Search Results (6)

Alfalfa mosaic virus (AMV) is one of the most widely distributed viruses. It often exhibits combined infection with white clover mosaic virus (WCMV) and occurs with a synergistic effect at 3:1 (AMV: WCMV). This study sought to clarify whether this synergistic effect is related to the molecular mutation of the coat protein (CP) sequences of the two viruses and their interactions, as well as the effect of the WCMV CP concentration on infection with AMV. This study identified and analyzed the CP sequences of two viruses after the co-infection of AMV and WCMV in Nicotiana benthamiana and found that the CP sequences of the two viruses mutated after co-infection with AMV and WCMV compared with the sequences from separate single infections with each virus. The mutation rate of the nucleotide bases was 7.66% and 3.37% in the Co-AMV CP and Co-WCMV CP, respectively, and 9.05% and 5.77% in the amino acid, respectively. The effect of WCMV CP and AMV at different proportions antagonistically affected infection with AMV when the proportion of WCMV CP: AMV was 3:1, 2:1, and 1:1. These proportions of treatment alleviated the symptoms caused by infection with N. benthamiana and reduced the relative expression of the AMV CP by 0.56, 0.47, and 0.76-fold, respectively, compared with single infection by AMV. Thus, the CP sequences of both viruses mutated after the co-infection of AMV and WCMV, and a proportion of WCMV CP: AMV of 3:1, 2:1, and 1:1 inhibited infection by AMV. Full article

Alfalfa mosaic virus (AMV) is one of the most widely distributed viruses; it often exhibits combined infection with white clover mosaic virus (WCMV). Even so, little is known about the effects of co-infection with AMV and WCMV on plants. To determine whether there is a synergistic effect of AMV and WCMV co-infection, virus co-infection was studied by electron microscopy, the double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), and real-time fluorescence quantitative PCR (RT-qPCR) of AMV and WCMV co-infection in Nicotiana benthamiana. Meanwhile, measurements were carried out on the photosynthetic pigments, photosynthetic gas exchange parameters, and chlorophyll fluorescence parameters. The results showed that the most severe disease development was induced by AMV and WCMV co-infection, and the disease grade was scale 7. N. benthamiana leaves induced mottled yellow-green alternating patterns, leaf wrinkling, and chlorosis, and chloroplasts were observed to be on the verge of disintegration. The relative accumulation of AMV CP and WCMV CP was significantly increased by 15.44-fold and 10.04-fold upon co-infection compared to that with AMV and WCMV single infection at 21 dpi. In addition, chlorophyll a, chlorophyll b, total chlorophyll, the net photosynthetic rate, the water use efficiency, the apparent electron transport rate, the PSII maximum photochemical efficiency, the actual photochemical quantum yield, and photochemical quenching were significantly reduced in leaves co-infected with AMV and WCMV compared to AMV- or WCMV-infected leaves and CK. On the contrary, the carotenoid content, transpiration rate, stomatal conductance, intercellular CO₂ concentration, minimal fluorescence value, and non-photochemical quenching were significantly increased. These findings suggest that there was a synergistic effect between AMV and WCMV, and AMV and WCMV co-infection severely impacted the normal function of photosynthesis in N. benthamiana. Full article

Many plant virus outbreaks have been recorded in the last two decades, threatening food security around the world. During pepper production seasons in 2008, 2014, and 2022, virus outbreaks were reported from Lara (western) and Miranda (central) states in Venezuela. Three hundred seventy-three plants exhibiting virus-like symptoms were collected and tested for virus infection through reverse transcription PCR (RT-PCR). The most prevalent viruses during the 2008 surveys conducted in Lara were potato virus Y (PVY, 66.25%), cucumber mosaic virus (CMV, 57.50%), pepper mild mottle virus (PMMoV, 35%), alfalfa mosaic virus (AMV, 23.75%), and tobacco rattle virus (TRV, 17.50%). This survey revealed for the first time that pepper is a natural host of AMV and TRV in Venezuela. A further, divergent potyvirus isolate was also detected in 23.75% of pepper plants from Lara state. In 2014, a follow-up survey after virus outbreaks reported in Lara and Miranda states also detected this divergent potyvirus isolate in 21.68% of pepper plants, with tomato spotted wilt virus (TSWV) and PMMoV dominating the viral landscape (62.65 and 21.68% of tested plants, respectively). By comparison, the surveys revealed significant changes in viral community composition. The complete capsid protein (CP) sequence of the putative potyvirus was obtained from two pepper samples. According to the Potyvirus taxonomic criteria, these results suggest that the isolate represents a distinct virus species, for which we propose the name “pepper severe mottle virus” (PepSMoV). Virus outbreaks could be attributed to agricultural and environmental factors, such as climate change, the use of wastewater, the use of uncertified seeds, misuse of agricultural chemicals, transmission with food trade networks, and the development of new viral strains due to mutations and recombination and pathogen spillover. This study demonstrates the value of knowledge of the prevalence and distribution of viral species to recommend virus-resistant cultivars to replace susceptible ones, especially in virus hotspot areas. Full article

