Structure of the cauliflower mosaic virus genome II. Variation in DNA structure and sequence between isolates

Abstract

The DNA genomes of four different cauliflower mosaic virus (CaMV) isolates (Cabbage B-Davis, Cabbage B-John Innes, CM4–184, and Australian) have been mapped using the restriction endonucleases, EcoRI, SalGI and BamHI, and S 1 nuclease. The differences between maps of the isolates indicate that one region of the CaMV genome is subject to considerable change while the rest is more highly conserved. EcoRI digestion patterns of the DNA from five other CaMV isolates correspond to two of the described isolates, Cabbage B-Davis and Cabbage B-John Innes. Minor DNA fragments (in less than molar amounts) appearing in restriction patterns of CaMV DNAs could be attributed to: (i) the presence of linear DNA molecules which appear to arise by double-strand breaks at specific points in the circular genome, (ii) heterogeneity within some of the viral ioslates, indicated by the appearance of a faint, underlying DNA restriction pattern characteristic of another isolate type, and (iii) the occurrence of a few “difficult” restriction sites in the genomes of some isolates.