VIEW ARTICLE

Physiology and Biochemistry

Differences in Attachment of the Biotypes of Agrobacterium tumefaciens and A. rhizogenes to Carrot Suspension Culture Cells. Lisa Sykes, Undergraduate student, Department of Biology, University of North Carolina, Chapel Hill 27599-3280; Ann G. Matthysse, Associate professor, Department of Biology, University of North Carolina, Chapel Hill 27599-3280. Phytopathology 78:1322-1326. Accepted for publication 3 May 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1322.

Attachment of Agrobacterium tumefaciens to cells of plant hosts is one of the early steps in the bacterial induction of tumors. We compared the effects of alterations in the incubation medium on attachment to carrot cells of bacterial strains belonging to the three biotypes of A. tumefaciens and A. rhizogenes. Attachment of biotype 1 bacteria was not affected by the composition of the medium. Aggregation of carrot cells by biotype 1 bacteria also was insensitive to medium composition. Attachment of biotype 3 bacteria also was not affected by alterations in the medium. However, the ability of biotype 3 bacteria to aggregate carrot cells was inhibited by 0.25 M NaCl. Attachment of biotype 2 strains to carrot cells in 2 hr occurred only at ionic strengths less than 0.09 M. A small amount of binding of these strains to carrot cells in Murashige and Skoog medium was observed microscopically after 24 hr. Biotype 2 strains failed to aggregate carrot cells at ionic strengths of 0.09 M or more. The differences in binding among the biotypes appeared to be due to differences in chromosomal rather than plasmid genes.