Haring M A, Teeuwen-de Vroomen M J, Nijkamp H J, Hille J
Free University, Dept. of Genetics, Amsterdam, Netherlands.
Plant Mol Biol. 1991 Jan;16(1):39-47. doi: 10.1007/BF00017915.
In Antirrhinum majus only autonomous Tam3 transposons have been characterized. We investigated whether an artificial dTam3 element, with a deletion in the presumptive transposase coding region, can be trans-activated in tobacco by an activator Tam3 element, which was immobilized by the deletion of one inverted repeat. A phenotypic assay based on restored hygromycin resistance demonstrates that a dTam3 element harbouring a bacterial plasmid can be trans-activated with a low frequency. Molecular analysis confirms that the dTam3 element has been excised from the HPTII marker gene. Reintegration of the dTam3 element into the tobacco genome is detected only in one out of six hygromycin-resistant plants analysed. PCR analysis of empty donor sites shows that excision of the dTam3 element in tobacco results in rearrangements (deletions and additions), that have been shown to be characteristic of Tam3 excision in the original host Antirrhinum majus. This trans-activation assay allowed us to establish that, in contrast to what has been detected in Antirrhinum majus, a periodical temperature shift down to 15 degrees C does not enhance dTam3 transposition in regenerating tobacco calli.
在金鱼草中，仅对自主型Tam3转座子进行了表征。我们研究了一个在假定转座酶编码区有缺失的人工dTam3元件，是否能被一个通过缺失一个反向重复序列而固定化的激活子Tam3元件在烟草中转激活。基于恢复潮霉素抗性的表型分析表明，携带细菌质粒的dTam3元件能够以低频率被转激活。分子分析证实，dTam3元件已从潮霉素磷酸转移酶II（HPTII）标记基因中切除。仅在分析的六株潮霉素抗性植株中的一株中检测到dTam3元件重新整合到烟草基因组中。对空供体位点的PCR分析表明，烟草中dTam3元件的切除会导致重排（缺失和添加），这已被证明是原始宿主金鱼草中Tam3切除的特征。这种转激活分析使我们能够确定，与在金鱼草中检测到的情况相反，周期性温度降至15摄氏度并不会增强再生烟草愈伤组织中dTam3的转座。
