Biological and molecular characterization of begomovirus and its DNA satellites associated with leaf curl disease of zinnia in India

Zinnia ( Zinnia elegans L.) is one of the important ornamental crops grown in gardens and is affected by number of diseases. Of these, leaf curl disease caused by begomovirus is one of the major limiting factors for its cultivation in the country. Survey data revealed that the incidence of zinnia leaf curl disease (ZiLCD) ranged from 4.44 to 68.96% in different horticultural nurseries and gardens located in Bengaluru and Kodagu districts of Karnataka State of India. Samples of naturally infected zinnia plants exhibiting symptoms of vein thickening, curling and reduction in leaf size, typical of begomovirus infection were collected from Bengaluru and Kodagu and designated as ZN-BLR and ZN-KOD, respectively. The virus was transmitted to healthy zinnia by whitefly, Bemisia tabaci (Asian-I group). The presence of begomovirus in zinnia samples was confirmed through polymerase chain reaction assay using begomovirus specific primers. Complete DNA A nucleotide sequence of virus isolates was amplified by rolling cycle amplification. Nucleotide sequence and phylogenetic analysis indicated that two isolates (ZNKOD, ZN-BLR) associated with zinnia belong to the tomato leaf curl Karnataka virus (ToLCKV). Further, DNA betasatellites (ZNβ-KOD and ZNβ-BLR) and alphasatellites associated with the virus were cloned and sequenced. The betasatellites shared the maximum nt identity (95.4 and 97.1%) with papaya leaf curl betasatellite (PaLCuB) and tomato leaf curl Bangladesh betasatellite (ToLCBDB) and alphasatellites shared maximum nt identity with ageratum enation alphasatellite (AEA) and parthenium leaf curl alphasatellite (ParLCuA) molecules. The recombination breakpoint analysis showed that the begomovirus and DNA satellites are recombinants. This is the first report of ZiLCD associated with ToLCKV along with alpha and betasatellites from India.