Croton yellow vein mosaic virus (CYVMV) is a widely occurring begomovirus in Croton bonplandianum, a common weed in the Indian subcontinent. In this study, CYVMV (genus Begomovirus, family Geminiviridae) was transmitted by whiteflies (Bemisia tabaci) to as many as 35 plant species belonging to 11 families, including many vegetables, tobacco varieties, ornamentals and weeds. CYVMV produced bright yellow vein symptoms in croton, whereas in all the other host species, the virus produced leaf curl symptoms. CYVMV produced leaf curl in 13 tobacco species and 22 cultivars of Nicotiana tabacum and resembled tobacco leaf curl virus (TobLCV) in host reactions. However, CYVMV was distinguished from TobLCV in four differential hosts, Ageratum conyzoides, C. bonplandianum, Euphorbia geniculata and Sonchus bracyotis. The complete genome sequences of four isolates originating from northern, eastern and southern India revealed that a single species of DNA-A and a betasatellite, croton yellow vein mosaic betasatellite (CroYVMB) were associated with the yellow vein mosaic disease of croton. The sequence identity among the isolates of CYVMV DNA-A and CroYVMB occurring in diverse plant species was 91.8-97.9 % and 83.3-100 %, respectively. The CYVMV DNA-A and CroYVMB generated through rolling-circle amplification of the cloned DNAs produced typical symptoms of yellow vein mosaic and leaf curling in croton and tomato, respectively. The progeny virus from both the croton and tomato plants was transmitted successfully by B. tabaci. The present study establishes the etiology of yellow vein mosaic disease of C. bonplandianum and provides molecular evidence that a weed-infecting monopartite begomovirus causes leaf curl in tomato.

During 2006, pumpkin leaf curl-a new disease was observed in the experimental field at Indian Agricultural Research Institute. The disease was characterized by upward leaf curl with chlorotic patches and stunting of plant. Polymerase chain reaction (PCR) with coat protein specific primers to Tomato leaf curl New Delhi virus (ToLCNDV) indicated association of a begomovirus with the disease. The sequence comparison and phylogenetic analysis of the complete DNA genome further revealed the identity of the virus as ToLCNDV. The study provides evidence that ToLCNDV is associated with the leaf curl of pumpkin (Cucurbita moschata) in northern India.

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Availability of adequate quantity of purified virus preparation from plant tissue is the major limitation in producing polyclonal antibodies (PAb) to begomovirus. Very few examples show successful utilization of E. coli expressed recombinant coat protein (CP) for immuno diagnosis of begomoviruses. In the present study, *771 bp CP gene (*29.0 kDa) of Pumpkin yellow vein mosaic virus (PYVMV) was expressed as a *71.0 kDa fusion protein with maltose binding protein (MBP) (*42.0 kDa) in E. coli. The MBP-CP was obtained in soluble state. The PAb to the purified fusion protein successfully detected PYVMV and other bipartite and monopartite begomoviruses in the field samples at 1:250 dilution in enzyme linked immunosorbent assay. Our study for the first time showed that MBP-tag fusion CP was suitable to produce diagnostic antibody to begomoviruses. Keywords Pumpkin yellow vein mosaic virusBegomoviruses (family Geminiviridae) are emerging constrain in the production of numerous crops [14]. Both, immune-and nucleo-based techniques have been employed for the detection of begomoviruses [5]. Begomoviruses are phloem limiting, generally not sap transmissible and many of them do not have suitable propagative hosts. As a result, transmission and purification of begomoviruses are difficult and yield of purified virus is usually low. However, tedious method of virus propagation in large number of host plants through whitefly (Bemisia tabaci) inoculation and purification of virus from large batches of infected plant tissues were performed to produce polyclonal antibodies (PAb) against a few begomoviruses such as squash leaf curl virus (SLCV) [3], tomato yellow leaf curl virus (TYLCV) [9] and tomato leaf curl Bangalore virus (ToLCBaV) [4]. The traditional method of begomovirus antigen preparation from infected plant tissue generally results into contamination with host proteins and thus limits their use in serological diagnosis. Begomovirus purification by conventional method further limits the renewable production of PAb. As a result, routine detection and identification using serology has been less commonly used for begomoviruses compared to the other plant viruses. To overcome these limitations, molecular biology techniques are currently being used to express the viral genes of interest in E. coli and the recombinant antigen is used for the production of PAb. Recombinant antigens for several RNA plant viruses were successfully produced in E. coli [6,7,10], whereas, very few DNA plant viruses have been used for successful expression of recombinant antigen in E. coli [1].Pumpkin yellow vein mosaic virus, a bipartite begomovirus is known in India since 1950s [13] and the virus was characterized based on host range and serology [8]. Further, phylogenetic analysis of DNA-A sequence revealed that PYVMV was synonymous to squash leaf curl China virus (SLCCNV) reported from China [11,12]. There is an increasing incidence of PYVMV and many other begomoviruses in the Indian subcontinent [14], but PAb to begomoviruses for immunodia...