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

烟草BY-2细胞的鸟氨酸脱羧酶（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。从烟草中分离到一个不含内含子的ODC核基因，由ODC启动子和GUS报告基因组成的融合基因（ODC: GUS）在转化的烟草BY-2细胞中对MeJA有较早的反应。虽然ODC: GUS融合基因的表达不受单独水杨酸（SA）的影响，但meja诱导的融合基因的表达在低浓度SA或阿司匹林的存在下增强了约2倍。因此，与meja诱导的基因在伤叶中的印象不同，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基因启动子进行序列缺失和内部缺失分析，发现-1457 ~ -1351和-943 ~ -746在meja诱导的ODC启动子表达中都很重要。这些序列不包含一些序列基序，如G-box，这些序列基序与meja诱导的植物二级反应基因的表达有关。从烟草BY-2细胞中提取的核提取物含有特异性结合ODC启动子的两个区域的活性，这些区域对meja负责的表达很重要。MeJA对烟草细胞的结合活性没有影响。

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.