Investigation of signal transduction pathways of jasmonic acid in higher plants

本研究对茉莉酸（JA）的功能及其信号转导途径进行了深入的研究，包括茉莉酸应答基因的启动子分析、JA生物合成酶基因的功能鉴定以及JA/激发子应答转录因子的详细鉴定。主要结论如下：（1）在水稻悬浮培养细胞中发现了一个含TGACG的序列，该序列是OsOPR 1 JA响应性表达的顺式调控元件，表明OsOPR 1转录的JA响应性表达过程中有一个碱性亮氨酸拉链（bZIP）转录因子参与。(2)我们提供的证据表明，水稻8号染色体上的OPR家族基因OsOPR 7编码的酶参与JA的生物合成。OsOPR 7 mRNA表达在机械伤后0.5h内达到最高水平，在伤后24 h内达到最高水平。 关于我们 随着OsOPR 7表达的增加，内源JA水平开始增加。(3)我们表明，JA响应bHLH转录因子基因RERJ 1从悬浮培养的水稻细胞中分离的表达响应于外源JA在叶片，叶鞘，根的水稻在营养阶段，和RERJ 1在叶片中的表达上调暴露于创伤和干旱胁迫。在我们最近的研究中，包括使用过表达正义RERJ 1 mRNA的转基因水稻的微阵列分析，已经表明RERJ 1参与了病程相关蛋白基因表达的调节。(4)我们为OsWRKY 53和OsWRKY 71参与调控几丁质寡糖和真菌糖苷诱导剂诱导的水稻防御相关基因的表达提供了有力的证据。虽然OsWRKY 53被认为是一个转录激活因子，但OsWRKY 71显示出转录抑制因子的特征，表明OsWRKY 71对防御相关基因的激活可能是间接的。少

In this project, in order to have basic information on jasmonic acid (JA) functions and its signal transduction pathways, we have performed extensive studies including promoter analysis of a jasmonic acid (JA)-responsive gene, functional identification of a JA biosynthetic enzyme gene, and detailed characterization of JA/elicitor-responsive transcription factors that play key roles in the regulation of defense responses in rice. The principal conclusions are as follows: (l) We identified a TGACG-containing sequence that is a cis element involved in the JA-responsiveness of OsOPR1 in suspension-cultured rice cells, suggesting that a basic leucine zipper (bZIP) transcription factor is involved in the JA-responsive expression of OsOPR1 transcription. (2) We provided evidence that an OPR family gene in rice chromosome 8, OsOPR7, encodes the enzyme involved in the JA biosynthesis. The expression of OsOPR7mRNA was induced and reached maximum levels within 0.5 h of mechanical wounding and dro … More ught stress, and the endogenous JA level started to increase in accordance with the increase in OsOPR7expression. (3) We indicated that the JA-responsive bHLH transcription factor gene RERJ1 isolated from suspension-cultured rice cells was expressed in response to exogenous JA in leaves, leaf sheaths, and roots of rice in a vegetative stage, and that RERJ1 expression in the leaves was up-regulated by exposure to wounding and drought stress. In our recent studies including microarray analysis using transgenic rice overexpressing sense-RERJ1 mRNA, it has been shown that RERJ1 is involved in regulation of pathogenesis-related protein genes expression. (4) We provided strong evidence for the involvement of OsWRKY53 and OsWRKY71 in regulating the expression of defense-related genes induced by chitin oligosaccharide and fungal cerebroside elicitors in rice. Although OsWRKY53 was suggested to be a transcriptional activator, OsWRKY71 showed features characteristic of a transcriptional repressor, indicating that the activation of defense-related genes by OsWRKY71 was probably indirect. Less