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

Abstract

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 (5μm 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.

Histopathology of black spot symptoms in sweet oranges

“…Hard spot lesions showed a pattern of lipid compound accumulation in the centres of the lesions and protein compound accumulation in the surrounding cells. This pattern has also been observed in citrus fruit with leprosis symptoms (Marques et al 2010).…”

Anatomia de lesões foliares causadas pelo vírus da Mancha Clorótica do Clerodendrum, transmitido pelo ácaro Brevipalpus phoenicis em diferentes espécies

“…Observa-se nas lesões cloróticas a ocorrência de hipertrofia nas células do parênquima lacunoso em regiões próximas onde ocorrem células plasmolisadas (Figura 2 D-E). Marques (20) descreveu em células infectados com CILV-N células do mesofilo plasmolisadas, além do aumento da espessura do limbo foliar devido a hipertrofia e a atividade hiperplásica das células do parênquima lacunoso. Em folhas infectadas por OFV e por SvRSV também observou-se a ocorrência de hipertrofia nas células do parênquima lacunoso.…”

“…Segundo Marques (19,20), a presença de células hipertrofiadas e em hiperplasia no halo intermediário das lesões causadas por CiLV-C ou CILV-N poderiam em conjunto com o halo necrótico promover uma barreira para que o vírus permanecesse confinado à lesão.…”

“…O objetivo deste trabalho foi verificar como os tecidos das diferentes plantas hospedeiras reagem à infecção pelo ClCSV a fim de complementar a caracterização deste vírus e comparar estas alterações histológicas com aquelas causadas por outros vírus transmitidas por Brevipalpus (2,7,16,19,20).…”

Citrus leprosis virus C Infection Results in Hypersensitive-Like Response, Suppression of the JA/ET Plant Defense Pathway and Promotion of the Colonization of Its Mite Vector

“…Induction of HR in cells of the vascular tissue of sweet orange leaves was previously proposed as the cause for the non-systemic spread of CiLV-C (Marques et al, 2007, 2010). In this regard, caution has to be taken to interpret these and our own results.…”