Viruses of the genus Mastrevirus (family Geminiviridae) are transmitted by leafhoppers to either monocotyledonous or dicotyledonous plants. They are native to the Old World and have been identified across Australia, Asia, Europe and Africa. Although a lot is known about the diversity of monocot-infecting mastreviruses, until recently little was known about the diversity of dicot-infecting mastreviruses. At the time of starting the studies described here a single dicot-infecting mastrevirus was known in Australia and a single mastrevirus had been identified in Pakistan and South Africa (although at the time the viruses in Pakistan and South Africa were considered separate species). During the time the study here was conducted our understanding of the diversity of dicot-infecting mastreviruses has increased exponentially, assisted in part by the study described here. The diversity of dicot-infecting mastreviruses in Pakistan was assessed by cloning and sequencing single-stranded DNA viruses occurring in chickpea and some other legumes which were collected from farms across the chickpea growing areas of Punjab province. A total of 20 full-length sequences were produced from either cloned virus genomes or reconstructed from next generation sequencing (NGS) reads. The majority of sequences were shown to be isolates of the species Chickpea chlorotic dwarf virus (CpCDV). Sequences produced as part of the study here contributed to the identification of three new strains of the virus - strains C, D and H. Additionally a chickpea sample from Syria was analyzed and the virus was cloned and sequenced. This sequence was shown to be an isolate of CpCDV strain A, which occurs across Iran and Turkey but not Pakistan. The clone of this virus was introduced back into plant by Agrobacterium-mediated inoculation to satisfy Koch’s postulates. Finally, in collaboration with researchers in New Zealand, a second species of dicot-infecting mastrevirus, for which the name Chickpea yellow dwarf virus has been proposed, was identified in Pakistan by NGS. Unusually this virus was shown to be more similar to dicot-mastreviruses from Australia than to CpCDV. This suggests that the diversity and host range of dicot-infecting mastreviruses may be greater than so far identified. Although previously reported to be a host of CpCDV, until the study presented here no conclusive proof that CpCDV infects lentil (Lens culinaris) was presented. Here the sequences of a total of 10 CpCDV isolates originating from lentil have been produced. However, NGS of samples from lentil identified plants containing a second geminivirus. Reconstruction of NGS reads showed the presence of the bipartite begomovirus Tomato leaf curl New Delhi virus (ToLCNDV). This was confirmed by PCR and by quantitative analysis of the titres of ToLCNDV and CpCDV in coinfected plants. This is the first identification of a begomovirus infecting lentil. However, the results suggest that ToLCNDV requires CpCDV to infect lentil - no lentil plants singly infected with ToLCNDV were identified. This also raises interesting questions about the transmission of CpCDV in co-infected plants. Three genes (replication associated protein A [Rep A], movement protein and coat protein) encoded by a dicot-infecting mastrevirus (CpCDV) and a monocotinfecting mastrevirus (Maize streak virus) were expressed from a Potato virus X vector in Nicotiana benthamiana. Overall the genes from CpCDV induced more severe symptoms than those of MSV, possibly due to this virus being adapted to dicotyledonous hosts. The Rep A proteins of both viruses were shown to induce necrosis, suggesting that they elicit a hypersensitive response due to interfering with the cell cycle. The significance of the results is discussed.