Partial characterization and identification of a virus associated with stunt disease of black pepper (Piper nigrum) in South India

A virus associated with stunt disease of black pepper (Piper nigrum) in South India was purified and partially characterized. The virus was transmitted through stem cuttings of black pepper and by grafting. It was also sap-transmitted with difficulty from black pepper to black pepper and to a few experimental plants. Chenopodium amaranticolor, C. quinoa, Vigna unguiculata, V. radiata and V. mungo reacted with local chlorotic/necrotic lesions. Cucumis sativus and five tested solanaceous plants reacted with systemic mosaic symptoms. The leaf extract of diseased black pepper or virus purified from diseased black pepper leaves in direct antigen coating-ELISA and electroblot immunoassay tests reacted positively with polyclonal antisera of cucumber mosaic cucumovirus (CMV)-Banana (India), CMV-Brinjal (India), CMV-Chilli (India), CMV-Tomato (India), CMV-L (USA) and CMV-A (China). The negatively stained purified virus preparation contained non-enveloped isometric virions. The Mr of double-stranded (ds) RNAs isolated from infected black pepper leaves was 2.42, 2.20 and 1.62 × 106 Da. The coat protein of disrupted purified virions in 12% SDS-PAGE was resolved into one major polypeptide with Mr 26.1 kDa and of nucleic acid in 1% agarose gel resolved into four species with Mr 1.21, 1.10, 0.81 and 0.37 × 106 Da. Particle morphology, antigenic relationships with CMV, coat protein and genome characteristics suggest that the virus associated with stunt disease of black pepper in the state of Kerala, South India could be an isolate of CMV.