorophylls a and b and carotenoids in virus-infected potato plants, it was established that the content of chlorophylls at different stages of virus infection was different, but the content of chlorophylls and carotenoids was higher in plants bacterized with Azogran. Conclusions. The complex bacterial preparation Azogran has a positive effect on the development of uninfected and infected plants, reducing the harmfulness of viral infections and contributing to the increase in potato productivity. Azogran can be successfully used in crop production to increase the quality and quantity of crop yields. [ABSTRACT FROM AUTHOR]

During virus infection, Argonaute (AGO) proteins bind to Dicer-produced virus small interfering RNAs and target viral RNA based on sequence complementarity, thereby limiting virus proliferation. The Arabidopsis AGO2 protein is important for resistance to multiple viruses, including potato virus X (PVX). In addition, AGO5 is important in systemic defense against PVX. Normally AGO5 is expressed only in reproductive tissues, and its induction by virus infection is thought to be important for its participation in antiviral defense. However, it is unclear what mechanisms induce AGO5 expression in response to virus infection. Here, we show that dde2-2, a mutant compromised in jasmonic acid (JA) biosynthesis, displays constitutive upregulation of AGO5. This mutant also showed increased resistance to PVX and this resistance was dependent on a functional AGO5 gene. Furthermore, methyl jasmonate treatment ablated AGO5 expression in leaves during virus infection and resulted in increased susceptibility to virus. Our results further support a role for AGO5 in antiviral RNA silencing and a negative regulation by JA, a plant hormone associated with defense against plant-feeding arthropods, which are often the vectors of plant viruses. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Background. Potato due to its vegetative propagation is affected by viruses, among which potato viruses Y (PVY), S (PVS) and M (PVM) are spread across all Russia’s territory. The VIR collection presents the diversity of the potato gene pool, including potato cultivars and related tuber-forming species. Diagnostics of viral infections in plants saved for several years by obtaining tuber reproductions is an important part of the work on the conservation and sustainable utilization of the potato gene pool. The purpose of the work was to evaluate the distribution of PVX, PVY, PVS and PVM on plants of potato cultivars and related Solanum spp. in the VIR field collection. Material and methods. Evaluation covered 315 accessions representing all groups of the potato gene pool. Diagnosis by enzyme-linked immunosorbent assay (ELISA) was carried out on plants that did not display symptoms of a virus infection. The Russian test system of RPA “BioTechnologies” and foreign one of Bioreba AG (Switzerland) were used. Statistical data processing was performed by the Statistica StatSoft 13 program. Results. Mosaic viruses are distributed with different frequencies on potato plants in the field collection: PVM dominates, detected in 64% of potato accessions; PVY is found in 41 %, PVX on 24 %, and PVS in 18 % of accessions. The connection between the botanical and taxonomic origin of potato accessions and their infection with viruses has been confirmed. Among wild species, more than half of accessions, while among cultivated species, only 5% are affected by XBK. PVM, on the contrary, was detected in a significant part (77–91%) of cultivated potato accessions. and much less frequently (16%) in accessions of wild species. Cvs, ‘Grand’, ‘Krasa Meshchery’, ‘Yantar’ and ‘Nur-Alem’, hybrids 99-1-3, 952-35 and 914-5-2018, accessions of wild species from North America, and cultivated species Solanum goniocalyx Juz. et Buk. (k-9922) are not affected by viruses.

The article discusses the search for plant factors required for virus infection, focusing on the role of the EXA1 gene in potexvirus infections. Through experiments with Arabidopsis, Nicotiana benthamiana, tomato, and rice, researchers found that EXA1 plays a crucial role in viral RNA accumulation and infection across different plant species. The study suggests that EXA1-mediated resistance to potexviruses may be applicable in developing potexvirus-resistant plants through genome editing, highlighting the broader role of EXA1 in plant defense mechanisms against various pathogens. [Extracted from the article]

