Neither inverted repeat T-DNA configurations nor arrangements of tandemly repeated transgenes are sufficient to trigger transgene silencing
Neither inverted repeat T-DNA configurations nor arrangements of tandemly repeated transgenes are sufficient to trigger transgene silencing
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DOI：
10.1046/j.1365-313x.2003.01746.x
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发表时间：
2003-05-01
期刊：
影响因子：
7.2
通讯作者：
Schmidt, R
中科院分区：
文献类型：
--
作者：
Lechtenberg, B;Schubert, D;Schmidt, R
分析了携带不同报告基因数目和排列的拟南芥T-DNA转化体中的转基因表达。所有转基因均置于CaMV35S启动子的控制下。在含有两个拷贝的β-葡萄糖醛酸苷酶(GUS)基因、两个或四个拷贝的绿色荧光蛋白(GFP)基因和两个、四个或六个拷贝的链霉素磷酸转移酶(SPT)基因的植物中观察到了高、稳定的转基因表达。因此，仅仅存在多个启动子和/或转基因序列并不会导致基因沉默。在所分析的病例中，没有一例是转基因和/或反向重复(IR)T-DNA结构的串联重复安排足以引发不同报告基因的沉默。相反，转录后基因沉默(PTGS)与高表达转基因的拷贝数相关。12个SPT拷贝和4个GUS基因拷贝引发了沉默。沉默通常与重复的T-DNA结构有关。我们赞成这样的观点，即在许多情况下，这可能归因于高转基因剂量，而不是重复安排本身。
Transgene expression was analysed in Arabidopsis T-DNA transformants carrying defined numbers and arrangement of different reporter genes. All transgenes were placed under the control of the strong constitutive CaMV 35S promoter. High, stable transgene expression was observed in plants containing two copies of the beta-glucuronidase (GUS) gene, two or four copies of the green fluorescent protein (GFP) gene and two, four or six copies of the streptomycin phosphotransferase (SPT) gene. Thus, the mere presence of multiple promoter and/or transgene sequences did not result in gene silencing. In none of the cases analysed were tandem repeat arrangements of transgenes and/or inverted repeat (IR) T-DNA structures sufficient to trigger silencing of the different reporter genes. Instead, post-transcriptional gene silencing (PTGS) correlated with the copy number of the highly expressed transgenes. Twelve copies of the SPT and four copies of the GUS gene triggered silencing. Silencing is frequently associated with repetitive T-DNA structures. We favour the idea that in many cases this may be attributed to the high transgene doses rather than the repeat arrangements themselves.