ICTV Virus Taxonomy Profile: Fimoviridae 2024.

Members of the family Fimoviridae are plant viruses with a multipartite negative-sense enveloped RNA genome (-ssRNA), composed of 4-10 segments comprising 12.3-18.5 kb in total, within quasi-spherical virions. Fimoviruses are transmitted to plants by eriophyid mites and induce characteristic cytopathologies in their host plants, including double membrane-bound bodies in the cytoplasm of virus-infected cells. Most fimoviruses infect dicotyledonous plants, and many cause serious disease epidemics. This is a summary of the ICTV Report on the family Fimoviridae, which is available at ictv.global/report/fimoviridae.

In planta expression of specific single chain fragment antibody (scFv) against nucleocapsid protein of fig mosaic virus (FMV).

Fig mosaic virus (FMV) is recognized as the main viral agent associated with the mosaic disease (MD) of fig trees (Ficus carica). Due to its worldwide occurrence, FMV represents the most significant global threat to the production of fig fruit. A disease management strategy against the MD in fig orchards has never been effective; and therefore, expression of recombinant antibody in plant cells could provide an alternative approach to suppress FMV infections. In this study we focused on expressing a specific recombinant antibody, a single-chain variable fragment (scFv), targeting the nucleocapsid protein (NP) of FMV in planta. To accomplish this objective, we inserted the scFv gene into a plant expression vector and conducted transient expression in leaves of Nicotiana tabacum cv. Samson plants. The construct was transiently expressed in tobacco plants by agroinfiltration, and antibody of the anticipated size was detected by immunoblotting. The produced plantibody was then assessed for specificity using ELISA and confirmed by Western blot analysis. In this study, the plantibody developed against FMV could be considered as a potential countermeasure to the infection by conferring resistance to MD.

Identification, Sequencing, and Molecular Analysis of RNA2 of Artichoke Italian Latent Virus Isolates from Known Hosts and a New Host Plant Species.

Despite its first description in 1977 and numerous reports of its presence in various plant species in many countries, the molecular information available in GenBank for artichoke Italian latent virus (AILV) is still limited to a single complete genome sequence (RNA1 and 2) of a grapevine isolate (AILV-V) and a partial portion of the RNA2 sequence from an isolate of unknown origin and host. Here, we report the results of molecular analyses conducted on the RNA2 of some AILV isolates, sequenced for the first time in this study, together with the first-time identification of AILV in a new host plant species, namely chard (Beta vulgaris subsp. vulgaris), associated with vein clearing and mottling symptoms on leaves. The different AILV isolates sequenced were from artichoke (AILV-C), gladiolus (AILV-G), Sonchus (AILV-S), and chard (AILV-B). At the molecular level, the sequencing results of the RNA2 segments showed that AILV-C, AILV-G, AILV-S, and AILV-B had a length of 4629 nt (excluding the 3' terminal polyA tail), which is one nt shorter than that of the AILV-V reported in GenBank. A comparison of the RNA2 coding region sequences of all the isolates showed that AILV-V was the most divergent isolate, with the lowest sequence identities of 83.2% at the nucleotide level and 84.7% at the amino acid level. Putative intra-species sequence recombination sites were predicted among the AILV isolates, mainly involving the genomes of AILV-V, AILV-C, and AILV-B. This study adds insights into the variability of AILV and the occurrence of recombination that may condition plant infection.

Annual (2023) taxonomic update of RNA-directed RNA polymerase-encoding negative-sense RNA viruses (realm Riboviria: kingdom Orthornavirae: phylum Negarnaviricota).

In April 2023, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by one new family, 14 new genera, and 140 new species. Two genera and 538 species were renamed. One species was moved, and four were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

Protective Activity of Rhizobium leguminosarum bv. viciae Strain 33504-Mat209 against Alfalfa Mosaic Virus Infection in Faba Bean Plants.

