Comparative morpho-anatomical studies of the lesions caused by citrus leprosis virus on sweet orange

The leprosis disease shows a viral etiology and the citrus leprosis virus is considered its etiologic agent. The disease may show two types of cytopatologic symptom caused by two virus: nuclear (CiLV-N) and cytoplasmic (CiLV-C) types. The aim of this study was to compare the morpho-anatomical differences in the lesions caused by leprosis virus-cytoplasmic and nuclear types in Citrus sinensis (L.) Osbeck 'Pêra'. Leaf and fruit lesions were collected in Piracicaba/São Paulo (cytoplasmic type) and Monte Alegre do Sul/São Paulo and Amparo/São Paulo (nuclear type). The lesions were photographed and then fixed in Karnovsky solution, dehydrated in a graded ethylic series, embedded in hydroxy-ethyl methacrylate resin (Leica Historesin), sectioned (5 μm thick), stained and mounted in synthetic resin. The digital images were acquired in a microscope with digital video camera. Leaf and fruit lesions caused by the two viruses were morphologically distinct. Only the lesion caused by CiLV-N virus presented three well-defined regions. In both lesions there was the accumulation of lipidic substances in necrotic areas that were surrounded by cells with amorphous or droplets protein. Only leaf and fruit lesions caused by CiLV-N virus exhibited traumatic gum ducts in the vascular bundles.

A doença leprose dos citros tem etiologia viral sendo o citrus leprosis virus seu agente etiológico. Demonstrou-se que há dois vírus distintos que causam sintomas de leprose em ci-tros: citoplasmático (CiLV-C) e o nuclear (CiLV-N). O objetivo desse estudo foi comparar as diferenças morfo-anatômicas nas lesões causadas por CiLV-C e por CiLV-N em laranjeira doce (Citrus sinensis (L.) Osbeck) 'Pêra'. As lesões foliares e dos frutos foram coletadas em Piracicaba/SP (tipo citoplas-mático) e em Monte Alegre do Sul/SP e Amparo/SP (tipo nuclear). As lesões foram fotografadas e em seguida fixadas em solução Karnovsky, desidratadas em série etílica, incluídas em historesina e secionadas em micrótomo rotativo. As lâminas foram coradas, analisadas e fotografadas. As lesões foliares e do fruto causadas pelos dois vírus eram morfologicamente distintas. Somente a lesão causada por CiLV-N apresentou três regiões bem definidas. Em ambas as lesões ocorreu acúmulo de substâncias lipídicas nas áreas necrosadas que se achavam envoltas por células com conteúdo protéico amorfo ou em gotas. Somente as lesões da folha e do fruto causadas pelo CiLV-N exibiram ductos traumáticos gomosos nos feixes vasculares.

Incidencia y distribución altitudinal de 13 virus en cultivos de solanum tuberosum (solanaceae) en Costa Rica / Incidence and altitudinal distribution of 13 virus cultures in Solanum tuberosum (Solanaceae) from Costa Rica

A survey was conducted in 30 fields located at three different altitudes in Cartago, Costa Rica's main potato producing area. Twenty plants were sampled per farm, for a total of 600 samples with 200 samples per altitude. ELISA was used with commercial reagents to independently test for PVX, PVY, PVM, PVA, PVS, PLRV, PMTV, PAMV, PVV, PVT, APLV, APMoV and TRSV. The presence of the following viruses was determined: PVX (77 %), PAMV (62 %), PLRV (42 %), TRSV (42 %), PVT (39 %), PVV (37 %), PMTV (31%), PVY (30 %), PVS (19 %), PVM (13 %), PVA (8 %), and APMoV (8%). APLV was not detected in any sample. This is the first report in Costa Rica of the presence of the viruses PMTV, PAMV, PVV, PVT and APMoV. A high viral incidence in the tuber seed production area as well as a high rate of mixed infections is reported.

En Cartago, la zona productora de papa más importante de Costa Rica, se realizó un muestreo en 30 fincas ubicadas a tres altitudes. Se recolectaron 20 plantas por finca y 200 muestras por altitud. Todas las muestras se analizaron independientemente mediante ELISA, para PVX, PVY, PVM, PVA, PVS, PLRV, PMTV, PAMV, PVV, PVT, APLV, APMoV y TRSV, utilizando reactivos comerciales. Se identificó la presencia de PVX (77 %), PAMV (62 %), PLRV (42 %), TRSV (42 %), PVT (39 %), PVV (37 %), PMTV (31 %), PVY (30 %), PVS (19 %), PVM (13 %), PVA (8 %), y APMoV (8 %). No se detectó APLV en ninguna de las muestras analizadas. Se informan por primera vez la presencia en Costa Rica de los virus PMTV, PAMV, PVV, PVT y APMoV. Se informa la alta incidencia viral en la zona dedicada a la producción de tubérculos como semilla y la alta tasa de infecciones mixtas.