VIEW ARTICLE

Genetics

Transmission of R Plasmids Among Xanthomonas spp. and Other Plant Pathogenic Bacteria. Mingtan Lai, Plant Pathologist, Laboratory Services, Division of Plant Industry, Department of Food and Agriculture, Sacramento, CA 95814; N. J. Panopoulos(2), and Steven Shaffer(3). (2)Department of Plant Pathology, University of California, Berkeley, CA 94720; (3)Technician, Laboratory Services, Division of Plant Industry, Department of Food and Agriculture, Sacramento, CA 95814. Phytopathology 67:1044-1050. Accepted for publication 4 January 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1044.

Plasmids RP4 and RK2 which specify resistance to carbenicillin, kanamycin, neomycin, and tetracycline were transmitted from Escherichia coli to Xanthomonas vesicatoria. Strains of X. vesicatoria that had acquired R plasmids were able to transmit them to other Xanthomonas spp., Pseudomonas phaseolicola, Erwinia chrysanthemi, and Agrobacterium tumefaciens, but not to Corynebacterium michiganense. The Xanthomonas plasmid transconjugants (ex-conjugants) exhibited multiple resistance to the above antibiotics and produced penicillinase. The stabilities of R plasmids in cells of xanthomonads differed with various cultures tested, ranging from 2 to 98% segregation during 10 days to 6 mo of storage. Different culture media affected frequencies of plasmid transfer. Acquisition of R plasmids had no effect on pathogenicity of X. vesicatoria transconjugants on tomato and pepper seedlings.