Abstract: A synthetic Bt (Bacillus thuringiensis) Cry1Ac gene was introduced into the genome of cut flower chrysanthemum (Chrysanthemum morifolium ) cultivar‘Japanese Yellow’in vitro with explants of internodal segmentsmediated by Agrobacterium tum efaciens. Results of PCR and Southern blot analysis indicated that Cry1Ac gene were integrated as one copy into the genome of chrysanthemum. Six transgenic lineswere obtained in total. Upon insect bioassay using Heliothis arm igera (Hubner) in the pot2culture and in petri dishes, two of the screened plants were demonstrated to be very highly resistant to the insect larvae, the corrected mortality of insect larvae was higher than 90% in five days. One individual line showed strong resistance,
the corrected mortality of insect larvae was higher than 80%. Three transformed lines showed relative strong resistance, the corrected mortality of insect larvae was ranged from 44.7% to 60.9%.

Key words: Chrysanthemum, Bt (Bacillus thuringensis), Cry1Ac gene, Insect-resistant, Transgenic plants, Heliothis armigera, Agrobacterium tumefaciens