The application of Rhizobium spp., nitrogen-fixing plant growth-promoting rhizobacteria, as biocontrol agents to enhance systemic disease resistance against plant viral infections is a promising approach towards achieving sustainable and eco-friendly agriculture. However, their potential as antivirals and biocontrol agents is less studied. Herein, the capability of Rhizobium leguminosarum bv. viciae strain 33504-Mat209 was evaluated to promote plant growth and enhance faba bean systemic resistance against alfalfa mosaic virus (AMV) infection. Under greenhouse conditions, the soil inoculation with 3504-Mat209 resulted in notable improvements in growth and an increase in chlorophyll content. This led to a marked decrease in the disease incidence, severity, and viral accumulation level by 48, 74, and 87%, respectively. The protective effect of 33504-Mat209 was linked to significant decreases in non-enzymatic oxidative stress indicators, specifically H2O2 and MDA. Additionally, there were significant increases in the activity of reactive oxygen species scavenging enzymes, such as peroxidase (POX) and polyphenol oxidase (PPO), compared to the virus treatment. The elevated transcript levels of polyphenolic pathway genes (C4H, HCT, C3H, and CHS) and pathogenesis-related protein-1 were also observed. Out of 18 detected compounds, HPLC analysis revealed that 33504-Mat209-treated plants increased the accumulation of several compounds, such as gallic acid, chlorogenic acid, catechin, pyrocatechol, daidzein, quercetin, and cinnamic acid. Therefore, the ability of 33504-Mat209 to promote plant growth and induce systemic resistance against AMV infection has implications for utilizing 33504-Mat209 as a fertilizer and biocontrol agent. This could potentially introduce a new strategy for safeguarding crops, promoting sustainability, and ensuring environmental safety in the agricultural sector. As far as we know, this is the first study of biological control of AMV mediated by Rhizobium spp. in faba bean plants.

Antiviral Activity of Biosynthesized Silver Nanoparticles from Pomegranate (Punica granatum L.) Peel Extract against Tobacco Mosaic Virus.

Tobacco mosaic virus (TMV) is a major pathogen affecting tomato plants worldwide. The efficacy of silver nanoparticles (Ag-NPs) mediated by Punica granatum biowaste peel extract in mitigating the negative impact of TMV infection on tomato growth and oxidative stress was investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Visible (UV-Vis) spectrophotometer, X-ray Diffraction (XRD), dynamic light scattering (DLS), zeta potential, energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectra (FTIR). Results of SEM analysis of green Ag-NPs revealed the presence of condensed spherical or round NPs with diameters ranging between 61 and 97 nm. TEM confirmed the SEM results and showed round-shaped Ag-NPs with an average size of 33.37 ± 12.7 nm. The elemental analysis (EDX) of prepared Ag-NPs revealed the presence of elemental Ag as a major peak (64.43%) at 3-3.5 KeV. The FTIR revealed several functional groups on the prepared Ag-NPs, for which three treatment strategies for Ag-NP applications were evaluated in the greenhouse study and compared to inoculated TMV and control plants: pre-infection treatment (TB), post-infection treatment (TA), and dual treatment (TD). The results showed that the TD strategy is the most effective in improving tomato growth and reducing viral replication, whereas all Ag-NP treatments (TB, TA, and TD) were found to significantly increase expression of the pathogenesis-related (PR) genes PR-1 and PR-2, as well as polyphenolic compounds, HQT, and C4H genes compared to control plants. In contrast, the flavonoid content of tomato plants was not affected by the viral infection, while the phenolic content was significantly reduced in the TMV group. Furthermore, TMV infection led to a significant increase in oxidative stress markers MDA and H2O2, as well as a reduction in the enzymatic activity of the antioxidants PPO, SOD, and POX. Our results clearly showed that the application of Ag-NPs on TMV-infected plants reduces virus accumulation, delays viral replication in all treatments, and greatly enhances the expression of the CHS gene involved in flavonoid biosynthesis. Overall, these findings suggest that treatment with Ag-NPs may be an effective strategy to mitigate the negative impact of TMV infection on tomato plants.

In-silico prediction of RT-qPCR-high resolution melting for broad detection of emaraviruses.

Twenty-four species of RNA viruses contain members infecting economically important crops that are classified within the genus Emaravirus, family Fimoviridae. There are at least two other non-classified species that may be added. Some of these viruses are spreading rapidly and cause economically important diseases on several crops, raising a need for a sensitive diagnostic technique for taxonomic and quarantine purposes. High-resolution melting (HRM) has shown to be reliable for the detection, discrimination, and diagnosis of several diseases of plants, animals, and humans. This research aimed to explore the ability to predict HRM outputs coupled to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). To approach this goal a pair of degenerate genus-specific primers were designed for endpoint RT-PCR and RT-qPCR-HRM and the species in the genus Emaravirus were selected to framework the development of the assays. Both nucleic acid amplification methods were able to detect in-vitro several members of seven Emaravirus species with sensitivity up to one fg of cDNA. Specific parameters for in-silico prediction of the melting temperatures of each expected emaravirus amplicon are compared to the data obtained in-vitro. A very distinct isolate of the High Plains wheat mosaic virus was also detected. The high-resolution DNA melting curves of the RT-PCR products predicted in-silico using uMeltSM allowed saving time while designing and developing the RT-qPCR-HRM assay since the approach avoided extensive searching for optimal HRM assay regions and rounds of HRM tests in-vitro for optimization. The resultant assay provides sensitive detection and reliable diagnosis for potentially any emaravirus, including new species or strains.

