Epidemiological Studies of Begomoviruses in South Asian Region

Abstract

Begomoviruses belongs to group of plant viruses that possesses circular single stranded (ss) DNA genome(s) transmitted by Bemisia tabaci G. and only infects dicotyledonous plants. Begmomoviruses affects a significant number of economically valuable number of plants including vegetables, weeds and ornamental plants. Weeds and ornamental plants acts as alternate reservoirs for economically important Begomoviruses, as source of inoculum and recombination sites. In addition, Begomovirus sequences submitted before updated classification in databases creates gray areas. The goal of this study was to examine the demarcation of species, geographic spread over the years and to disclose the alternate hosts of Begomoviruses in South Asian countries. FASTA and GenBank sequences of the full-length genome of Begomovirus are accessible in the database, were extracted and the parameters - host range, year of collection and geographic distribution of Begomoviruses were tabulated. The sequences were aligned by muscle alignments and species were identified through species demarcation tool (SDT) and confirmed by sequence distance. Graphs were generated using MS Excel, while, Phylogenetic tree was constructed using MEGA X’s maximum likelihood. Till date 307 species of Begomoviruses are reported across the globe, among which 64 species and ~1917 isolates are present in South Asian countries. 28 species which possessed 1613 isolates are originated from Pakistan and infects different plant groups of Pakistan and and neighbor countries which are mentioned in Maqsood, (2019) thesis, remaining 252 isolates of 36 species are originated from other South Asian countries (India, Sri Lanka, Bangladesh, Bhutan, Maldives, Afghanistan, and Iran). Among the 36 species, the maximum number of alternate hosts are found to be of ToLCV (71), followed by SLCMV (20) and ToLCBaV (20) respectively. Number of isolates among 36 species were determined and renamed them, as, the number of species are increased because of previous classification; the number of virus isolates are sharing different species of viruses (ChiLCD, ToLCPatV and ToLCBV).Begomoviruses have widened their choice of host, and they do have multiple alternative hosts. A single specie has potential to affect members of several groups of plants. Moreover, single plant is also the host to many types of Begomoviruses. The number of isolates that demands renaming is increased, and they move from one country to another.