Transfer, maintenance, and expression of bacterial Ti-plasmid DNA in plant cells transformed with A. tumefaciens.
Transfer, maintenance, and expression of bacterial Ti-plasmid DNA in plant cells transformed with A. tumefaciens.
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发表时间：
1977-05
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通讯作者：
J. Schell;M. V. Montagu
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作者：
J. Schell;M. V. Montagu
本文简述了根癌农杆菌诱发植物根癌的机理。其要点如下。1.分子量为（100至150）S 10（6）的大质粒，称为Ti质粒，对转化过程至关重要。2. Ti质粒携带DNA片段，其可以转移到转化的植物细胞中并在转化的植物细胞中维持和表达。3.这段DNA已被确定的Ti DNA片段和冠瘿DNA之间的直接杂交实验和Ti质粒的缺失突变体的研究。4.间接证据表明，参与冠瘿细胞合成异常氨基酸（如章鱼碱和胭脂碱）的基因，已知携带在Ti质粒上，实际上位于转移到植物细胞的DNA片段上。5. Ti质粒是有效的接合质粒，因为它们可以通过接合到各种无质粒的细菌菌株来促进其自身的转移。它们的接合特性可能也参与了Ti DNA从农杆菌到植物细胞的转移。6.初步证据表明，Ti质粒的可转移片段具有转座子的结构，因为它似乎侧接显示已知细菌耐药基因转座子边界序列的大部分特性的序列。
The mechanism of induction of the plant cancer crown gall by Agrobacterium tumefaciens has been briefly described. The salient points are as follows. 1. Large plasmids of molecular weight (100 to 150) S 10(6), called Ti-plasmids, are essential to the transformation process. 2. Ti-plasmids carry a DNA segment that can be transferred to, and maintained and expressed in, transformed plant cells. 3. This DNA segment has been identified both by direct hybridization experiments between Ti DNA fragments and crown gall DNA and by the study of a deletion mutant of a Ti-plasmid. 4. Indirect evidence suggests that genes involved in the synthesis of abnormal amino acids (such as octopine and nopaline) by crown gall cells, and known to be carried on the Ti-plasmids, are in fact located on the DNA segment that is transferred to the plant cells. 5. Ti-plasmids are efficient conjugative plasmids, since they can promote their own transfer by conjugation to various plasmid-free bacterial strains. Their conjugative properties may be involved also in the Ti DNA transfer from Agrobacterium to plant cells. 6. Preliminary evidence indicates that the transferable segment of the Ti-plasmid has the structure of a transposon, since it appears to be flanked by a sequence exhibiting most of the properties of the sequences that border the known bacterial drug-resistance gene transposons.