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We identified a novel plant rhabdovirus infecting native joa (Solanum aculeatissimum) plants in Brazil. Infected plants showed yellow blotches on the leaves, and typical enveloped bacilliform rhabdovirus particles associated with the nucleus were seen in thin sections by electron microscopy. The virus could be graft-transmitted to healthy joa and tomato plants but was not mechanically transmissible. RT-PCR using degenerate plant rhabdovirus L gene primers yielded an amplicon from extracted total RNA, the sequence of which was similar to those of alphanucleorhabdoviruses. Based on close sequence matches, especially with the type member potato yellow dwarf virus (PYDV), we adopted a degenerate-primer-walking strategy towards both genome ends. The complete genome of joa yellow blotch-associated virus (JYBaV) is comprised of 12,965 nucleotides, is less than 75% identical to that of its closest relative PYDV, and clusters with PYDV and other alphanucleorhabdoviruses in L protein phylogenetic trees, suggesting that it should be taxonomically classified in a new species in the genus Alphanucleorhabdovirus, family Rhabdoviridae. The genome organization of JYBaV is typical of the 'PYDV-like' subgroup of alphanucleorhabdoviruses, with seven genes (N-X-P-Y-M-G-L) separated by conserved intergenic regions and flanked by partly complementary 3' leader and 5' trailer regions.

For the first time, an isolate of the dichorhavirus orchid fleck virus (OFV, family Rhabdoviridae) was found infecting an orchid plant in Mexico. The infected sample of Epidendrum veroscriptum was collected in a nursery in Lagunillas, municipality of Zihuateutla, Edo. Puebla. Mites gathered on this plant were analyzed by light and scanning electron microscopy, which consistently indicated the presence of adults of the species Brevipalpus californicus, the common vector of OFV. Viral identification was based on symptoms, cytopathology, and reverse transcriptase-PCR/sequencing of genome fragments of the RNA1 and 2 molecules. Since isolates of OFV causing citrus leprosis have been previously detected in the Mexican states of Chiapas, Querétaro, and Jalisco, we promote a pertinent discussion and thought-provoking questions regarding the epidemiology and putative evolution of OFV.

Dentre os problemas fitossanitários da videira (Vitis spp.), destacam-se os vírus, patógenos que podem reduzir a qualidade e o rendimento da produção de uva. No entanto, detectar e ldentíficar infecções virais em videiras pode ser um desafio. Os objetivos deste trabalho foram identifrcar as principais espécies virais presentes em vinhedos comerciais de municípios do Vale do Rio do Peixe, em Santa Catarina, e avaliar a detecção viral em diferentes estádios de desenvolvimento da videira e em tecidos, expressando diferentes intensidades de sintomas, utilizando RT-PCR em tempo real (RT-qPCR). Todos os sete vírus e o viroide avaliados estão amplamente disseminados nas áreas amostradas, frequentemente em altas incidências, variando de 27,1% a 85,4%, e em infecções múltiplas. Evidencia-se a importância que as viroses possuem dentro dessa prestigiada região de cultivo da videira no Brasil. Em dois ensaios, foram avaliadas a capacidade e a confrabilidade da RT-qPCR em detectar vírus e viroide em tecidos vegetais em diferentes estádios de desenvolvimento e em folhas com sintomas severos, intermediários ou assintomáticas. Amostras de videiras com pouco desenvolvimento vegetativo (até 74 dias após a poda) não foram adequadas para a diagnose. A detecção viral foi possível na maioria dos tecidos foliares, expressando diferentes intensidades de sintomas, inclusive em folhas assintomáticas. Essa informação contribui para definir parâmetros de amostragem determinantes para um diagnóstico confiável. Palavras-chave: levantamento, detecção, amostragem, RT-qPCR, Vitis. Made available in DSpace on 2021-11-09T14:01:10Z (GMT). No. of bitstreams: 1 Fajardo-RBVE-2021.pdf: 9090584 bytes, checksum: c67f5bb1e0bea36cb209e776009a8a8c (MD5) Previous issue date: 2021

For the first time, the near-complete genome sequence of the betacarmovirus, hibiscus chlorotic ringspot virus (HCRSV) isolated from the Americas is disclosed. High throughput sequencing of the total RNA extract from a Hibiscus-rosa sinensis (L.) plant collected in Sao Paulo state, Brazil, revealed the genome sequence of HCRSV isolate SBO1, which is 3945 nucleotides long and shows 93.1% nucleotide sequence identity with HCRSV_Singapore (X86448), considered the type member of the species. These two viruses display a similar genomic organization and potentially encode seven open reading frames (ORFs). In addition, a phylogenetic analysis based on a fragment with 557 nts of p38, the coat protein gene, from a cohort of 14 samples collected in Brazil revealed a no clearly defined segregation of South American isolates from those previously detected in geographical areas outside this continent. The practical consequences of the use of p38 ORF-derived amplicons for detection and variability studies of HCRSV are concisely discussed.

