Symptoms, aetiology and serological analysis of sweet potato virus disease in Uganda |
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| Authors: | R W Gibson I Mpembe T Alicai E E Carey R O M Mwanga S E Seal & H J Vetten |
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| Institution: | NRI, University of Greenwich, Central Ave, Chatham Maritime, Kent ME4 4TB, UK,;Namulonge Agricultural and Animal Production Research Institute, PO Box 7084, Kampala, Uganda,;CIP, Regional Office for SubSaharan Africa, PO Box 25171, Nairobi, Kenya,;Department of Horticultural Science, Box 7609, North Carolina State University, Raleigh, NC 27695–7609, USA,;Institut für Biochemie und Pflanzenvirologie, Biologische Bundesanstalt für Land und Forstwirtschaft, Messeweg 11/12, 38104 Braunschweig, Germany |
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| Abstract: | Sweet potato virus disease (SPVD) is the name used to describe a range of severe symptoms in different cultivars of sweet potato, comprising overall plant stunting combined with leaf narrowing and distortion, and chlorosis, mosaic or vein-clearing. Affected plants of various cultivars were collected from several regions of Uganda. All samples contained the aphid-borne sweet potato feathery mottle potyvirus (SPFMV) and almost all contained the whitefly-borne sweet potato chlorotic stunt closterovirus (SPCSV). SPCSV was detected by a mix of monoclonal antibodies (MAb) previously shown to react only to a Kenyan isolate of SPCSV, but not by a mixture of MAb that detected SPCSV isolates from Nigeria and other countries. Sweet potato chlorotic fleck virus (SPCFV) and sweet potato mild mottle ipomovirus (SPMMV) were seldom detected in SPVD-affected plants, while sweet potato latent virus (SPLV) was never detected. Isolates of SPFMV and SPCSV obtained by insect transmissions together induced typical symptoms of SPVD when graft-inoculated to virus-free sweet potato. SPCSV alone caused stunting and either purpling or yellowing of middle and lower leaves when graft-inoculated to virus-free plants of two cultivars. Similarly diseased naturally inoculated field plants were shown consistently to contain SPCSV. Both this disease and SPVD spread rapidly in a sweet potato crop. |
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