Abstract: Active oxygen species (AOS) and peroxidase are believed to involve in many important processes in plants in general and in plant-pathogen interaction in particular. Using DAB (3,3’-diaminobenzidine) staining method, the subcellular localization of H₂O₂ and peroxidase in the inner epidermal cells of rice leaf sheaths infected with compatible and incompatible races of Magnaporthe grisea were detected successfully. DAB staining was detected at the wounding, guard cells and penetration sites of M. grisea. Compared with compatible interaction, H₂O₂ and peroxidase accumulated quickly at the fungal penetration sites in incompatible interaction during initial stage of infection. An increase in the level of H₂O₂ and peroxidase activities in the incompatible interaction was also observed. Histochemical analysis of peroxidase distribution by electron microscopy revealed a striking, highly localized increase in peroxidase activities in the cell wall, plasma membrane, vesicle membrane and around invading hyphae of M. grisea in the penetrated host cells. However, the accumulation of peroxidase activities was delayed and at a much lower level in the penetrated host cells in compatible interaction.

Key words: rice blast, hydrogen peroxide, peroxidase, histochemistry, ultrastructure

摘要： 利用联苯胺蓝（3，3'-diaminobenzidine, DAB）染色法原位检测了水稻稻瘟病菌互作过程中H2O2和过氧化物酶被诱导产生和积累的过程。结果表明在病原菌接种后，水稻叶鞘内表皮细胞在伤口、气孔保卫细胞及病菌侵染点等3种情况下可以检测到染色反应。在水稻-稻瘟病菌非亲和性互作中，H2O2产生和过氧化物酶活性上升快，并逐渐积累到较高的水平；而在亲和性互作反应中，H2O2产生和过氧化物酶活性上升被延迟，积累水平较低。超微结构研究表明，在非亲和性互作反应中，过氧化物酶主要定位于被侵染寄主细胞的细胞壁、细胞质、细胞膜、侵染菌丝周围及由膜系统构成的囊泡膜上；而在亲和性互作反应中，早期（接种后16 h）几乎难以观察到过氧化物酶的聚集，后期（接种后30 h）过氧化物酶聚集增多，但仍明显低于非亲和性互作反应。

关键词: 稻瘟病, 过氧化氢, 过氧化物酶, 细胞化学, 超微结构