A cultura do trigo é acometida por duas viroses principais: o nanismo-amarelo e o mosaico-comum. O nanismo-amarelo ocorre em todas as regiões tritícolas, enquanto o mosaico-comum é mais frequente na Região sul.

Forty-eight tomato genotypes, differing in their genotypic constitution (genes Ty and/or Mi + allelochemicals), were placed in a greenhouse with a high infestation of whiteflies, which had been previously fed with tomato plants infected by ToYVSV. The genotypes were kept in the same greenhouse throughout the entire experiment and were evaluated using a symptom rating scale. The estimated area under the disease progress curve (Area) and the mean scores from the last assessment were used to perform Dunnett's test with the susceptible and resistant controls. The genotypes were categorized according to their contents of acylsugar (AS) and zingiberene (ZB) and the presence or absence of the genes Mi, Ty-1, Ty-2, and Ty-3+Ty-4 to perform contrasts between groups and associate their effects to the different resistance levels observed. Alleles Mi and Ty-1 were more effective in promoting ToYVSV resistance in homozygozity than in heterozygosity. Lines homozygous for Ty-2 and Ty-3+Ty-4 showed significantly fewer symptoms than the resistant control, indicating that those alleles in homozygosity are the most effective in reducing ToYVSV symptoms. The results highlight the importance of pyramiding different resistance genes in adequate allelic dosages, in the process of lineages development aiming to obtain tomato genotypes with higher and more durable resistance to ToYVSV.

Using a high-throughput sequencing approach, we identified four genomoviruses (family Genomoviridae) associated with a sweet orange (Citrus sinensis) plant collected in Tunisia. The ssDNA genomes of these genomoviruses, which were amplified, cloned and Sanger sequenced, range in size from 2156 to 2191 nt. Three of these viruses share > 99% full-genome pairwise sequence identity and are referred to as citrus Tunisia genomovirus 1 (CTNGmV-1). The CTNGmV-1 isolates share

In Brazil, passion flower is grown across almost the entire country. The predominant disease of the passion flower cropis passion fruit woodiness, caused by the potyvirus cowpea aphid-borne mosaic virus (CABMV), and transmitted byaphids in a nonpersistent manner. The disease reduces the useful life of the orchard from 36 months to approximately18 months. Up to now, there has not been an efficient method for disease management. The aim of this work was toevaluate the efficiency of systematic roguing of diseased plants through weekly inspections, for disease management inthe field. The latent and incubation periods of CABMV in passion flower vines were determined in order to optimizeroguing efficiency. Passion fruit plants inoculated with CABMV started to act as sources of inoculum from 3 days afterinoculation (DAI), and the symptoms were expressed, on average, at 8 DAI. Five field experiments, conducted in thestates of S~ao Paulo and Bahia, Brazil, demonstrated that systematic roguing of diseased plants was significantly efficientfor managing passion fruit woodiness disease. In order to facilitate identification and subsequent removal of theinfected plants, they need to be grown separately. This cultural practice can be recommended for managing passionfruit woodiness disease, provided it is applied on a regional scale by all passion fruit growers. The development ofsome pilot plantings for the application of roguing in a passion flower-producing region is recommended to validatethe use of this technique for managing passion fruit woodiness disease. Made available in DSpace on 2020-02-12T18:09:33Z (GMT). No. of bitstreams: 1 Longlastingsystematicroguing2019.pdf: 557891 bytes, checksum: 92a54d52de1484d1506a3b1545811030 (MD5) Previous issue date: 2019

Tomato spotted wilt virus (TSWV) was identified in green red-rimmed ringspots on spider lily (Hymenocallis spp.) leaves in Brisbane, Australia. Tospovirus-like particles were seen in thin sections of those lesions. RT-PCR using tospovirus-specific primers amplified a DNA fragment whose sequence matched TSWV S RNA. The virus caused symptoms in Nicotiana benthamiana following mechanical transmission and was confirmed as TSWV by RT-PCR.

