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On-line version ISSN 1678-4677
Fitopatol. bras. vol.32 no.2 Brasília Mar./Apr. 2007
PHYTOPATHOLOGICAL NOTES NOTAS FITOPATOLÓGICAS
First report of Turnip mosaic virus in horseradish in Brazil
Primeiro relato do Turnip mosaic virus em raiz-forte no Brasil
Marcelo Eiras; Alexandre L.R. Chaves; Addolorata Colariccio; César M. Chagas
Centro de Pesquisa e Desenvolvimento de Sanidade Vegetal, Instituto Biológico, Av. Conselheiro Rodrigues Alves, 1252, CEP 04014-002, São Paulo, SP, Brazil, e-mail: firstname.lastname@example.org
Este trabalho relata a primeira ocorrência do Turnip mosaic virus (TuMV) em plantas de raiz-forte (Armoracia rusticana G. Gaertn., B. Mey. & Scherb.) provenientes de cultivos comerciais no Estado de São Paulo. Até então, este vírus somente havia sido descrito em espécies do gênero Brassica no Brasil.
Horseradish (Armoracia rusticana G. Gaertn., B. Mey. & Scherb.) is a vegetatively propagated perennial plant grown as an annual crop. Among the viruses already reported on this species (Pound, J. Agricult. Res. 77:97. 1948; Hickman & Varma, Plant Pathology 17:26. 1968), Turnip mosaic virus (TuMV) is considered one of the most common pathogens of horseradish. TUMV is a Potyvirus with filamentous particles ca. 720 nm, sap-transmissible to a wide host range and transmitted by aphids in a non-persistent manner. In species of Brassicaceae it induces mottling, black necrotic spots, ringspots and mosaic. Symptoms of TuMV in horseradish include foliar mottling, mosaic or ring spots, dark streaks on the petioles and root discoloring, which results in an undesirable product (Horwitz et al., Plant Disease 69:246. 1985). Here we described the occurrence of TuMV on horseradish in Brazil. Sap from horseradish leaves showing chlorotic ringspots, mottling, mosaic and necrosis (Figure 1) was used in biological and serological tests, and electron microscopy. Chenopodium amaranticolor, C. quinoa, Nicotiana clevelandii, N. megalosiphon, N. sylvestris, N. tabacum 'White Burley' and 'Samsun' developed necrotic local lesions, while N. glutinosa and Brassica oleraceae showed systemic chlorotic spots, mosaic and necrosis. Chenopodium murale, Datura stramonium and Gomphrena globosa did not show any symptoms. The electron microscope observations of foliar extracts revealed flexuous particles ca. 720 x 13 nm, and in foliar ultra-thin sections pin-wheels, scrolls and laminar aggregates were recognized. In immunomicroscopy tests (decoration), using specific antiserum against TuMV, particles appeared surrounded by a densely stained halo (Figure 2). The original leaf samples and inoculated N. glutinosa plants reacted positively in PTA-ELISA with a polyclonal antiserum against TuMV. Under our conditions, TuMV types I and II have already been reported in Brassica oleraceae (Colariccio et al., Summa Phytopathologica 26:455. 2000); however, to our knowledge, this is the first report of TuMV infecting horseradish in South America, more specifically in São Paulo State, Brazil.
Received 21 novembro 2006 - Accepted 14 Maio 2007 - FB 6117
Author for correspondence: Marcelo Eiras