Exploring Active Peptides with Antimicrobial Activity In Planta against Xylella fastidiosa.

Xylella fastidiosa (Xf) is a xylem-limited quarantine plant bacterium and one of the most harmful agricultural pathogens across the world. Despite significant research efforts, neither a direct treatment nor an efficient strategy has yet been developed for combatting Xylella-associated diseases. Antimicrobial peptides (AMPs) have been gaining interest as a promising sustainable tool to control pathogens due to their unique mechanism of action, broad spectrum of activity, and low environmental impact. In this study, we disclose the bioactivity of nine AMPs reported in the literature to be efficient against human and plant pathogen bacteria, i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, against Xf, through in vitro and in vivo experiments. Based on viable-quantitative PCR (v-qPCR), fluorescence microscopy (FM), optical density (OD), and transmission electron microscopy (TEM) assays, peptides Ascaphin-8 (GF19), DASamP1 (FF13), and DASamP2 (IL14) demonstrated the highest bactericidal and antibiofilm activities and were more efficient than the peptide PB178 (KL29), reported as one of the most potent AMPs against Xf at present. Furthermore, these AMPs showed low to no toxicity when tested on eukaryotic cells. In in planta tests, no Xf disease symptoms were noticed in Nicotiana tabacum plants treated with the AMPs 40 days post inoculation. This study highlighted the high antagonistic activity of newly tested AMP candidates against Xf, which could lead to the development of promising eco-friendly management of Xf-related diseases.

2022 taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

In March 2022, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by two new families (bunyaviral Discoviridae and Tulasviridae), 41 new genera, and 98 new species. Three hundred forty-nine species were renamed and/or moved. The accidentally misspelled names of seven species were corrected. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

Identification and Characterization of Erwinia Phage IT22: A New Bacteriophage-Based Biocontrol against Erwinia amylovora.

Erwinia amylovora is a quarantine phytopathogenic bacterium that is the causal agent of fire blight, a destructive disease responsible for killing millions of fruit-bearing plants worldwide, including apple, pear, quince, and raspberry. Efficient and sustainable control strategies for this serious bacterial disease are still lacking, and traditional methods are limited to the use of antibiotics and some basic agricultural practices. This study aimed to contribute to the development of a sustainable control strategy through the identification, characterization, and application of bacteriophages (phages) able to control fire blight on pears. Phages isolated from wastewater collected in the Apulia region (southern Italy) were characterized and evaluated as antibacterial agents to treat experimental fire blight caused by E. amylovora. Transmission electron microscopy (TEM) conducted on purified phages (named EP-IT22 for Erwinia phage IT22) showed particles with icosahedral heads of ca. 90 ± 5 nm in length and long contractile tails of 100 ± 10 nm, typical of the Myoviridae family. Whole genome sequencing (WGS), assembly, and analysis of the phage DNA generated a single contig of 174.346 bp representing a complete circular genome composed of 310 open reading frames (ORFs). EP-IT22 was found to be 98.48% identical to the Straboviridae Erwinia phage Cronus (EPC) (GenBank Acc. n° NC_055743) at the nucleotide level. EP-IT22 was found to be resistant to high temperatures (up to 60 °C) and pH values between 4 and 11, and was able to accomplish a complete lytic cycle within one hour. Furthermore, the viability-qPCR and turbidity assays showed that EP-IT22 (MOI = 1) lysed 94% of E. amylovora cells in 20 h. The antibacterial activity of EP-IT22 in planta was evaluated in E. amylovora-inoculated pear plants that remained asymptomatic 40 days post inoculation, similarly to those treated with streptomycin sulphate. This is the first description of the morphological, biological, and molecular features of EP-IT22, highlighting its promising potential for biocontrol of E. amylovora against fire blight disease.