Tobacco Mosaic Virus (TMV) and Potato Virus Y (PVY) pose significant threats to crop production. Non-destructive and accurate surveillance is crucial to effective disease control. In this study, we propose the adoption of hyperspectral and machine learning technologies to discern the type and severity of tobacco leaves affected by PVY and TMV infection. Initially, we applied three preprocessing methods - Multivariate Scattering Correction (MSC), Standard Normal Variate (SNV), and Savitzky-Golay smoothing filter (SavGol) - to corrected the leaf full-length spectral sheet data (350-2500nm). Subsequently, we employed two classifiers, support vector machine (SVM) and random forest (RF), to establish supervised classification models, including binary classification models (healthy/diseased leaves or PVY/TMV infected leaves) and six-class classification models (healthy and various severity levels of diseased leaves). Based on the core evaluation index, our models achieved accuracies in the range of 91-100% in the binary classification. In general, SVM demonstrated superior performance compared to RF in distinguishing leaves infected with PVY and TMV. Different combinations of preprocessing methods and classifiers have distinct capabilities in the six-class classification. Notably, SavGol united with SVM gave an excellent performance in the identification of different PVY severity levels with 98.1% average precision, and also achieved a high recognition rate (96.2%) in the different TMV severity level classifications. The results further highlighted that the effective wavelengths captured by SVM, 700nm and 1800nm, would be valuable for estimating disease severity levels. Our study underscores the efficacy of integrating hyperspectral technology and machine learning, showcasing their potential for accurate and non-destructive monitoring of plant viral diseases. [ABSTRACT FROM AUTHOR]

The unfolded protein response (UPR) is a cell-designated strategy that maintains the balance of protein folding in the endoplasmic reticulum (ER). UPR features a network of signal transduction pathways that reprogram the transcription, mRNA translation, and protein post-translational modification to relieve the ER stresses from unfolded/misfolded proteins. Infection with plant viruses can induce the UPR, and activated UPR often promotes plant viral infections in turn. However, the mechanism used by plant viruses to balance UPR and achieve robust infection remain largely unknown. In this study, P1SCSMV was identified as a virus-encoded RNA silencing suppressor (VSR). Heterologous overexpression of P1SCSMV via potato virus X (PVX) was found lead to programmed cell death (PCD) in Nicotiana benthamiana. Furthermore, P1SCSMV was also found to inhibit the PVX infection-triggered UPR by downregulating UPR-related genes and directly induced the distortion and collapse of the ER polygonal meshes on PVX-P1SCSMV infected N. benthamiana. Moreover, self-interaction, VSR activity, UPR inhibition, and cell death phenotype of P1SCSMV were also found to be dependent on its bipartite nuclear localization signal (NLS) (251RKRKLFPRIPLK262). P1SCSMV was found to directly bind to the stem-loop region of NbbZIP60U via its NLS and inhibit the UPR pathways, ultimately resulting in a PCD phenotype in PVX-P1SCSMV infected N. benthamiana leaves. This study also revealed the balancing role of potyviruses encoded P1SCSMV in the UPR pathway to achieve robust viral infection. This may represent a novel virulence strategy for plant viruses. Author summary: Unfolded protein response (UPR) is a cell designated strategy that maintains the balance of protein folding in the endoplasmic reticulum (ER). UPR contains a network of signal transduction pathways that reprogram the transcription, mRNA translation, and protein post-translational modification to relieve the ER stresses from unfolded/misfolded proteins. Plant viruses' infection induce the UPR, and activated UPR often promotes plant viral infection in turn. However, it is unclear how plant viruses balance the UPR to achieve robust infection. In this study, P1SCSMV was identified as a virus-encoded RNA silencing suppressor (VSR). P1SCSMV was found to inhibit PVX infection-triggered UPR by directly binding to the stem-loop region of NbbZIP60U with its bipartite nuclear localization signal (NLS) and inhibits the UPR pathways, thus leading to the distortion and collapse of the ER polygonal meshes and the cell-death phenotype on PVX-P1SCSMV infected N. benthamiana. The self-interaction, VSR activity, UPR inhibition, and cell-death phenotype of P1SCSMV are dependent on its NLS (251RKRKLFPRIPLK262). This study reveals the balancing role to the UPR pathway by potyviruses encoded P1SCSMV, which enriched the multi-functionality of the viral-encoded VSRs. This may represent a novel virulence strategy by plant viruses. [ABSTRACT FROM AUTHOR]

