부산대학교 도서관

THE gram-negative bacterium Agrobacterium tumefaciens induces crown gall tumours in many, mostly dicotyledonous, plants. Zaenen et al.1demonstrated the presence of one or more large plasmids in a number of crown gall-inducing Agrobacterium strains belonging to seven different Agrobacterium groups. They were not able to find such plasmids in eight non-pathogenic Agrobacterium strains belonging to four of the same groups2,3. They therefore formulated the hypothesis that the genetic information for the tumour-inducing principle4in crown gall-inducing Agrobacterium strains is carried by one or several large plasmids.