Mosaic symptoms in Mirabilis jalapa plants from a public garden in the city of Sao Paulo, Brazil, were associated with the presence of Tomato chlorotic spot virus (TCSV-Mir-BR07). TCSV-Mir-BR07 was mechanically transmitted to healthy M. jalapa plants. Phylogenetic analysis revealed a monophyletic group formed by South American TCSV isolates separate to those from Central and North America. This is the first report of natural TCSV infection in M. jalapa.

International audience; In some epidemics that have devastating consequences, the primary inoculum plays an important role in both epidemic onset and intensification. This article documents the dynamics of such epidemics, and illustrates their importance using two examples: Huanglongbing of citrus and begomoviruses of tomato. The latter disease is a major constraint to tomato production in Brazil, while the former has become a threat to global citrus production and farmers' livelihoods. In spite of their importance little is known of the characteristics of these diseases and their management. This is because classical botanical epidemiology considers two types of diseases: polycyclic diseases, where the inoculum that causes infections is produced during the epidemic in or on individual plants that had been previously infected in the course of that epidemic; or monocyclic diseases, where inoculum that causes infection is not produced in or on individual plants that had been infected in the course of the epidemic, but in the soil, on secondary hosts, or in infected crop plants of the same host in other fields. Diseases of the first type typically present a logistic disease progress curve and management is based on reducing the rate of infection, whereas diseases of the second type present a monomolecular disease progress curve and management is based on reducing the initial inoculum. This article deals with plant diseases that depart in their structure and behaviour from these two archetypes, because they borrow elements from both. We address polycyclic diseases in which the primary inoculum has a continuous and dynamic role, and in which the secondary inoculum contributes to epidemic build-up, i.e., polycyclic diseases with continuous primary spread. This epidemiological structure generates less clear-cut disease progress curves, but usually follows a monomolecular dynamic. Our focus on this type of disease is multifold because (1) this more complex, combined, pattern is actually quite common, often leading to grave plant diseases epidemics, with impacts at the farm, community, and country scales, and (2) such epidemics are among the most difficult to manage. Our analysis leads us to assess past errors and current courses of action. It allows us to recognize, in addition to the conventional tools for management with local effects, the critical importance of collective action. Collective management action - at the farm, community, or national scales - is congruent with the characteristics of many epidemics, because they also entail properties at successive and nested scales. The management of such epidemics needs to address both the primary and secondary inoculum. More importantly, these actions have to be performed in an area-wide, regional basis in order to be effective.

Crinivírus, transmitidos por mosca-branca, engrossam a lista de viroses enfrentadas pelos produtores de tomate no Brasil e se somam a desafios como a incidência de Begomovírus e Tospovírus. A busca por cultivares resistentes tem se mostrado indispensável diante da ampla gama de hospedeiros e das limitações no controle do inseto-vetor.

As viroses são um sério problema para a agricultura, podendo se tomar um fator limitante para o desenvolvimento de determinadas espécies. Medidas de controle, como a eliminação dos vetores, o uso de material sadio, a rotação de culturas e a erradicação de plantas infectadas são apenas soluções temporárias. A mais eficiente estratégia de controle envolve o uso de cultivares melhoradas para resistência ao vírus ou a seu vetor. A reduzida disponibilidade de fontes de resistência pode ser aumentada através da tecnologia do DNA recombinante, que traz novas perspectivas para o melhoramento de plantas resistentes a viroses. Virus diseases are a serious problem to agricuiture, can be a limitant factor to normal development of some crops. Control measures, like vectors elimination, healthy material use, culture rotation and infected plants eradication, are only transient solutions. The more efficient approach for control involves plant breeding resistant to virus or its vector. Reduced availability of resistance source can be increased through recombinant DNA technology, which brings new breeding perspectives to virus resistant crops.

