Suter-Crazzolara C, Brzobohaty B, Gazdova B, Schell J, Reiss B
Max-Planck-Institut für Züchtungsforschung, Köln, Germany.
J Mol Evol. 1995 Oct;41(4):498-504. doi: 10.1007/BF00160322.
A number of T-DNA insertions in the genome of Nicotiana tabacum were characterized. One class of integrations was found to have occurred in a new family of highly repetitive sequences. Three genomic regions (ecoA, ecoB, and ecoC) were isolated, all of which contain basic units of 180 bp, organized in direct tandem repeats. Several of the 180-bp elements contain an EcoRI recognition site within the repeating unit and are therefore named "eco repeats." All members of this family are weakly homologous in sequence to a previously described class of repeat elements which contained a BamHI site (HRS60 repeat family), which suggests that both groups of sequences are of common evolutionary origin. The allotetraploid genome of N. tabacum is presumed to originate from the hybridization of two diploid genomes. The HRS60 elements previously described have been found exclusively in the genome of one of the ancestors, N. sylvestris, and in N. tabacum itself. Our DNA hybridization data suggest that the eco elements originate from the genome of the other ancestor, N. tomentosiformis. Whereas the HRS60 elements are transcriptionally silent, at least some eco elements appear to be transcribed.
对烟草基因组中的多个T-DNA插入进行了表征。发现一类整合发生在一个新的高度重复序列家族中。分离出了三个基因组区域（ecoA、ecoB和ecoC），它们都包含180 bp的基本单元，以直接串联重复的形式排列。180 bp元件中的几个在重复单元内含有EcoRI识别位点，因此被命名为“eco重复序列”。该家族的所有成员在序列上与先前描述的一类含有BamHI位点的重复元件（HRS60重复序列家族）弱同源，这表明这两组序列具有共同的进化起源。烟草的异源四倍体基因组被推测起源于两个二倍体基因组的杂交。先前描述的HRS60元件仅在其中一个祖先林烟草的基因组以及烟草自身的基因组中被发现。我们的DNA杂交数据表明，eco元件起源于另一个祖先绒毛状烟草的基因组。虽然HRS60元件转录沉默，但至少一些eco元件似乎会被转录。