Background The quick and accurate identification of viruses is essential for plant disease management. Next-generation sequencing (NGS) technology may allow the discovery, detection, and identification of plant pathogens. This study adopted RNA-sequencing (RNA-Seq) technology to explore the viruses in three potato plants (S3, S4, and S6) growing under field conditions. Results Potato-known infecting viruses, such as alfalfa mosaic virus (AMV), potato leafroll virus (PLRV), and potato virus Y (PVY), were identified using bioinformatics programs and validated using RT-PCR. The presence of these potato viruses was also confirmed by visual inspection of host symptoms. In addition, the nearly complete genome of PLRV and the complete or partial genome sequence of multipartite virus segments have been identified. Besides the three major potato viruses that BLASTn analysis revealed were present in our samples, BLASTx analysis revealed some reads are derived from other potato viruses, such as potato virus V (PVV), Andean potato latent virus (APLV), and tomato chlorosis virus (ToCV), which are not frequently reported in potato field screenings in Egypt. Other microbial agents, such as bacteria and fungi, were also identified in the examined sample sequences. Some mycovirus sequences derived from ourmia-like viruses and Alternaria alternata chrysovirus were also identified in sample S4, confirming the complexity of the potato microbiome under field conditions. Conclusion NGS quickly and accurately identifies potato plant viruses under field conditions. Implementing this technology on a larger scale is recommended to explore potato fields and imported plants, where symptoms may be absent, unspecific, or only triggered under certain conditions. [ABSTRACT FROM AUTHOR]

Vegetative propagation of potatoes makes it possible for potato viruses to be transmitted through tubers. Potato virus A (PVA) is one of these viruses, which belongs to the Potyvirus genus in the Potyviridae family. Potato tuber yield can be reduced by 30–40% by PVA alone. Losses can be further exacerbated by potato virus X and/or potato virus Y infection. PVA is transmitted primarily by several species of aphids in non-persistent manner. With the aim of resolving this problem, we developed one-step reverse transcription-recombinase polymerase amplification (RT-RPA), a highly sensitive and cost-effective method for detecting PVA in both potato tubers and leaves. Detection and amplification are performed using isothermal conditions in this method. There was good amplification of the coat protein gene in PVA with all three primers tested. To conduct this study, a primer set that can amplify specific 185 base pair (bp) product was selected. PVA detection was optimized by 30-min amplification reactions, which showed no cross-reactivity with other potato viruses. A simple heating block or water bath was used to amplify PVA product using RT-RPA at a temperature range of 38–42 °C. In comparison to conventional reverse transcription-polymerase chain reaction (RT-PCR), the newly developed RT-RPA protocol exhibited high sensitivity for both potato leaves and tuber tissues. Using cellular paper-based simple RNA extraction procedure, the virus was detected in leaf samples as efficiently as purified total RNA. We also found that combining LiCl-based RNA precipitation with cellular paper discs allowed us to successfully optimize RNA extraction for one-step RT-RPA for detecting PVA in tubers. Tests using this simplified one-step RT-RPA method were successfully applied to 300 samples of both leaves and tubers from various potato cultivars. In our knowledge, this is the first report of an RT-RPA assay utilizing simple RNA obtained from either cellular disc paper or LiCl coupled with cellular disc paper to detect PVA. As a result, this method was equally sensitive and specific for detecting PVA in potatoes. The developed RT-RPA assay is more versatile, durable, and do not require highly purified RNA templates, thus providing an effective alternative to RT-PCR assays for screening of germplasm, certifying planting materials, breeding for virus resistance, and real-time monitoring of PVA. [ABSTRACT FROM AUTHOR]

Summary: The hyperosmolality‐gated calcium permeable channel 4.1 (OSCA4.1) belongs to an evolutionarily conserved small family of mechano‐sensitive channels. OSCA members may represent key players in plant resistance to drought and to pathogen infection but are scarcely studied. After screening for resistance to pepino mosaic virus (PepMV) a collection of 1000 mutagenized tomato families, we identified a mutant showing no symptoms and reduced virus accumulation. Resistance was mapped to chromosome 2 between positions 46 309 531 to 47 044 163, where a missense mutation caused the putative truncation of the OSCA4.1 protein. A CRISPR/Cas9 slosca4.1 mutant was resistant to PepMV, but not to tobacco mosaic virus or potato virus X. Inoculation of mutant and wild type tomato protoplasts showed that resistance was expressed in single cells, suggesting a role for SlOSCA4.1 in early viral function(s); congruently, SlOSCA4.1 re‐localized to structures reminiscent of viral replication complexes. We propose that SlOSCA4.1 contributes to the correct regulation of the Ca2+ homeostasis necessary for optimal PepMV infection. PepMV is a pandemic virus that causes significant losses in tomato crops worldwide. In spite of its importance, no tomato‐resistant varieties have been deployed yet; the mutant identified here has great potential to breed tomato varieties resistant to PepMV. [ABSTRACT FROM AUTHOR]

