Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Characterization of Tomato yellow spot virus, a novel tomato-infecting begomovirus in Brazil(Pesquisa Agropecuária Brasileira, 2007-09) Calegario, Renata Faier; Ferreira, Sávio de Siqueira; Andrade, Eduardo Chumbinho de; Zerbini, Francisco MuriloThe objective of this work was the biological and molecular characterization of a begomovirus detected in São Joaquim de Bicas, Minas Gerais, Brazil, named TGV-[Bi2], by determining its host range, complete nucleotide sequence and phylogenetic relationships with other begomoviruses. Biological characterization consisted of a host range study using either sap inoculation or particle bombardment as inoculation methods. The yellow spot virus can infect plants in Solanaceae and Amaranthaceae, including economically importat crops as sweet pepper, and weeds as Datura stramonium and Nicotiana silvestris. For the molecular characterization, the full-length genome (DNA-A and DNA-B) was amplified, cloned and completely sequenced. Sequence comparisons and phylogenetic analyses indicated that TGV-[Bi2] constitutes a novel begomovirus species named Tomato yellow spot virus (ToYSV), closely related to Sida mottle virus (SiMoV).Item Genetic diversity of begomoviruses infecting soybean, bean and associated weeds in Northwestern Argentina(Fitopatologia Brasileira, 2006-07) Rodríguez-Pardina, Patricia E.; Zerbini, F. Murilo; Ducasse, Daniel A.The subtropical Northwestern region of Argentina (provinces of Tucumán, Salta, Jujuy, Santiago del Estero and Catamarca) suffers from a high incidence of the whitefly Bemisia tabaci, and the detection of begomoviruses is also common. The Northwest is the main bean-growing region of the country, and approximately 10% of Argentina's soybean crop is grown in this area. We have used a PCR-based assay to establish the identity and genetic diversity of begomoviruses associated with bean and soybean crops in Northwestern Argentina. Universal begomovirus primers were used to direct the amplification of a fragment encompassing the 5' portion of the capsid protein gene. Amplified fragments were cloned, sequenced and subjected to phylogenetic analysis to determine the sequence identity to known begomoviruses. The data indicated the presence of four distinct begomoviruses, all related to other New World begomoviruses. The prevalent virus, which was present in 94% of bean and soybean samples and also in two weed species, is closely related to Sida mottle virus (SiMoV). A virus with high sequence identity with Bean golden mosaic virus (BGMV) was found in beans. The two remaining viruses displayed less than 89% identity with other known begomoviruses, indicating that they may constitute novel species. One of these putative novel viruses was detected in bean, soybean and tomato samples.Item Biological and molecular properties of Tomato rugose mosaic virus (ToRMV), a new tomato-infecting begomovirus from Brazil(Plant Pathology, 2006-05-30) Fernandes, J. J.; Carvalho, M. G.; Andrade, E. C.; Brommonschenkel, S. H.; Fontes, E. P. B.; Zerbini, F. M.A viral complex causing golden mosaic and leaf distortion (rugosity) in tomato plants was obtained from viruliferous whiteflies, and named TGV-Ub1. This complex was sap-transmitted from tomato to Nicotiana benthamiana. PCR amplification using universal begomovirus primers yielded two distinct fragments for DNA-A, suggesting that the TGV-Ub1 complex comprised at least two distinct viruses. Clones corresponding to full-length viral genomes were obtained from tomato plants infected with TGV-Ub1. Comparisons of the complete sequences of clones pUb1-49 (DNA-A), pUb1-62 and pUb1-81 (both DNA-B) indicated that they constitute novel western hemisphere begomoviruses. Clones pUb1-49 and pUB1-81 have identical common regions, thus representing the cognate DNA-A and -B of a novel begomovirus, named Tomato rugose mosaic virus (ToRMV). Clone pUb1-62 has a distinct common region from ToRMV and all other geminiviruses. A cognate DNA-A for pUb1-62 was not found. Clones containing 1·8 copies of the genomic components were constructed. Infectivity assays of these clones in tomato and N. benthamiana demonstrated that the clones corresponding