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Genetics

Properties of F and P Group Plasmids in Erwinia stewartii. D. L. Coplin, Assistant Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster, OH 44691; Phytopathology 68:1637-1643. Accepted for publication 30 May 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1637.

The F group plasmids F’lac⁺ and R100drd56 and P group plasmids RP1, R68.45, RK212.1, and R751 were transferred into strains of Erwinia stewartii from Escherichia coli. All antibiotic resistance markers and the lac⁺ genes carried on these plasmids were expressed. The Lac⁺ transconjugants were generally unstable, insensitive to phage M13, and transferred F’lac⁺ at very low frequency, whereas several RP1 transconjugants were sensitive to phages PRR1 and PRD1 and could donate RP1 at frequencies between 2 × 10^–6 and 9 × 10^–4/donor cell. Donor ability correlated with sensitivity to PRR1 and PRD1, and RP1 was stable in all strains. The virulence of RP1-containing strains was essentially the same as that of their wild-type parents. Agarose gel electrophoresis of cleared lysates indicated that RP1 was present as an autonomous plasmid in E. stewartii. After transfer back to E. coli, RP1 and F’lac⁺ appeared unaltered by passage through E. stewartii.