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Fusarium head blight (FHB), a disease inflicted by Fusarium graminearum and F. asiaticum, poses a growing threat to wheat in China, particularly in the face of climate change and evolving agricultural practices. This study unveiled the discovery of the victorivirus FgVV2 from the F. asiaticum strain F16176 and comprehensively characterized the function of the two victoriviruses FaVV1 and FaVV2 in virulence. Through comparative analysis with a virus-free strain, we established that these mycoviruses markedly repress the sexual reproduction and pathogenicity of their fungal hosts. Furthermore, we synthesized the coat protein (CP) genes CP1 from FaVV1 and CP2 from FaVV2, which were fused with the green fluorescent protein (GFP) gene and successfully expressed in Fusarium strains in wild-type isolates of F. asiaticum and F. graminearum. Similar to virus-infected strains, the transformed strains expressing CPs showed a significant decrease in perithecia formation and pathogenicity. Notably, CP2 exhibited a stronger inhibitory effect than CP1, yet the suppression of sexual reproduction in F. graminearum was less pronounced than that in F. asiaticum. Additionally, the pathogenicity of the F. asiaticum and F. graminearum strains expressing CP1 or CP2 was substantially diminished against wheat heads. The GFP-tagged CP1 and CP2 revealed distinct cellular localization patterns, suggesting various mechanisms of interaction with the host. The findings of this study provide a significant research foundation for the study of the interaction mechanisms between FaVV1 and FaVV2 with their hosts, as well as for the exploration and utilization of fungal viral resources. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Banana bract mosaic virus (BBrMV), transmitted by aphids, is a major threat to banana cultivation, causing substantial economic losses. This study focuses on the development of BBrMV-resistant lines of banana cv. 'Grand Naine' by silencing viral coat protein (CP) gene using RNA interference (RNAi) strategy. To achieve this, an intron hairpin RNA (ihpRNA) construct containing a 326 bp fragment of the CP gene was designed using the pSTARLING vector. Identification of a Dicer substrate within the CP gene facilitated the prediction of small interfering RNAs (siRNAs) through Custom Dicer-Substrate siRNA analysis. The absence of viral silencing suppressors was validated using the VsupPred tool. Cloning of the sense and antisense fragments of the CP gene into the pSTARLING vector, flanking the cre intron, was confirmed through PCR analysis. Subsequently, the NotI fragment comprising the ubiquitin promoter, ubiquitin intron, sense fragment inserts, cre intron, antisense strand insert, and tumour morphology locus (tmL) terminator was transferred to the Agrobacterium tumefaciens binary vector pART27. Embryogenic calli were transformed with the ihpRNA-CP cassette, and regenerated plantlets were screened for complete cassette integration using PCR. Northern hybridization confirmed the production of siRNAs against coat protein mRNA. Upon exposure to virulent aphids carrying BBrMV, the transformed lines exhibited no disease symptoms. Additionally, reverse transcription quantitative PCR (RT-qPCR) demonstrated the absence of BBrMV, with transformed lines resembling healthy, non-inoculated controls both morphologically and in terms of coat protein gene expression. This RNAi-based approach showcases the successful creation of BBrMV-resistant banana lines, presenting a promising strategy for combating the virus's detrimental effects on banana cultivation. [ABSTRACT FROM AUTHOR]

Abstract Background Although potato virus Y (PVY) is the most serious virus-infecting potato plants worldwide, the losses concurred by it remain unmanageable due to the lack of efficient anti-PVY agents. Hence, the objective of this study was to assess the antiviral properties of secondary metabolite compounds obtained from culture filtrates of four Trichoderma spp. isolates. The assessment was conducted using computational methods, including molecular docking, absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis, as well as molecular dynamics simulations. The aim was to develop novel and effective agents for combating PVY. Results The GC–MS analysis of the studied Trichoderma spp. secondary metabolites revealed 24 compounds with relative amounts exceeding 10%. Molecular docking was then performed using MOE software to evaluate the activity of these compounds against the PVY protein coat (PDB-ID: 6HXX). Ningnanmycin and ribavirin, known plant virus inhibitors, were employed as reference ligands for comparison. Among the compounds tested, C9, C10, C13, and C19 exhibited superior docking scores, root mean square deviation (RMSD) values, and binding modes compared to the reference ligands. In addition, these compounds successfully passed the ADMET analysis. Further investigation focused on compounds C13 and C19, which underwent in-depth analysis through MDs for 100 ns. The MDs trajectories demonstrated that both complexes exhibited favorable stability, compactness, and binding modes throughout the simulation period. However, the C19/PVY-CP complex outperformed the C13 complex in all calculated parameters such as RMSD, root mean square fluctuation (RMSF), radius of gyration (RoG), solvent-accessible surface area (SASA), and intermolecular hydrogen bonds. Interestingly, these findings aligned with the results obtained from the docking analysis, indicating that C9 and C10 possess high potential against PVY, as they exhibited binding modes like that of C19. Conclusion These promising outcomes provide a solid foundation for considering the potential use of compounds C9, C10, C13, and C19 as antiviral agents. Further experimental validation and in-depth studies are warranted to assess the efficacy and safety of these compounds and their potential as antiviral therapeutics. To our knowledge, this is the first report to study the biological activities of the Trichoderma-based bioactive compounds against PVY using computational techniques. Graphical abstract

Background: Although potato virus Y (PVY) is the most serious virus-infecting potato plants worldwide, the losses concurred by it remain unmanageable due to the lack of efficient anti-PVY agents. Hence, the objective of this study was to assess the antiviral properties of secondary metabolite compounds obtained from culture filtrates of four Trichoderma spp. isolates. The assessment was conducted using computational methods, including molecular docking, absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis, as well as molecular dynamics simulations. The aim was to develop novel and effective agents for combating PVY. Results: The GC–MS analysis of the studied Trichoderma spp. secondary metabolites revealed 24 compounds with relative amounts exceeding 10%. Molecular docking was then performed using MOE software to evaluate the activity of these compounds against the PVY protein coat (PDB-ID: 6HXX). Ningnanmycin and ribavirin, known plant virus inhibitors, were employed as reference ligands for comparison. Among the compounds tested, C9, C10, C13, and C19 exhibited superior docking scores, root mean square deviation (RMSD) values, and binding modes compared to the reference ligands. In addition, these compounds successfully passed the ADMET analysis. Further investigation focused on compounds C13 and C19, which underwent in-depth analysis through MDs for 100 ns. The MDs trajectories demonstrated that both complexes exhibited favorable stability, compactness, and binding modes throughout the simulation period. However, the C19/PVY-CP complex outperformed the C13 complex in all calculated parameters such as RMSD, root mean square fluctuation (RMSF), radius of gyration (RoG), solvent-accessible surface area (SASA), and intermolecular hydrogen bonds. Interestingly, these findings aligned with the results obtained from the docking analysis, indicating that C9 and C10 possess high potential against PVY, as they exhibited binding modes like that of C19. Conclusion: These promising outcomes provide a solid foundation for considering the potential use of compounds C9, C10, C13, and C19 as antiviral agents. Further experimental validation and in-depth studies are warranted to assess the efficacy and safety of these compounds and their potential as antiviral therapeutics. To our knowledge, this is the first report to study the biological activities of the Trichoderma-based bioactive compounds against PVY using computational techniques. [ABSTRACT FROM AUTHOR]