to ToRMV systemically infected both hosts. Symptoms were analogous to those observed when using the pure isolates obtained in this study. The combination of pUb1-49 and -62 did not result in systemic infection, indicating that these components do not form a viable virus. ToRMV was sap-transmitted from N. benthamiana to N. benthamiana, and by grafting to Solanum tuberosum and Datura stramonium. ToRMV-A and ToRMV-B were detected in plants of Nicandra physaloides and Phaseolus vulgaris, respectively, growing in nearby tomato fields, in association with distinct DNA components.Item Alphasatellitidae: a new family with two subfamilies for the classification of geminivirus- and nanovirus-associated alphasatellites(Archives of Virology, 2018-05-09) Murilo Zerbini, F.; Briddon, Rob W.; Martin, Darren P.; Roumagnac, Philippe; Navas-Castillo, Jesús; Fiallo-Olivé, Elvira; Moriones, Enrique; Lett, Jean-Michel; Varsani, ArvindNanoviruses and geminiviruses are circular, single stranded DNA viruses that infect many plant species around the world. Nanoviruses and certain geminiviruses that belong to the Begomovirus and Mastrevirus genera are associated with additional circular, single stranded DNA molecules (~ 1-1.4 kb) that encode a replication-associated protein (Rep). These Rep-encoding satellite molecules are commonly referred to as alphasatellites and here we communicate the establishment of the family Alphasatellitidae to which these have been assigned. Within the Alphasatellitidae family two subfamilies, Geminialphasatellitinae and Nanoalphasatellitinae, have been established to respectively accommodate the geminivirus- and nanovirus-associated alphasatellites. Whereas the pairwise nucleotide sequence identity distribution of all the known geminialphasatellites (n = 628) displayed a troughs at ~ 70% and 88% pairwise identity, that of the known nanoalphasatellites (n = 54) had a troughs at ~ 67% and ~ 80% pairwise identity. We use these pairwise identity values as thresholds together with phylogenetic analyses to establish four genera and 43 species of geminialphasatellites and seven genera and 19 species of nanoalphasatellites. Furthermore, a divergent alphasatellite associated with coconut foliar decay disease is assigned to a species but not a subfamily as it likely represents a new alphasatellite subfamily that could be established once other closely related molecules are discovered.Item Synergism and negative interference during co-infection of tomato and Nicotiana benthamiana with two bipartite begomoviruses(Virology, 2009-03-12) Alves-Júnior, Miguel; Alfenas-Zerbini, Poliane; Andrade, Eduardo C.; Esposito, Débora A.; Silva, Fábio N.; Cruz, Ana Cláudia F. da; Ventrella, Marília C.; Otoni, Wagner C.; Zerbini, F. MuriloIn Brazil, at least eight begomoviruses including Tomato rugose mosaic virus (ToRMV) and Tomato yellow spot virus (ToYSV) infect tomatoes. ToYSV symptoms in tomato and Nicotiana benthamiana appear earlier and are more severe compared to those of ToRMV. We investigated the role of several factors in this differential adaptation. To analyze infection kinetics, a single leaf was inoculated and subsequently detached after different periods of time. Viral DNA accumulation was quantified in plants, viral replication was analyzed in protoplasts, and tissue tropism was determined by in situ hybridization. Results indicate that ToYSV establishes a systemic infection and reaches a higher concentration earlier than ToRMV in both hosts. ToRMV negatively interferes with ToYSV during the initial stages of infection, but once systemic infection is established this interference ceases. In N. benthamiana, ToYSV invades the mesophyll, while ToRMV is phloem-restricted. During dual infection in this host, ToYSV releases ToRMV from the phloem.Item Recombination and pseudorecombination driving the evolution of the begomoviruses Tomato severe rugose virus (ToSRV) and Tomato rugose mosaic virus (ToRMV): two recombinant DNA-A components sharing the same DNA-B(Virology Journal, 2014-04-05) Silva, Fábio N; Lima, Alison TM; Rocha, Carolina S; Castillo-Urquiza, Gloria P; Alves-Júnior, Miguel; Zerbini, F MuriloBegomoviruses are dicot-infecting, whitefly-transmitted viruses with a