A small DNA molecule containing covalently-linked ribonucleotides originates from the large intergenic region of the cauliflower mosaic virus genome

Abstract

We have detected a small DNA molecule (sa-DNA), 725 nucleotides long, in cauliflower mosaic virus (CaMV)-infected, but not non-infected, turnip leaves. Alkali and RNase A treatments shortened as-DNA by 100 nuleotides and we conclude that it contains covalently-linked ribonucleotides. This DNA co-purified with cellular polyadenylated RNA. It is complementary to the β-strand of CaMV DNA and of opposite polarity to RNAs transcribed from the α-strand. Hybridisation studies suggest that sa-DNA originates from the large intergenic region (IRI) of the CaMV genome. A small double-stranded DNA with three single-stranded components, which co-purifies with cellular DNA, appears to be related to sa-DNA but lacks detectable ribonucleotides.