A new tomato leaf curl virus from the Seychelles archipelago

Abstract

In July 2004, a survey of plants with virus disease symptoms wasconducted in the Seychelles archipelago on Mahe Island, located north ofMadagascar. A small number of leaf samples showing curling symptomswere collected from bean (Phaseolus vulgaris), pepper (Capsicumannuum) and tomato ( Lycopersicon esculentum ). Leaf extracts were testedfor the presence of begomoviruses by polymerase chain reaction (PCR),using two sets of degenerate primers designed to amplify portions of thecoat protein (CP) gene of the DNA A component. The first primer set(AV494 and AC1048) amplified the core region of the CP gene (approxi-mately 550 bp) (Wyatt & Brown, 1996). The second primer set (VD360and CD1266) amplified another fragment representing more than 90% ofthe CP gene (approximately 900 bp) (Delatte et al., 2005). No PCRproducts were obtained from pepper or bean leaf extracts. For two tomatosamples, PCR products of the expected size were obtained with both setsof primers. One product, obtained with the primer set VD360-CD1266(924 bp), was cloned and sequenced (EMBL accession No. AM259286).No PCR products were obtained using degenerate primers designed forbegomovirus DNA B or DNA β (Delatte et al., 2005). The most significantnucleotide sequence identities (NCBI BLASTn) were 88% with Tomatoleaf curl Mayotte virus from Dembeni (ToLCYTV-[Dem]; AJ865341) and83% with Pepper yellow vein virus from Mali (AY502935), Tomato leafcurl Madagascar virus isolates (AJ865339 and AJ865338) and a SouthAfrican cassava mosaic virus isolate (AF155806). Analysis (DNAMAN,Lynnon BioSoft) using the 522bp core CP sequences, previously used toprovide provisional identification of begomoviruses (Brown et al., 2001),showed between 88% and 89% nucleotide sequence identity withToLCYTV isolates (AJ865339 and AJ865340) and between 85 and 86%identity with Tomato yellow leaf curl virus isolates from Reunion Island(TYLCV-[RE], AM234066; and TYLCV-Mld[RE], AJ865337). Theseresults suggest the presence of a new tomato begomovirus in the Seychellesarchipelago; genetically related to the ToLCYTV isolates and so to theAfrican tomato monopartite begomoviruses previously identified inthe South West Islands of the Indian Ocean (Delatte et al., 2005). Thenew virus is tentatively named Tomato leaf curl Seychelles virus(ToLCSCV).AcknowledgementsThis study was initiated by the Regional Program of Plant Protection andfunded by the European Union and the Conseil Regional de La Reunion.ReferencesBrown JK, Idris AM, Torres-Jerez I, Banks GK, Wyatt SD, 2001. The core region of the coat protein gene is highly useful for establishing the provisional identification and classification of begomoviruses.