Gerats A G, Huits H, Vrijlandt E, Maraña C, Souer E, Beld M
Department of Genetics, Vrije Universiteit of Amsterdam, The Netherlands.
Plant Cell. 1990 Nov;2(11):1121-8. doi: 10.1105/tpc.2.11.1121.
An insertion sequence of 283 base pairs has been isolated from the DFR-C gene (dihydroflavonol-4-reductase) of petunia. This insert was found only in a line unstable for the An1 locus (anthocyanin 1, located on chromosome VI) and not in fully pigmented progenitor and revertant lines or in stable white derivative lines. This implies that the An1 locus encodes the DFR-C gene. The unstable An1 system in the line W138 is known to be a two-element system, the autonomous element being located on chromosome I. In the presence of the autonomous element, W138 flowers exhibit a characteristic pattern of red revertant spots and sectors on a white background. In the absence of the autonomous element, the W138 allele gives rise to a stable recessive (white) phenotype. Sequence analysis of progenitor, unstable, and revertant alleles revealed dTph1 to contain perfect terminal inverted repeats of 12 base pairs. In DFR-C, it is flanked by an 8-base pair target site duplication. Sequences homologous to dTph1 are present in at least 50 copies in the line W138. Sequence analysis of An1 revertant alleles indicated that excision, including removal of the target site duplication, is required for reversion to the wild-type phenotype. Derivative stable recessive alleles showed excision of dTph1 and a rearrangement of the target site duplication. dTph1 is the smallest transposable element described to date that is still capable of transposition. The use of dTph1 in tagging experiments and subsequent gene isolation is discussed.
从矮牵牛的DFR-C基因（二氢黄酮醇-4-还原酶）中分离出了一段283个碱基对的插入序列。该插入片段仅在An1位点（花青素1，位于第六条染色体上）不稳定的品系中发现，而在完全色素沉着的祖代和回复品系或稳定的白色衍生品系中未发现。这意味着An1位点编码DFR-C基因。已知品系W138中的不稳定An1系统是一个双元件系统，自主元件位于第一条染色体上。在自主元件存在的情况下，W138花朵在白色背景上呈现出红色回复斑点和扇形的特征模式。在没有自主元件的情况下，W138等位基因产生稳定的隐性（白色）表型。对祖代、不稳定和回复等位基因的序列分析表明，dTph1包含12个碱基对的完美末端反向重复序列。在DFR-C中，它两侧有一个8个碱基对的靶位点重复序列。与dTph1同源的序列在品系W138中至少有50个拷贝。An1回复等位基因的序列分析表明，回复到野生型表型需要切除，包括去除靶位点重复序列。衍生的稳定隐性等位基因显示dTph1的切除和靶位点重复序列的重排。dTph1是迄今为止描述的最小的仍能转座的转座元件。讨论了dTph1在标签实验及后续基因分离中的应用。