Coffee ringspot is a minor coffee disease caused by the nuclear type of Brevipalpus mite-transmitted virus, Coffee ringspot virus (CoRSV). Recently outbreaks of the disease in some growing regions of the state of Minas Gerais, Brazil, were registered with qualitative and quantitative yield losses. Coffea arabica was the only species registered as natural host. A survey was made on a germplasm collection of Coffea and related species kept at the Centro de Cafe "Alcides Carvalho", Instituto Agronomico, Campinas, state of Sao Paulo (SP), Brazil, to assess natural susceptibility of Coffee species, other than C. arabica and some interspecific hybrids of Coffea as well as other non-Coffea plant species to the Coffee ringspot virus (CoRSV). The following plants were found with ringspot symptoms on their leaves and/or fruits besides C. arabica L.: C. kapakata (IAC 4511), C. dewevrei cv. Excelsa, C. canephora cv. Robusta, hybrid derivative of the C. arabica × C. racemosa (IAC1195-5-6-2), C. arabica × C. dewerei (Piata IAC 387), Hibrido de Timor CIFC 832/1 (derivative from a natural crossing between C. arabica × C. canephora) and C. racemosa. Also Psilanthus ebracteolatus, a species close to the genus Coffee was also found with ringspot lesions on their leaves. All these plants were also found infested by Brevipalpus mites identified as B. phoenicis. Infection of these plants by CoRSV was confirmed by the observation of characteristic cytopathic effects in the tissues of the lesion and by RT-PCR using a pair of primer specific for CoRSV. Only with C. racemosa RT-PCR failed to amplify the CoRSV genome. The susceptibility of P. ebracteolatus to CoRSV adds new dimension regarding its controversial taxonomic position.

No mundo há milhares de viroses descritas, cada uma possuindo uma específica gama de hospedeiros. A sintomatologia produzida varia bastante, dependendo do vírus ou da estirpe presente, da planta infectada e das condições do ambiente. No Brasil, em fruteiras tropicais, citros e mandioca já se constatou a ocorrência de várias viroses, como o vírus associado com a murcha do abacaxi, o vírus das estrias da bananeira, o vírus da meleira do mamoeiro, o vírus da tristeza dos citros e o vírus do mosaico das nervuras da mandioca. Na natureza, a maioria das viroses são transmitidas por insetos, mas também é comum sua transmissão por sementes, manivas ou enxertos obtidos de plantas infectadas. As ferramentas de corte contaminadas também podem propiciar a disseminação de algumas viroses. Disponível em : Acesso em : 24 jan. 2011.

Potato leafroll virus (PLRV) is a major menace for the potato production all over the world. PLRV is transmitted by aphids, and until now, the only strategy available to control this pest has been to use large amounts of insecticides. Transgenic approaches involving the expression of viral replicases are being developed to provide protection for plants against viral diseases. The purpose of this study was to compare the protection afforded by the differential expression of PLRV replicase transgene in potato plants cv. Desirée. Plants were genetically modified to express the complete sense PLRV replicase gene. Two constructions were used, one containing the constitutive 35SCaMV promoter and the other the phloem-specific RolA promoter from Agrobacterium rhizogenes. Transgenic plants were infected with PLRV in vitro, using infested aphids. In plants in which 35SCaMV controlled the expression of the PLRV replicase gene, signs of infection were initially detected, although most plants later developed a recovery phenotype showing undetectable virus levels 40 days after infection. In turn, those plants with the RolA promoter displayed an initial resistance that was later overcome. Different molecular mechanisms are likely to participate in the response to PLRV infection of these two types of transgenic plants. Made available in DSpace on 2018-05-30T00:49:51Z (GMT). No. of bitstreams: 1 ID24891.pdf: 644096 bytes, checksum: 661828c592746010e2380c4f024058da (MD5) Previous issue date: 2005-04-18

Made available in DSpace on 2018-03-28T00:32:16Z (GMT). No. of bitstreams: 1 Virosesemcultura.pdf: 1610792 bytes, checksum: 3975fbcb3eb6499496aacd2016d4e51e (MD5) Previous issue date: 2003-08-28

Foram comparados vinhos da cultivar Cabernet Franc (Vitis vinifera L.) provenientes de plantas sadias e atacadas pela virose do enrolamento da folha. O experimento foi realizado em Bento Gonçalves, RS, durante as safras de 1986, 1987, 1988, 1990 e 1991. O vinhedo foi instalado em 1982, sendo as videiras enxertadas sobre o porta-enxerto '101-14' e dispostas em 10 fileiras divididas por plantas sadias e plantas doentes. Os vinhos foram elaborados pelo processo de microvinificação a partir de 20kg de uva colhidos de maneira homogênea em toda a área. Os principais efeitos da virose na composição dos vinhos foram a diminuição do teor alcoólico, pH, cinzas, intensidade de cor e polifenóis totais. A virose também diminuiu o teor de acetato de etila e a soma de álcoois superiores. Quanto aos minerais, a virose determinou uma diminuição do K e Rb e um aumento nos teores de Ca e Mg. Made available in DSpace on 2021-02-05T12:18:36Z (GMT). No. of bitstreams: 1 Zanus-1992-219-226.pdf: 4065839 bytes, checksum: 48b016cba60a9cbd5580d30e79768fc5 (MD5) Previous issue date: 1992