M. A. V. Alexandre

Phylogenetic analysis of Tomato mosaic virus from Hemerocallis sp. and Impatiens hawkeri

The culture and commercialization of ornamental plants have considerably increased in the last years. To supply the commercial demand, several Hemerocallis and Impatiens varieties have been bred for appreciated qualities such as flowers with a diversity of shapes and colors. With the aim of characterizing the tobamovirus isolated from Hemerocallis sp. (tobamo-H) and Impatiens hawkeri (tobamo-I) from the USA and Sao Paulo, respectively, as well as to establish phylogenetic relationships between them and other Tobamovirus species, the viruses were submitted to RNA extraction, RT-PCR amplification, coat-protein gene sequencing and phylogenetic analyses. Comparison of tobamovirus homologous sequences yielded values superior to 98.5% of identity with Tomato mosaic virus (ToMV) isolates at the nucleotide level. In relation to tobamo-H, 100% of identity with ToMV from tomatoes from Australia and Peru was found. Based on maximum likelihood (ML) analysis it was suggested that tobamo-H and tobamo-I share a common ancestor with ToMV, Tobacco mosaic virus, Odontoglossum ringspot virus and Pepper mild mottle virus. The tree topology reconstructed under ML methodology shows a monophyletic group, supported by 100% of bootstrap, consisting of various ToMV isolates from different hosts, including some ornamentals, from different geographical locations. The results indicate that Hemerocallis sp. and I. hawkeri are infected by ToMV. This is the first report of the occurrence of this virus in ornamental species in Brazil.

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.

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.

A new Potyvirus species in Cotyledon orbiculata in mixed infection with a Nucleorhabdovirus.

Several species and varieties of the family Crassulaceae have been introduced and cultivated for ornamental as well as medicinal purposes in Brazil, more prominently Cotyledon orbiculata (pig’s ear). This work reports the identification and characterization of viruses associated with foliar mosaic and distortion of C. orbiculata from the succulent plant collection of the garden of the University of Sao Paulo, Brazil. In situ analyses revealed enveloped bacilliform particles in the perinuclear space of infected C. orbiculata cells, and cytoplasmic cylindrical inclusions, typical of the family Potyviridae. Viruses were mechanically transmitted and separated by differential indicator hosts and aphid transmission (Myzus persicae). Chenopodium amaranticolor and Datura stramonium served as differential hosts for the potyvirus and the bacilliform virus, respectively. Positive serological reactions were obtained when leaf extracts from naturally infected C. orbiculata and experimental hosts were exposed to an antiserum to Sonchus yellow net virus (genus Nucleorhabdovirus). Identification of the potyvirus by RT-PCR, cloning into pGEM-T vector and sequencing generated a 1,752 nt fragment corresponding to part of the nuclear inclusion protein b (NIb), the complete coat protein (CP) and the untranslated region (UTR). Amino acid identities below 80% were observed, indicating that the potyvirus of C. orbiculata may be a new species for which the name Cotyledon virus Y (CotVY) is suggested.