NUCLEOTIDE-SEQUENCES OF 2 CIRCULAR SINGLE-STRANDED DNAS ASSOCIATED WITH BANANA BUNCHY TOP VIRUS

Two circular single-stranded DNAs designated DNA I and II of the banan a bunchy top virus (BBTV) genome were cloned and sequenced. The sequen ce of BBTV DNA I consisted of 1,106 nucleotides and contained four ope n reading frames (ORFs) potentially encoding proteins with molecular m asses ranging from 5.4 to 33.18 kDa and one putative stem-loop structu re of 29 nucleotides. The sequence of BBTV DNA II had 1,096 nucleotide s and contained four ORFs encoding putative proteins with sizes rangin g from 5.6 to 32.77 kDa and one putative stem-loop structure of 32 nuc leotides. The largest ORF (V2) in DNA II encoded a putative replicase with the nucleotide triphosphate-binding motif (GGEGKS). DNAs I and II had a 54.3% identity in total sequence and two conserved regions with more than 80% sequence identity. The two BBTV DNA sequences showed no close relationship with geminivirus DNA sequences but some similarity with the coconut foliar decay virus (CFDV) DNA sequence (about 39% id entity). DNAs I and II showed considerable similarity with BBTV compon ent 1, with 50.3 and 52.9% identity, respectively. The loop sequences of putative stem-loop structures in both BBTV DNAs were highly homolog ous and also had considerable similarity with those of geminivirus, CF DV DNAs, and BBTV component 1.