An annotated list of plant viruses described in Paraguay (1920-2023) / Una lista comentada de virus de plantas descritos en Paraguay (1920-2023)

Abstract Despite an economy based mostly on agriculture, literature on viral diseases of plants is scarce in Paraguay. Only recently, researches on plant viruses took an impulse resulting in a precise identification of many of them affecting plants either cultivated or not. To provide reliable information regarding plant viruses present in Paraguay, an annotated list of them was prepared, covering descriptions from 1920 to present day. There have been some important outbreaks with severe yield losses in crops as cucurbits, citrus, sesame, bean, maize, peanuts and tomato. Many of older descriptions are included for their historical significance, but most identifications made require confirmation. On the other hand, recent descriptions have been completed, based on several assays, especially molecular characterization. This list is organized alphabetically following scientific names of the plant species found naturally infected by viruses, with comments about symptoms, geographical distribution, incidence, identification procedures, and other information, with due literature references. It is based on a compilation of publications made on plant virus diseases in Paraguay. Described virus species, in a total of 38 recognized by ICTV, belonging to 17 different genera (Alphaendornavirus, Ampelovirus, Begomovirus, Benyvirus, Carlavirus, Cilevirus, Closterovirus, Comovirus, Cucumovirus, Dichorhavirus, Fabavirus, Luteovirus, Ophiovirus, Orthotospovirus, Potexvirus, Potyvirus and Tobamovirus), besides two unclassified, and four unidentified. There is also a case of viroid described in Citrus spp. Infections caused by potyviruses are the most numerous. These viruses were described in more than 40 plant species, belonging to 18 botanical families. Because of crop diversity and richness in native flora, many more viruses must be present in Paraguay, which future works will certainly reveal, especially with the increase in manpower involving researches, especially cooperative with foreign centers, on plant viruses, which has been very limited until now. Also, knowledge on existing viruses may have relevance in understanding their epidemiology and provide the basis for their control strategies and quarantine measures, to avoid new variants of existing viruses or new viruses being introduced.

Resumo A pesar de una economía basada principalmente en la agricultura, la literatura sobre enfermedades virales de las plantas es escasa en Paraguay. Sólo recientemente se han impulsado las investigaciones sobre los virus de plantas, lo que ha permitido identificar con precisión muchos de ellos que afectan a plantas cultivadas o no. Para brindar información confiable sobre los virus de plantas presentes en el Paraguay, se elaboró una lista comentada de los mismos, abarcando descripciones desde 1920 hasta la actualidad. Se han producido algunos focos importantes con severas pérdidas de rendimiento en cultivos de cucurbitáceas, cítricos, sésamo, frijol, maíz, maní y tomate. Muchas de las descripciones más antiguas se incluyen por su importancia histórica, pero la mayoría de las identificaciones realizadas requieren confirmación. Por otro lado, las descripciones recientes han sido completadas, basadas en varios ensayos, especialmente de caracterización molecular. Esta lista está organizada alfabéticamente siguiendo los nombres científicos de las especies de plantas que se encontraron naturalmente infectadas por virus, con comentarios sobre síntomas, distribución geográfica, incidencia, procedimientos de identificación y otras informaciones, con las debidas referencias bibliográficas. Se basa en una recopilación de publicaciones realizadas sobre enfermedades virales de plantas en Paraguay. Especies de virus descritas, en un total de 38 reconocidas por el ICTV, pertenecientes a 17 géneros diferentes (Alphaendornavirus, Ampelovirus, Begomovirus, Benyvirus, Carlavirus, Cilevirus, Closterovirus, Comovirus, Cucumovirus, Dichorhavirus, Fabavirus, Luteovirus, Ophiovirus, Orthotospovirus, Potexvirus, Potyvirus y Tobamovirus), además de dos sin clasificar y cuatro sin identificar. También existe un caso de un viroide descrito en Citrus spp. Las infecciones causadas por potyvirus son las más numerosas. Estos virus fueron descritos en más de 40 especies de plantas, pertenecientes a 18 familias botánicas. Debido a la diversidad de cultivos y la riqueza de la flora nativa, muchos más virus deben estar presentes en Paraguay, lo que seguramente revelarán trabajos futuros, especialmente con el aumento de la mano de obra involucrada en investigaciones, en cooperación con centros extranjeros, sobre virus de plantas, que ha sido muy limitada hasta el momento. Además, el conocimiento sobre los virus existentes puede ser relevante para comprender su epidemiología y proporcionar una base para sus estrategias de control y medidas de cuarentena, para evitar la introducción de nuevas variantes de virus existentes o nuevos virus.

