Archivio Journal of Plant Pathology

Abstract:

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 São 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.