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Occurrence of Citrus leprosis virus in Llanos Orientales, Colombia

In Colombia, citrus is cultivated in mostly small plantings that total 55,000 ha by approximately 25,000 farmers. Production includes 1,200 tons of fresh fruits and 60 tons of juice for domestic consumption, resulting in a net worth of US$650,000 per year. Most of the production comes from areas located between the Cordillera Occidental and Cordillera Central mountain ranges (departments of Antioquia, Caldas, Quindio, and Risaralda) near coffee plantations. The departments of Meta and Casanare, located at the east plains (Llanos Orientales), include a zone parallel (4 to 5°N, 72 to 74°W) to the east mountain range and generate approximately 10% of the total Colombian citrus production. Suspected citrus leprosis symptoms on leaves and fruits of sweet oranges (Citrus sinensis (L.) Osb.) were first observed by plant pathologists for CORPOICA (Colombian National Agricultural Research Organization) in citrus orchards in Casanare in 2003, and later in 2004, in Meta. To confirm the visual identification, leaves and fruits from Valencia sweet orange exhibiting typical lesions of leprosis were collected from several locations in the departments of Casanare (Yopal, Aguazul) and Meta (Guamal, Villavicencio, and Cumaral). Samples were fixed in cacodylate-buffered paraformaldehyde/glutaraldehyde solution and subsequently processed for examination in thin sections using electron microscopy. Samples were processed and examined at the Citrus Research and Educational Center (CREC) of the University of Florida, Lake Alfred, and the Agricultural College (ESALQ) of the Universidade de São Paulo at Piracicaba, SP, Brazil. Some leaf samples collected in Meta were also dried and used for detection of Citrus leprosis virus, cytoplasmic type (CiLV-C) by reverse transcription-polymerase chain reaction (RT-PCR) at the Centro APTA Citros Sylvio Moreira at Cordeirópolis (CAPTACSM). The RT-PCR was performed with primers that specifically amplify a fragment of the viral genome that codes for the putative cell-to-cell movement protein (1). Locations at CREC and ESALQ each observed, using electron microscopy, cell changes characteristic of CiLV-C that include short bacilliform particles in the endoplasmic reticulum and dense, vacuolated, and irregularly shaped viroplasm in the cytoplasm (2) in samples from Casanare and Meta. RT-PCR amplified cDNA fragments of the expected size for samples collected in Meta and one of the amplicons was sequenced (GenBank Accession No. DQ272491). The sequence obtained was found to have 98% nucleotide sequence identity to the Brazilian CiLV-C isolate (GenBank Accession No. AY289190.1). Mites collected from affected plants from the department of Meta were identified at ESALQ as Brevipalpus phoenicis (Geijskes), a known principal vector of CiLV-C (2). These several lines of evidence confirmed that the symptoms observed in sweet oranges at Meta and Casanare are due to the infection by CiLV-C. To our knowledge, this is the first report of this virus in Colombia.

References:(1) E. C. Locali et al. Plant Dis. 87:1317, 2003, (2) J. C. V. Rodrigues et al. Exp. Appl. Acarol. 30:161, 2003.