Takeda S, Sugimoto K, Otsuki H, Hirochika H
Department of Molecular Genetics, National Institute of Agrobiological Resources, Ibaraki, Japan.
Plant Mol Biol. 1998 Feb;36(3):365-76. doi: 10.1023/a:1005911413528.
The tobacco retrotransposon Tto1, one of a few active retrotransposons of plants, has been shown to be activated by tissue culture. Its transposition is regulated mainly at the transcriptional level. It is shown here that expression of Tto1 can be induced in leaves of tobacco by wounding stress. Exogenous supply of methyl jasmonate, which is known to be a potent inducer of certain wound-responsive genes in plants, also induces Tto1 RNA expression. Tto1 RNA was detected within 2 to 4 h after wounding/cutting treatment, and increased levels of Tto1 RNA were observed during subsequent incubation periods for 48 h. Expression of Tto1 RNA after cutting treatment was induced more significantly in young expanding leaves rather than in older mature leaves, suggesting that developmental or physiological factors may be required for the strong response to Tto1 transcription to wounding stimuli. Experiments with transgenic tobacco plants carrying the Tto1-LTR: beta-glucuronidase fusion gene (LTR:GUS) revealed that Tto1 actually contains cis-regulatory regions in response to wounding and methyl jasmonate. These findings are discussed in relation to the mechanism of transcriptional activation and the evolutionary role played by retrotransposons.
烟草反转录转座子Tto1是植物中少数活跃的反转录转座子之一，已被证明可被组织培养激活。其转座主要在转录水平受到调控。本文表明，创伤胁迫可诱导烟草叶片中Tto1的表达。已知茉莉酸甲酯是植物中某些创伤响应基因的有效诱导剂，外源供应茉莉酸甲酯也可诱导Tto1 RNA的表达。在创伤/切割处理后2至4小时内可检测到Tto1 RNA，在随后48小时的培养期内观察到Tto1 RNA水平升高。切割处理后Tto1 RNA的表达在幼嫩的展开叶片中比在较老的成熟叶片中诱导更为显著，这表明对创伤刺激的Tto1转录产生强烈反应可能需要发育或生理因素。对携带Tto1-LTR:β-葡萄糖醛酸酶融合基因（LTR:GUS）的转基因烟草植株进行的实验表明，Tto1实际上含有响应创伤和茉莉酸甲酯的顺式调控区域。本文结合转录激活机制和反转录转座子所起的进化作用对这些发现进行了讨论。
