Partial characterization of a Potyvirus causing mosaic and flower variegation in Catharanthus roseus

A vinca (Catharanthus roseus) é uma planta perene, arbustiva, pertencente à família Apocinaceae, cujas folhas e raízes possuem propriedades medicinais. A presença de sintoma de mosaico e deformação foliar em plantas dessa espécie, associados com a presença de partículas alongadas e flexuosas, característica de vírus pertencentes ao gênero Potyvirus, conduziu a estudos complementares para a identificação e caracterização desse vírus. No estudo da gama parcial de hospedeiras foram testadas 28 espécies, envolvendo oito famílias botânicas. Catharanthus roseus e Nicotiana benthamiana apresentaram sintomas de mosaico foliar e Chenopodium amaranticolor e C. quinoa apresentaram lesões locais cloróticas nas folhas inoculadas. A transmissão do vírus com afídeos foi avaliada com as espécies Aphis gossypii, Myzus nicotianae e Toxoptera citricidus. Apenas Aphis gossypii e Myzus nicotianae transmitiram o vírus. O antissoro policlonal produzido contra este potyvirus reagiu com o vírus homólogo e com o Passionfruit woodiness virus (PWV) e Cowpea aphid-borne mosaic virus (CABMV), mas não com o Lettuce mosaic virus (LMV), Papaya ringspot virus - type W (PRSV-W), Potato virus Y (PVY) e Zucchini yellow mosaic virus (ZYMV). O peso molecular da proteína capsidial (CP) foi de aproximadamente 34 kDa. A reação de PCR realizada com os oligonucleotídeos universais de potyvirus e oligonucleotídeos específicos posteriomente confeccionados amplificaram três fragmentos de aproximadamente 0,8, 1,0 e 1,4 Kb, os quais após o seqüênciamento geraram um fragmento de 1654 nucleotídeos (nt) da região 3' terminal do genoma, que inclui parte do gene da replicase viral (Nib), a região codificadora completa do gene da proteína capsidial (CP), seguida de 286 nt da região 3' não traduzida (3'NTR). A identidade da seqüência de nucleotídeos do gene da CP variou de 67,0 a 76,0%, quando comparada com as de outros membros da família Potyviridae. A maior identidade foi com o Omphalodes virus Y (76,0%). A identidade dos aminoácidos deduzidos da proteína capsidial variou de 62,0 a 71,0%, sendo a maior com East Asian Passiflora virus (71%). Para a região não traduzida (3'NTR) a identidade variou de 16,8 a 28,6%. Em conjunto esses dados indicam que este vírus é uma nova espécie dentro do gênero Potyvirus, para o qual se propõe o nome de Vírus do mosaico do Catharanthus (Catharanthus mosaic virus - CatMV).Catharanthus roseus is known as the common periwinkle or Madagascar periwinkle. It is a perennial, evergreen herb in the family Apocynaceae, which was originally native to the island of Madagascar, although both name and classification are contradictory in some literature. The plants grow up to 80 cm high; have glossy, dark green leaves and bloom during summer. The flowers range from white to hot pink to purple. The species has historically been used in popular medicine to treat a wide assortment of human diseases, as it contains more than 150 useful alkaloids. Plants of C. roseus exhibiting mosaic symptoms followed by malformation of the leaf blades and flower variegation were collected from a garden at the University of São Paulo, School of Agriculture (Piracicaba, State of São Paulo, Brazil). Preliminary electron microscopy exams of negatively stained leaf sap revealed that the symptoms were associated with potyvirus-like particles. The objective of the present work was to obtain further biological, immunological and molecular data to better characterize this species of the genus Potyvirus, family Potyviridae. Of 28 plant species from eight botanical families inoculated mechanically with this potyvirus, only C. roseus and Nicotiana benthamiana developed systemic mosaic, whereas Chenopodium amaranticolor and C. quinoa exhibited only chlorotic local lesions. The virus was transmitted by Aphis gossypii and Myzus nicotianae, but not by Toxoptera citricidus. Polyclonal antiserum raised against this potyvirus reacted with the homologous virus, Passion fruit woodiness virus (PWV) and Cowpea aphid borne mosaic virus (CABMV) in PTA-ELISA. The molecular mass of the coat protein (CP) was approximately 34 kDa. RT-PCR from viral RNA amplified a fragment of approximately 1654 nucleotides (nt) at the 3'-terminal of the viral genome, containing portion of the replicase gene (Nib), the entire CP gene and the 3' untranslated region (3'UTR) (286 nt). When the nucleotide sequence of the CP gene was compared with other members of the Potyviridae family, identities varied from 67.0 to 76.0%. The highest identity was with Omphalodes virus Y. Identity of the deduced amino acid of the CP varied from 62.0 to 71.0%, with the highest for East Asian Passiflora virus. For the 3' UTR, identities varied from 16.8 to 28.6%. The name Catharanthus mosaic virus (CatMV) is proposed for this new potyvirus