Specific nucleic acids in host plant infected by Indian cassava mosaic geminivirus

J.Rovinson B.D.Harrison(Scottish Crop research Institute, Dundee,DD2 5DS,U.K.)Nucleic acids extracted from Indian cassava mosaic geminivirus infected plant leaves(Nicotiana ben thamiana)and further purified through 1.0% LMT agarose gel electrophoresis were treated with RNA ase,DNAase,Nuclease Sl,Exonuclease Ⅲ and restriction endonuclease EcoR I.Two kinds ofvirus-specific DNA existed in infected plants as shown by Southern and Dot blotting using virus ssDNAprobes synthesized by nick translation,These two DNAs were circu lar double stranded and singlestranded DNA(dsDNA and ssDNA)respectively.The dsDNA was in the form of open circular and covalently closed circular molecules(ee and ccc dsDNA).Both oc and ccc dsDNA were digested byEcoR I to produce lincar molecules of abeut 2.7 kb,The virus genome contained two components(DNA1 and DNA2)Furthermore,the circular viral ssDNA in plants was largely the miunus strandednot the plus stranded ssDNA reported from particles,This may be an important clue to the understandin