Genome rearrangements and gene regulation in higher plants

日本牵牛花（lpomoea nil）显示蓝色的花有广泛的遗传和生理研究的历史。许多与花色相关的自发突变体已经被分离出来，一些证据表明，与En/ spm相关的转座因子Tpn 1及其亲属是这些自发突变的主要来源。事实上，包括白花突变体在内的许多花色突变都是由Tpn - 1相关的非自主元件的整合引起的。其中之一是紫色可变等位基因，赋予紫色花朵蓝色斑点和扇形。紫色基因被鉴定为编码一个液泡Na^+/H^+交换器，该交换器负责提高液泡pH值，从而使蓝色花着色。常见的牵牛花（Ipomoea purpurea）的变异鳞片系显示白色的花朵和彩色的鳞片，鳞片突变是由于在用于花青素生物合成的CHS-D基因中插入了转座元件Tip 100引起的。3.9 kb的Tip 100元素属于AciDs族。我们研究了Tip 100是否在异源烟草植株中是一个能够转位的自主元件。完整的Tip 100元件能够从其在引入载体中的原始位置切除并重新插入烟草基因组中的新位点，而其内部缺失衍生物则不能。根据这些结果，我们得出结论，Tip 100是一个自治元素。通过同源重组修饰目标染色体基因是反向遗传学表征基因功能的有力工具。我们正在尝试开发一种利用同源重组对水稻单位点基因Waxy进行靶向基因破坏的方法。分离到一株目标基因被转基因破坏的转基因水稻植株，该植株似乎是一个杂合子，其基因组中只有一个整合的转基因拷贝。

The Japanese morning glory (lpomoea nil) displaying blue flowers has an extensive history of genetic and physiological studies. A number of its spontaneous mutants related to the flower colors have been isolated, and several lines of evidence indicate that an En/Spm-related transposable element Tpn 1 and its relatives are major sources of these spontaneous mutations. Indeed, many flower color mutants including white flower mutants are caused by integration of Tpn 1-related non-autonomous elements. One of them is a purple-mutable allele conferring purple flowers with blue spots and sectors. The purple gene was identified to encode a vacuolar Na^+/H^+ exchanger that is responsible for increase vacuolar pH for blue flower coloration.The mutable flaked line of the common morning glory (Ipomoea purpurea) displays white flowers with colored flakes, and the flaked mutation is caused by the insertion of a transposable element Tip 100 into the CHS-D gene for anthocyanin biosynthesis. The 3.9 kb Tip 100 element belongs to the AciDs family. We examined whether Tip 100 is an autonOmous element capable of transposition in heterologous tobacco plants. The intact Tip 100 element was able to excise from its original position in an introduced vector and to reinsert into new sites in the tobacco genome, whereas its internal deletion derivative was not. Based on these results, we concluded that Tip 100 is an autonomous element.The modification of targeted chromosomal genes through homologous recombination is a powerful tool of reverse genetics for characterizing gene functions. We are trying to develop a procedure for targeted gene disruption by homologous recombination in the single locus gene Waxy of rice. A transgenic rice plant having a targeted gene disrupted by a transgene was isolated, which appears to be a heterozygote with only one copy of the integrated transgene in its genome.