Induction of tumours by various strains of Agrobacterium tumefaciens on Abies nordmanniana and Picea abies

Abstract
Abies nordmanniana and Picea abies seedlings were inoculated with a wild‐type (C 58) or an attenuated strain (rooter or shooter mutants) of Agrobacterium tumefaciens. Large tumours were formed on A. nordmanniana in response to the wild‐type and rooter strains, 60–65 % of the seedlings being susceptible. Smaller tumours were formed on Picea abies in response to the wild‐type strain, at least 12% of the seedlings being susceptible. Tumours from both species induced by the wild‐type strain grew in vitro on medium without added phytohormones.