INDUCTION OF HAIRY AND NORMAL ROOTS ON PICEA-ABIES, PINUS-SYLVESTRIS AND PINUS-CORTORTA BY AGROBACTERIUM-RHIZOGENES

Two- to three-week-old seedlings of Picea abies, Pinus sylvestris and Pinus contorta were inoculated with the supervirulent strain Agrobacte rium rhizogenes R1600 2 cm above the base of the hypocotyl; other trea tments included inoculation with Agrobacterium tumefaciens strain A281 (pTVK291) or mock inoculation. Hairy or highly branched roots formed on 2-3% of seedlings of all 3 species that were infected by R1600 but on none of the other seedlings. Normal adventitious roots were also in duced on 5-10% of Agrobacterium-treated seedlings but none appeared on the other seedlings. Opine assays and growth rates of hairy and norma l roots indicated that only roots with the hair morphology were transf ormed.