Transcription Factors Involved in the induction of Jasmonate-Primary Responsive Gene in Plant Cells

烟草BY-2细胞鸟氨酸脱羧酶(ODC)基因的转录即使在蛋白质合成抑制剂存在的情况下也被激活。从烟草中分离的ODC核基因不含内含子，由ODC启动子和GUS报告基因组成的融合基因(ODC：GUS)在转化烟草BY-2细胞中表现出对MeJA的早期反应。虽然ODC：GUS融合基因的表达不受水杨酸(SA)的单独影响，但在低浓度SA或阿司匹林的存在下，MeJA诱导的融合基因的表达增强了约2倍。因此，与MeJA诱导的受伤叶片基因印记不同，JA诱导的ODC基因在烟草BY-2细胞中的表达不受SA的抑制。对ODC基因启动子序列和内部缺失的分析表明，-1457和-1351之间的序列和-943和-746之间的序列在MeJA诱导的ODC启动子的表达中都是重要的。这些序列不包含几个序列基序，如G-box，这些基序被认为参与了MeJA诱导的植物次生反应基因的表达。从烟草BY-2细胞制备的核提取物含有与ODC启动子的两个区域特异结合的活性，这两个区域对MeJA负责表达至关重要。用MeJA处理烟草细胞不影响其结合活性。

Transcription of the gene for ornithine decarboxylase (ODC) of tobacco BY-2 cells is activated even in the presence of an inhibitor of protein synthesis. A nuclear gene for ODC isolated from tobacco did not contain intron, and the fusion gene composed of the ODC promoter and the GUS reporter gene (ODC : GUS) showed early response to MeJA in transformed tobacco BY-2 cells. Although expression of the ODC: GUS fusion gene was not affected by salicylic acid (SA) alone, MeJA-inducible expression of the fusion gene was enhanced to about 2-fold by the presence of low concentrations of SA or aspirin. Thus, unlike MeJA-inducible gene impression in wounded leaves, JA-inducible expression of the ODC gene in tobacco BY-2 cells is not inhibited by SA. Analysis using serial deletions and internal deletions of the ODC gene promoter revealed that the sequence between -1457 and -1351 and the sequence between -943 and -746 are both important in the MeJA-inducible expression of the ODC promoter. These sequences did not contain several sequence motifs such as G-box that had been implicated to be involved in the MeJA-inducible expression of secondary-responsive genes in plants. Nuclear extracts prepared from tobacco BY-2 cells contained activities which specifically bind to the two regions of the ODC promoter important for the MeJA-responsible expression. Treatment of tobacco cells with MeJA did not affect the binding activities.