First report of Tomato leaf curl Karnatka virus infecting soybean in India

During a survey in September 2005, a leaf crumple disease of soybean (Glycine max) was observed in Lucknow with a disease incidence of more than 80%. The diseased plants exhibited severe yellowing, crumpling and distortion of leaves. The infected plants remained dwarf with fewer flowers which resulted in a very low yield. The causal pathogen was suspected to be a begomovirus due to the large population of whitefly (Bemisia tabaci; the vector of begomoviruses) observed on the crop.

The presence of a begomovirus was detected by PCR using begomovirus coat protein gene-specific primers (Singh, 2005) and total DNA isolated from infected leaf tissues. An amplicon of the expected size (~800 bp) was obtained only from leaf samples with symptoms. The PCR product was cloned, sequenced and the 771 bp sequence data was submitted to Genbank (accession number DQ343284). Analysis of nucleotide sequence data by Blast search revealed the highest nucleotide sequence identity (96-98%) with Tomato leaf curl Karnataka virus (ToLCKV) [TLU38239, AJ810342, AY753203, AJ810370 and AJ810347]. These results indicated that the virus of soybean is an isolate of ToLCKV. Mungbean yellow mosaic India virus (Usahrani, et al., 2004) and Pepper golden mosaic virus (Mendez-Lozano et al., 2006) have been reported on soybean from India and Mexico respectively. However, ToLCKV infection of soybean in India has not been report previously.