SUGAR beet (Beta vulgaris) is one of the principal sources for sugar production in Egypt. Viral infections could seriously impact its cultivation and development. This study was performed to investigate genetic diversity of cucumber mosaic virus (CMV) isolates infecting sugar beet and other crops growing nearby such as pepper, cowpea, common bean and sweet potato. A total of nine CMV isolates were characterized at the molecular level, according to capsid protein gene sequence analysis (6 isolates from sugar beet and other three isolates from other crops). Four isolates showed highest identity to CMV subgroup IA. The other five isolates showed the highest levels of nucleotide identity to CMV group II. While group IA and 1B were known to occur in Egypt, to our knowledge, this is the first report of CMV group II from sugar beet and sweet potato in Egypt indicating recent introduction of new CMV genotypes. [ABSTRACT FROM AUTHOR]

Chilli leaf curl virus (ChiLCV) is a significant begomovirus that infects chili plants. To detect ChiLCV infection, a loop-mediated isothermal amplification (LAMP) assay was designed to be easy, quick, and efficient. The assay uses a set of five specific primers that target the coat protein gene (av1) of the target virus to detect the presence of the virus. The LAMP reaction amplifies the target gene within 45 min at 63 °C, with an 8mM dNTP concentration. This method showed no cross-reactivity with other tested begomoviruses that confirmed selective ChiLCV amplification. The sensitivity test revealed that LAMP was more sensitive than PCR. The LAMP assay displayed a remarkable detection limit of 10 fg/μL, which is superior than the PCR sensitivity of 10 pg/μL. Field sample validation yielded concordant results with PCR. This study introduces a cost-effective, and highly sensitive method for ChiLCV detection. Validation of LAMP with symptomatic leaves samples produced consistent results with PCR, demonstrating that the LAMP method could detect all infected samples. [ABSTRACT FROM AUTHOR]

Sri Lankan cassava mosaic virus (SLCMV) is a prominent causative agent of cassava mosaic disease in Asia and relies on the whitefly Bemisia tabaci cryptic complex for its transmission. However, the molecular mechanisms involved in SLCMV transmission by B. tabaci have yet to be understood. In this study, we identified an aminopeptidase N‐like protein (BtAPN) in B. tabaci Asia II 1, an efficient vector of SLCMV, which is involved in the SLCMV transmission process. Through the use of glutathione S‐transferase pull‐down assay and LC‐MS/MS analysis, we demonstrated the interaction between BtAPN and the coat protein (CP) of SLCMV. This interaction was further confirmed in vitro, and we observed an induction of BtAPN gene expression following SLCMV infection. By interfering with the function of BtAPN, the quantities of SLCMV were significantly reduced in various parts of B. tabaci Asia II 1, including the whole body, midgut, hemolymph, and primary salivary gland. Furthermore, we discovered that BtAPN is conserved in B. tabaci Middle East‐Asia Minor 1 (MEAM1) and interacts with the CP of tomato yellow leaf curl virus (TYLCV), a begomovirus known to cause severe damage to tomato production. Blocking BtAPN with antibody led to a significant reduction in the quantities of TYLCV in whitefly whole body and organs/tissues. These results demonstrate that BtAPN plays a generic role in interacting with the CP of begomoviruses and positively regulates their acquisition by the whitefly. [ABSTRACT FROM AUTHOR]

Rockmelon is a popular tropical fruit with high nutritional value. Cucumber mosaic virus (CMV), an aphid-transmitted virus, causes severe damage to rockmelon production. Exogenous application of double-stranded RNA (dsRNA) targeting viral sequences has shown promising results in controlling viral infection but has not been reported for CMV in rockmelon. In the current study, the protective effect of exogenous dsRNAs targeting the CMV coat protein (CP) and movement protein (MP) was tested in rockmelon. The effectiveness of dsRNA-mediated protection was measured by disease severity index (DSI) and compound enzyme-linked immunosorbent assay. The individual dsRNA CP and MP treatments each showed protection by reducing the DSI and virus titre, whilst a combination of dsRNA of CP and MP treatment showed much lower DSI (4.31-fold lower) and virus titre (4.91-fold lower) compared to CMV-inoculated plants without dsRNA treatment. Chlorophyll content, relative water content, plant height and number of leaves were not significantly different between virus challenged dsRNA-treated and mock-inoculated plants. Based on the DSI, two applications containing 9000 ng of dsRNA CP and MP in combination showed maximum CMV protection. Taken together, these results indicate that exogenous treatment containing a combination of dsRNA of CP and MP can control CMV infection in rockmelon. [ABSTRACT FROM AUTHOR]

Ridge gourd (Luffa acutangula L. Roxb.) is one of the most important vegetable crops in India. It belongs to the family Cucurbitaceae; like any other crop, it is also highly susceptible to biotic and abiotic stresses. Among the biotic stresses, tomato leaf curl New Delhi Virus (ToLCNDV) is becoming a major constraint in cultivation of ridge gourd. ToLCNDV is naturally transmitted through whitefly in a circulative and persistent manner and causes the yield loss to the tune of 40–100% (Patil et al. in Virus Dis 28(2):146–155, 2017. https://doi.org/10.1007/s13337-017-0376-6). In present investigation, coat protein gene of ToLCNDV was used to construct a phylogenetic tree showing no host-specificity in the population studied. Further, for in vitro expression studies, the coat protein gene was cloned into pET28a and successfully overexpressed in E. coli BL21 (DE3) cells. The expression of recombinant coat protein varied with different induction time and the highest expression was recorded in 4 h of induction period, incubated with 1-mM IPTG at 37 °C. Overexpressed protein was further purified using Ni–NTA column and confirmed through SDS-PAGE analysis. The present study will help to develop ELISA-based detection tools to diagnose the disease as well as to take up immediate management practices. [ABSTRACT FROM AUTHOR]

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

Copyright of Jurnal Fitopatologi Indonesia is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Papaya (Carica papaya L.) is widely grown in tropical and subtropical regions. The destructive disease caused by emerging strains of Papaya ringspot virus (PRSV) demands effective transgenic resistance to target atypical virus strains threatening the crop. Papaya transformations are mainly conducted on the explants of immature zygotic or somatic embryos, which are difficult to obtain and proceed, and are largely affected by seasonal factors. Here, we attempted to develop an efficient process for organogenesis using various tissues of ex-vitro or in-vitro grown papaya seedlings. Leaf lamina, hypocotyl and stem sections of seedlings of the papaya variety Sindhi were used for establishment of callus culture through 12 different callus induction treatments (CIT 1–12), with various combinations of plant growth regulators (PGRs). Our results revealed that CIT-11 and CIT-10 enhanced callus induction from ex-vitro leaf discs with midrib, with 86% and 80% efficiency respectively, superior to 53% of CIT-10 using in-vitro leaf discs with midrib. The expression of binary vector construct pSN-PRSV CP in Agrobacterium strain GV3101 was verified in Nicotiana benthamiana and papaya by RT-PCR analysis. Calli derived from leaf tissues (with midrib) of papaya, transformed with the binary vector were successfully regenerated on the shoot induction treatment SIT-13 (Gamborg B5 medium + 0.5 mg/L TDZ + 0.01 mg/L NAA) and were subsequently rooted on root induction treatment RIT-4 (Gamborg B5 medium + 1 mg/L IBA). The transformed explants were regenerated with an efficiency of 26%. The whole process is unique in term of explant selection, source of explant (ex-vitro grown papaya plants) and media formulations as, the leaf tissue from ex-vitro grown papaya showed highest callusing and regeneration efficiency overall.Key message: Successful transgenic papaya regeneration is possible from transformed calli, obtained from in-vitro and ex-vitro leaf explants. [ABSTRACT FROM AUTHOR]

