He Y, Gan S
Plant Physiology/Biochemistry/Molecular Biology Program, Department of Agronomy and Tobacco and Health Research Institute, University of Kentucky, Lexington 40546-0236, USA.
Plant Mol Biol. 2001 Nov;47(5):595-605. doi: 10.1023/a:1012211011538.
Like other developmental processes, the terminal phase of leaf development, generally referred to as leaf senescence. regulates a subset of genes whose transcript abundances are increased during senescence. Jasmonic acid (JA), a plant growth regulator, also regulates the expression of subsets of genes in many aspects of plant growth and development, including leaf senescence. However, the underlying molecular mechanisms by which senescence and JA modulate gene expression are poorly understood. During an effort to isolate senescence-associated genes, we identified an Arabidopsis enhancer trap line in which the reporter gene GUS is up-regulated by both senescence and JA. The T-DNA tagged gene was subsequently cloned using thermal asymmetric interlaced PCR (TAIL-PCR). This gene encodes a 12-oxo-phytodienoic acid-10,11-reductase (OPR1). Consistent with the GUS expression data, RNA gel blot analysis showed that OPR1 was indeed up-regulated by both senescence and JA. Promoter deletion analysis and linker-scanning mutagenesis assays were employed to unveil the molecular bases of OPR1 regulation by senescence and JA. Two regulatory cis elements, namely JASE1 (5'-CGTCAATGAA-3') and JASE2 (5'-CATACGTCGTCAA-3'), in the promoter region of the gene, were identified. While JASE2 contains a mixed A/C box-like motif, JASE1 represents a new motif without any signature sequence so far reported. Both elements were required for the up-regulation of OPR1 by leaf senescence and JA. suggesting that leaf senescence and JA may share a common molecular mechanism for modulating OPR1.
与其他发育过程一样，叶片发育的末期阶段，通常称为叶片衰老，它调控着一组在衰老过程中转录丰度增加的基因。茉莉酸（JA）作为一种植物生长调节剂，也在植物生长发育的许多方面，包括叶片衰老过程中，调控基因子集的表达。然而，衰老和JA调节基因表达的潜在分子机制仍知之甚少。在分离衰老相关基因的过程中，我们鉴定出一个拟南芥增强子捕获系，其中报告基因GUS在衰老和JA处理下均上调表达。随后利用热不对称交错PCR（TAIL-PCR）克隆了T-DNA标签基因。该基因编码一种12-氧代植物二烯酸-10,11-还原酶（OPR1）。与GUS表达数据一致，RNA凝胶印迹分析表明OPR1确实在衰老和JA处理下均上调表达。采用启动子缺失分析和接头扫描诱变分析来揭示衰老和JA对OPR1调控的分子基础。在该基因的启动子区域鉴定出两个调控顺式元件，即JASE1（5'-CGTCAATGAA-3'）和JASE2（5'-CATACGTCGTCAA-3'）。JASE2包含一个混合的A/C盒样基序，而JASE1代表一个迄今为止尚未报道过任何特征序列的新基序。这两个元件都是叶片衰老和JA上调OPR1所必需的，这表明叶片衰老和JA可能共享一种调控OPR1的共同分子机制。
