The increased GUS gene inactivation over generation in Arabidopsis transgenic lines

The effect of transgene inactivation in T2, T3 and F2 generations was analyzed in progeny seedlings which had been generated by Agrobacterium (LBA4404/pBI121)-mediated transformation in Arabidopsis thaliana. In a system which investigated in the expression of $\beta$-glucuronidase(GUS)gene in kanamycin-resistant (ke $n^{R}$)seedlings, GUS inactivated seedlings were observed in 5 of 12 tested lines of T2 generation and the frequency of GUS inactivation was approximately 2.3%. Lines with multi-copies of T-DNA exhibited severe GUS gene inactivation with the frequency of 5.8% in T2 generation. In T3 generation lines exhibited GUS gene inactivation with the frequency of 1.3%. In contrast, inactivation increased dramatically up to 12.6% in multi-copy T-DNA line. A similar phenomenon was also found in F2 progeny from a transgenic line which had been crossed with wild-type Arabidopsis plant, WS-O (GUS gene inactivation frequency 9.9%). These results indicate that the foreign gene introduced into the plant was inactivated progressively in its transmission during subsequent generations and the transgenic line with multi-copies of T-DNA tended to show more increased inactivation.

애기장대 형질전환 식물체의 세대경과에 따른 GUS유전자의 비활성화에 관한 연구

Agrobacterium(LBA4404/pBI1121)을 이용하여 형질전환된 애기장대 (Arabidopsis thaliana)를 대상으로 T2, T3, F3세대에서의 도입된 외래 유전자의 비활성화 현상을 조사하였다. Kanamaycin저항성 개체들의 GUS유전자 발현을 분석한 결과, T2세대에서 조사된 12계통 중 5계통에서 GUS 비활성 개체가 관찰되었다 (GUS유전자 비활성율 2.3%). Multi copy T-DNA 계통을 조사한 결과, GUS 비활성 정도가 더욱 심해짐이 관찰되었다 (5.8%). T3 세대에서 single copy T-DNA 계통들은 1.3%의 GUS 비활성율을 보인 반면, multi-copy T-DNA 계통에서의 비활성율은 12.6%로 급격히 증가하였다. 유사한 현상이 형질전환 식물체와 정상개체를 교배하여 생산된 F2 계통에서도 관찰되었다 (비활성율 9.9%). 본 실험으로 식물체에 도입된 외래 유전자가 후대에서의 전이과정동안 점진적으로 비활성화되고, 이 현상은 multi copy T-DNA 계통에서 훨씬 심각함이 밝혀졌다.