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 (5 microm 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.
Highlights
IntroductionAccording to Bastianel et al (2006), electron microscopic studies supported by molecular analyses re-
Citrus leprosis is a viral disease of significant economic relevance due to the economic losses it causes, in some cases leading to plant weakening, premature fruit drop and, when the plant presents intense infection, the disease can lead to the plant death (Bitancourt 1955, Rodrigues et al 2003b).According to Bastianel et al (2006), electron microscopic studies supported by molecular analyses re-an electron-dense and vacuolated mass, appears within the cytoplasm.CiLV-C is widespread and prevails in most samples assessed in Brazil, Argentina, Costa Rica, Panama, Colombia, Bolivia and Guatemala, while CiLVN is rarely found and seems to occur associated with lower temperatures
It has been noticed that lesions caused by CiLV-C and CiLV-N in sweet orange (Citrus sinensis (L.) Osbeck) leaves, though similar, present subtle differences. Those induced by CiLV-C tend to grow larger, usually with a pale green color, and show one or more concentric brownish rings containing gum material, while lesions caused by CiLV-N tend to be smaller, with a dark necrotic center and a chlorotic halo (Bastianel et al 2006). In this communication we report the morpho-anatomical changes in the leaf and fruit lesions caused by CiLV-N and by CiLV-C from the field, and discuss the results comparing these changes with the alterations observed previously with CiLV-C (Marques et al 2007)
Summary
According to Bastianel et al (2006), electron microscopic studies supported by molecular analyses re-. CiLV-C is widespread and prevails in most samples assessed in Brazil, Argentina, Costa Rica, Panama, Colombia, Bolivia and Guatemala, while CiLVN is rarely found and seems to occur associated with lower temperatures. It was found in Panama and in some cities of the state of São Paulo (Amparo, Monte Alegre do Sul, Santo Antonio da Posse, Serra Negra and São Roque), Rio Grande do Sul, (Marquês de Souza) and Minas Gerais (Andradas) (Kitajima et al 2004, Freitas-Astúa et al 2004, Chagas et al 2006). From the morphologic and cytopathologic viewpoints, the CiLV-N is similar to Orchid fleck virus (OFV) and may belong to the recently proposed genus Dichorhabdovirus, within the family Rhabdoviridae for OFV (Kondo et al 2006)
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