First report of Tomato leaf curl New Delhi virus infecting Bitter Gourd in Pakistan

Bitter Gourd (Momordica charantia; family Cucurbitaceae) is a vegetable cultivated in many areas of Pakistan. Plants showing yellow blotch symptoms were observed in several fields in the vicinity of Lahore, Pakistan, with an average incidence of 60-70%. Leaf samples were collected from 4 symptomatic and from 2 apparently healthy (symptomless) plants and used for DNA extraction.

The presence of a begomovirus was confirmed by PCR amplification using a degenerate primer pair, designed to conserved regions of the coat protein genes from published sequences of begomoviruses from the Old World (Haider, 1996; virion-sense primer 5'-ATG(C/A/T)(G/C) (G/C/A)AAGCG(A/T)(C/A)C(A/C)G(G/C)(A/C)GATAT-3'; complementary-sense primer 5'-TTAATT(T/G/C)(C/G/A)(A/T/C)(A/T/G)A(C/T)(A/T/C)(G/C)(C/A/T)(A/G)TCATA(G/A)AA(A/G)TA-3'). An amplification product of the expected size (approx. 750 bp) was produced from symptomatic samples but not from the symptomless plants. The PCR product was cloned and sequenced (Acc. No. AJ854186). The sequence showed the highest levels of sequence identity (95%) to Tomato leaf curl New Delhi virus (ToLCNDV; U15015), indicating that the virus of M. charantia is a strain of ToLCNDV.

Recent reports indicate that many Old World begomoviruses are associated with a single-stranded DNA satellite (DNA β; Briddon et al., 2003). Attempts to identify the presence of a DNA β in infected M. charantia using universal DNA β primers (Briddon et al., 2002) produced a 0.6 kb band that may be a defective DNA β. Efforts are now underway to sequence this and to produce full-length clone(s) of the virus. To the best of our knowledge this is the first report of ToLCNDV infecting M. charantia.