Ocurrence of pepper yellow mosaic virus and cucumber mosaic virus on Capsicum chinense in the state of Amazonas, Brazil / Ocorrência do pepper yellow mosaic virus e cucumber mosaic virus em Capsicum chinense no estado do Amazonas, Brasil

The habanero chilli pepper, Capsicum chinense is an important crop in the Amazon Basin, mainly grown by small-scale producers. Capsicum chinense plants in an experimental field in the northern Brazilian state of Amazonas were found exhibiting characteristic symptoms of viral infection. Leaf sap from symptomatic plants examined under a transmission electron microscope revealed the presence of elongated flexuous particles and isometric particles. Using molecular assays, the viruses were identified as pepper yellow mosaic virus (PepYMV) and cucumber mosaic virus (CMV). Aphids, identified as Aphis gossypii, were found colonizing the C. chinense plants in the field and may be the vector for both PepYMV and CMV. We report the first occurrence of these viruses infecting C. chinense in the state of Amazonas.

A pimenta-de-cheiro, Capsicum chinense é uma cultura importante na Bacia Amazônica, cultivada principalmente por pequenos produtores. Plantas de C. chinense em um campo experimental localizado no norte do estado brasileiro do Amazonas, foram encontradas apresentando sintomas característicos de infecção viral. Extratos de amostras de folhas sintomáticas examinados ao microscópio eletrônico de transmissão revelaram a presença de partículas alongadas e flexuosas e de partículas isométricas. Análises moleculares permitiram identificar a presença do pepper yellow mosaic virus (PepYMV) e do cucumber mosaic virus (CMV). Pulgões, identificados como Aphis gossypii foram encontrados colonizando pimenteiras-de-cheiro neste campo experimental e podem representar o provável vetor de PepYMV e CMV. Este trabalho relata a primeira ocorrência desses vírus infectando C. chinense no estado do Amazonas.

Ocurrence of pepper yellow mosaic virus and cucumber mosaic virus on Capsicum chinense in the state of Amazonas, Brazil

The habanero chilli pepper, Capsicum chinense is an important crop in the Amazon Basin, mainly grown by small-scale producers. Capsicum chinense plants in an experimental field in the northern Brazilian state of Amazonas were found exhibiting characteristic symptoms of viral infection. Leaf sap from symptomatic plants examined under a transmission electron microscope revealed the presence of elongated flexuous particles and isometric particles. Using molecular assays, the viruses were identified as pepper yellow mosaic virus (PepYMV) and cucumber mosaic virus (CMV). Aphids, identified as Aphis gossypii, were found colonizing the C. chinense plants in the field and may be the vector for both PepYMV and CMV. We report the first occurrence of these viruses infecting C. chinense in the state of Amazonas. (AU)

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.

Ultrastructural observations on trypanosoma herpetosoma rangeli in the salivary glands of rhodnius ecuadoriensis, hemiptera, reduvidae

Fue realizado un estudio ultraestructural de las glándulas salivares del triatomino rhodnius ecuadoriensis experimentalmente infectado por el tripanosomatídeo, trypanosoma (herpetosoma) rangeli, con la finalidad de documentar los aspectos básicos de la infección glandular por este flagelado. Gran número de formas epimastigotes fueron encontradas en la hemolinfa que baña la parte externa de las glándulas en el hemoceloma. Algunos flagelados parecían intimamente asociados a la membrana basal del epitelio glandular y varios de ellos parecían estar iniciando el proceso de su invasión, rompiendo la lámina basal con el flagelo. En el interior de las células glandulares observamos que, T. rangeli se presentaba en la forma de esteromastigotes, células redondeadas rodeadas externamente por un flagelo, que envolvía apretadamente el parásito. En la luz glandular también observamos gran número de epimastigotes mezclados con los productos de la secreción glandular, el material presentó apenas pocas formas paramastigotes y trypomastigotes identificadas de manera inquívoca. El significado de los paramastigotes en el ciclo evolutivo del T. rangeli aguarda futuros estudios