Plant viral vectors have become a promising tool for the rapid and cost-effective production of recombinant proteins in plants. Among the numerous genera of viruses that have been used for heterologous expression, potyviruses offer several advantages, such as polyprotein expression strategy or a broad host range. In our work, the expression vectors pAD/pAD-agro based on the plum pox virus (PPV) genome were used for the heterologous expression of different foreign polypeptides: alfalfa mosaic virus capsid protein (AMV CP), zucchini yellow mosaic virus capsid protein (ZYMV CP), the small heat-shock protein of Cronobacter sakazakii fused with hexahistidine (sHSP-his), a fragment of influenza A virus hemagglutinin (HA2-2), influenza A virus protein PB1-F2, SARS-CoV-2 nucleocapsid protein (CoN2-his), and its N- and C-terminal fragments (CoN-1-his and CoN3-his, respectively), each fused with a hexahistidine anchor. Particular proteins differed in their accumulation, tissue localization, stability, and solubility. The accumulation rate of produced polypeptides varied from low (N, hemagglutinin fragment) to relatively high (plant viral CPs, N-terminal fragment of N, PB1-F2). Some proteins preferentially accumulated in roots (sHSP, hemagglutinin fragment, PB1-F2), showing signs of proteolytic degradation in leaf tissues. Thus, each expression requires an individual approach and optimization. Here, we summarize our several-year experiments and discuss the usefulness of the pAD/pADep vector system. Full article

During the spring of 2019, distinct virus-like symptoms were observed in the Kafr El-Sheikh Governorate in Egypt in naturally infected eggplants. Leaves of affected plants showed interveinal leaf chlorosis, net yellow, chlorotic sectors, mottling, blisters, vein enation, necrotic intervention, and narrowing symptoms. The Alfalfa mosaic virus (AMV) was suspected of to be involved in this disease. Forty plant samples from symptomatic eggplants and 10 leaf samples with no symptoms were collected. The samples were tested by double antibody sandwich ELISA (DAS-ELISA) using AMV-IgG. Six of the 40 symptomatic leaf samples tested positive for AMV, while, DAS-ELISA found no AMV in the 10 leaf samples without symptoms. The AMV Egyptian isolate (AMV-Eggplant-EG) was biologically isolated from the six positive samples tested by DAS-ELISA and from the similar local lesions induced on Chenopodium amaranticolor and then re-inoculated in healthy Solanum melongena as a source of AMV-Eggplant-EG and confirmed by DAS-ELISA. Reverse transcription polymerase chain reaction (RT-PCR) assay with a pair of primers specific for coat protein (CP) encoding RNA 3 of AMV yielded an amplicon of 666 bp from infected plants of Solanum melongena with AMV-Eggplant-EG. The amplified PCR product was cloned and sequenced. Analysis of the AMV-Eggplant-EG sequence revealed 666 nucleotides (nt) of the complete CP gene (translating 221 amino acid (aa) residues). Analysis of phylogeny for nt and deduced aa sequences of the CP gene using the maximum parsimony method clustered AMV-Eggplant-EG in the lineage of Egyptian isolates (shark-EG, mans-EG, CP2-EG, and FRE-EG) with a high bootstrap value of 88% and 92%, respectively. In addition to molecular studies, melatonin (MTL) and salicylic acid (SA) (100 μM) were used to increase the resistance of eggplant to AMV- infection. Foliar spray with MLT and SA caused a significant increase in the morphological criteria (shoot, root length, number of leaves, leaf area, and leaf biomass), chlorophyll and carotenoid content, antioxidant enzymes, and gene expression of some enzymes compared to the infected plants. On the other hand, treatment with MLT and SA reduced the oxidative damage caused by AMV through the reduction of hydrogen peroxide, superoxide anions, hydroxyl radicals, and malondialdehyde. In conclusion, MLT and SA are eco-friendly compounds and can be used as antiviral compounds. Full article

Prune dwarf virus (PDV) is an important viral pathogen of plum, sweet cherry, peach, and many herbaceous test plants. Although PDV has been intensively investigated, mainly in the context of phylogenetic relationship of its genes and proteins, many gaps exist in our knowledge about the mechanism of intercellular transport of this virus. The aim of this work was to investigate alterations in cellular organelles and the cell-to-cell transport of PDV in Cucumis sativus cv. Polan at ultrastructural level. To analyze the role of viral proteins in local transport, double-immunogold assays were applied to localize PDV coat protein (CP) and movement protein (MP). We observe structural changes in chloroplasts, mitochondria, and cellular membranes. We prove that PDV is transported as viral particles via MP-generated tubular structures through plasmodesmata. Moreover, the computer-run 3D modeling reveals structural resemblances between MPs of PDV and of Alfalfa mosaic virus (AMV), implying similarities of transport mechanisms for both viruses. Full article