水稻基腐病菌毒素对烟草活性氧代谢及细胞超微结构的影响

Effect of toxin produced by Dickeya zeae on reactive oxidative specifies(ROS) metabolism and cell ultrastructure in tobacco

用水稻基腐病菌毒素注射烟草叶片后,烟草细胞中O.2-和NO大量增加,H2O2含量明显降低,SOD、CAT和POD等酶的活性发生变化。毒素引起烟草细胞死亡,但没有细胞程序性死亡(PCD)的DNA梯特征。病菌毒素处理烟草叶片后,电导率增大,细胞膜透性增加。电镜观察烟草细胞的超微结构表明,毒素处理8h后,叶绿体变形,叶绿体基质片层大部分消解,基粒结构消失,叶绿体外膜和内膜剥离,质壁分离和细胞膜内陷,细胞器消解;处理48h后,细胞内含物完全消解,细胞膜消失,细胞壁皱缩变形。本研究表明,毒素引起烟草细胞死亡与植物抗病反应HR中细胞坏死的生理生化机制不同,但可能存在相似的信号传导途径。

After treated with toxin produced by Dickeya zeae, the pathogen of rice bacterial foot rot, the contents of O; and nitric oxide （NO） and the activities of SOD, CAT and POD in tobacco leaves were increased and changed, while the H2O2 content was decreased distinctly. The death of tobacco cells caused by toxin treatment was different from programmed cell death（PCD） because of the absence of DNA ladder. Moreover, both the electric conductivity and cell membrane permeability increased in the treated tobacco leaves. 8 hours after toxin treatment, the cell ultrastructure of tobacco leaves was observed under an electronic microscope, and the results showed that the chloroplast in the leaves was deformed, most chloroplast grana were dissolved, the inner and out membrane of chloroplast delaminated. In addition, some organelles were dissolved and plasmolysis and inner membrane were embolic. Finally, with the toxin action 48h later, the inclusions of tobacco cell were dissolved completely and the cell membrane disappeared, cell wall was deforming and cuffing. In our study, a conclusion could be derived that the mechanism of the tobacco cell death caused by toxin was different from the resistant reaction caused by HR in physiology and biochemistry, but they might have similar signal transduction way.