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Molecular characterization of a Begomovirus and Betasatellite infecting wild sunflower (Helianthus spp.) in India.

Wild sunflower (Helianthus spp.) plants exhibiting Begomovirus disease like symptoms: yellow vein net and leaf curl were observed growing in road side in Jaipur (Rajasthan), India. The causal virus was successfully transmitted on healthy seedlings of Helianthus spp. by whitefly (Bemisia tabacci) which induced similar symptoms to those of naturally infected plants that indicated presence of Begomovirus. The association of Begomovirus and betasatellite with these symptoms of Helianthus spp. was investigated by sequence analyses of viral DNA genome and satellite DNAs amplified by rolling circle amplification (RCA) and polymerase chain reaction (PCR), respectively. The highest sequence identities and closest phylogenetic relationships for the Begomovirus and betasatellite detected in Helianthus spp. were to Ageratum enation virus (AEV) and Ageratum leaf curl betasatellite (ALCB), respectively. These findings identified the virus and satellite DNAs infecting Helianthus spp. as AEV and ALCB, respectively. Helianthus spp. and Tobacco (Nicotiana glutinosa) seedlings infected with cloned AEV and ALCB by Agroinoculation developed yellow vein net and leaf curl symptoms, whereas plants infected with AEV alone or ALCB did not develop any symptom. The results show that this complex infects and causes disease in Helianthus spp. and Tobacco. Helianthus spp. is an invasive weed commonly found around agricultural fields and along roadsides in Rajasthan, India. These results also indicate that Helianthus spp. plants infected with AEV and associated betasatellite DNA may act as an alternate host (reservoir) for other economically important plants.

Author(s): Susheel Kumar, Meraj Jaidi, Raj SK