genome comprised of one or two molecules of circular, single-stranded DNA. In Brazil, tomato-infecting begomoviruses have emerged as serious pathogens since the introduction of a new biotype of the insect vector in the mid-1990’s. Tomato rugose mosaic virus (ToRMV) and Tomato severe rugose virus (ToSRV) are often found in tomato fields. The complete sequence of the DNA-B components of ToSRV and ToRMV show an identity of 98.2%. Additionally, the high nucleotide identity (96.2%) between their common regions indicates that these two viruses may share the same DNA-B. Tomato seedlings were biolistically inoculated with ToSRV (DNA-A and DNA-B) and ToRMV (DNA-A and DNA-B) infectious clones in every possible combination of single or mixed infection. Symptom expression was evaluated for up to 35 days post-inoculation (dpi). DNA was extracted at 28 dpi and the presence of each viral genomic component was examined by rolling circle amplification (RCA) followed by digestion, as well as by quantitative, real-time PCR. Sequence comparisons, recombination and phylogenetic analyzes were performed using EMBOSS needle, RDP program and maximum likelihood inference, respectively. Symptoms in tomato plants inoculated with the different combinations of ToRMV and ToSRV DNA-A and DNA-B components consisted of a typical mosaic in all combinations. Pseudorecombinants were formed in all possible combinations. When two DNA-A or two DNA-B components were inoculated simultaneously, the ToRMV components were detected preferentially in relation to the ToSRV components. The combination of minor changes in both the Rep protein and the CR may be involved in the preferential replication of ToRMV components. Recombination and phylogenetic analyzes support the exchange of genetic material between ToRMV and ToSRV. ToRMV and ToSRV form viable pseudorecombinants in their natural host (Solanum lycopersicum) and share the same DNA-B. ToRMV DNA components are preferentially replicated over ToSRV components. These results indicate that the emergence of ToRMV involved both recombination and pseudorecombination, further highlighting the importance of these mechanisms in the emergence and adaptation of begomoviruses.Item The diversification of begomovirus populations is predominantly driven by mutational dynamics(Virus Evolution, 2017-03-02) Lima, Alison T. M.; Silva, Jose ́ C. F.; Silva, Fábio N.; Castillo-Urquiza, Gloria P.; Silva, Fabyano F.; Seah, Yee M.; Mizubuti, Eduardo S. G.; Duffy, Siobain; Zerbini, MuriloBegomoviruses (single-stranded DNA plant viruses) are responsible for serious agricultural threats. Begomovirus populations exhibit a high degree of within-host genetic variation and evolve as quickly as RNA viruses. Although the recombination-prone nature of begomoviruses has been extensively demonstrated, the relative contribution of recombination and mutation to the genetic variation of begomovirus populations has not been assessed. We estimated the genetic variability of begomovirus datasets from around the world. An uneven distribution of genetic variation across the length of the cp and rep genes due to recombination was evident from our analyses. To estimate the relative contributions of recombination and mutation to the genetic variability of begomoviruses, we mapped all substitutions over maximum likelihood trees and counted the number of substitutions on branches which were associated with recombination (ηr) and mutation (ημ). In addition, we also estimated the per generation relative rates of both evolutionary mechanisms (r/μ) to express how frequently begomovirus genomes are affected by recombination relative to mutation. We observed that the composition of genetic variation in all begomovirus datasets was dominated by mutation. Additionally, the low correlation between the estimates indicated that the relative contributions of recombination and mutation are not necessarily a function of their relative rates. Our results show that, although a considerable fraction of the genetic variation levels could be assigned to recombination, it was always lower than that due to mutation, indicating that the diversification of begomovirus populations is predominantly driven by mutational dynamics.