Occurrence of Papaya ringspot virus Infecting Papaya in Ivory Coast

摘要

Papaya orchards located in different production areas in Ivory Coast as well as papaya plants growing in the district of Abidjan were surveyed in early February 2006. A wide range of leaf symptoms including mosaic, yellowing, chlorotic-line patterns,downward and upward curving of margins, and shoe-stringing was observed in the field. Ringspots were also observed on some stems and fruits. Sixty leaf samples of which fifty seven symptomatic samples were collected in the field for virus identification.In order to test for the presence of Papaya ringspot virus (PRSV) and Papaya mosaic virus (PapMV), the double antibody sandwich-enzyme linked immuno-sorbent assay (DAS-ELISA) was conducted using leaf extracts made from dried samples. None of the sampleswas positive for PaMV. Nine samples out of the 60 tested, coming from three locations, were positive for PRSV. Transmission electron microscope observation of leaf-dip preparation of the ELISA-positive samples revealed flexuous particles characteristicof potyviruses. To confirm the identity of PRSV, a 676 bp RNA fragment representing part of the coat protein gene with the 3'-untranslated region, was amplified by reverse transcription-polymerase chain reaction (RT-PCR) from one PRSV-positive sample (An1) using appropriate primers. The nucleotide sequence of the PCR product (Genbank Accession Number DQ84023) confirmed the taxonomy of the virus as being PRSV (Diallo et al. 2007). The PRSV Anyama isolate (Anl) of PRSV identified in this study shows 97 %identity with PRSV strain P (PAYP) (Genbank Accession Number D00595). There is a possibility of other papaya infecting viruses present in the country.