To move from cell to cell through plasmodesmata, many plant viruses require the concerted action of two or more movement proteins (MPs) encoded by transport gene modules of virus genomes. A tetra-cistron movement block (TCMB) is a newly discovered transport module comprising four genes. TCMB encodes three proteins, which are similar to MPs of the transport module known as the "triple gene block", and a protein unrelated to known viral MPs and containing a double-stranded RNA (dsRNA)-binding domain similar to that found in a family of cell proteins, including AtDRB4 and AtHYL1. Here, the latter TCMB protein, named vDRB for virus dsRNA-binding protein, is shown to bind both dsRNA and single-stranded RNA in vitro. In a turnip crinkle virus-based assay, vDRB exhibits the properties of a viral suppressor of RNA silencing (VSR). In the context of potato virus X infection, vDRB significantly decreases the number and size of "dark green islands", regions of local antiviral silencing, supporting the VSR function of vDRB. Nevertheless, vDRB does not exhibit the VSR properties in non-viral transient expression assays. Taken together, the data presented here indicate that vDRB is an RNA-binding protein exhibiting VSR functions in the context of viral infection. [ABSTRACT FROM AUTHOR]

In mixed infections between begomoviruses, common in tropical and subtropical regions, events such as transcomplementation and transreplication can occur. The aim of this research was to evaluate the possibility of asymmetric transreplication and transcomplementation events between Potato yellow mosaic virus (PYMV) and three begomoviruses previously isolated from tomato crop-associated weeds: Croton golden mosaic virus (CohGMV), Rhynchosia golden mosaic Colombia virus (RhGMCV) and Verbena mottle virus (VeMV). To achieve this goal, tomato leaves were inoculated with artificial mixtures of genomic components from PYMV, CohGMV, RhGMCV, or VeMV by using biolistic. The possible interactions between the viruses at the level of replication, movement and symptom expression were analyzed. Our results showed asymmetric complementation at the level of movement and replication, as well as heterologous transactivation events in mixed infections between PYMV with CohGMV, RhGMCV, or VeMV. To explain the possible asymmetrical complementation at the level of movement and replication between these begomoviruses, a bioinformatic analysis of the viral promoters of PYMV, CohGMV, RhGMCV and VeMV was performed. Similarities in cis-regulatory elements of the analyzed regions in the begomovirus studied were identified in our analysis. Asymmetrical complementation and transactivation events observed under experimental conditions suggest that if mixed infections occur under natural field conditions, new pseudorecombinats could emerge. [ABSTRACT FROM AUTHOR]