Ocimum basilicum-Mediated Synthesis of Silver Nanoparticles Induces Innate Immune Responses against Cucumber Mosaic Virus in Squash.

Cucumber mosaic virus (CMV) causes a significant threat to crop output sustainability and human nutrition worldwide, since it is one of the most prevalent plant viruses infecting most kinds of plants. Nowadays, different types of nanomaterials are applied as a control agent against different phytopathogens. However, their effects against viral infections are still limited. In the current study, the antiviral activities of the biosynthesized silver nanoparticles (Ag-NPs) mediated by aqueous extract of Ocimum basilicum against cucumber mosaic virus in squash (Cucurbita pepo L.) were investigated. The prepared Ag-NPs were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and zeta potential distribution techniques. DLS, SEM, and TEM analyses showed that the Ag-NPs were spherical, with sizes ranging from 26.3 to 83 nm with an average particle size of about 32.6 nm. FTIR identified different functional groups responsible for the capping and stability of Ag-NPs. The zeta potential was reported as being -11.1 mV. Under greenhouse conditions, foliar sprays of Ag-NPs (100 µg/mL) promoted growth, delayed disease symptom development, and significantly reduced CMV accumulation levels of treated plants compared to non-treated plants. Treatment with Ag-NPs 24 h before or after CMV infection reduced CMV accumulation levels by 92% and 86%, respectively. There was also a significant increase in total soluble carbohydrates, free radical scavenging activity, antioxidant enzymes (PPO, SOD, and POX), as well as total phenolic and flavonoid content. Furthermore, systemic resistance was induced by significantly increasing the expression levels of pathogenesis-related genes (PR-1 and PR-5) and polyphenolic pathway genes (HCT and CHI). These findings suggest that Ag-NPs produced by O. basilicum could be used as an elicitor agent and as a control agent in the induction and management of plant viral infections.

Protective and Curative Activities of Paenibacillus polymyxa against Zucchini yellow mosaic virus Infestation in Squash Plants.

The use of microbial products as natural biocontrol agents to increase a plant's systemic resistance to viral infections is a promising way to make agriculture more sustainable and less harmful to the environment. The rhizobacterium Paenibacillus polymyxa has been shown to have strong biocontrol action against plant diseases, but its antiviral activity has been little investigated. Here, the efficiency of the culture filtrate of the P. polymyxa strain SZYM (Acc# ON149452) to protect squash (Cucurbita pepo L.) plants against a Zucchini yellow mosaic virus (ZYMV, Acc# ON159933) infection was evaluated. Under greenhouse conditions, the foliar application of the culture filtrate of SZYM either in protective or curative treatment conditions enhanced squash growth, reduced disease severity, and decreased ZYMV accumulation levels in the treated plants when compared to the non-treated plants. The protective treatment group exhibited the highest inhibitory effect (80%), with significant increases in their total soluble carbohydrates, total soluble protein content, ascorbic acid content, and free radical scavenging activity. Furthermore, a considerable increase in the activities of reactive oxygen species scavenging enzymes (superoxide dismutase, polyphenol oxidase, and peroxidase) were also found. In addition, the induction of systemic resistance with a significant elevation in the transcriptional levels of polyphenolic pathway genes (CHS, PAL, and C3H) and pathogenesis-related genes (PR-1 and PR-3) was observed. Out of the 14 detected compounds in the GC-MS analysis, propanoic acid, benzenedicarboxylic acid, tetradecanoic acid, and their derivatives, as well as pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) were the primary ingredient compounds in the ethyl acetate extract of the SZYM-culture filtrate. Such compounds may act as elicitor molecules that induce systemic resistance against viral infection. Consequently, P. polymyxa can be considered a powerful plant growth-promoting bacterium (PGPB) in agricultural applications as well as a source of bioactive compounds for sustainable disease management. As far as we know, this is the first time that P. polymyxa has been shown to fight viruses in plants.

Exploring Antimicrobial Peptides Efficacy against Fire Blight (Erwinia amylovora).

