Abstract: The transgenic hairy roots were formed on cut leaves of chrysanthemum plantlet by Agrobacterium rhizogenes K599 with frequencies of 88.0%. The calli were induced from hairy roots and plantlets were regenerated from calli at rates of 75.0% and 63.3% respectively. The transgenic hairy roots and plantlet were confirmed by PCR analysis with primers from K599 Ri plasmid rolC gene. Quantitative RT-PCR（qRT-PCR）analysis showed that rolC gene was normally expressed in the regenerated transgenic plants. Regenerated plants harbored a character of dwarf，more hairy roots and flowering normally. Organism in vivo directly as a receptor for infection by Agrobacterium rhizogenes K599，it overcame the emergence of false-positive transgenic hairy roots. In addition，using the process of hairy roots propagation characteristics of the top growing point region sterile and the interception of adventitious roots near the growing point to the top for subculture，combined with cefotaxime sterilization，it can inhibit and kill the Agrobacterium effectively. In the subsequent callus induction and redifferentiation from hairy roots，it is no antibiotics added to medium for killing Agrobacterium. It genetically enhanced efficiency of plant regeneration.The transgenic hairy roots were induced by Agrobacterium rhizogenes K599 in chrysanthemum in vivo and plant regenerated from hairy roots highly efficiently in the study. It is useful to dwarf breeding and the target gene transformation of chrysanthemum.

Key words: chrysanthemum, Agrobacterium rhizogenes, hairy root, induction, regeneration