First report of Tomato leaf curl New Delhi virus infecting chilli in India

Chilli (Capsicum annuum), a member of the family Solanaceae is an important spice crop cultivated in tropical and sub-tropical countries. The crop is severely affected by leaf curl disease in most of the chilli cultivating areas of India. Symptoms consisting of leaf curling, shortening of internodes and petioles, crowding of leaves and stunting of whole plant were observed in chilli fields around Lucknow. The disease was experimentally transmitted from infected to healthy chilli and tomato seedlings by the whitefly Bemisia tabaci. Inoculated chilli plants developed typical symptoms of the disease. However, the inoculated tomato plants developed severe leaf curl symptoms similar to those of leaf curl disease of tomato caused by Tomato leaf curl New Delhi virus (ToLCNDV).

To confirm the association of a begomovirus with the disease, polymerase chain reaction (PCR) was performed using the total DNA isolated from naturally infected chilli leaves and a set of primers designed to amplify the coat protein region of ToLCNDV (previously called Indian tomato leaf curl virus; Hallan, 1998). An amplification product of the expected size (~800 bp) was produced. The amplicon was cloned and sequenced (AY883570). A Blast search analysis of the nucleotide sequence showed 89-93% identity with various ToLCNDV isolates (X78956, AY428769, TLU15016 and AF448058). However, the isolate under study was found to be only distantly related to Pepper leaf curl Bangladesh virus (AF314531) and Chilli leaf curl virus-[Multan] (AF336806) to which it shows 86% and 81% identity, respectively.

Based on these findings the virus infecting chilli has been tentatively identified as an isolate of ToLCNDV. This is the first report of ToLCNDV affecting chilli crops in India. Taken together with the recent report of ToLCNDV affecting chilli cultivation in Pakistan (Hussain et al., 2004), this indicates that, on the Indian sub-continent, chilli is a major alternative host of ToLCNDV.