Alexandre L. R. Chaves

Erigeron bonariensis: hospedeira alternativa do Lettuce mosaic virus no Brasil

The genus Erigeron, Asteraceae family, comprises weed plants spread over Southern and Southeastern Brazil, and, frequently, is found among annual and perennial crop plants. Erigeron bonariensis L.plants showing symptoms of mosaic, similar to those caused by plant viruses, were collected in Sao Paulo State and submitted to electron microscopy, biological, serological and molecular analysis. Ultrathin sections of the original foliar tissues samples showed tubular and pinwheel inclusions dispersed in the cytoplasm of infected cells. Following transmission by mechanical inoculation, only Chenopodium amaranticolor, C. quinoa, Nicotiana benthamiana and N. clevelandii were infected. The ELISA results were negative with antisera against Turnip mosaic virus (TuMV) and Potato virus Y (PVY) and positive for Lettuce mosaic virus (LMV) antiserum. With specific primers to LMV, 280 bp fragments were amplified and sequenced, confirming the virus identity as LMV. The occurrence of LMV in E. bonariensis, which belongs to the lettuce (Lactuca sativa) family, is significant since it may also act as LMV reservoir for lettuce field crops. This is the first report in Brazil of a virus infecting Erigeron sp. which has also been reported as a natural host of Bidens mottle virus and Tomato spotted wilt virus in the United States.

Caracterização do Tomato chlorotic spot virus isolado de jiló no Vale do Paraíba, Estado de São Paulo

Tospoviruses are responsible for important losses in most crops, mainly Solanaceae. Gilo (Solanum gilo) plants showing mosaic, blistering, stunting and 100% production losses were collected for analysis from Sao Jose dos Campos in the State of Sao Paulo. Biological, electron microscopy, serological and molecular tests were carried out in order to characterize the virus isolate. The mechanical inoculation on Amaranthaceae, Solanaceae and Chenopodiaceae plants showed typical tospovirus-induced symptoms. Pleomorphic particles from 80 to 110 nm were observed in negatively stained preparations and in vesicles of the endoplasmic reticulum of infected cells. Tomato chlorotic spot virus (TCSV) was identified by DAS-ELISA. DNA fragments were amplified by RT-PCR, with specific primers designed to the nucleocapsid gene (N) of the main Tospovirus species, sequenced and compared with others in the GenBank. The nucleotide and amino acid deduced sequences homology was 99 and 95%, respectively, with TCSV. Comparison with other Tospovirus species presented values between 74 and 81%. These results confirmed the identity of this virus isolate as TCSV, the main tospovirus species in Sao Paulo that also damages other Solanaceous crops. Varieties of gilo have been inoculated showing susceptibility to TCSV, Tomato spotted wilt virus (TSWV) and Groundnut ringspot virus (GRSV).

Transmissão experimental revela novos potenciais reservatórios do Cowpea aphid-borne mosaic virus

Projeto financiado pela Fapesp, processo: 2011/11796-5.Autor para correspondencia: Marcelo Eiras (eiras@biologico.sp.gov.br)Data de chegada: 19/03/2012. Aceito para publicacao em: 15/04/2012. 1809O Brasil e, atualmente, o maior produtor mundial de maracuja.Porem, o rendimento da cultura ainda e limitado devido as doencasque causam perdas significativas na producao (Meletti LMM.Revista Brasileira de Fruticultura v. especial, p. 83-91, 2011). Oendurecimento dos frutos, induzido pelo

CHRYSANTHEMUM STUNT VIROID IN BRAZIL: SURVEY, IDENTIFICATION, BIOLOGICAL AND MOLECULAR CHARACTERIZATION AND DETECTION METHODS

In Brazil, the ornamental flowers and plants market moves in the wholesale and retail more than two billion US dollars annually, and chrysanthemum stands out as one of the most valuable commercial species. The stunting disease induced by Chrysanthemum stunt viroid (CSVd) has become a serious problem in chrysanthemum production systems worldwide. CSVd incites also colour breaking and retards flowering, but in many situations it does not induce visible symptoms, facilitating its spread in the field and passing international borders unnoticed. In Brazil there are few studies on this pathogen, with a single report of its possible occurrence in chrysanthemum in the State of Sao Paulo. In this work we aimed at surveying, identifying and characterizyng viroids in chrysanthemum crops in the State of Sao Paulo; challenging chrysanthemum varieties with a Brazilian CSVd isolate; and establishing diagnostic strategies to strengthen quarantine and indexing programs. Our survey showed that CSVd is widely disseminated in chrysanthemum crops in the State of Sao Paulo. All evaluated chrysanthemum varieties were susceptible of infection, although infection was sometimes symptomless. The complete genome sequencing of seven CSVd isolates showed high nucleotide identity when compared with other isolates from databases. Specific oligonucleotides were designed for conventional RT-PCR and RT-qPCR CSVd analysis. Results show that CSVd can be identified with a sensitivity about 100,000 times higher than PAGE. Dot-blot proved also to be highly sensitive and, consequently, most useful for large scale diagnosis. This is the first biological and molecular identification and characterization of CSVd isolates in Brazil.

