两个不同株系大豆花叶病毒侵染大豆细胞的超微病变比较研究

Comparative studies on ultrastructural alteration of soybean infected with two different strains of soybean mosaic virus

以大豆品种冀豆7号和大豆花叶病毒(SMV)株系SC-8、N3分别组成感病和抗病组合,运用电子显微镜比较观察了不同组合中大豆叶片细胞的超微结构变化。结果显示:在抗病组合的叶肉细胞中,侵染早期(接种8～12h),叶绿体膨胀,叶绿体片层结构轻微零乱,核染色质发生凝集现象;接种后24h,叶绿体继续膨胀变形,线粒体结构清晰完整,核变形严重;侵染后期(接种后72 h),细胞核近乎衰败,双层核膜已基本辨认不清,叶绿体结构基本解体。此时线粒体嵴突已发生退化,只有双层膜结构,内部出现空虚状态。细胞中的病毒粒子很少,也没发现柱状内含体结构。在此过程中,叶绿体和细胞核是最早做出反应的细胞器,而线粒体是最后解体的细胞器。感病组合中叶肉细胞超微结构的变化比抗病组合晚了10 h以上,细胞器的结构变化特征与抗病组合相似,但在所观察的整个互作过程中,核、叶绿体和线粒体的衰退是同步的,显示出了细胞被动死亡的特征;且在细胞死亡的整个过程中叶绿体上均有淀粉粒的积累,另外还观察到线粒体的异常增加现象,这可能是为了病毒粒子的增殖和柱状内含体的产生提供能量所致。

The ultrastructural alteration of soybean cultivar jidou 7 leaves infected with SC-8 strain of SMV （Compatible combination） and N3 strain of SMV （Incompatible combination）, respective- ly, was examined by the transmission electron microscope. The results showed： at the early stage （8 to 12 h after inoculation）, chloroplasts dilated and nuclei agglomerated; at 24 h after infection, the changes of chloroplasts and nuclei were greater and the mitochondrion was complete; at the later stage （72 h after infection）, nuclei degraded, and the membrane of nuclei and chloroplasts disappeared. Mitochondria degradation had only two layers of membrane structure. There were only a few viruses observed in the cells, and the cylindrical inclusions were not found in cytoplasm. During the course, chloroplasts and nuclei were the first declined organs, but mitochondria was the last degraded organ. In compatible combination the similar ultrastructural features changed 10 hours later than the incompatible combination, but the changes of nuclei, chloroplast and mitochondria were synchronous. These showed some characters of passive cell death. In addition, the starches synthesized in all the time before cell breakdown. In the cytoplasm the number of mitochondria increased abnormaly, perhaps for the sake of energy anabolism for virus multiplication.