First report of a begomovirus associated with leaf curl disease of bell pepper in Pakistan

Bell pepper (Capsicum annuum var. grossum; family Solanaceae) is a vegetable commonly cultivated in most of the vegetable growing areas of Pakistan. Leaf samples from three bell pepper plants showing leaf curl symptoms and from two apparently healthy (symptomless) plants were collected during a recent survey for begomoviruses, from the vegetable fields around the Lahore city. Overall the disease incidence was 60-70 % with severe leaf curl symptoms. DNA was extracted from both types of samples. 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 et al., 2005; 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 for the coat protein gene (approx. 750 bp) was produced from symptomatic samples but there was no amplification from the symptomless plants. The PCR product was cloned and sequenced. The sequences obtained from bell pepper (Accession No. AM051090) showed the highest levels of sequence identity to Tomato leaf curl New Delhi virus - [Pakistan:Solanum] (syn. Solanum yellow leaf curl virus) segment A (84% over a stretch of 656 nucleotides, Accession number AJ620187). Since the coat protein gene is the most conserved gene among whitefly-transmitted geminiviruses (Padidam et al., 1995), it is predicted that overall homology for the complete genome may be even less than 84%. These findings indicate that the virus of bell pepper is a new species of begomovirus for which we suggest the name Bell pepper leaf curl virus (BPLCV).

Recent reports have shown that many begomoviruses of the Old World are associated with a single-stranded DNA satellite (DNA β; Briddon et al., 2003). Attempts to identify the presence of a DNA β in the infected Capsicum annuum var. grossum samples, using universal DNA β primers (Briddon et al., 2002) produced a ca. 1.4 kb product, corresponding to that expected for a full-length amplicon from a satellite. This has not been sequenced but probably indicates that BPCLV is associated with a DNA satellite. To the best of our knowledge this the first report of a begomovirus associated with leaf curl disease of Capsicum annuum var. grossum.