Tomato chlorotic spot virus in hydroponically-grown lettuce in São Paulo State, Brazil

In the regions of Campinas and Sumare, Sao Paulo, Brazil, hidroponically grown crops of Lettuce (Lactuca sativa) cv. Veronica, which showed virus-like symptoms were examined by electron microscope, biological, serological and molecular tests. Pleomorphic, enveloped particles (80-100 nm in diameter) were always detected in these samples. Experimentally inoculated host plants, including lettuce, reacted with tospoviruses-induced symptoms. Some differences were observed in Gomphrena globosa, which reacted by showing local lesions and systemic mosaic. Two isolates of Tomato chlorotic spot virus (TCSV) were identified by DAS-ELISA and by RT-PCR. The sequencing and alignment of the RT-PCR coat protein amplified fragments have indicated a high degree of homology with the TCSV sequences stored in the GenBank. This is the first report of losses due to a virus from the genus Tospovirus in commercial hydroponic lettuce crops in Brazil. Further epidemiological studies are needed for better understanding the spread of the virus in hydroponic crops, since Tomato spotted wilt virus (TSWV) is reported to spread through the nutritive solution.

First report of Tomato chlorotic spot virus on Mirabilis jalapa

Mosaic symptoms in Mirabilis jalapa plants from a public garden in the city of São 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.

Tomato rugose mosaic virus in Tomato Crops in São Paulo State, Brazil

Geminiviruses were of limited economic importance to tomato crops until the introduction of biotype B, when an increase in the incidence of begomovirus was reported (Ribeiro ., Arch. Virol. 148:281. 2003). In recent years, the occurrence of geminivirus in tomato causing a severe outbreak has been observed in the Campinas region, SP. In preliminary surveys (ToYVSV) turned out to be the most frequent begomovirus species, affecting about 70% of tomato crops. Occasionally, however, another possible begomovirus, inducing leaf crumple, has been noticed affecting tomato in that region (Colariccio ., Summa Phytopathol. 27:105. 2001). The present work aimed to identify the virus associated with the leaf crumple symptom. Thus, leaf samples from affected ‘Carmen’ tomato plants from Mogi Guacu, SP, showing growth reduction, green and yellow mosaic, besides leaf crumple and curling, were submitted to electron microscopy, mechanical, graft and transmissions, as well as DNA extraction for PCR using universal primers (Rojas ., Plant Dis. 77:340. 1993). Sequencing and phylogenetic analysis were performed to compare this virus with other geminivirus sequences deposited in the GenBank. Typical geminated particles were observed in negatively stained preparations from foliar veins. observation revealed the presence of hexagonally-packed crystalline array or of loose aggregates in the nuclei of phloem-infected parenchyma cells, with partial alteration of nucleoli into a granular structure. These cytopathic effects corresponded to those described for begomoviruses. The virus was transmitted by and graft, but not mechanically, like (ToRMV) from Minas Gerais State. A DNA-A fragment of about 1.2 kbp

Canna paniculata as natural host of canna yellow streak virus in Brazil

Canna yellow streak virus (CaYSV) was identified on Canna paniculata with foliar mosaic symptoms from Piracicaba municipality (São Paulo state, Brazil) by transmission electron microscopy, biological, serological and molecular assays. Pairwise analyses of nucleotide and amino acid sequences (potyvirus cylindrical inclusion region) with homologous sequences revealed the highest identity (88.6 and 97.8%) with CaYSV. This is the first detection of CaYSV in Brazil.

First report of Turnip mosaic virus on Tropaeolum majus in Brazil.

