Abstract: The microstructure and ultrastructure of mycorrhizal root of Cymbidum sinenese (Andr.) Wild were studied. The results showed that this species possesses the typical root structure of orchids. There is no passage cells in the exodermis of root. Mycorrhizal fungi invade into the cortex by destroying the velamen and exodermal cells, and form pelotons in cortical cells. The hyphae colonizing cortical cells were separated from the cortical cells by electron- lucent material and cortical cell plasma membrane and digested. They often gathered to form clumps. Localization of acid phosphatase revealed that this enzyme possessed higher activity in the cortical cells containing hyphae. Many products of it also occurred on cortical cell plasma membrane surrounding hyphae and degenerated hyphae cell wall. Higher acid phosphatase activity was observed in many vesicles in the cortical cells infected by fimgi. These enzyme vesicles gathered around the invaded hy-phae and often fused with each other, or with cortical cell plasma membrane surrounding hyphae to digest these hyphae. It means cortical cells were able to release hydrolytic enzyme to digest the invaded hyphae.

Key words: Cymidium sinense

摘要： 利用光学显微镜、电子显微镜及细胞化学方法，对墨兰菌根的结构和酸性磷酸酶定位进行了初步研究。结果表明墨兰具有典型的兰科植物根结构，发现该兰花的根的外皮层不具薄壁通道细胞，菌根真菌通过破坏部分根被和外皮层细胞而侵人根的皮层细胞并在细胞内形成菌丝结，侵人的菌丝被染菌皮层细胞质膜和电子透明物质包围，进一步被消化并聚集成衰败菌丝团块。酸性磷酸酶在染菌皮层细胞及包围菌丝的皮层细胞质膜和衰败菌丝细胞壁上有强烈的酶反应，衰败菌丝周围分布有许多单层膜的合酶小泡，它们可相互愈合形成大的合酶泡或与包围菌丝的质膜融合，类似于兰科植物共生原球茎中观察到的现象。说明皮层细胞可主动释放水解酶参与对菌丝的消化。

关键词: 墨兰, 菌根, 酸性磷酸酶