First report of Tomato leaf curl New Delhi virus infecting Eclipta prostrata in Pakistan

Eclipta prostrata (local name Daryai booti; family Compositae) is a common weed around water courses throughout the Indian sub-continent. This plant frequently shows yellow vein symptoms, which are characteristic of some begomoviruses. Previously, we have reported the association of a begomovirus (which we provisionally designated Eclipta prostrata yellow vein virus) with the disease, based on DNA hybridisation studies (Haider et al., 2003b), and its transmissibility by the whitefly vector of begomoviruses, Bemisia tabaci (Haider et al., 2003a). In this report, it is shown that this virus is a strain of Tomato leaf curl New Delhi virus.

Symptomatic and apparently healthy E. prostrata leaf samples were collected from Lahore (Punjab University Campus). Total DNA was extracted from both types of samples. The presence of a begomovirus was confirmed by PCR amplification using a pair of degenerate primers designed to conserved regions of the coat protein genes of 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 in PCR reactions containing DNA extracted from plants with symptoms but not from those without. The PCR product was cloned and sequenced in both orientations. The sequence of the virus obtained from E. prostrata (accession No. AJ889185) showed the highest levels of sequence identity (98%) to Tomato leaf curl New Delhi virus (ToLCNDV; accession No. U15015), indicating that the virus infecting this weed is a strain of ToLCNDV. Efforts are now underway to identify the second genomic component (DNA B) and to produce full-length clones of the virus. To the best of our knowledge this is the first report of ToLCNDV infecting E. prostrata.