Characterisation of caufiflower mosaic virus DNA forms isolated from infected turnip leaves

Abstract
Several different forms of cauliflower mosaic virus (CaMV) DNA were detected in nucleic acid preparations from CaMV–infected turnip leaves. As well as supercoiled and open–circular molecules, various linear DNA structures were identified. The relative amounts of these DNA forms varied in plants infected with different CaMV Isolates. Restriction enzyme mapping and one and twodimensional gel electrophoresis revealed the presence of linear molecules apparently formed by breaks in the second strand at each of the three discontinuities. Two major linear DNA forma are doublestranded over part of their length and appear to have singlestranded extensions of the strand of variable length. Since these DNA forms are not produced during extraction and probably exist as unencapsidated or partially encapsidated molecules, they may represent intermediates either in DNA replication or in virion assembly.