title: Molecular analysis of Cotton leaf curl virus-Sudan reveals an evolutionary history of recombination.
abstract: Monopartite begomoviral DNAs (2761 bp) were cloned and sequenced from field cotton, okra, and Sida alba, from Gezira, and field okra from Shambat. Comparison of the four apparent full-length begomoviral DNAs revealed 99.3-99.5% shared nucleotide (nt) identity, indicating that they are the same viral species, hereafter, referred to as Cotton leaf curl virus-Sudan (CLCuV-SD). Host range studies revealed that the field okra isolate of CLCuV-SD was whitefly-transmissible from okra to okra, M. parviflora, and hollyhock, but not to cotton. In contrast, the cotton isolate of CLCuV-SD infected cotton and hollyhock, but not okra. The genome of CLCuV-SD encodes six open reading frames (ORFs), and was most closely related to other monopartite begomoviruses of the Eastern Hemisphere. CLCuV-SD shared highest nucleotide sequence identity (95.5%) with Okra enation virus (OkEV), but was distantly related (approximately 74% nt sequence identity) to begomoviruses isolated from cotton in Pakistan. While extensive genomic regions of CLCuV-SD and OkEV are highly conserved (approximately 99% nt identity), nt sequence identity of the V1 ORF encoding the coat protein was uncharacteristically low (87.9%), suggesting a history of recombination. An analysis conducted with Sawyer's GENECONV program support the recombination hypothesis, indicating that the V1 ORF and a small segment of the intergenic region of CLCuV-SD and OkEV were derived from other begomoviruses. As a BLAST analysis failed to identify a prospective extant source of either V1 ORF, the parental viruses serving as CP donors remain undiscovered or are extinct.
authors.affiliation: Department of Plant Sciences, University of Arizona, Tucson 85721, USA.
authors.forename: Ali M
authors.initials: AM
authors.lastname: Idris
authors.forename: Judith K
authors.initials: JK
authors.lastname: Brown
mesh_terms: D019143:Evolution, Molecular; D017791:Geminiviridae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D016679:Genome, Viral; D003368:Gossypium / Q000821:virology*; D010802:Phylogeny; D011995:Recombination, Genetic