中文摘要：

利用光镜和电镜技术系统研究了苹果轮纹病菌葡萄座腔菌在成熟果实上的侵染扩展过程及其细胞学特征。扫描电镜观察发现，接种后3h位于皮孔处的分生孢子开始萌发，萌发后的孢子从一端或两端产生芽管直接侵入皮孔细胞，接种后9h完成侵入。30d后果面接种部位表现症状，45d后产生子实体。对接种部位取样进行光镜和透射电镜观察发现，病菌菌丝主要存在于寄主细胞壁、细胞内、细胞间隙及细胞壁与细胞膜之间。菌丝呈丝状，分枝，具隔膜。菌丝细胞内含有细胞核、线粒体、液泡等细胞器；菌丝外散发出一些高电子密度的颗粒物质，这些物质以菌丝为中心，呈放射状分布。病菌在果肉细胞生长扩展过程中，果肉细胞发生一系列变化。果肉细胞壁膨胀、变形，胞间层分离、破裂。与菌丝接触或相邻的果肉细胞细胞壁电子致密度降低，被降解成为如散发状的胞壁纤维束丝。果肉细胞的液泡破裂，质壁分离，细胞质凝结坏死并沉积于细胞壁周围，或通过受损的细胞壁胞间连丝从一个细胞转移到另一个细胞。后期菌丝在表皮下聚集生长、发育成分生孢子器。分生孢子器内壁细胞排列紧密，细胞中含有由数条丝状物平行排列而成的细胞器。该细胞器形状多样，周围总是分布着丰富的脂肪粒，推测可能与营养的运输与积累有关。

英文摘要：

The infection process and ultrastructure of Botryosphaeria dothidea （Bd） on apple fruit were observed by light and electron microscopy in detail. The results observed by scanning electron microscopy showed that Bd conidia in the lenticel of apple fruit initially germinated from one or both ends, and the germ tubes directly penetrated through lenticel at 3 hours after inoculation （hai）. The infection process normally completed at 9h. Disease symptoms could be observed in 30 days after inoculation （dai） and the pycnidium generated in 45dai. Subsequent observation through light and transmission electron microscopy showed that the filamentous Bd hyphae were septigenous and elongated in host cell gap, cell wall and the space between cell wall and cytomembrane. Several organelles were also observed in Bd hypha cells, such as nucleus, mitochondria and vacuole. Some granules with high electron density distributed radially around the hyphae. Huge changes in apple fruit tissue occurred with the expand of Bd hyphae, such as swollen distortion of cell wall, separation and fracture of middle layer, reduction of cell wall electron density, breakdown of vacuole, plasmolysis, coagulation and deposition of cytoplasm. In some case, the dead cytoplasm was transported from one cell to another by impaired cell wall plasmodesma. Pycnidia were generated by coagulation of hyphae under epidermis. The inwall cells of pycnidium were arranged tightly and a structure assembled by several filaments in parallel was observed. The fat granule around and this specific structure may function together in nutrition transportion and accumulation.