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用带水稻苯丙氨酸解氨酶PAL 2启动子和GUS读码框嵌合基因的水稻悬浮细胞证明毛地黄皂苷能诱导水稻PAL 2的转录。NAD-PH、NADH、过氧化氢、超氧歧化酶、过氧化氢酶、甘露醇、1,2-羟基苯-3,5-二磺酸(Tiron)、paraquat、精氨酸、还原型和氧化型的谷胱甘肽、N-乙酰-L-半胱氨酸、二硫苏糖醇等都不影响毛地黄皂苷诱导的PAL2转导。只有在超氧歧化酶和过氧化氢酶或超氧歧化酶和Tiron一起时才微弱地抑制这种诱导。毛地黄皂苷能在缺钙培养基中诱导胞外介质碱性化,但它只在含钙离子的条件下才诱导PAL 2转录。钙离子载体A 23187及Stauros-poline不诱导PAL 2基因转录和胞外介质碱性化。钙调素的拮抗剂N-(6-Aminohexy1)-5-chloro-1-naphthalenesulfonamide(W7)和trifluoperazine(TFP)能抑制毛地黄皂苷诱导的PAL 2转录,但一些蛋白激酶的激活剂和抑制剂包括phorbol-12-myristate(TPA)、1-(5-Isoquinoline sulfony1)-2-methylpiperaz-ine(H7)、staurosporine及genestein不干扰它对PAL 2转录的诱导,G蛋白激活剂GTP-γS和抑制剂百日咳毒素也不影响这种诱导。毛地黄皂苷不诱导几丁酶转录。二硫苏糖醇能抑制几丁酶转录。伴刀豆球蛋白及麦胚凝集素能微弱地促进几丁酶基因转录,但对PAL 2表达没有影响。看来毛地黄皂苷诱导的水稻悬浮细胞PAL 2转录与活性氧激活没有简单和直接的关系。但它依赖于胞外介质碱性化和钙-钙调素,它的信号传导途径与诱导几丁酶转录的信号传导途径是不同的。
Indigo rice saponins were able to induce rice PAL 2 transcription using rice suspension cells with the rice phenylalanine ammonia lyase PAL 2 promoter and the GUS reading frame chimeric gene. NAD-PH, NADH, hydrogen peroxide, superoxide dismutase, catalase, mannitol, Tiron, paraquat, arginine, Oxidized glutathione, N-acetyl-L-cysteine, dithiothreitol and the like did not affect ghrelin-induced PAL2 transduction. This induction is only weakly inhibited by superoxide dismutase and catalase or superoxide dismutase and Tiron. Digitonin induces extracellular extracellular basicisation in calcium deficient media, but it only induces PAL2 transcription only in the presence of calcium ions. Calcium ionophore A 23187 and Stauros-poline did not induce PAL 2 gene transcription and extracellular matrix alkalization. Calmodulin antagonists N- (6-Aminohexy1) -5-chloro-1-naphthalenesulfonamide (W7) and trifluoperazine (TFP) inhibited digitonin-induced PAL2 transcription but activators and inhibitors of some protein kinases Including phorbol-12-myristate (TPA), 1- (5-Isoquinoline sulfony1) -2-methylpiperazine (H7), staurosporine and genestein did not interfere with its induction of PAL2 transcription, GTP- Pertussis toxin does not affect this induction. Digitonin does not induce chitinase transcription. Dithiothreitol can inhibit chitinase transcription. Concanavalin and wheat germ agglutinin can weakly promote chitinase gene transcription but have no effect on PAL 2 expression. It appears that there is no simple and direct relationship between digitonin-induced PAL2 transcription of rice suspension cells and activation of reactive oxygen species. But it relies on the extracellular mediator alkalization and calcium-calmodulin, and its signaling pathway is different from the signaling pathway that induces chitinase transcription.