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A Method for the Transfer of Tumorigenicity Between Strains of Agrobacterium tumefaciens in Carrot Root Disks. C. H. Liao, Research Associate, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403; G. T. Heberlein, Professor, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403. Phytopathology 68:135-137. Accepted for publication 19 July 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-135.

Surface-sterilized carrot root disks were inoculated concurrently with 0.1 ml each of a virulent (donor) and an avirulent (recipient) strain of Agrobacterium tumefaciens cultures (1.2 ×10⁹ colony-forming-units/ml). After 4-7 wk of contact between donor and recipient bacteria, two or three of 20 recipient colonies reisolated from tumor tissues became virulent. Transfer of tumorigenicity was not observed with recipient colonies reisolated from nontumor portions of tissue.