Abstract: The generation of superoxide(O₂^-) in incompatible and compatible combinations among nineteen rice (Oryza sativa L. ) cultlvars and eight Pyricularia oryzae races or their hyphal metabolites (RBHM) had been measured. The O₂^- generation was enhanced in incompatible combinations but not in compatible combinations. Digitonln could induce O₂^- generation increased rapidly in rice seedlings and accompanied by the increase of their resistance to the infection by compatible blast pathogen. Dethyldithiocarbamate (DDTC), the inhibitor of cooper-type superoxide dismutase (SOD), could induce O₂^- generation seriously. N-ethylmaleimide (NEM), the scavenger of O₂^-, could induce the increase of rice SOD activity. Actinomycin D and cycloheximide could also induce O₂^- generation accompanied by the inhibition of SOD activity. The activity of phenylalanine ammonia-lyase (PAL) could be induced stronger and faster in incompatible system than in compatible system. However, the inducible PAL activity seems to be no specific relationship to rice resistance to blast infection because it could be induced by many different chemicals including digitonin, DDTC and NEM. The activity of chitinase and β-1,3-glucanase could not be induced by DDTC, NEM and digitonin. Their activation seems no relationship to O₂^- generation, and the signal transduction pathway for induction of their expression may not be similar to the pathway for PAL activation.

Key words: chitinase, β-1, 3-glucanase, phenylalanine ammonia-lyse, resistance to blast, superoxide

摘要： 19个水稻(Oryza sativa L.)品种和8个稻瘟菌生理小种，或它们菌丝代谢产物(RBHM)组成的亲和与非亲和组合, 及一些品种和稻瘟菌生理小种间交叉组合的实验结果表明,在非亲和组合中的水稻品种都有超氧(O₂^-)产率的诱导升高。 毛地黄皂苷诱导O₂^-产率增高同时，也使稻苗对原亲和病原表现出抗性。二乙基二硫代氨基甲酸(DDTC)对超氧歧化酶(SOD)活性近乎完全抑制时,能使O₂^-产率猛增;N- 乙烯马来酰亚胺(NEM)近乎完全清除O₂^-时,也可增加SOD活性。 放线菌素D和环己亚胺处理后能抑制SOD活性,而使O₂^-产率明显增高。除了抗病时苯丙氨酸解氨酶(PAL) 活性诱导比感病时增长较强或较早外,无论用RBHM也好,毛地黄皂苷、DDTC、NEM也好,PAL活性都会增加。但它们都不能诱导几丁酶、β-1,3-葡聚糖酶活性升高。这样，PAL活性的诱导似乎并不是水稻对病原攻击一种特异的反应。几丁酶、β-1,3- 葡聚糖酶活性诱导升高未必与O₂^-产率相关,而且诱导它们表达的信号传导与PAL也可能是不相同的。

关键词: 稻瘟病抗性, 超氧, 苯丙氨酸解氨酶, 几丁酶, β-1, 3-葡聚糖酶