First Report of Chrysanthemum stem necrosis virus on Russell Prairie Gentian in Brazil.

In November 2012, plants of Russell prairie gentian (Eustoma grandiflorum, Lisianthus russellianus) were collected from a commercial greenhouse in Atibaia, SP, Brazil, displaying necrotic spots on leaves and necrosis on stems, followed by generalized systemic necrosis. Disease symptom incidence was estimated at 10%. Preliminary electron microscopy observations of negatively stained leaf extracts prepared from those lesions revealed the presence of a large number of spherical tospovirus-like, approximately 100 nm in diameter. Samples of infected leaves were ground in 0.01 M phosphate buffer containing 0.5% sodium sulphide and mechanically inoculated in six plants of each species of Nicotiana glutinosa, N. tabacum cv. White Burley, N. megalosiphon, N. debneyii, Datura stramonium, Chenopodium amaranticolor, C. quinoa, and E. grandiflorum. All inoculated plants displayed local lesions 4 to 5 days after inoculation, while N. debneyii and D. stramonium showed systemic symptoms, typical of Tospovirus infection. In addition, E. grandiflorum reproduced the original symptoms. Total RNA was extracted from infected E. grandiflorum and D. stramonium, and reverse transcription (RT)-PCR was performed using universal primers BR60 and BR65 (2) targeting conserved regions of the nucleocapsid gene (N). The amplification products of approximately 450 bp were purified, cloned, and sequenced. The unknown virus was identified as Chrysanthemum stem necrosis virus (CSNV-Lis) based on host range and nucleotide sequence (Genbank Accession No. KC894721) and showed 99% identity with a CSNV chrysanthemum isolate from Japan (AB600872). Maximum likelihood phylogenetic analysis using nine homologous CSNV sequences available in GenBank classified CSNV-Lis into a monophyletic group formed by chrysanthemum isolates from Japan and China while a Japanese lisianthus isolate was separately clustered. CSNV is a member of the genus Tospovirus (Bunyaviridae) and was first reported on chrysanthemum in Brazil (1) and later in the Netherlands, Slovenia, United Kingdom, and Japan (3). Despite scattered recent reports of CSNV, the simultaneous production of chrysanthemum and lisianthus crops along the year by Brazilian farmers has contributed to the virus maintenance in the field. The high identity between Brazilian and Japanese isolates of CSNV suggest a possible reintroduction of the virus through exchange of vegetative propagating material. References: (1) L. M. L. Duarte et al. J. Phytopathol. 143:569, 1995. (2) M. Eiras et al. Fitopatol. Bras. 26:170, 2001. (3) K. Momonoi et al. J. Gen. Plant Pathol. 77:142, 2011.

First Report of Konjac mosaic virus in Zamioculcas zamiifolia.

