Chemical elucidation for the mechanism of the defense reaction of plant cells

在植物培养细胞生物催化剂的研究过程中，我们研究了植物细胞对外源底物化学胁迫的防御反应。在烟草、洋甘菊、芹菜、大豆和苔类等几种植物的培养细胞中添加了各种类异戊二烯作为应激化合物。结果表明，经香叶醇处理后，细胞细胞核浓缩破碎，基因组dna呈阶梯状断裂。香叶醇的作用具有浓度和时间依赖性。这些结果表明，香叶醇具有促进植物细胞凋亡样细胞死亡的活性。此外，环己亚胺和放线菌素D分别作为蛋白质和RNA合成抑制剂，对植物细胞凋亡没有抑制作用。这表明香叶醇诱导的细胞凋亡过程不需要合成新的蛋白。另一方面，细胞分裂素的加入阻止了香叶醇诱导的细胞DNA断裂。本项目探讨了化学胁迫诱导植物凋亡的机制。

In the course of the studies on the biocatalysts with plant cultured cells, we have examined the defense reaction of plant cells against chemical stress with exogenous substrates. Various isoprenoids as a stress compounds were added to the cultured cells of several plants such as tabacco, chamomile, celery, soybean and liverwort. It was observed that the' nuclei of the cells on treatment with geraniol were condensed and fragmented, and then genomic DNAs were fragmented in a ladder form. Such the effect of geraniol was concentration- and time-dependent. These observations reveal that geraniol has an activity for apoptosis-like cell death of the plant cells.Furthermore, cycloheximide and actinomycin D, inhibitors of protein and RNA syntheses, respectively, did not suppress the apoptosis of the plant cells. This suggests that the apoptotic process induced by geraniol does not require the synthesis of new proteins. On the other hand, addition of cytokinins prevented the geraniol-induced DNA fragmentation in the cells. The mechanism of the plant apoptosis induced by chemical stress was examined and discussed in this project.