The coat protein (CP) is an important structural protein that plays many functional roles during the viral cycle. In this study, the CP of pepper mild mottle virus (PMMoV) was genetically fused to GFP using the foot-and-mouth disease virus peptide 2A linker peptide and the construct (PMMoV-GFP2A) was shown to be infectious. The systemic spread of the virus was monitored by its fluorescence in infected plants. Electron microscopy and immunocolloidal gold labelling confirmed that PMMoV-GFP2A forms rod-shaped particles on which GFP is displayed. Studies of tissue ultrastructure and virion self-assembly confirmed that PMMoV-GFP2A could be used to monitor the real-time dynamic changes of CP location during virus infection. Aggregations of GFP-tagged virions appeared as fluorescent plaques in confocal laser microscopy. Altogether, PMMoV-GFP2A is a useful tool for studying the spatial and temporal changes of PMMoV CP during viral infection. [ABSTRACT FROM AUTHOR]

The Saffron Latent Virus (SaLV) is new species in the Potyvirus genus, which has been recently characterized from Iran. Even though most of the symptoms on infected plants remain hidden, it causes considerable damage to saffron fields. There is no data available on the phylogenetic relationship among different strains of this virus based on its coat protein, despite its high incidence and economic significance. To address this, we collected 152 samples of saffron leaves, flowers, and corms from fields in South Khorasan and Razavi Khorasan provinces, both with and without symptoms like stunting, yellowing, and twisting. After extracting RNA, the presence of SaLV was examined using reverse transcriptionpolymerase chain reaction (RT-PCR) with specific primers targeting the coat protein. The findings revealed that 92 out of 152 samples (60%) were infected with the virus. Subsequently, seven representative samples, each from a selected region were sequenced. Phylogenetic analysis using MEGAX software showed that the virus strains formed two distinct groups, and the strains studied were placed in the second group. Interestingly, strains from the same geographical region and product were distributed among different groups, suggesting that geographical separation and host type did not significantly impact the viral diversity. This study is the first in detecting of SaLV in saffron flowers and corms and pinpointing the diversity of its new strains based on the coat protein in Iran. [ABSTRACT FROM AUTHOR]

A novel partitivirus, Fusarium commune partitivirus 1 (FcoPV1), was identified in Fusarium commune strain CP-SX-3 isolated from diseased roots of strawberry with symptoms of root rot. The complete genome of FcoPV1 comprises three double-stranded RNAs (dsRNAs): dsRNA1 (1,825 nt), dsRNA2 (1,592 nt), and dsRNA3 (1,421 nt). dsRNA1 contains a single open reading frame (ORF1) encoding an RNA-dependent RNA polymerase (RdRp), and dsRNA2 contains a single ORF (ORF2) encoding a coat protein (CP). dsRNA3 is a possible satellite RNA that does not appear to encode a known protein. BLASTp analysis revealed that RdRp (86.59%) and CP (74.13%) encoded by the two ORFs (ORF1 and ORF2) had the highest sequence similarity to their counterparts in Fusarium equiseti partitivirus 1 (FePV1). Phylogenetic analysis based on the complete amino acid sequence of RdRp suggested that FcoPV1 should be considered a member of a new species in the proposed genus “Zetapartitivirus” within the family Partitiviridae. To the best of our knowledge, this is the first report of a zetapartitivirus infecting phytopathogenic F. commune. [ABSTRACT FROM AUTHOR]

Introduction: Saffron with the scientific name Crocus sativus L belongs to the lily family (Iridaceae) and is one of the important economic and strategic products of Iran, which is important to investigate its limiting factors. In order to detect and identify Common bean mosaic virus as one of the limiting factors in saffron farms, sampling of 705 samples of saffron in Khorasan Razavi province, Khaf city was carried out during the spring of 1402. The saffron samples had mosaic symptoms, dwarfism, plant deformity and zigzagging, which were transferred to the laboratory under cool conditions. In the RT-PCR test, using specific primers of the nucleoprotein gene, in three saffron samples, a fragment of 343 pairs was found. They were reproduced and sent to Macrogen Korea for sequencing. The results confirmed the infection of three saffron samples with the mentioned virus, and in the genealogy studies of three saffron isolates in the nucleoprotein coding region of the mentioned virus, compared to the world isolates available in the gene bank, which were related to different geographical regions, five separate groups were formed, from three Iranian isolate related to saffron, two isolates (B1, B2) were placed in group 4 close to isolates from Brazil and one isolate (B3) was placed in group 5 close to two isolates from Iran (Ahvaz and Zanjan). The most similarity of the isolates in this research was between two Iranian isolates B1 and B2 with three isolates MW534342, MW534343 and MW534344 from the country of Zambia from the African continent with a similarity percentage of 99% and also the least similarity of the Iranian isolates B1, B2 and B3 with isolate KC702888 from Iran in Lorestan with a similarity level of 71%. Material and Methods: In order to detect and identify Bean common mosaic virus as one of the limiting factors in saffron farms, sampling of 705 samples of saffron in Khorasan Razavi province, Khaf city was carried out during the spring of 1402. The saffron samples had mosaic symptoms, dwarfism, plant deformity and zigzagging, which were transferred to the laboratory under cool conditions. Their total RNA was extracted and then RT-PCR test, using specific primers of the coat protein gene was carried out, in three saffron samples, a fragment of 343 base pairs was amplified. The amplified fragments were reproduced, then extracted from gel and sent to Macrogen Korea for sequencing. Results and Discussion: The results confirmed the infection of three saffron samples with the mentioned virus, and in the phylogeny studies of three saffron isolates in the nucleoprotein coding region of the mentioned virus, compared to the world isolates available in the gene bank, which were related to different geographical regions, five separate groups were formed, from three Iranian isolate related to saffron, two isolates (B1, B2) were placed in group 4 close to isolates from Brazil and one isolate (B3) was placed in group 5 close to two isolates from Iran (Ahvaz and Zanjan). The most similarity of the isolates in this research was between two Iranian isolates B1 and B2 with three isolates MW534342, MW534343 and MW534344 from the country of Brazil from the African continent with a similarity percentage of 100% and also the least similarity of the Iranian isolates B1, B2 and B3 with isolate KC702888 from Iran in Lorestan with a similarity level of 71%. Conclusion: This is the first survey of this virus in Razavi Khorasan that showed the infection of saffron field of Khafe city as one of the major areas of production of this product. Phylogenetic analysis of this virus showed that khaf isolates were located in two different groups that could be the result of different sources for entering of this virus in this area. Conflict of Interest: Authors declared no conflict of interest. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), a disease inflicted by Fusarium graminearum and F. asiaticum, poses a growing threat to wheat in China, particularly in the face of climate change and evolving agricultural practices. This study unveiled the discovery of the victorivirus FgVV2 from the F. asiaticum strain F16176 and comprehensively characterized the function of the two victoriviruses FaVV1 and FaVV2 in virulence. Through comparative analysis with a virus-free strain, we established that these mycoviruses markedly repress the sexual reproduction and pathogenicity of their fungal hosts. Furthermore, we synthesized the coat protein (CP) genes CP1 from FaVV1 and CP2 from FaVV2, which were fused with the green fluorescent protein (GFP) gene and successfully expressed in Fusarium strains in wild-type isolates of F. asiaticum and F. graminearum. Similar to virus-infected strains, the transformed strains expressing CPs showed a significant decrease in perithecia formation and pathogenicity. Notably, CP2 exhibited a stronger inhibitory effect than CP1, yet the suppression of sexual reproduction in F. graminearum was less pronounced than that in F. asiaticum. Additionally, the pathogenicity of the F. asiaticum and F. graminearum strains expressing CP1 or CP2 was substantially diminished against wheat heads. The GFP-tagged CP1 and CP2 revealed distinct cellular localization patterns, suggesting various mechanisms of interaction with the host. The findings of this study provide a significant research foundation for the study of the interaction mechanisms between FaVV1 and FaVV2 with their hosts, as well as for the exploration and utilization of fungal viral resources.