Zamioculcas zamiifolia (Lodd.) Engl. ("Zanzibar Gem," "ZZ plant") is the monotypic species of the genus belonging to the family Araceae. It is a stemless perennial plant native to Africa, from Kenya to South Africa, that produces succulent rhizomes at the base of its attractive dark green and glossy foliage. Symptoms of mosaic and foliar distortion were observed on a plant purchased at an ornamental plants shop in São Paulo state, Brazil. In order to identify the causal agent, transmission and serological tests, as well as electron microscopy (EM) observations, reverse transcription (RT)-PCR, and sequencing were carried out. EM observations revealed the presence of elongated, flexuous viral particles in foliar extracts and cytoplasmic lamellar aggregates of type II lamellar inclusions (Edwardson's classification), in thin sections. No symptoms were induced following mechanical inoculation on Chenopodium amaranticolor, C. murale, Gomphrena globosa, Nicotiana megalosiphon, N. debneyii, nor on the aroids Philodendron scandens, P. selloum, Dieffenbachia amoena, Colocasia esculenta, and Z. zamiifolia. Up to 2 months after inoculation, plants were still symptomless, and the virus was not detected by RT-PCR. The indirect ELISA tests were negative with antisera against Dasheen mosaic virus (gift from F. W. Zettler, University of Florida) and Turnip mosaic virus (gift from P. Roggero, IFA, Turin, Italy). RT-PCR performed on the original purchased ornamental plant with potyvirus-specific primers (CI-R = ACICCRTTYTCDATDATRTTIGTIGC and CI-F = GGIVVIGTIGGIWSIGGIAARTCIAC) targeting the cytoplasmic inclusion protein cistron of the potyvirus genome produced a fragment of approximately 650 bp (GenBank Accession No. KC990386). The sequence was similar to those of potyvirus species with nucleotide identity, determined by PAUP v.4.0b10 for Macintosh, ranging from 64% for Pokeweed mosaic virus (JQ609065) to 93% for Konjac mosaic virus KoMV-F (NC007913). KoMV has been detected in aroid species in Taiwan, India, Korea, Japan (1,2), Germany, and The Netherlands (3,4). This is the first report of a viral disease on Z. zamiifolia and of KoMV in the Americas. Such information along with the vegetative propagation of ZZ plants strongly suggests that KoMV is spread worldwide. References: (1) P. Manikonda et al. J. Phytopathol. 159:133, 2011. (2) M. Nishiguchi et al. Arch Virol. 151:1643, 2006. (3) D.-E. Lesemann and S. Winter. Acta Hort. 568:135, 2002. (4) K. Pham et al. Acta Hort. 568:143, 2002.

First Report of a Tobamovirus in Dieffenbachia and Impatiens.

Tobamoviruses were detected in two ornamental plants, Dieffenbachia picta (Araceae) and Impatiens hawkeri (Balsaminaceae), from different counties in São Paulo State, Brazil. Symptoms were chlorotic spots and rings in D. picta and mosaic, blistering, and leaf deformation in I. hawkeri. Mechanical transmission from both species induced different kinds and intensities of symptoms in the same experimental hosts (Balsaminaceae, Chenopodiaceae, and Solanaceae), except Gomphrena globosa, which was infected only by the isolate from D. picta. The viruses did not infect Cucurbitaceae and Fabaceae. Indirect enzyme-linked immunosorbent assay performed with extracts from infected Nicotiana tabacum 'White Burley' and antisera against Cucumber green mottle, mosaic, Frangipani mosaic, Odontoglossum ringspot, Ribgrass mosaic, Tobacco mosaic (TMV), Tomato mosaic, Turnip vein clearing, and Youcai mosaic viruses (genus To-bamovirus) was positive only for TMV. Furthermore, the viruses isolated from D. picta and I. hawkeri cross-reacted with their heterologous antisera. Two sense primers for regions ≍200 and 90 nt upstream of the start codon and an antisense primer ≍60 nt downstream of the terminal codon of the coat protein (CP) gene were designed for two amplification assays. Migrating fragments the same size as the reverse-transcription polymerase chain reaction products from the TMV type strain (479 and 800 bp with internal and external primers, respectively) were produced. The CP gene sequence will allow comparison and identification of the two viruses isolated from D. picta and I. hawkeri.

Petunia vein banding virus: Characterization of a New Tymovirus from Petunia × hybrida.

Petunia plants from a nursery in the State of Rio Grande do Sul, Brazil, showed pronounced vein banding and contained isometric particles with diameters of approximately 45 and 30 nm. The larger ones apparently represent a caulimovirus, while the smaller ones, which included both empty shells and full particles, were identified as those of a new tymovirus for which we propose the name Petunia vein banding virus (PetVBV). Originally, PetVBV was transmitted only with difficulty to healthy petunia plants. However, from an experimentally infected petu-nia, it was later readily transmitted also to Nicotiana benthamiana and Nicandra physalodes, but not to other species in the Solanaceae or other plant families. It produces cytopathic effects typical for tymovirus infections. Its coat protein shows approximately 65% amino acid sequence identity with those of Eggplant mosaic and Andean potato latent viruses, to which it is also serologically more closely related than to any other tymoviruses.