Occurrence and detection of sweet potato virus disease (SPVD) in West Bengal

Abstract

The natural occurrence of sweet potato virus disease (SPVD) in 26 Indian sweet potato cultivars was evaluated at Horticultural Experimental Field of the B.C.K.V. University, West Bengal during 2004-2005 seasons based on the possible symptoms and serology. The leaves from virus suspected plants were indexed for viruses by nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) and coat protein study. Disease incidence was highest in Pol-4-9 during 2004 (12.87%) and 2005 (25.19%). Results were confirmed in several seropositive plants with higher incidence and diversity of viruses. Sweet potato feathery mottle virus (SPFMV), sweet potato cauliflower mosaic like virus (SPCaLV), Sweet potato mild speck virus (SPMSV) and C-6 virus were detected serologically in single or mixed infections in many leaf samples of the cultivars. The frequency of C-6 virus was very high (73.07%) followed by SPCaLV (34.61%), SPFMV (26.92%) and SPMSV (23.07%). Attempt was made to characterize the virus coat protein of the partially purified virus from the leaves with most frequently observed symptoms. Protein analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a major protein band of 65 kDa, and 38 kDa which were assumed to be the viral coat proteins of associated virus. Minor protein bands of 24 kDa were also observed. The viral protein degraded upon storage at 4°C over time to yield a protein band of 22 kDa.