van Nuenen M, de Ruffray P, Otten L
C.N.R.S. Institute of Plant Molecular Biology, Strasbourg, France.
Mol Gen Genet. 1993 Jul;240(1):49-57. doi: 10.1007/BF00276883.
The octopine/cucumopine (o/c) Ti plasmids of the grapevine-associated Agrobacterium vitis strains constitute a family of related DNA molecules. Restriction maps were established of two limited-host-range o/c Ti plasmids, pTiAg57 and pTiAB3, and of the wide-host-range o/c Ti plasmid pTiHm1. Together with the previously obtained map of the wide-host-range o/c Ti plasmid pTiTm4, about 1000 kb were mapped with a resolution of 0.2 kb, allowing a detailed comparison of the various structures. One region of the o/c Ti plasmids is highly conserved and differs mainly by the presence or absence of relatively small DNA fragments (0.9-2.7 kb); the other region has been modified more extensively and carries large sequences specific for each Ti plasmid type. The sequence similarity within large conserved regions shows that these plasmids have diverged recently and that their evolution was driven by large-scale genetic events rather than single nucleotide changes. These results have important implications for studies on bacterial evolution.
与葡萄相关的根癌土壤杆菌菌株的章鱼碱/黄瓜碱（o/c）Ti质粒构成了一个相关DNA分子家族。构建了两个有限宿主范围的o/c Ti质粒pTiAg57和pTiAB3以及广宿主范围的o/c Ti质粒pTiHm1的限制酶切图谱。连同先前获得的广宿主范围的o/c Ti质粒pTiTm4的图谱，约1000 kb的区域以0.2 kb的分辨率进行了定位，从而能够对各种结构进行详细比较。o/c Ti质粒的一个区域高度保守，主要区别在于相对较小的DNA片段（0.9 - 2.7 kb）的有无；另一个区域则有更广泛的修饰，并携带每种Ti质粒类型特有的大序列。大的保守区域内的序列相似性表明这些质粒是最近才分化的，并且它们的进化是由大规模遗传事件而非单核苷酸变化驱动的。这些结果对细菌进化研究具有重要意义。