Tropaeolum majus (Tropaeolaceae), popularly known as garden nasturtium and often confused with Nasturtium officinale (Brassicaceae), is widely cultivated in southern and southeastern regions of Brazil as ornamental, medicinal and food plant. T. majus plants from Sao Paulo state showing symptoms of mosaic, blistering and leaf distortion were subjected to biological, serological and molecular tests for virus diagnosis. Inoculations on Chenopodium species induced local lesions and reproduced the original symptoms on T. majus. Naturally and experimentally infected T. majus reacted positively to an antiserum raised against a potyvirus group in DAS-ELISA and against a Turnip mosaic virus (TuMV) antiserum in indirect ELISA. Total RNA was extracted from infected T. majus leaf, and RT-PCR carried out using primers designed on the sequence of part of the cytoplasmic inclusion region of the potyviral genome (Ha et al., 2008), produced a fragment ca. 700 bp in size The fragment was directly sequenced (GenBank accession No. KJ635891) and its sequence (TuMV-TR02) was similar to that of TuMV isolates NDJ (AB093616) and Al (AB093598) with 78.8 and 92.1% nucleotide identity, respectively. Phylogenetic trees constructed with maximum parsimony, maximum likelihood and neighbor-joining algorithms using the PAUP program were similar. The TuMV-TR02 isolate formed a monophyletic group with isolates from Italy belonging to the basal-B group proposed by Oshima et al. (2002). This is the first report of TuMV on garden nasturtium in Brazil.

First report of Tomato mottle leaf curl virus infecting tomato in São Paulo State, Brazil

Diseases caused by several species of the genus Begomovirus (family Geminiviridae) affect the tomato (Solanum lycopersicum) production worldwide. These viruses are transmitted to dicotyledonous in a circulative (non-propagative) manner by the cryptic species complex of Bemisia tabaci (Hemiptera: Aleyrodidae) (De Barro et al., Annual Review of Entomology, v.56, p.1-19, 2011). About eighty species of begomoviruses have already been described in tomato worldwide (Brown et al., Archives of Virology, v.160, p.1593-1619, 2015). In Brazil, begomoviruses started to cause losses to tomato producers in the early 1990’s, with the introduction of B. tabaci “biotype B” (Fernandes et al., Virus Genes, v.36, p.251-258, 2008). Brazil is the largest center for begomovirus diversity, where, to date, fourteen recognized species of tomato-infecting begomoviruses have already been described (Inoue-Nagata et al., Horticultura Brasileira, v.34, p.8-18, 2016); however, the most common species are: Tomato severe rugose virus (ToSRV), a bipartite species of widespread occurrence, reported in Goiás, Minas Gerais and São Paulo; Tomato chlorotic mottle virus (ToCMoV), a bipartite species of minor importance, already reported in Bahia, Goiás and Pernambuco; and Tomato mottle leaf curl virus (ToMoLCV), a monopartite species of major importance especially for the northeast region, reported in Bahia, Distrito Federal, Espírito Santo, Minas Gerais, Rio de Janeiro, Paraíba and Pernambuco. There is evidence that these species have high recombination capacity, which can frequently change begomovirus population structure in a given region (Rocha et al., Journal of Virology, v.87, p.5784-5799, 2013). Samples of tomato leaves showing severe chlorosis, from the municipality of Santo Antônio da Posse, east São Paulo State (Figure 1), were subjected to mechanical transmission to several host plants (solanaceous), as well as DNA extraction and PCR with primers specific to begomoviruses (Rojas et al., Plant Disease, v.77, p.340-347, 1993). The virus was not mechanically transmitted. DNA fragments with ca. 1,500 bp were amplified, sequenced and compared to other sequences deposited in the GenBank, revealing high identity to ToMoLCV Brazilian isolates. Comparisons of the nucleotide sequence of this isolate, named ToMoLCV/SP, showed 98% similarity with another ToMoLCV tomato isolate from Minas Gerais State (KC706616). ToMoLCV isolates from Bahia, Paraíba, Pernambuco and Distrito Federal showed about 88 to 97% similarity with ToMoLCV/SP. The area from where ToMoLCV/SP isolate was collected is close to south Minas Gerais State, a large tomato producer region, and, together with intense flocks of whiteflies, may be associated with the occurrence of ToMoLCV in the state of São Paulo. The potential emergency of new begomovirus species, resulting from recombination between ToMoLCV and Tomato yellow vein streak virus (ToYVSV), was already reported in tomato plants from Distrito Federal (Inoue-Nagata et al., Pesquisa Agropecuária Brasileira, v. 87, p. 1329-1332, 2006). ToYVSV is not a common species but is recurrent in São Paulo State (Colariccio et al., Journal Plant Pathology, v.89, p.585-390, 2007), and its association with ToMoLCV may, in the short-term, originate an aggressive complex of begomovirus species.