Apple stem pitting virus is a species in the genus Foveavirus in the family Betaflexiviridae. Apple stem pitting virus (ASPV) commonly infects apple and pear plants grown worldwide. In this study, by integrating bimolecular fluorescence complementation, split‐ubiquitin‐based membrane yeast two‐hybrid, and Agrobacterium‐mediated expression assays, the interaction relationships and the subcellular locations of ASPV proteins TGBp1–3 and CP in Nicotiana benthamiana leaf cells were determined. Proteins CP, TGBp1, TGBp2, and TGBp3 were self‐interactable, and TGBp2 played a role in the formation of perinuclear viroplasm and enhanced the colocalization of TGBp3 with CP and TGBp1. We found that the plant microfilament and endoplasmic reticulum structures were involved in the production of TGBp3 and TGBp2 vesicles, and their disruption decreased the virus accumulation level in the systemic leaves. The TGBp3 motile vesicles functioned in delivering the viral ribonucleoprotein complexes to the plasma membrane. Two cysteine residues at sites 35 and 49 of the TGBp3 sorting signal were necessary for the diffusion of TGBp3‐marked vesicles. Furthermore, our results revealed that TGBp1, TGBp2, and CP could increase plasmodesmal permeability and move to the adjacent cells. This study demonstrates an interaction network and a subcellular location map of four ASPV proteins and for the first time provides insight into the functions of these proteins in the movement of a foveavirus. [ABSTRACT FROM AUTHOR]

Wheat is an essential cereal crop for the economy and food safety of Kazakhstan. In the present work, a screening of wheat and barley from different regions of Kazakhstan was conducted using newly developed specific primers for reverse transcription PCR and loop-mediated isothermal amplification (LAMP) assays. In total, 82 and 19 of 256 samples of wheat and barley tested positive for wheat streak mosaic virus (WSMV) and barley stripe mosaic virus (BSMV), respectively. A phylogenetic analysis using two independent methods revealed that most of the analyzed isolates had a European origin. Molecular data on the distribution and diversity of cereal viruses in Kazakhstan were obtained for the first time and will help lay a foundation for the implementation of genetics and genomics in wheat phyto-epidemiology in the country. [ABSTRACT FROM AUTHOR]

Rice stripe disease caused by the rice stripe virus (RSV), which infects many Poaceae species in nature, is one of the most devastating plant viruses in rice that causes enormous losses in production. Ailanthone is one of the typical C20 quassinoids synthesized by the secondary metabolism of Ailanthus altissima, which has been proven to be a biologically active natural product with promising prospects and great potential for use as a lead structure for pesticide development. Based on the achievement of the systemic infection and replication of RSV in Nicotiana benthamiana plants and rice protoplasts, the antiviral properties of Ailanthone were investigated by determining its effects on viral-coding RNA gene expression using reverse transcription polymerase chain reaction, and Western blot analysis. Ailanthone exhibited a dose-dependent inhibitory effect on RSV NSvc3 expression in the assay in both virus-infected tobacco plants and rice protoplasts. Further efforts revealed a potent inhibitory effect of Ailanthone on the expression of seven RSV protein-encoding genes, among which NS3, NSvc3, NS4, and NSvc4 are the most affected genes. These facts promoted an extended and greater depth of understanding of the antiviral nature of Ailanthone against plant viruses, in addition to the limited knowledge of its anti-tobacco mosaic virus properties. Moreover, the leaf disc method introduced and developed in the study for the detection of the antiviral activity of Ailanthone facilitates an available and convenient screening method for anti-RSV natural products or synthetic chemicals. [ABSTRACT FROM AUTHOR]

The strawberry mottle virus (SMoV) is a huge threat to the strawberry production, which seriously reduces the productivity of strawberries. The systematic study on the distribution, structural variation and genetic diversity of SMoV is useful for the prevention and control of SMoV. In this study, 159 strawberry leaves were randomly collected from 7 major strawberry growing areas in Shanxi Province for RT-PCR detection. The cp genes of positive samples were sequenced and analyzed through MEGA5, SDTv 1.2, DnaSP v5.10 and RDP v.4.31. RT-PCR detection showed that 65 samples of the 159 strawberry leaves were positive with a detection rate of 38.46%. The 65 positive samples were isolated, sequenced, and cloned to obtain three SMoV isolates. The phylogenetic tree analysis showed the 25 SMoV isolates were divided into three groups with group 1 containing 14 isolates from China, group 2 containing 10 isolates from Canada, Japan, and the United States, and group 3 containing 1 isolate from Japan. The results of selective pressure analysis and neutrality test in group 1 and group 2 showed that there were significant genetic differences between group 1 and group 2. The negative selection pressure maybe the reason for the genetic diversity of SMoV. Sequence similarity analysis displayed that the nucleotide identity range and the consistency range of amino acids was ranged from 94.68% to 99.53%, while from 98.12% to 99.84% for amino acids. This study demonstrated that SMoV was of high genetic variation, and the negative selection pressure may be the cause of SMoV genetic diversity, which provides theoretical guidance for SMoV in Shanxi. [ABSTRACT FROM AUTHOR]

