Investigation of signal transduction pathways of jasmonic acid in higher plants

为了了解茉莉酸(JA)的功能及其信号转导途径，我们进行了大量的研究，包括茉莉酸(JA)应答基因的启动子分析、茉莉酸生物合成酶基因的功能鉴定以及茉莉酸/激发子应答转录因子(JA/激发子应答转录因子)的详细鉴定。主要结论如下：(L)我们在悬浮培养的水稻细胞中发现了一个含有TGACG的序列，这是一个参与OsOPR1对JA反应的顺式元件，表明碱性亮氨酸拉链(BZIP)转录因子参与了OsOPR1对JA的反应表达。(2)我们提供了水稻8号染色体上一个OPR家族基因OsOPR7编码JA生物合成相关酶的证据。在机械伤和…损伤后0.5h，OsOPR7mRNA的表达达到最高水平胁迫越严重，内源茉莉酸水平开始随着OsOPR7表达的增加而增加。(3)从悬浮培养的水稻细胞中分离到的JA反应转录因子基因RERJ1在营养生长期的水稻叶片、叶鞘和根中表达，并且RERJ1在叶片中的表达受到伤害和干旱胁迫的上调。在我们最近的研究中，包括利用过表达正义-RERJ1基因的转基因水稻的芯片分析，已经表明RERJ1参与了病程相关蛋白基因的表达调控。(4)我们为OsWRKY53和OsWRKY71参与调控甲壳素低聚糖和真菌脑苷脂激发子诱导的水稻防御相关基因的表达提供了有力证据。虽然OsWRKY53被认为是转录激活因子，但OsWRKY71表现出转录抑制因子的特征，这表明OsWRKY71对防御相关基因的激活可能是间接的。较少

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