Antimicrobial peptides (AMPs) are a various group of molecules found in a wide range of organisms and act as a defense mechanism against different kinds of infectious pathogens (bacteria, viruses, and fungi, etc.). This study explored the antibacterial activity of nine candidates reported in the literature for their effect on human and animal bacteria, (i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) against Erwinia amylovora (E. amylovora), the causal agent of fire blight disease on pome fruits. The antibacterial activity of these peptides against E. amylovora was evaluated in vitro using viable-quantitative PCR (v-qPCR), fluorescence microscopy (FM), optical density (OD), and transmission electron microscopy (TEM), while the in vivo control efficacy was evaluated in treating experimental fire blight on pear fruits. With a view to their safe and ecofriendly field use in the future, the study also used animal and plant eukaryotic cells to evaluate the possible toxicity of these AMPs. Results in vitro showed that KL29 was the most potent peptide in inhibiting E. amylovora cell proliferation. In addition, the results of v-qPCR, FM, and TEM showed that KL29 has a bifunctional mechanism of action (lytic and non-lytic) when used at different concentrations against E. amylovora. KL29 reduced fire blight symptoms by 85% when applied experimentally in vivo. Furthermore, it had no impact on animal or plant cells, thus demonstrating its potential for safe use as an antibacterial agent. This study sheds light on a new and potent antibacterial peptide for E. amylovora and its modes of action, which could be exploited to develop sustainable treatments for fire blight.

Exploring in-silico prediction for the development of a RT-qPCR-high resolution melting assay for the broad detection of emaraviruses.

High-resolution melting (HRM) has shown to be reliable for the detection, discrimination, and diagnosis of several diseases of plants, animals, and humans. The aim of this research was to explore the ability to predict HRM outputs when coupled to reverse transcription quantitative polymerase chain reaction (RT-qPCR). This research used the species in the Emaravirus genus as model to framework the development of genus-specific RT-qPCR-HRM assays. A pair of degenerate genus-specific primers were designed for use in endpoint RT-PCR and RT-qPCR-HRM detection of emaraviruses. Eleven species of RNA viruses infecting economically important crops are classified within the genus Emaravirus, family Fimoviridae. There are at least fifteen other non-classified species that may be added. Some of these viruses are spreading rapidly and cause economically important diseases on several crops, raising a need for a sensitive diagnostic technique for taxonomic and quarantine purposes. RT-PCR and RT-qPCR-HRM were able to detect seven emaravirus species in-vitro with sensitivity up to one fg of cDNA. Specific parameters for prediction in-silico of the melting temperatures of each expected emaravirus amplicon are provided and compared to the data obtained in-vitro. A very distinct isolate of the High Plains wheat mosaic virus was also detected. The prediction in-silico of fluorescence of high-resolution DNA melting curves of predicted RT-PCR products using uMeltSM speeded the design and development of RT-qPCR-HRM assay. This approach avoided rounds of HRM tests in-vitro when searching for the optimal regions that provides accurate diagnosis. The resultant assay provided sensitive detection and reliable diagnosis for potentially any emaravirus, including new species or strains.

Maize (Zea mays L.): A New Host for Ligustrum witches' Broom Phytoplasma.

In the 2019-2020 growing season, two corn fields located in Imamoglu town (Adana Province, Turkey) were surveyed following the appearance of phytoplasma-like symptoms on maize plants. A total of 40 samples were collected and tested in first-round and nested PCR using universal primer pairs P1/P7 and R16F2n/R16R2, respectively. All maize-diseased plants reacted positively, whilst no PCR amplifications were obtained from asymptomatic plants. Blast sequence analysis of R16F2n/R16R2-primed amplicons from different maize isolates showed 99.2% to 100% of identity with the 16S rRNA gene of Ligustrum witches' broom phytoplasma (LiWBP). To gain additional molecular information on the 16S ribosomal RNA and 23S rRNA intergenic spacer region of LiWBP, not identified previously, the P1/P7-primed amplicons were also sequenced and analyzed. The results show that maize isolates from Turkey share 99.6% to 100% of identity among them, whereas the highest identity found (91%) was with members of groups 16SrII and 16SrXXV (peanut and tea witches' broom groups, respectively). This distant relationship between LiWBP and members of 16SrII and XXV was also confirmed by RFLP and phylogenetic analyses. This is the first finding of LiWBP on maize in nature, where it was found responsible for phyllody disease of corn plants in Turkey. The additional molecular information acquired in this study on the 16S-23S rRNA intergenic spacer region of LiWBP further corroborates its distant relationship to any other phytoplasma groups.

Development of singleplex and multiplex real-time (Taqman®) RT-PCR assays for the detection of viruses associated with fig mosaic disease.

