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The complete DNA A genome of a virus isolate associated with yellow mosaic disease of a medicinal plant, Hemidesmus indicus, from India was cloned and sequenced. The length of DNA A was 2825 nucleotides, 35 nucleotides longer than the unit genome of monopartite begomoviruses. Comparison of the nucleotide sequence of DNA A of the virus isolate with those of other begomoviruses showed maximum sequence identity of 69 % to DNA A of ageratum yellow vein China virus (AYVCNV; AJ558120) and 68 % with tomato yellow leaf curl virus- LBa4 (TYLCV; EF185318), and it formed a distinct clade in phylogenetic analysis. The genome organization of the present virus isolate was found to be similar to that of Old World monopartite begomoviruses. The genome was considered to be monopartite, because association of DNA B and β satellite DNA components was not detected. Based on its sequence identity (<70 %) to all other begomoviruses known to date and ICTV (International Committee on Taxonomy of Viruses) species demarcating criteria (<89 % identity), it is considered a member of a novel begomovirus species, and the tentative name "Hemidesmus yellow mosaic virus" (HeYMV) is proposed.

Tomato leaf curl is a serious malady in the state of Maharashtra, India, causing nearly 100 % yield loss. An extensive survey was done in the affected fields of tomato in the year 2008, and members of three species of begomoviruses were identified as causing the disease. More than 60 % of the samples from diseased plants were infected with tomato leaf curl Gujarat virus (ToLCGuV). Isolates collected from these fields differed from the Varanasi isolate of ToLCGuV in not having a DNA B component. Instead, they were like typical Old World monopartite begomoviruses in that they were associated with only one betasatellite, tomato yellow leaf curl Thailand betasatellite (TYLCTHB). ToLCGuV alone is readily infectious, expressing systemic symptoms in Nicotiana benthamiana and tomato. Co-inoculation of ToLCGuV with TYLCTHB, increased symptom severity and reduced the incubation time required for symptom expression. ToLCGuV successfully interacted with heterologous DNA B component of ToLCNDV [IN:Pun:JID:08], and co-inoculation of these two resulted in yellow mottling symptoms that were typical of DNA B.

A begomovirus was isolated from tomato plants showing leaf curl and stunting symptoms in farmers' fields near the district of Kalyani, West Bengal, India. Viral genomic components amplified by rolling-circle amplification were cloned and sequenced. The genome organization of this virus was found to be similar to those of Old World monopartite begomovirus, with DNA A and a betasatellite component. Neither alphasatellite nor DNA B component was detected. The begomovirus showed highest sequence identity of 93.6% to tomato leaf curl Joydebpur virus (ToLCJoV-[IN:Kal:Chi:06]) and was thus identified to be an isolate of ToLCJoV. The betasatellite isolated from these samples was identified as tomato leaf curl Joydebpur betasatellite. ToLCJoV-[IN:Kal:Tom:08] alone induced severe symptoms in Solanum lycopersicum, N. benthamiana and N. glutinosa plants, and its severity was enhanced when co-inoculated with the cognate betasatellite. ToLCJoV-[IN:Kal:Tom:08] trans-replicated four more non-cognate betasatellites and induced severe symptoms in N. benthamiana and tomato. Since DNA A replicated efficiently and caused systemic symptom expression, it is hypothesized that ToLCJoV is essentially a monopartite virus, which could have acquired a betasatellite from an unknown source.