【摘要】 对感染桑萎缩病的桑叶及嫩梢进行超薄切片的电镜观察发现，其韧皮部组织，筛管及伴胞内有多型性类菌原体。菌体为圆形及椭圆形，大小约为50～160nm，双层膜，厚度约为8～10nm，内含物中具有核质样的纤维状物质，而在健株叶梢中未观察到任何病原体．随着病害的发展，可观察到细胞成份的降解。第一，在感病植株叶肉细胞内存在部分细胞核的降解、核膜破裂或核质流失甚至核仁分散消失。第二，叶绿体内有不同程度的淀粉粒和嗜锇颗粒累积，部分叶绿体外膜破裂，基质流失，基粒降解。第三，线粒体及粗面内质网在数量上有所增加，部分线粒体嵴已降解。更多还原

【Abstract】 The pathogen causing the dwarf disease of mulberry in Tongxiang, Zhejiang Province was inveshgated based on transmission electronic microscopy of the leaf vein of diseased plants collected in the field. A mycoplasma-like organism was idenhfied in the sieve tUbe, compamon, and parenchyma cells of the phloem hssues infected. The organism was spheric or oval in shape, ranging from 50urn to 160urn in diameter, and with bildrina unit membrane of 8～10um in abackness, and was filled with nuclear sir’ands or fibrous material. Some nuclei of mesophyll cells in the diseased leaves were found disrupted as their nuclear membrane was broken, followed by loss of nudeo-cytoplasmic matrix and dispersive disappearance of nucleoli. Furthermore, other ultrastructural aberration including depletion of chloroplast stroma, disruption of chloroplast grana, increase of mitochondria and rough endoplasndc rehculum, and discomposihon of some mitochondrial cristae were also observed associated with the pathological changes caused by the mycoplasma-like organism. In contrast this type of orgedsm was not found in healthy plantS exndned. Thus, the mycoplasma-like organnsm is likely to be a Pathogen attributable to the mulberry dwarf disease.更多还原