Abstract
Two filamentous phages of Xanthomonas campestris pv. oryzae, Xf and Xf2, are almost similar in DNA base composition. To investigate the degree of homology between Xf and Xf2 more in detail, the cleavage patterns of their replicative form DNA (RFI-DNA) treated with restriction endonucleases were compared by means of polyacrylamide gel electrophoresis. RFI-DNA was prepared by ethanol-precipitation method from the lysate of phage infected-bacteria. DNAs of Xf-RFI and Xf2-RFI thus obtained had infectivity to X. campestris pv. oryzae and their molecular weights were estimated at 4.5×106 and 4.7×106 daltons, respectively, from their relative mobilities. Both RFI-DNAs were treated with endo R. Hpa II, Hha I, Hind II, Hae III and Alu I to be subjected to the electrophoresis. Since most of the cleavage products of both RFI-DNAs showed remarkable difference in electrophoresis patterns, the phages Xf and Xf2 were considered to be heterogeneous.