Coat proteins (CP) of the potato virus A virions (PVA) contain partially disordered N-terminal domains, which are necessary for performing vital functions of the virus. Comparative analysis of the structures of coat proteins (CPs) in the intact PVA virions and in the virus particles lacking N-terminal 32 amino acids (PVAΔ32) was carried out in this work based on the tritium planigraphy data. Using atomic-resolution structure of the potato virus Y potyvirus (PVY) protein, which is a homolog of the CP PVA, the available CP surfaces in the PVY virion were calculated and the areas of intersubunit/interhelix contacts were determined. For this purpose, the approach of Lee and Richards [Lee, B., and Richards, F. M. (1971) J. Mol. Biol., 55, 379-400] was used. Comparison of incorporation profiles of the tritium label in the intact and trypsin-degraded PVA∆32 revealed position of the ΔN-peptide shielding the surface domain (a.a. 66-73, 141-146) and the interhelix zone (a.a. 161-175) of the PVA CP. Presence of the channels/cavities was found in the virion, which turned out to be partially permeable to tritium atoms. Upon removal of the ∆N-peptide, decrease in the label incorporation within the virion (a.a. 184-200) was also observed, indicating possible structural transition leading to the virion compactization. Based on the obtained data, we can conclude that part of the surface ∆N-peptide is inserted between the coils of the virion helix thus increasing the helix pitch and providing greater flexibility of the virion, which is important for intercellular transport of the viruses in the plants. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are closely related to the antiviral immune response of plants, while virus can regulate ROS through various pathways to facilitate their own infection or replication. Citrus yellow vein clearing virus (CYVCV) is one of the most devastating viruses affecting lemon (Citrus limon) industry worldwide. However, the pathogenesis of CYVCV remains poorly understood. In this study, direct interaction between the coat protein (CP) of CYVCV and the ascorbate peroxidase 1 of lemon (ClAPX1) was confirmed for the first time by yeast two-hybrid, Bimolecular Fluorescence Complementation, and Co-immunoprecipitation assays. Transient expression of CP in lemon and Nicotiana benthamiana significantly enhanced the enzyme activity of the ClAPX1, and then inhibited the accumulation of H2O2. In addition, overexpression of ClAPX1 in lemon by transgene significantly promoted CYVCV accumulation and depressed the expression of most genes involved in jasmonic acid (JA) signaling pathway. Correspondingly, ClAPX1 silencing by RNA interference inhibited CYVCV accumulation and increased the expression of most genes involved in JA signaling pathway. To our knowledge, this is the first report that viruses regulate ROS by targeting APX directly, thereby suppressing host immune response and promoting viral accumulation, which may be mediated by JA signaling pathway. [ABSTRACT FROM AUTHOR]

Celery mosaic virus (CeMV), member of genus Potyvirus, is reported for the first time in Indonesia, from celery plants (Apium graveolens) in a vegetable field at Berastagi, North Sumatera Province. The plants possessed mosaic and vein clearing symptoms on the leaves as typical of CeMV infection. Virus incidence was confirmed by RT-PCR using degenerate potyvirus primer which amplified partial coat protein and 3’-UTR of the viral genome. Phylogenetic tree analysis placed Indonesian CeMV isolates in one separated clade within CeMV group and shared 96.5%–96.7% nucleotide identity with exemplar isolate of CeMV.

The apple stem grooving virus (ASGV) is one of the most harmful latent viruses infecting pear orchards worldwide. To examine the genetic diversity of ASGV in Korean pear orchards, the complete coat protein (CP) gene of five ASGV isolates collected from various regions were identified. The five Korean ASGV isolates showed 88–96% nucleotide identity with the 11 isolates worldwide occurring elsewhere in the world. Phylogenetic analysis of five isolates, as well as the previously sequenced isolates, indicated that the ASGV clusters had no correlation with the host or geographical regions of origin. Recombination analysis showed that one of the five Korean isolates is a recombinant, with a recombination site in the CP gene region (nt 532–708). This study is the first report of natural recombination within the CP gene of ASGV isolates from pears grown in Korea.

Pepino mosaic virus (PepMV) causes significant economic losses in tomato crops worldwide. Since its first detection infecting tomato in 1999, aggressive PepMV variants have emerged. This study aimed to characterize two aggressive PepMV isolates, PepMV-H30 and PepMV-KLP2. Both isolates were identified in South-Eastern Spain infecting tomato plants, which showed severe symptoms, including bright yellow mosaics. Full-length infectious clones were generated, and phylogenetic relationships were inferred using their nucleotide sequences and another 35 full-length sequences from isolates representing the five known PepMV strains. Our analysis revealed that PepMV-H30 and PepMV-KLP2 belong to the EU and CH2 strains, respectively. Amino acid sequence comparisons between these and mild isolates identified 8 and 15 amino acid substitutions for PepMV-H30 and PepMV-KLP2, respectively, potentially involved in severe symptom induction. None of the substitutions identified in PepMV-H30 have previously been described as symptom determinants. The E236K substitution, originally present in the PepMV-H30 CP, was introduced into a mild PepMV-EU isolate, resulting in a virus that causes symptoms similar to those induced by the parental PepMV-H30 in Nicotiana benthamiana plants. In silico analyses revealed that this residue is located at the C-terminus of the CP and is solvent-accessible, suggesting its potential involvement in CP–host protein interactions. We also examined the subcellular localization of PepGFPm2E236K in comparison to that of PepGFPm2, focusing on chloroplast affection, but no differences were observed in the GFP subcellular distribution between the two viruses in epidermal cells of N. benthamiana plants. Due to the easily visible symptoms that PepMV-H30 and PepMV-KLP2 induce, these isolates represent valuable tools in programs designed to breed resistance to PepMV in tomato. [ABSTRACT FROM AUTHOR]

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA‐1 and RNA‐2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS‐ELISA and RT‐PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS‐ELISA and 67 samples by RT‐PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA‐1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA‐1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy. [ABSTRACT FROM AUTHOR]

Beauveria bassiana polymycovirus 4(BbPmV-4)increases the virulence of host fungus Beauveria bassiana; however, the mechanism of its replication, transmission and interaction with host fungi is still unclear. In the present study, the prokaryotic expression vector of mycovirus BbPmV-4 coat protein(CP)was constructed, designated as pET-28a(+)∷BbPmV-4-CP, which was transformed into Escherichia coli BL21(DE3)for prokaryotic expression. The Japanese big ear rabbits were immunized to prepare polyclonal antibodies, which were used to detect the intracellular localization and extracellular replication of the virus by immunological methods including indirect ELISA, Western blot and immunofluorescence, respectively. The results showed that the expressed BbPmV-4-CP was a soluble protein with a relative molecular weight of approximately 28.56 kD, the titer of prepared rabbit polyclonal antibody against which was 1∶256 000. Western blot analysis confirmed that the prepared antibody recognized the corresponding antigen protein and the virus BbPmV-4 in the host strain of B. bassiana. The mycelia of nontoxic healthy strains and B. bassiana containing virus BbPmV-4 were collected for liquid culture, and the virus content in the supernatant and precipitation of the culture was detected by indirect ELISA using the prepared antibody. The results showed that there was virus in the supernatant, indicating that mycovirus BbPmV-4 replicated in the host fungal cells and dissociated outside. The indirect immunofluorescence detection results revealed that the virus was located on the fungal nucleus. In this study, highly effective and specific polyclonal antibodies against mycovirus coat protein are prepared, and a serological detection system for mycovirus is established, which may provide experimental materials for studying the replication of mycovirus in host fungi and the mechanism of its interaction with host fungi, and hypervirulent mycovirus infection and its interactive genes may be used to regulate host virulence and create high virulence strains of B. bassiana. [ABSTRACT FROM AUTHOR]

