The nucleotide sequence of abutilon mosaic virus reveals prokaryotic as well as eukaryotic features

The complete nucleotide sequence of abutilon mosaic virus (West Indian isolate, AbMVa) is presented. The resulting genomic structure resembles that of other geminiviruses which are transmitted by the whitefly Bemisia tabaci: AbMV possesses a bipartite circular genome with bidirectional orientation of the open reading frames (ORF). Both components have a common region of 180 bases with 99% homology while the rest of their sequence is distinct. Eukaryotic regulatory transcription elements precede most ORFs and polyadenylation signals are present at the end of most ORFs. However, two ORFs show features of prokaryotic genes. This chimaeric genome organisation is discussed with reference to the finding that AbMV DNA is present in plastids as well as in the nucleus of infected cells.