Natural Infection of Swinglea glutinosa by the Citrus leprosis virus Cytoplasmic Type (CiLV-C) in Colombia

Swinglea glutinosa (Blanco) Merr., a perennial plant in the family Rutaceae, is originally from southeast Asia but which is now grown worldwide. In Colombia, it is used as an ornamental and principally as a living fence around rural properties and farms in several regions of the country. Citrus leprosis virus cytoplasmic type (CiLV-C) was recently detected in orange groves of the Colombian Piedmont eastern plains, an area known as the Llanos Orientales (2). Because of the potential for country-wide infection of citrus, some measures are being taken to avoid CiLV-C spread to other regions of Colombia. Further surveys made from June to December 2005 to evaluate the extent of the spread of CiLV-C in the Llanos Orientales revealed some plants in S. glutinosa hedges surrounding citrus orchards exhibiting chlorotic spots and ringspots of varied size on the leaves, similar to those caused by CiLV-C on sweet oranges leaves. These plants were found near citrus orchards in the municipalities of Guamal and in some urban areas of Villavicencio City in the Meta Department. The possibility that these symptoms were caused by CiLV-C was investigated soon after sample collection by the same procedures as described previously for sweet orange (2). In the leaf lesions of S. glutinosa, typical bacilliform particles and dense cytoplasmic viroplasm were found with electron microscopy. Total RNA extracted from symptomatic leaves was subjected to reverse transcription-PCR (RT) using primers (Fwd. 5'GATACGGGACGCATAACA-3'/Rev. 5'-TTCTGGCTCAACATCTGG-3') that specifically amplify a region within the CiLV-C putative methyltransferase gene and this yielded a single fragment of the expected 402 bp (3). Analysis of the consensus sequence derived from 20 RT-PCR products (GenBank Accession No. EU689106) showed 96% nucleotide and 92% amino acid sequence identity to the sequence of a Brazilian CiLV-C isolate (GenBank Accession Nos. DQ352194.1 and YP_654565.1), respectively. Recently, published work described mite transmission of CiLV-C to some nonrutaceous plants (1), but to our knowledge, this is the first report of a nonCitrus rutaceous plant naturally infected by CiLV-C. Mites found in citrus orchards and previously identified as Brevipalpus phoenicis (Geijskes) (2), which are likely the most important vector of CiLV-C in citrus in Colombia, were observed feeding on healthy and symptomatic S. glutinosa, indicating that S. glutinosa is a host for B. phoenicis. Because the use of S. glutinosa as a living fence or hedge is a common practice in Colombia, CiLV-C-infected S. glutinosa plants may play a role in the epidemiology of leprosis in commercial citrus by serving as an inoculum source for this lethal virus. References: (1) M. Bastianel et al. Summa Phytopathol. 32:211, 2006. (2) G. A. León et al. Plant Dis. 90:682, 2006. (3) E. C. Locali et al. Plant Dis. 87:1317, 2003.