Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus (TCSV) are two emerging tospoviruses in Florida. In a survey of the southeastern United States, GRSV and TCSV were frequently detected in solanaceous crops and weeds with tospovirus-like symptoms in south Florida, and occurred sympatrically with Tomato spotted wilt virus (TSWV) in tomato and pepper in south Florida. TSWV was the only tospovirus detected in other survey locations, with the exceptions of GRSV from tomato (Solanum lycopersicum) in South Carolina and New York, both of which are first reports. Impatiens (Impatiens walleriana) and lettuce (Lactuca sativa) were the only non-solanaceous GRSV and/or TCSV hosts identified in experimental host range studies. Little genetic diversity was observed in GRSV and TCSV sequences, likely due to the recent introductions of both viruses. All GRSV isolates characterized were reassortants with the TCSV M RNA. In laboratory transmission studies, Frankliniella schultzei was a m...

In the regions of Campinas and Sumaré, São Paulo, Brazil, hidroponically grown crops of Lettuce (Lactuca sativa) cv. Verônica, 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 unde...

A distinct isolate (TY-PF36) of Tomato yellow fruit ring virus (TYFRV) was obtained from potato (Solanum tuberosum) in Iran. Chlorosis and necrotic spots on leaves associated with leaf and stem necrosis symptoms appear on the affected plants. Of 32 plant species and cultivars mechanically inoculated, 24 were susceptible to the virus isolate. The isolate strongly reacted with TYFRV antibodies in enzyme-linked immunosorbent assay (ELISA), but not with the specific antibodies of other tospoviruses tested. TYFRV-specific N gene primers described previously, however, failed to produce DNA fragments from the total RNA extracts of the infected plants in reverse transcription–polymerase chain reaction (RT-PCR). Nucleotide sequencing of the complete N gene and partial L gene of this isolate revealed considerable differences to those reported for TYFRV with identities ranging from 83.9 to 84.2% and 84.9 to 85.4%, respectively. Two specific primers were designed for detecting TY-PF36 using RT-...

A tospovirus from onion causing a disease known as “sapeca” by growers in Brazil was characterized. Symptoms on onion consisted of numerous eyelike spots on the leaves and flower stalks resulting in flower abortion. Nicotiana benthamiana and N. rustica were the only systemic hosts experimentally found. Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) experiments demonstrated that this virus was serologically related to iris yellow spot virus (IYSV), a tospovirus recently described in the Netherlands. This virus, from onion, based on an amino acid sequence identity of 90.5% for the N gene protein, is regarded as a strain of IYSV and is designated IYSVBR This 10% divergence in the nucleocapsid protein may represent an adaptation of the virus to distinct ecological niches.

Introduction Lettuce (Lactuca sativa) is an Asian vegetable introduced into Brazil through the Portuguese. Nowadays, it is the most appreciated vegetable in the country where its cultivation reaches a high level of technology, comprising green house, hydroponic and organic cultivation (Filgueira, 2000). Hydroponics is an alternative growing method that allows a relatively high number of plants per area at short time intervals. Although a reduction of disease incidence was thought to be expected on hydroponic lettuce, the presence of virus-like diseases has also been noted in several growing regions in São Paulo State. Lettuce diseases constitute a great problem, since they usually affect leaves, and viruses are especially harmful to commercial lettuce. In Brazil, the first report of Tospovirus in lettuce was made by Costa and Forster (1938), and later by Chagas (1970). At that time, this disease was known as Tomato spotted wilt virus (Ie, 1970) and sporadically found on lettuce. But...

Several viruses have been reported to infect lettuce. The most important is Lettuce mosaic virus (LMV), a potyvirus found worldwide transmitted by seeds and aphids, in a non-persistent manner. LMV causes quite variable symptoms, including mosaic, dwarfing, failure to form proper heads, and sometimes necrotic reactions. Cultivars carrying the mo11 and mo12 genes have resistance to the common strains, although most (mo breaking seed transmitted) strains can overcome this resistance. At least three species of tospovirus, including Tomato spotted wilt virus (TSWV), Tomato chlorotic spot virus (TCSV) and Groundnut ringspot virus (GRSV) causes significant losses, especially during summer, in which high populations of thrips vectors can be found in the field. Tospoviruses causes systemic necrosis and plant death. During the cooler season (May to September), two viruses have been found associated with big-vein disease, Mirafiori lettuce big-vein virus (MLBVV) which belongs to the genus Ophi...