Search Results (6)

Banana bunchy top virus (BBTV) was recently detected in Mozambique and appears to be limited to the provinces of Gaza, Maputo and Zambezia, but it has great potential to spread to other provinces. Despite its importance, nothing is known about the BBTV isolates that occur in Mozambique. In this study, the sequences of the S and R genes of forty isolates chosen as representatives of samples collected previously from eleven farms of the four administrative posts of the district of Chóckwè, province of Gaza, were sequenced and analyzed. The S-DNA nucleotide sequences of the analyzed isolates were highly conserved, with identity ranging from 97% to 100%. The same was observed for the R-DNA sequences, with most identities ranging between 98% and 100% among the isolates from Chókwè and above 90% when compared to the isolates from GenBank. The phylogenetic analysis showed that the Mozambican BBTV isolates belong to the Pacific–Indian Oceans (PIO) group, showing greater proximity to the isolate JQ820453 from Malawi than to the isolates from sub-Saharan countries, which were grouped in a distinct subclade. This is the first study conducted to determine the molecular characteristics of BBTV isolates present in Mozambique. Full article

Single-stranded DNA (ssDNA) plant viruses belong to the families Geminiviridae and Nanoviridae. They are transmitted by Hemipteran insects in a circulative, mostly non-propagative, manner. While geminiviruses are transmitted by leafhoppers, treehoppers, whiteflies and aphids, nanoviruses are transmitted exclusively by aphids. Circulative transmission involves complex virus–vector interactions in which epithelial cells have to be crossed and defense mechanisms counteracted. Vector taxa are considered a relevant taxonomic criterion for virus classification, indicating that viruses can evolve specific interactions with their vectors. Thus, we predicted that, although nanoviruses and geminiviruses represent related viral families, they have evolved distinct interactions with their vector. This prediction is also supported by the non-structural Nuclear Shuttle Protein (NSP) that is involved in vector transmission in nanoviruses but has no similar function in geminiviruses. Thanks to the recent discovery of aphid-transmitted geminiviruses, this prediction could be tested for the geminivirus alfalfa leaf curl virus (ALCV) and the nanovirus faba bean necrotic stunt virus (FBNSV) in their common vector, Aphis craccivora. Estimations of viral load in midgut and head of aphids, precise localization of viral DNA in cells of insect vectors and host plants, and virus transmission tests revealed that the pathway of the two viruses across the body of their common vector differs both quantitatively and qualitatively. Full article

Subterranean clover stunt virus (SCSV) is a type species of the genus Nanovirus in the family Nanoviridae. It was the first single-stranded DNA plant virus with a multipartite genome, of which genomic DNA sequences had been determined. All nanoviruses have eight genome components except SCSV, for which homologs of two genome components present in all other nanovirus genomes, DNA-U2 and DNA-U4, were lacking. We analysed archived and more recent samples from SCSV-infected legume plants to verify its genome composition and found the missing genome components. These results indicated that SCSV also has eight genome components and is a typical member of the genus Nanovirus. Full article

The experience with a diagnostic technology based on rolling circle amplification (RCA), restriction fragment length polymorphism (RFLP) analyses, and direct or deep sequencing (Circomics) over the past 15 years is surveyed for the plant infecting geminiviruses, nanoviruses and associated satellite DNAs, which have had increasing impact on agricultural and horticultural losses due to global transportation and recombination-aided diversification. Current state methods for quarantine measures are described to identify individual DNA components with great accuracy and to recognize the crucial role of the molecular viral population structure as an important factor for sustainable plant protection. Full article

Geminiviral single-stranded circular DNA genomes replicate in nuclei so that the progeny DNA has to cross both the nuclear envelope and the plasmodesmata for systemic spread within plant tissues. For intra- and intercellular transport, two proteins are required: a nuclear shuttle protein (NSP) and a movement protein (MP). New characteristics of ectopically produced Abutilon mosaic virus (AbMV) MP (MP^AbMV), either authentically expressed or fused to a yellow fluorescent protein or epitope tags, respectively, were determined by localization studies in mammalian cell lines in comparison to plant cells. Wild-type MP^AbMV and the distinct MP^AbMV: reporter protein fusions appeared as curled threads throughout mammalian cells. Co-staining with cytoskeleton markers for actin, intermediate filaments, or microtubules identified these threads as re-organized microtubules. These were, however, not stabilized by the viral MP, as demonstrated by nocodazole treatment. The MP of a related bipartite New World begomovirus, Cleome leaf crumple virus (ClLCrV), resulted in the same intensified microtubule bundling, whereas that of a nanovirus did not. The C-terminal section of MP^AbMV, i.e., the protein’s oligomerization domain, was dispensable for the effect. However, MP expression in plant cells did not affect the microtubules network. Since plant epidermal cells are quiescent whilst mammalian cells are proliferating, the replication-associated protein Rep^AbMV protein was then co-expressed with MP^AbMV to induce cell progression into S-phase, thereby inducing distinct microtubule bundling without MP recruitment to the newly formed threads. Co-immunoprecipitation of MP^AbMV in the presence of Rep^AbMV, followed by mass spectrometry identified potential novel MP^AbMV-host interaction partners: the peptidyl-prolyl cis-trans isomerase NIMA-interacting 4 (Pin4) and stomatal cytokinesis defective 2 (SCD2) proteins. Possible roles of these putative interaction partners in the begomoviral life cycle and cytoskeletal association modes are discussed. Full article

Although single stranded (ss) DNA viruses that infect humans and their domesticated animals do not generally cause major diseases, the arthropod borne ssDNA viruses of plants do, and as a result seriously constrain food production in most temperate regions of the world. Besides the well known plant and animal-infecting ssDNA viruses, it has recently become apparent through metagenomic surveys of ssDNA molecules that there also exist large numbers of other diverse ssDNA viruses within almost all terrestrial and aquatic environments. The host ranges of these viruses probably span the tree of life and they are likely to be important components of global ecosystems. Various lines of evidence suggest that a pivotal evolutionary process during the generation of this global ssDNA virus diversity has probably been genetic recombination. High rates of homologous recombination, non-homologous recombination and genome component reassortment are known to occur within and between various different ssDNA virus species and we look here at the various roles that these different types of recombination may play, both in the day-to-day biology, and in the longer term evolution, of these viruses. We specifically focus on the ecological, biochemical and selective factors underlying patterns of genetic exchange detectable amongst the ssDNA viruses and discuss how these should all be considered when assessing the adaptive value of recombination during ssDNA virus evolution. Full article