Antimicrobial acroautophagy/autophagy plays a vital role in degrading intracellular pathogens or microbial molecules in host-microbe interactions. However, microbes evolved various mechanisms to hijack or modulate autophagy to escape elimination. Vector-transmitted phloem-limited bacteria, Candidatus Liberibacter (Ca. Liberibacter) species, cause Huanglongbing (HLB), one of the most catastrophic citrus diseases worldwide, yet contributions of autophagy to HLB disease proliferation remain poorly defined. Here, we report the identification of a virulence effector in "Ca. Liberibacter asiaticus" (Las), SDE3, which is highly conserved among the "Ca. Liberibacter". SDE3 expression not only promotes the disease development of HLB and canker in sweet orange (Citrus sinensis) plants but also facilitates Phytophthora and viral infections in Arabidopsis, and Nicotiana benthamiana (N.benthamiana). SDE3 directly associates with citrus cytosolic glyceraldehyde-3-phosphate dehydrogenases (CsGAPCs), which negatively regulates plant immunity. Overexpression of CsGAPCs and SDE3 significantly inhibits autophagy in citrus, Arabidopsis, and N.benthamiana. Intriguingly, SDE3 undermines autophagy-mediated immunity by the specific degradation of CsATG8 family proteins in a CsGAPC1-dependent manner. CsATG8 degradation is largely rescued by treatment with an inhibitor of the late autophagic pathway, E64d. Furthermore, ectopic expression of CsATG8s enhances Phytophthora resistance. Collectively, these results suggest that SDE3-CsGAPC interactions modulate CsATG8-mediated autophagy to enhance Las progression in citrus. Abbreviations: ACP: asian citrus psyllid; ACD2: ACCELERATED CELL DEATH 2; ATG: autophagy related; Ca. Liberibacter: Candidatus Liberibacter; CaMV: cauliflower mosaic virus; CMV: cucumber mosaic virus; Cs: Citrus sinensis; EV: empty vector; GAPC: cytosolic glyceraldehyde-3-phosphate dehydrogenase; HLB: huanglongbing; H2O2: hydrogen peroxide; Las: liberibacter asiaticus; Laf: liberibacter africanus; Lam: liberibacter americanus; Pst: Pseudomonas syringae pv. tomato; PVX: potato virus X; ROS: reactive oxygen species; SDE3: sec-delivered effector 3; TEM: transmission electron microscopy; VIVE : virus-induced virulence effector; WT: wild-type; Xcc: Xanthomonas citri subsp. citri; [ABSTRACT FROM AUTHOR]

Faba bean is an important cool-season edible legume crop that is constantly threatened by abiotic stresses such as drought. The basic leucine zipper (bZIP) gene family is one of the most abundant and diverse families of transcription factors in plants. It regulates plant growth and development and plays an important role in the response to biotic and abiotic stresses. In this study, we identified 18 members of the faba bean bZIP transcription factor family at the genome-wide level based on previous faba bean drought stress transcriptome sequencing data. A phylogenetic tree was constructed to group the 18 VfbZIP proteins into eight clades. Analysis of cis-acting elements in the promoter region suggested that these 18 VfbZIPs may be involved in regulating abiotic stress responses such as drought. Transcriptome data showed high expression of seven genes (VfbZIP1, VfbZIP2, VfbZIP5, VfbZIP7, VfbZIP15, VfbZIP17, and VfbZIP18) in the drought-tolerant cultivar under drought stress, in which VfbZIP1, VfbZIP2, and VfbZIP5 were consistently expressed as detected by quantitative real-time polymerase chain reaction (qRT-PCR) compared to the transcriptome data. Ectopic overexpression of the three VfbZIPs in tobacco, based on the potato Virus X (PVX) vector, revealed that VfbZIP5 enhanced the drought tolerance. Overexpressed VfbZIP5 in plants showed lower levels of proline (PRO), malondialdehyde (MDA), and peroxidase (POD) compared to those overexpressing an empty vector under 10 days of drought stress. Protein-protein interaction (PPI) analysis showed that VfbZIP5 interacted with seven proteins in faba bean, including VfbZIP7 and VfbZIP10. The results depict the importance of VfbZIPs in response to drought stress, and they would be useful for the improvement of drought tolerance. [ABSTRACT FROM AUTHOR]

Viruses within the Polerovirus genus in the family of Solemoviridae have a single-stranded positive-sense RNA genome of about 5.6–6.2 kb in length. In this study, the bitter gourd leaves showing yellowing and crumple symptoms were collected for small RNAs (sRNAs) sequencing. Analysis of the contigs de novo assembled from sRNA-sequencing data, followed by RT-PCR and cloning, determined the complete viral genome to be 5665 nucleotides. This virus isolate contains conserved ORF3a, ORF3, ORF4, and other typical features of poleroviruses. The P0 protein of this virus isolate shares less than 74.80% amino acid sequence identity with any of the previously characterized poleroviruses, indicating that it should be a novel polerovirus. We name this virus as bitter gourd yellowing crumple virus (BYCV). We further revealed the dynamic subcellular localization and protein accumulation of seven proteins encoded by BYCV in Nicotiana benthamiana plants over time, and these viral proteins displayed specific subcellular localization. Expressing the BYCV P0 protein using a potato virus X vector caused severe symptoms in N. benthamiana plants, while P0 exhibited weak RNA silencing suppression activity. These findings provide an example for investigating the dynamic subcellular localizations of viral proteins and demonstrate that P0 is a critical protein potentially playing an important role in virus infection. [ABSTRACT FROM AUTHOR]

