摘要
用透射电镜观察了豌豆根瘤侵染细胞在衰老过程中的超微结构变化,结果表明,侵染细胞和拟菌体的衰老有一定的规律和特征,首先是一些包裹拟菌体的包囊变得疏松,包囊和拟菌体之间出现较大间隙,间隙中常有一些纤维状和泡状物质。然后,细胞质失去正常结构,逐渐凝聚为染色很深的团块,进而完全泡状化。伴随着拟菌体的衰老,寄主细胞质染色由深变浅,细胞器逐渐减少。最后,液泡和质膜相继破裂,细胞完全瓦解。有时在衰老细胞的胞间隙,或在衰老的细胞质中有一些年轻的细菌,甚至在一片崩溃的拟菌体中还有侵染丝,有的还正在向寄主细胞质释放细菌。
Ultrastructural changes of the infected cells have been observed by transmission electron microscopy during pea root nodule senescence.The infected cells and bacteroids of pea no- dules ultimately senesce,their senescence has certain laws and features.Firstly,peribacteroid membrane were loosened,leaving a large electron-empty space with fibrillar and vesicular material.Then bacteroid cytoplasm lost features and aggregated into some clustered electron- dense material.At next stage bacteroids were structurally emtpy and appeared like“ghost” cells.Companying bacteroid senescence,host cytoplasm changed from dark to light in electron density and cell organelles gradually decreased.After the host cell tonoplasts and plasmalemma broke down,the infected cells showed a chaotic state of bacteroids and host cell debrises.Fi- nally,infected cells disintegrated completely.Sometimes some young bacteria were seen in the intercellular spaces surrounded by degenerating cells,in the degenerating cytoplasm.A few infection threads were also found among the disintegrated bacteroids,even some of them were releasing the bacteria into the degenerating host cytoplasm.
