César M. Chagas

Detection and coat protein gene characterization of an isolate of Grapevine virus B from corky bark-affected grapevines in Southern Brazil

ABSTRACT An isolate of Grapevine virus B (GVB), obtained by indexing Vitis labrusca andV. vinifera grapevines on the indicator LN33,was transmitted mechanically to several Nicotiana species. The viruswas partially purified from N. cavicola and the coat protein estimatedat 23 kDa by SDS-PAGE. In negatively stained leaf extracts ofexperimentally inoculated N. cavicola and N. occidentalis , flexuousparticles with cross banding were observed, predominantlymeasuring 750-770 x 12 nm, with a modal length of 760 nm.Decoration indicated a clear, positive reaction against AS-GVB. InDAS-ELISA, GVB was detected in N. cavicola and grapevineextracts, and Western blots showed homologous and cross reactionof GVB and GVA antisera with GVB coat protein. Using specificprimers for GVB, a fragment of 594 bp, comprising the coat proteingene coding for 197 amino acids, was amplified by RT-PCR withviral RNA extracted from GVB-infected N. occidentalis . Thenucleotide and the deduced amino acid sequences of the coat proteingene showed high identities with Italian and Japanese isolates ofGVB.

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).

A new Badnavirus species detected in Bougainvillea in Brazil

Badnavirus in Bougainvillea spectabilis showing virus-like symptoms was identified by the presence of bacilliform particles, measuring 125–130 × 30–40 nm in leaf-dip preparations and by analysis of its putative open reading frame 3 sequence. The virus, tentatively named Bougainvillea bacilliform virus (BBV), had the highest identities (up to 60%) with Spiraea yellow leaf spot virus, Gooseberry vein banding associated virus, Taro bacilliform virus, and Citrus yellow mosaic virus. In phylogenetic analysis, BBV clustered with Badnavirus putative species. Attempts to transmit the virus to several hosts failed. This is the first report of a new Badnavirus detected in Bougainvillea.

Biological and physicochemical properties of cowpea severe mosaic comovirus isolated from soybean in the State of Paraná

Soybean plants with symptoms of bud blight were growing close to cowpea with severe symptoms of mosaic associated with blisters in the leaves. A group of plants of both species were collected and used for etiological studies. This kind of symptom in soybeans was common in certain areas of the State of Parana, induced by tobacco streak ilarvirus. Host range, serological reaction, particle morphology and size, protein and nucleic acid analysis, and transmission by beetles from species Cerotoma arcuata Oliv. showed that the virus involved was cowpea severe mosaic comovirus. This is the first report on the occurrence of this virus in soybean plants in the State of Parana. Results using indirect ELISA showed that in cowpea the relative virus concentration was higher in green leaf areas than in chlorotic ones. Also, virus concentration, determined through indirect ELISA was much higher in plants kept at diurnal regime of 25o C x 23o C (12 x 12 h) than at 30o C x 28o C.

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.

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

First report of Turnip mosaic virus in horseradish in Brazil

FIG. 2 – A. Electron micrographs of flexuous filamentous particles, about 720 nm long, strongly decorated with specific antiserum against Turnip mosaic virus (TuMV), note a dense halo surrounding particles; B. Dense laminar aggregates, scrolls and pin-wheel are observed in ultra-thin section of an infected horseradish mesophyll cell. Bars = 200 nm A B RESUMO Primeiro relato do Turnip mosaic virus em raiz-forte no Brasil Este trabalho relata a primeira ocorrencia do Turnip mosaic virus (TuMV) em plantas de raiz-forte (Armoracia rusticana G. Gaertn., B. Mey. & Scherb.) provenientes de cultivos comerciais no Estado de Sao Paulo. Ate entao, este virus somente havia sido descrito em especies do genero Brassica no Brasil.