T1 and T2 were cultured in a multiplication medium (MM) for cassava shoot tips (Medina et al., [19]), whereas T3 was cultured in a plant regeneration medium specific for cassava shoot apical meristems (Collavino et al., [6]). To our knowledge, this is the first report of CsCMV infecting meristematic cells of cassava plants and shows that in vitro culture of meristems does not always lead to complete virus eradication. 10 Faccioli, G. & Colombarini, A. (1996) Correlation of potato virus S and virus M contents of potato meristem tips with the percentage of virus-free plantlets produced in vitro. (2010) Tobacco ringspot virus persists in the shoot apical meristem but not in the root apical meristem of infected tobacco. [Extracted from the article]

Tomato yellow leaf curl virus (TYLCV) is a monopartite geminivirus, and one of the most devastating plant viruses in the world. TYLCV is traditionally known to encode six viral proteins in bidirectional and partially overlapping open reading frames (ORFs). However, recent studies have shown that TYLCV encodes additional small proteins with specific subcellular localizations and potential virulence functions. Here, a novel protein named C7, encoded by a newly-described ORF in the complementary strand, was identified as part of the TYLCV proteome using mass spectrometry. The C7 protein localized to the nucleus and cytoplasm, both in the absence and presence of the virus. C7 was found to interact with two other TYLCV-encoded proteins: with C2 in the nucleus, and with V2 in the cytoplasm, forming conspicuous granules. Mutation of C7 start codon ATG to ACG to block the translation of C7 delayed the onset of viral infection, and the mutant virus caused milder virus symptoms and less accumulations of viral DNAs and proteins. Using the potato virus X (PVX)-based recombinant vector, we found that ectopic overexpression of C7 resulted in more severe mosaic symptoms and promoted a higher accumulation of PVX-encoded coat protein in the late virus infection stage. In addition, C7 was also found to inhibit GFP-induced RNA silencing moderately. This study demonstrates that the novel C7 protein encoded by TYLCV is a pathogenicity factor and a weak RNA silencing suppressor, and that it plays a critical role during TYLCV infection. • The C7 ORF is highly conserved and is present in many viruses in the Begomovirus genus (the family Geminiviridae). • The C7 protein of TYLCV localizes to the nucleus and cytoplasm, both in the absence and presence of the virus. • C7 is an important pathogenic factor and a virulence factor during TYLCV infection. • C7 is able to inhibit GFP-induced RNA silencing moderately, and interact with the other two TYLCV-encoded proteins C2 and V2. [ABSTRACT FROM AUTHOR]

Bacterial wilt, caused by the Ralstonia solanacearum species complex (RSSC), is a severe disease that significantly threatens potato cultivation. Our previous research identified a major strain-specific resistance quantitative trait locus (QTL) on potato chromosome 6, designated as PBWR-6b, which exhibited resistance to Ralstonia pseudosolanacearum (phylotype I/biovar 3) strains of the RSSC, and was most effective at relatively low temperatures. In this study, we compared the nucleotide sequences of one of the candidate genes located within the QTL region of PBWR-6b between the parents used for the QTL analysis. We identified a resistance allele and developed an allele-specific molecular marker (Rbw6-1) for PBWR-6b. This marker assay detected this resistance allele only in genotypes derived from Inca-no-mezame among 107 cultivars and breeding clones; PBWR-6b is thought to have been derived from Solanum tuberosum spp. andigena, which is the hybrid parent of Inca-no-mezame. By utilizing the resistance allele-specific marker, resistant genotypes can be selected from both diploid and tetraploid populations. The inheritance mode of PBWR-6b was then inferred to exhibit dominant inheritance. Furthermore, we developed the Rbw6-2 marker, which can be incorporated into existing multiplex polymerase chain reaction (PCR) methods, to efficiently select resistance genes against bacterial wilt (PBWR-6b), golden cyst nematode (H1), Potato virus Y (Rychc), Potato virus X (Rx1), and late blight (R1 and Saya-akane-derived R2), thus significantly enhancing resistance breeding in potato. [ABSTRACT FROM AUTHOR]

