Identification of an Australian-like dicot-infecting mastrevirus in Pakistan.

Although members of five distinct viral species in the genus Mastrevirus (family Geminiviridae) infect dicotyledonous plants in Australia, in the remainder of the world, only a single dicot-infecting mastrevirus, chickpea chlorotic dwarf virus (CpCDV) has ever been identified. This virus has been found infecting leguminous hosts in Africa, the Middle East and the Indian subcontinent. To further explore the diversity of CpCDV in Pakistan, ten full mastrevirus genome sequences from chickpea and lentil plants were determined. Eight of these genomes were from previously described CpCDV strains and included the first reported strain D and H isolates in Pakistan. Two other genomes derived from infected chickpea plants are more closely related to dicot-infecting mastreviruses found in Australia than they are to CpCDV. These two divergent genomes shared less than 75 % genome-wide nucleotide sequence identity with other characterised mastreviruses and therefore are likely to belong to a second species of dicot-infecting mastreviruses outside of Australia. We propose naming this species Chickpea yellow dwarf virus. We discuss how the presence of chickpea yellow dwarf virus (CpYDV) in Pakistan weakens the hypothesis that Australia is the geographical origin of the dicot-infecting mastreviruses.

Analysis of the sequence of a dicot-infecting mastrevirus (family Geminiviridae) originating from Syria.

Chickpea stunt disease (CSD) across southern Asia, the Middle East and North Africa is caused by a number of viruses that include single-stranded DNA viruses of the genus Mastrevirus (family Geminiviridae). Despite the importance of CSD in reducing chickpea and lentil production, until recently little was known of the nature of the pathogens causing the disease. Sequence characterisation of virus isolates from Sudan and Pakistan showed the viruses concerned to potentially be new mastrevirus species related to Bean yellow dwarf virus (BeYDV), a virus known to occur in both southern Africa and southern Asia. Here we have determined the complete nucleotide sequence of a mastrevirus associated with CSD in Syria. This virus represents a proposed new species, closely related to the recently characterised Chickpea chlorotic dwarf Sudan virus and Chickpea chlorotic dwarf Pakistan virus but with the highest sequence identity to BeYDV, for which we propose the name Chickpea chlorotic dwarf Syria virus. In addition the biological integrity of the clone was confirmed by infection of Nicotiana benthamiana plants using Agrobacterium-mediated inoculation.