RESUMEN
Brown Rot disease of potato is an important plant disease. It leads to significant decreases in potato yield in Egypt and other parts of the world. Therefore, the focus of this work aimed an analysis of the causal agent of this disease [Ralstonia solanacearum] and its phages [from the rhizosphere of potato plants in Egypt] that infect an avirulent strain of this bacterium. The approach taken was to use random amplified polymorphic DNAs [RAPD] by the polymerase chain reaction [PCR] technology. Five decamer oligonucleotide primers OP-Al3; OP-BO2, OP-Bo3, OP-Bo8 and OP-B09 were used in this study to differentiate between the two bacterial isolates virulent [WRCI] and avirulent [DRI] isolataes of R. solanacearum and three lytic phages growing on avirulent strains of this pathogen [RSP1, RSP2 and RSP3]. Statistical analysis of RAPD-PCR polymorphisms results revealed a degree of similarity with ratio of 92.7% between these bacterial isolates. In the case of phages, the statistical analysis of RAPD-PCR polymorphisms revealed a degree of similarities with ratio from 85.7% to 94.7. Therefore, the study paid an attention for the use of RAPD-PCR technology as a new molecular tool for identification and classification of the bacteria as well as the phages