Factor Inducing Hypersensitive Resistance of Rice Plants to Blast Fungus, Pyricularia oryzae

稻瘟病菌分泌的因子诱导水稻悬浮培养细胞的局部死亡和苯丙素类代谢的激活。显微镜观察显示，在愈伤组织周围的细胞死亡后1小时内出现的TCA沉淀级分（TCAp）的真菌培养滤液。死亡细胞的数量持续增加达24小时，然后在约48小时后愈伤组织普遍布朗宁。然而，培养物在愈伤组织块内仍然含有未损伤的细胞，并且与未处理的愈伤组织的培养物活力没有显著差异。苯丙氨酸解氨酶（PAL）和过氧化物酶（POX）活性在TCAp处理后6 h和1- 2d分别达到最大值。TCAp诱导的培养细胞PAL活性无品种特异性。在TCAp处理的愈伤组织中发现酚类化合物。在这些酚类化合物中，对香豆酸的积累是显着的。用<18>反相色谱法测定了真菌培养滤液的不同组分诱导细胞布朗宁的能力和培养细胞中PAL的活性：在各组分中，诱导细胞布朗宁能力最强的组分刺激PAL活性。

Localized cell death and activation of phenylpropanoid metabolism in suspension-cultured rice cells are induced by factors secreted by blast fungus. Microscopic observation revealed that the death of cells at the periphery of calli appeared within 1 h after addition of a TCA-precipitable fraction (TCAp) of the fungus culture filtrate. The number of dead cells continued to increase for up to 24 h, followed by general browning of the calli after about 48 h. However, the culture still contained uninjured cells within the callus clumps, and there was no significant difference in culture viability from non-treated callus. Phenylalanine ammonia-lyase (PAL) and peroxidase (POX) activities were induced by TCAp and reached a maximum at 6 h and 1-2 days after treatment, respectively. No cultivar-race specificity was found in PAL activity of cultured cells induced by TCAp. Phenolic compounds were found in callus tissue treated with TCAp. Among these phenolic compounds, accumulation of p-coumaric acid was remarkable. Fractions of fungal culture filtrate obtained by C_<18> reverse-phase chromatography were assayd for the ability to induce cell browning, PAL activity in cultured cells : Among the individual fractions, that which had the most potent activity to induce browning stimulated PAL activity.