Dual targeting is a relatively little explored phenomenon by which some proteins are transported to two different subcellular compartments, such as chloroplasts and mitochondria. We previously showed that the R domain and the arm region of the melon necrotic spot virus coat protein could act as a dual-targeting peptide, which shares many relevant features in structure, amino acid composition, and functionality with that of the Thr-tRNA synthetases, the best-studied dual-targeted proteins by far. Here, we show that a viral coat protein hijacks the general pathways for organellar protein import and identifies the coat protein-interacting organellar translocon receptors. Our findings demonstrate for the first time that an exogenous dual-targeted protein uses the general Toc and Tom import systems to reach mitochondria and chloroplasts because it depends on the availability of NbToc75 and NbTom40. Interaction studies, subcellular localization analysis, and viral infection assays in silenced plants revealed the significance of plant receptors, such as the mitochondrion NbOm64 and chloroplast NbToc159A, in this transport. We also show that chloroplast protein translocation impairment could be interlinked with retrograde communication triggering a JA-based response that incidentally impairs viral infection. Future research may profit from our results to better comprehend cellular communication, protein import mechanisms, how preproteins interact with their receptors, and how plant pathogens manipulate host machinery to their ends. IMPORTANCE Many plant proteins and some proteins from plant pathogens are dually targeted to chloroplasts and mitochondria, and are supposed to be transported along the general pathways for organellar protein import, but this issue has not been explored yet. Moreover, organellar translocon receptors exist as families of several members whose functional specialization in different cargos is supposed but not thoroughly studied. This article provides novel insights into such topics showing for the first time that an exogenous protein, the melon necrotic spot virus coat protein, exploits the common Toc/Tom import systems to enter both mitochondria and chloroplasts while identifying the involved specific receptors. [ABSTRACT FROM AUTHOR]

Zucchini yellow mosaic virus (ZYMV) is a severe threat to cucurbit crops worldwide, including Pakistan. This study was pursued to evaluate the prevalence, geographic distribution, and molecular diversity of ZYMV isolates infecting cucurbits in Pakistan's Pothwar region. Almost all the plant viruses act as a biotic stress on the host plants, which results in a yield loss. These viruses cause losses in single-infection or in mixed-infection cucurbit crops, and we have found a number of mixed-infected samples belonging to the Curubitaceae family. Serological detection of the tested potyviruses in the collected cucurbit samples revealed that ZYMV was the most prevalent virus, with a disease incidence (DI) at 35.2%, followed by Papaya ringspot virus (PRSV) with an incidence of 2.2%, and Watermelon mosaic virus (WMV) having an incidence as little as 0.5% in 2016. In the year 2017, a relatively higher disease incidence of 39.7%, 2.4%, and 0.3% for ZYMV, WMV, and PRSV, respectively, was recorded. ZYMV was the most prevalent virus with the highest incidence in Attock, Rawalpindi, and Islamabad, while PRSV was observed to be the highest in Islamabad and Jhelum. WMV infection was observed only in Rawalpindi and Chakwal. Newly detected Pakistani ZYMV isolates shared 95.8–97.0% nucleotide identities among themselves and 77.1–97.8% with other isolates retrieved from GenBank. Phylogenetic relationships obtained using different ZYMV isolates retrieved from GenBank and validated by in silico restriction analysis revealed that four Pakistani isolates clustered with other ZYMV isolates in group IIb with Chinese, Italian, Polish, and French isolates, while another isolate (MK848239) formed a separate minor clade within IIb. The isolate MK8482490, reported to infect bitter gourd in Pakistan, shared a minor clade with a Chinese isolate (KX884570). Recombination analysis revealed that the recently found ZYMV isolate (MK848239) is most likely a recombinant of Pakistani (MK848237) and Italian (MK956829) isolates, with a recombinant breakpoint between 266 and 814 nucleotide positions. Local isolate comparison and recombination detection may aid in the development of a breeding program that identifies resistant sources against recombinant isolates because the ZYMV is prevalent in a few cucurbit species grown in the surveyed areas and causes heavy losses and economic damage to the agricultural community. [ABSTRACT FROM AUTHOR]

Citrus yellow vein clearing virus (CYVCV) is an emerging virus that causes serious economic damage to the lemon industry worldwide. The coat protein (CP) of CYVCV is a strong RNA silencing suppressor and is associated with the severity of symptoms in citrus, yet the interaction between CP and host factors remains unknown. In this study, the 40S ribosomal subunit protein S9‐2 (ClRPS9‐2) was identified as a CP‐binding partner using the yeast two‐hybrid system from a lemon (cv. Eureka) cDNA library, and the interaction between CP and ClRPS9‐2 was demonstrated by in vivo methods. The results suggest that the N‐terminal 8–108 amino acid sequence of ClRPS9‐2 is crucial for its interaction with CP and may be associated with the nuclear localization of ClRPS9‐2. The accumulation and silencing suppressor activity of CP were reduced by transient expression of ClRPS9‐2 in Nicotiana benthamiana. Reverse transcription‐quantitative PCR analysis showed that the content of CYVCV in ClRPS9‐2 transgenic Eureka lemon plants was approximately 50% of that in CYVCV‐infected wild‐type plants 1 month after inoculation, and mild yellowing and vein clearing symptoms were observed in the transgenic plants. These findings demonstrate that ClRPS9‐2 plays a role in host defensive reactions, and the enhanced resistance of transgenic plants to CYVCV may be associated with the up‐regulation of salicylic acid‐related and R genes. [ABSTRACT FROM AUTHOR]

Abstract The soil-borne viral disease, caused by wheat yellow mosaic virus (WYMV) and Chinese wheat mosaic virus (CWMV), is one of the most destructive wheat diseases in China. Considering the large wheat growing area in China, the genetic diversity of WYMV and CWMV could be high in the country. However, studies on genetic diversity of WYMV and CWMV in China are limited, making it difficult to prevent and control viral diseases on wheat. During 2021–2022, the wheat leaves with typical yellow mosaic virus symptoms were randomly collected from wheat fields in seven provinces. Nine WYMV and one CWMV isolates were identified in the samples using small RNA sequencing and RACE technology. Sequence alignment showed that several amino acid substitutions were occurred in the coat protein (CP) from these isolates. Moreover, we replaced the CP of WYMV and CWMV infectious clones with CP of newly identified isolates and found that natural variation of CP is involved in the pathogenicity of WYMV. Moreover, the WYMV infectious clones containing CP of the WYMV isolates from Junan at Shandong Province or Yangzhou at Jiangsu Province have enhanced WYMV infection in several local wheat resistance cultivars. Taken together, our findings suggest that the distribution of WYMV and CWMV in wheat growing areas has expanded in these years and the natural variation of viral genome is involved in pathogenicity of WYMV. Our results also provide a theoretical basis to explain the real distribution of wheat viral resistance varieties in China.