Singleplex and multiplex real-time (TaqMan®) RT-PCR assays were developed to detect seven fig-infecting viruses, i.e., fig leaf mottle-associated virus 1 (FLMaV-1), fig leaf mottle-associated virus 2 (FLMaV-2), fig mild mottle-associated virus (FMMaV), fig mosaic virus (FMV), fig latent virus 1 (FLV-1), fig cryptic virus 1 (FCV-1) and fig fleck-associated virus (FFkaV). The sensitivity of the newly developed TaqMan® assays was compared with the corresponding conventional RT-PCR (RT-PCR) using 10° to 10-6 serial dilutions of both cDNA and crude fig extracts. The results showed that the Taqman® RT-PCR assays were generally 102 to 103-fold more sensitive than the RT-PCR assays, except in the case of FLV-1 detection, where the two techniques had the same sensitivity. In the multiplex Taqman® RT-PCR, only a maximum of five viruses could be detected simultaneously in naturally infected fig trees, regardless of which combination of the virus-specific probes and primers were used. Both the RT-PCR and Taqman® RT-PCR assays were used in a large-scale survey of 100 field-grown fig trees in Egypt. The results showed the presence of all seven viruses under study, mostly occurring as mixed infections (63 %). The prevalence of infections observed in the tested samples were as follows: FMV (62 %), FFkaV (59 %), FLMaV-2 (32 %), FLV-1 (16 %), FLMaV-1 (14 %), FCV-1 (7%) and FMMaV (4%). FMV was invariably associated with diseased trees that presented mosaic-like symptoms. In the few cases where the mosaic-affected trees were found to be free of FMV, they were found to be infected with a mixture of two or more other viruses.

Detection and Phylogenetic Analysis of Viruses Linked with Fig Mosaic Disease in Seventeen Fig Cultivars in Palestine.

Fig mosaic is a viral disease (FMD) that spreads in Palestinian common fig ( Ficus carica L.) orchards. Recognizing the economic value of fig plants and the harmful nature of FMD, the disease poses a significant threat to the economy of the fig production in Palestine. We applied the reverse transcription and amplification (RT-PCR) and PCR technique to leaf samples of 77 trees and 14 seedlings of 17 fig cultivars. The samples were collected from orchards in the main fig-growing provinces of the Palestinian West Bank, to assess the prevalence of viruses associated with FMD, and confirm a possible link of symptoms with viruses detected. Four viruses were detected: Fig mosaic virus (FMV), Fig badnavirus-1 (FBV-1), Fig leaf mottle-associated virus 2 (FLMaV-2), and Fig fleck-associated virus (FFkaV). FMV and FBV-1 were found in all tested fig plants (100%), while FLMaV-2 and FFkaV were detected in 61.5% and 33% of the fig samples, respectively. The high incidence of FBV-1 in the newly propagated symptomatic and symptomless seedlings from different cultivars may be an indication that FBV-1 is integrated into the genome of the fig in a cultivar nondiscriminatory manner. Very weak or no association was detected between FMD symptoms severity in the 17 Palestinian fig cultivars with the various viruses' combinations observed (i.e., number of the viruses infecting the plant). These results support the notion that FMD symptom severity expression is likely to be controlled by a combination of FMV infection, cultivars, and environmental factors, rather than the number of viruses infecting the plant.

Complete Sequence, Genome Organization and Molecular Detection of Grapevine Line Pattern Virus, a New Putative Anulavirus Infecting Grapevine.

: Grapevine line pattern virus (GLPV) was first described 30 years ago in Hungary. The lack of its genomic sequences and of an available antiserum made its detection impossible in other parts of the world. Three different high-throughput sequencing (HTS) protocols applied on a GLPV-infected vine allowed the construction of the full genome sequence of this virus. It includes three RNA segments, encoding four proteins: methyltransferase-helicase (1a), RNA-dependent RNA polymerase (2a), movement protein (3a) and coat protein (3b). The obtained sequences were used to design specific primers for its detection by RT-PCR and Northern blot hybridization, respectively. These diagnostic methods were used to test the presence of GLPV in graft-inoculated plants and in 220 grapevine accessions of different Mediterranean origins. The three RNAs-encoding proteins of GLPV shared a very high amino acid identity with those of hop yellow virus, a tentative member of the Anulavirus genus, leaving no doubt that both are two isolates of the same viral species. A circular RNA originating from the RNA2 was found, for which an alternative silencing suppressor role is hypothesized. Further investigation is needed to determine this possibility and also the host range and pathological significance of the virus.