Sugarcane yellow leaf virus (SCYLV), a member of the genus Polerovirus in the family Luteoviridae, causes severe damage and represents a great threat to sugarcane cultivation and sugar industry development. In this study, inoculation of Nicotiana benthamiana plants with a potato virus X (PVX)-based vector carrying the SCYLV P0 gene induced typical mosaic, leaf rolling symptoms and was associated with a hypersensitive-like response (HLR) necrosis symptom, which is accompanied with a systemic burst of H2O2 and also leads to higher PVX viral genome accumulation levels. Our results demonstrate that SCYLV P0 is a pathogenicity determinant and plays important roles in disease development. To further explore its function in pathogenic processes, a yeast two-hybrid assay was performed to screen the putative P0-interacting host factors. The recombinant plasmid pGBKT7-P0 was constructed as a bait and transformed into the yeast strain Y2HGold. The ROC22 cultivar (an important parental resource of the main cultivar in China) cDNA prey library was constructed and screened by co-transformation with the P0 bait. We identified 28 potential interacting partners including those involved in the optical signal path, plant growth and development, transcriptional regulation, host defense response, and viral replication. To our knowledge, this is the first time we have reported the host proteins interacting with the P0 virulence factor encoded by sugarcane yellow leaf virus. This study not only provides valuable insights into elucidating the molecular mechanism of the pathogenicity of SCYLV, but also sheds light on revealing the probable new pathogenesis of Polerovirus in the future. [ABSTRACT FROM AUTHOR]

Biotic and abiotic stresses are among major factors limiting crop yields, and Filamentation temperature-sensitive (FtsH) genes are one of the key regulators of plant response to these stresses. The FtsH is an ATP-dependent metalloprotease in prokaryotes and eukaryotes. Due to the economic importance and cultivation of potato grown in the biotic and abiotic stress prone areas, identification and characterization of FtsH family members are crucially important. The present research was conducted to investigate FtsH family members in potato under stressful regime. To detect the FtsH genes in potato, we performed genome-wide analysis of FtsH genes in the Solanum tuberosum genome using the Ensemble Plant. All putative sequences were approved with the Pfam. Bioinformatics analysis was conducted using phylogenetic tree, gene structure, Transcription factor-binding site (TFBS) analysis, protein–protein interaction, and gene expression. The members of FtsH were categorized into eight groups. Some of the FtsH proteins were subcellularly located in the nucleus and chloroplast. The number of introns was ranged from 3 to 14 in gene family members. Totally, 33 TFBS including biotic and abiotic stress-responsive elements were found in FtsH promoter sequences. MYB and WRKY were the highest number among TFBS which were involved in abiotic and biotic stresses. Gene expression analysis revealed that the StFtsH2 and StFtsH5 had the highest gene expression, induced by abiotic and biotic stresses in all three tissues of stem, root, and leaves. It is expected that the StFtsH2 and StFtsH5 could be used in plant manipulation and breeding programs aimed for tolerance enhancement to abiotic (cold, heat, and high light) and biotic stresses [Potato virus Y (PVY), Potato virus X (PVX), Potato virus A (PVA), Potato virus X (PVA), and Potato virus S (PVS)]. [ABSTRACT FROM AUTHOR]

The potential of immune-evasive mutation accumulation in the SARS-CoV-2 virus has led to its rapid spread, causing over 600 million confirmed cases and more than 6.5 million confirmed deaths. The huge demand for the rapid development and deployment of low-cost and effective vaccines against emerging variants has renewed interest in DNA vaccine technology. Here, we report the rapid generation and immunological evaluation of novel DNA vaccine candidates against the Wuhan-Hu-1 and Omicron variants based on the RBD protein fused with the Potato virus X coat protein (PVXCP). The delivery of DNA vaccines using electroporation in a two-dose regimen induced high-antibody titers and profound cellular responses in mice. The antibody titers induced against the Omicron variant of the vaccine were sufficient for effective protection against both Omicron and Wuhan-Hu-1 virus infections. The PVXCP protein in the vaccine construct shifted the immune response to the favorable Th1-like type and provided the oligomerization of RBD-PVXCP protein. Naked DNA delivery by needle-free injection allowed us to achieve antibody titers comparable with mRNA-LNP delivery in rabbits. These data identify the RBD-PVXCP DNA vaccine platform as a promising solution for robust and effective SARS-CoV-2 protection, supporting further translational study. [ABSTRACT FROM AUTHOR]