Abstract Viral infection commonly induces autophagy, leading to antiviral responses or conversely, promoting viral infection or replication. In this study, using the experimental plant Nicotiana benthamiana, we demonstrated that the rice stripe virus (RSV) coat protein (CP) enhanced autophagic activity through interaction with cytosolic glyceraldehyde-3-phosphate dehydrogenase 2 (GAPC2), a negative regulator of plant autophagy that binds to an autophagy key factor, autophagy-related protein 3 (ATG3). Competitive pull-down and co-immunoprecipitation (Co-IP)assays showed that RSV CP activated autophagy by disrupting the interaction between GAPC2 and ATG3. An RSV CP mutant that was unable to bind GAPC2 failed to disrupt the interaction between GAPC2 and ATG3 and therefore lost its ability to induce autophagy. RSV CP enhanced the autophagic degradation of a viral movement protein (MP) encoded by a heterologous virus, citrus leaf blotch virus (CLBV). However, the autophagic degradation of RSV-encoded MP and RNA-silencing suppressor (NS3) proteins was inhibited in the presence of CP, suggesting that RSV CP can protect MP and NS3 against autophagic degradation. Moreover, in the presence of MP, RSV CP could induce the autophagic degradation of a remorin protein (NbREM1), which negatively regulates RSV infection through the inhibition of viral cell-to-cell movement. Overall, our results suggest that RSV CP induces a selective autophagy to suppress the antiviral factors while protecting RSV-encoded viral proteins against autophagic degradation through an as-yet-unknown mechanism. This study showed that RSV CP plays dual roles in the autophagy-related interaction between plants and viruses.

The coat protein (CP) is an important structural protein that plays many functional roles during the viral cycle. In this study, the CP of pepper mild mottle virus (PMMoV) was genetically fused to GFP using the foot-and-mouth disease virus peptide 2A linker peptide and the construct (PMMoV-GFP2A) was shown to be infectious. The systemic spread of the virus was monitored by its fluorescence in infected plants. Electron microscopy and immunocolloidal gold labelling confirmed that PMMoV-GFP2A forms rod-shaped particles on which GFP is displayed. Studies of tissue ultrastructure and virion self-assembly confirmed that PMMoV-GFP2A could be used to monitor the real-time dynamic changes of CP location during virus infection. Aggregations of GFP-tagged virions appeared as fluorescent plaques in confocal laser microscopy. Altogether, PMMoV-GFP2A is a useful tool for studying the spatial and temporal changes of PMMoV CP during viral infection.

Reactive oxygen species (ROS) are closely related to the antiviral immune response of plants, while virus can regulate ROS through various pathways to facilitate their own infection or replication. Citrus yellow vein clearing virus (CYVCV) is one of the most devastating viruses affecting lemon (Citrus limon) industry worldwide. However, the pathogenesis of CYVCV remains poorly understood. In this study, direct interaction between the coat protein (CP) of CYVCV and the ascorbate peroxidase 1 of lemon (ClAPX1) was confirmed for the first time by yeast two-hybrid, Bimolecular Fluorescence Complementation, and Co-immunoprecipitation assays. Transient expression of CP in lemon and Nicotiana benthamiana significantly enhanced the enzyme activity of the ClAPX1, and then inhibited the accumulation of H2O2. In addition, overexpression of ClAPX1 in lemon by transgene significantly promoted CYVCV accumulation and depressed the expression of most genes involved in jasmonic acid (JA) signaling pathway. Correspondingly, ClAPX1 silencing by RNA interference inhibited CYVCV accumulation and increased the expression of most genes involved in JA signaling pathway. To our knowledge, this is the first report that viruses regulate ROS by targeting APX directly, thereby suppressing host immune response and promoting viral accumulation, which may be mediated by JA signaling pathway.

The surface hydrophobicity of native or engineered non-enveloped viruses and virus-like particles (VLPs) is a key parameter regulating their fate in living and artificial aqueous systems. Its modulation is mainly depending on the structure and environment of particles. Nevertheless, unexplained variations have been reported between structurally similar viruses and with pH. This indicates that some modulating factors of their hydrophobicity remain to be identified. Herein we investigate the potential involvement of RNA cargo in the MS2 phage used as non-enveloped RNA virus model, by examining the SDS-induced electrophoretic mobility shift (SEMS) determined for native MS2 virions and corresponding RNA-free VLPs at various pH. Interestingly, the SEMS of VLPs was larger and more variable from pH 5 to 9 compared to native virions. These observations are discussed in term of RNA-dependent changes in surface hydrophobicity, suggesting that RNA cargo may be a major modulator/regulator of this viral parameter. • VLPs of MS2 phage were prepared from native MS2 virions and characterized. • The SDS-induced electrophoretic mobility shift of MS2 virions and VLPs were studied. • The results obtained from pH 5 to 9 are discussed in term of surface hydrophobicity. • The RNA cargo is suspected to influence the pH-dependent hydrophobicity of virions. [ABSTRACT FROM AUTHOR]

Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite Begomovirus belonging to the family Geminiviridae, causes severe damage to many economically important crops worldwide. In the present study, pathogenicity of Asian (ToLCNDV-In from Pakistan) and Mediterranean isolates (ToLCNDV-ES from Italy) were examined using infectious clones in tomato plants. Only ToLCNDV-In could infect the three tomato cultivars, whereas ToLCNDV-ES could not. Genome-exchange of the two ToLCNDVs revealed the ToLCNDV DNA-A segment as the main factor for ToLCNDV infectivity in tomato. In addition, serial clones with chimeric ToLCNDV-In A and ToLCNDV-ES A genome segments were generated to identify the region determining viral infectivity in tomatoes. A chimeric clone carrying the ToLCNDV-In coat protein (CP) exhibited pathogenic adaptation in tomatoes, indicating that the CP of ToLCNDV is essential for its infectivity. Analyses of infectious clones carrying a single amino acid substitution revealed that amino acid at position 143 of the CP is critical for ToLCNDV infectivity in tomatoes. To better understand the molecular basis whereby CP function in pathogenicity, a yeast two-hybrid screen of a tomato cDNA library was performed using CPs as bait. The hybrid results showed different interactions between the two CPs and Ring finger protein 44-like in the tomato genome. The relative expression levels of upstream and downstream genes and Ring finger 44-like genes were measured using quantitative reverse transcription PCR (RT-qPCR) and compared to those of control plants. This is the first study to compare the biological features of the two ToLCNDV strains related to viral pathogenicity in the same host plant. Our results provide a foundation for elucidating the molecular mechanisms underlying ToLCNDV infection in tomatoes. [ABSTRACT FROM AUTHOR]

The cucumber green mottle mosaic virus (CGMMV) and tobacco vein banding mosaic virus (TVBMV) (Tobamovirus and Potyvirus genera, respectively) are responsible for significant economic damage to cucurbitaceous and tobacco crops worldwide. In this research, we show that the Nicotiana benthamiana protease inhibitor (NbPI) interacts with the coat proteins (CP) of these two viruses. When the NbPI gene was silenced by virus-induced gene silencing (VIGS), inoculation of CGMMV or TVBMV into plants resulted in more severe symptoms and a higher viral RNA replication level compared to plants without gene silencing. These results indicate the antiviral role of host factor NbPI against CGMMV and TVBMV in N. benthamiana. [ABSTRACT FROM AUTHOR]

