Abstract: The wounded cotyledon and hypocotyl explants from sunflower seedlings grown in vitro were soaked in suspension cultures of wild type strain B6S3 or T37 of A. tumefaciens which were at logarithmic growth phage. After 20-30 min the infected explants were transfered into MS medium lacking hormones and co-cultivated for three days at 25°C and weak light. The non-attached bacteria were then removed by washing the infected explants for 8-10 times. The selection for hormone-independent growth and elimination for the rest of the free bacteria were made in hormone-free medium supplemented with 500 mg/l carbenicillin. Transformed tumor tissues from infected both cotyledon and hypocotyl explants haev been induced by A. tumefaciens with the in vitro transformation system. Frequencies of transformation were ca. 60-96. Transformants were confirmed by their ability to proliferate tumor callus in hormone-free medium and to contain opine synthase activities in their tissues. In the process of subculture the isolated tumor tissues retained their growth trait of homone autonomy. In addition the growth rate of tumor tissues was much higher than that of normal callus cultures induced by hormones in hormone-free conditions.

Key words: In vitro transformation

摘要： 利用根癌农杆菌B6S3和T37菌株离体感染向日葵切伤的子叶、下胚轴外植体。感染处理的外植体与菌共培养三天后，在无激素条件下以60—96％的频率获得了离体转化的瘤组织。瘤组织在继代培养过程中具有激素自主性生长特性。在无激素培养基上瘤组织的生长速率显著高于正常愈伤组织。所有随机取样测定的瘤组织内均有相应冠瘿碱的存在。

关键词: 离体转化, T-DNA转移, 冠瘿碱合成酶, 激素自主性生长