With the increasing global population, saving crops from diseases caused by different kinds of bacteria, fungi, viruses, and nematodes is essential. Potato is affected by various diseases, destroying many crops in the field and storage. In this study, we developed potato lines resistant to fungi and viruses, Potato Virus X (PVX) and Potato Virus Y (PVY), by inoculating chitinase for fungi and shRNA designed against the mRNA of the coat protein of PVX and PVY, respectively. The construct was developed using the pCAMBIA2301 vector and transformed into AGB-R (red skin) potato cultivar using Agrobacterium tumefaciens. The crude protein extract of the transgenic potato plant inhibited the growth of Fusarium oxysporum from ~13 to 63%. The detached leaf assay of the transgenic line (SP-21) showed decreased necrotic spots compared to the non-transgenic control when challenged with Fusarium oxysporum. The transgenic line, SP-21, showed maximum knockdown when challenged with PVX and PVY, i.e., 89 and 86%, while transgenic line SP-148 showed 68 and 70% knockdown in the PVX- and PVY-challenged conditions, respectively. It is concluded from this study that the developed transgenic potato cultivar AGB-R showed resistance against fungi and viruses (PVX and PVY). [ABSTRACT FROM AUTHOR]

Cereal yellow dwarf virus (CYDV-RPV) encodes a P0 protein that functions as a viral suppressor of RNA silencing (VSR). The strength of silencing suppression is highly variable among CYDV-RPV isolates. In this study, comparison of the P0 sequences of CYDV-RPV isolates and mutational analysis identified a single C-terminal amino acid that influenced P0 RNA-silencing suppressor activity. A serine at position 247 was associated with strong suppressor activity, whereas a proline at position 247 was associated with weak suppressor activity. Amino acid changes at position 247 did not affect the interaction of P0 with SKP1 proteins from Hordeum vulgare (barley) or Nicotiana benthamiana. Subsequent studies found P0 proteins containing a P247 residue were less stable than the P0 proteins containing an S247 residue. Higher temperatures contributed to the lower stability and in planta and the P247 P0 proteins were subject to degradation via the autophagy-mediated pathway. A P247S amino acid residue substitution in P0 increased CYDV-RPV replication after expression in agroinfiltrated plant leaves and increased viral pathogenicity of P0 generated from the heterologous Potato virus X expression vector system. Moreover, an S247 CYDV-RPV could outcompete the P247 CYDV-RPV in a mixed infection in natural host at higher temperature. These traits contributed to increased transmission by aphid vectors and could play a significant role in virus competition in warming climates. Our findings underscore the capacity of a plant RNA virus to adapt to climate warming through minor genetic changes in gene-silencing suppressor, resulting in the potential for disease persistence and prevalence. Author summary: Climate change and extreme weather events pose an increased risk for crops to become infected with pathogens, which could severely affect global food security. However, the studies about the effects of climate change on plant virus diseases are still obscure. Yellow dwarf disease is one of the most important diseases of small grain cereals worldwide, which is caused by viruses belonging to the genera Luteovirus and Polerovirus. The gene encoding the P0 protein of poleroviruses has been reported to be the most rapidly evolving ORF of the Polerovirus genus. P0 functions as a viral suppressor of RNA silencing (VSR) and the strength of silencing suppression of P0 is highly variable among CYDV-RPV isolates. However, little is known about the molecular mechanism that determine P0 suppressor activity. Here, we identify a naturally occurring, single-amino-acid substitution in the CYDV-RPV P0 protein that enhances its protein stability to increasing thermal stress. This is the first study to identify a naturally occurring amino acid substitution in a plant virus-encoded protein that determines its adaption to increasing thermal stress. As climate change and extreme weather events occur frequently, we expect that our research can supply insight into how a plant RNA virus evolves to adapt climate change. [ABSTRACT FROM AUTHOR]