The soil-borne viral disease, caused by wheat yellow mosaic virus (WYMV) and Chinese wheat mosaic virus (CWMV), is one of the most destructive wheat diseases in China. Considering the large wheat growing area in China, the genetic diversity of WYMV and CWMV could be high in the country. However, studies on genetic diversity of WYMV and CWMV in China are limited, making it difficult to prevent and control viral diseases on wheat. During 2021–2022, the wheat leaves with typical yellow mosaic virus symptoms were randomly collected from wheat fields in seven provinces. Nine WYMV and one CWMV isolates were identified in the samples using small RNA sequencing and RACE technology. Sequence alignment showed that several amino acid substitutions were occurred in the coat protein (CP) from these isolates. Moreover, we replaced the CP of WYMV and CWMV infectious clones with CP of newly identified isolates and found that natural variation of CP is involved in the pathogenicity of WYMV. Moreover, the WYMV infectious clones containing CP of the WYMV isolates from Junan at Shandong Province or Yangzhou at Jiangsu Province have enhanced WYMV infection in several local wheat resistance cultivars. Taken together, our findings suggest that the distribution of WYMV and CWMV in wheat growing areas has expanded in these years and the natural variation of viral genome is involved in pathogenicity of WYMV. Our results also provide a theoretical basis to explain the real distribution of wheat viral resistance varieties in China. [ABSTRACT FROM AUTHOR]

Raspberry bushy dwarf virus (RBDV) is an economically significant pathogen of raspberry and grapevine, and it has also been found in cherry. Most of the currently available RBDV sequences are from European raspberry isolates. This study aimed to sequence genomic RNA2 of both cultivated and wild raspberry in Kazakhstan and compare them to investigate their genetic diversity and phylogenetic relationships, as well as to predict their protein structure. Phylogenetic and population diversity analyses were performed on all available RBDV RNA2, MP and CP sequences. Nine of the isolates investigated in this study formed a new, well-supported clade, while the wild isolates clustered with the European isolates. Predicted protein structure analysis revealed two regions that differed between α- and β-structures among the isolates. For the first time, the genetic composition of Kazakhstani raspberry viruses has been characterized. [ABSTRACT FROM AUTHOR]

The movement protein (MP) and coat protein (CP) of tobamoviruses play critical roles in viral cell‐to‐cell and long‐distance movement, respectively. Cucumber green mottle mosaic virus (CGMMV) is a member of the genus Tobamovirus. The functions of CGMMV MP and CP during viral infection remain largely unclear. Here, we show that CGMMV MP can interact with CP in vivo, and the amino acids at positions 79–128 in MP are vital for the MP–CP interaction. To confirm this finding, we mutated five conserved residues within the residue 79–128 region and six other conserved residues flanking this region, followed by in vivo interaction assays. The results showed that the conserved threonine residue at the position 107 in MP (MPT107) is important for the MP–CP interaction. Substitution of T107 with alanine (MPT107A) delayed CGMMV systemic infection in Nicotiana benthamiana plants, but increased CGMMV local accumulation. Substitutions of another 10 conserved residues, not responsible for the MP–CP interaction, with alanine inhibited or abolished CGMMV systemic infection, suggesting that these 10 conserved residues are possibly required for the MP movement function through a CP‐independent manner. Moreover, two movement function‐associated point mutants (MPF17A and MPD97A) failed to cause systemic infection in plants without impacting on the MP–CP interaction. Furthermore, we have found that co‐expression of CGMMV MP and CP increased CP accumulation independent of the interaction. MP and CP interaction inhibits the salicylic acid‐associated defence response at an early infection stage. Taken together, we propose that the suppression of host antiviral defence through the MP–CP interaction facilitates virus systemic infection. [ABSTRACT FROM AUTHOR]

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Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite Begomovirus belonging to the family Geminiviridae, causes severe damage to many economically important crops worldwide. In the present study, pathogenicity of Asian (ToLCNDV-In from Pakistan) and Mediterranean isolates (ToLCNDV-ES from Italy) were examined using infectious clones in tomato plants. Only ToLCNDV-In could infect the three tomato cultivars, whereas ToLCNDV-ES could not. Genome-exchange of the two ToLCNDVs revealed the ToLCNDV DNA-A segment as the main factor for ToLCNDV infectivity in tomato. In addition, serial clones with chimeric ToLCNDV-In A and ToLCNDV-ES A genome segments were generated to identify the region determining viral infectivity in tomatoes. A chimeric clone carrying the ToLCNDV-In coat protein (CP) exhibited pathogenic adaptation in tomatoes, indicating that the CP of ToLCNDV is essential for its infectivity. Analyses of infectious clones carrying a single amino acid substitution revealed that amino acid at position 143 of the CP is critical for ToLCNDV infectivity in tomatoes. To better understand the molecular basis whereby CP function in pathogenicity, a yeast two-hybrid screen of a tomato cDNA library was performed using CPs as bait. The hybrid results showed different interactions between the two CPs and Ring finger protein 44-like in the tomato genome. The relative expression levels of upstream and downstream genes and Ring finger 44-like genes were measured using quantitative reverse transcription PCR (RT-qPCR) and compared to those of control plants. This is the first study to compare the biological features of the two ToLCNDV strains related to viral pathogenicity in the same host plant. Our results provide a foundation for elucidating the molecular mechanisms underlying ToLCNDV infection in tomatoes.

Gansu Province is a district renowned for the cultivation of Angelica sinensis (Oliv.) Diels, accounting for greater than 90% of China's total annual production. However, virus infection has caused a reduction in A. sinensis yield. Here, we collected suspected virus-infected A. sinensis leaf samples from Gansu Province's A. sinensis cultivation area. For the first time, using small RNA deep sequencing and RT-PCR, lychnis mottle virus (LycMoV) was found to naturally infect A. sinensis. The coat protein (cp) gene of the Gansu A. sinensis LycMoV isolate was obtained through cloning, where its nucleotide and amino acid identity was highest while having the closest affinity to the China Pearl (i.e., Prunus persica) isolate. Recombination analysis indicated that genetic recombination had only a limited influencing effect on the molecular evolution of LycMoV. Moreover, results from genetic diversity analysis indicated that the host, geographic isolation, and genetic drift may be the main factors that contributed to the formation of genetic diversity and differentiation in LycMoV. Furthermore, the LycMoV population trend was expansionary. Selection pressure may also be the main driver for the evolution of the entire LycMoV population, while the driving effect of genetic recombination is limited. This study marks a new LycMoV host (i.e., A. sinensis) for the first time and provides scientific support for the identification, prevention, and control of LycMoV.

Wheat is an essential cereal crop for the economy and food safety of Kazakhstan. In the present work, a screening of wheat and barley from different regions of Kazakhstan was conducted using newly developed specific primers for reverse transcription PCR and loop-mediated isothermal amplification (LAMP) assays. In total, 82 and 19 of 256 samples of wheat and barley tested positive for wheat streak mosaic virus (WSMV) and barley stripe mosaic virus (BSMV), respectively. A phylogenetic analysis using two independent methods revealed that most of the analyzed isolates had a European origin. Molecular data on the distribution and diversity of cereal viruses in Kazakhstan were obtained for the first time and will help lay a foundation for the implementation of genetics and genomics in wheat phyto-epidemiology in the country.