玉米叶片受新月弯孢菌侵染后的细胞病理学变化

Cytopathological changes of maize leaf tissue infected by Curvularia lunata (Wakker) Boed

本文利用透射电子显微镜技术与细胞化学技术研究了玉米叶片受弯孢菌侵染后的超微结构和细胞壁的组成成份变化。透射电镜观察发现,病菌侵入后,菌丝先在寄主细胞间扩展,随着寄主细胞病变、坏死,菌丝可进入寄主细胞形成胞内菌丝。随病菌侵入和在寄主体内扩展,寄主细胞先后发生了一系列的超微结构变化,叶绿体、液泡等细胞器解体,出现质壁分离现象,并最终解体、坏死、变形。细胞化学标记定位发现,受侵寄主细胞壁中纤维素、木聚糖和果胶质的标记密度明显低于未接种的健康组织,表明细胞壁降解酶(如纤维素酶、木聚糖酶和果胶酶)的产生与病菌侵染和致病过程密切相关。

The transmission electron microscope and cytochemical technique were employed to examine the alteration of ultrastructure and cell wall components of maize leaf tissue, uninfected and infected by Curvularia lunata (Wakker) Boed. After invading into the maize leaf tissue, the pathogen spread inter-cellularly and then formed intracellular hyphae in the necrotic host cells. As the extension of the hy-phae, a series of cytopathological changes occurred in the host tissue, including plasmolysis, necrosis of protoplasm, degeneration of organelles such as chloroplasts and vacuoles, and collapse of host cells. The cytochemical labeling of main cell wall components in C. lunata-infected leaf tissue showed that the labeling densities for cellulose, xylan, pectin were significantly reduced as compared with that in unino-culated healthy tissue. These results indicate that cell wall-degrading enzymes such as cellulases, xy-lanases, pectinases secreted by C. lunata are closely related to the penetration and extension of pathogen.