Complete nucleotide sequence and host range of South African cassava mosaic virus: further evidence for recombinations amongst begomoviruses

Complete nucleotide sequences of the DNA-A (2800 nt) and DNA-B (2760 nt) co mponents of a novel cassava-infecting begomovirus, South African cassava mo saic virus (SACMV), were determined and compared with various New World and Old World begomoviruses. SACMV is most closely related to East African cas sava mosaic virus (EACMV) in both its DNA-A (85% with EACMV-MH and -MK) and -B (90% with EACMV-UG2-Mld and EACMV-UG3-Svr) components; however, percent age sequence similarities of less than 90% in the DNA-A component allowed S ACMV to be considered a distinct virus. One significant recombination event spanning the entire AC4 open reading frame was identified; however, there was no evidence of recombination in the DNA-B component. Infectivity of the cloned SACMV genome was demonstrated by successful agroinoculation of cass ava and three other plant species (Phaseolus vulgaris, Malva parviflora and Nicotiana benthamiana). This is the first description of successful infect ion of cassava with a geminivirus using Agrobacterium tumefaciens.