水稻对白叶枯病抗性的生物诱导及凝集素的作用

用白叶枯非亲和性菌株G-3-1,G-3-2,78-3的活/死细胞剪叶法,分别于孕穗期对高感的金刚30和中抗的74-105水稻品种植株的顶部展开叶连续3次(间隔4d)诱导接种,7d后在同一叶片及其上一叶接种亲和性菌株76-25,结果发现两品种的被接种叶及紧接其上的一叶均获得了诱导抗性,活体诱导物较死体诱导物诱导的抗性强,74-105品种获得的抗性较金刚30强,金刚30,74-105及抗病的南粳15经78-3活细胞诱导接种的叶片组织液,对78-3和76-25菌株的生长有显著的抑制作用;抗病品种的正常和受伤叶片组织浓也有抑菌作用,但均较诱导叶弱,从前述3个水稻品种的胚及叶片组织提取凝集素并纯化,经测定,二者对供测的5个白叶枯菌株均有凝集作用,但对非亲和性菌株的凝集作用比对亲和性菌株强;洗去胞外多糖可增加这种凝集作用;凝集素对病原菌无抑菌作用;诱导处理后叶片的凝集素含量与未诱导处理者无明显差异,初步认为凝集素在诱导抗性的初始阶段起着寄主对病原菌的识别作用,且其半抗原糖具有诱导抗性的活性。

BIOINDUCTION OF RICE RESISTANCE TO BACTERIAL BLIGHT AND THE ROLE OF RICE LECTINS IN INDUCED RESISTANCE

Suceptible cultivar Jingang 30 and medium resistant cultivar 74-105 were used to test the induced resistance. Alive and dead cells of incompat-ible strains 78-3, G-3-1 and G-3-2 of Xantbomonas campestris pv. oryzae werepre-inoculated respectively on the top expanding leaves three times at a 4-dayinterval at booting stage by clipping method seven days after the last pre-inoc-ulation, the compatible strain 76-25 was inoculated on the same leaves and theleaves closely above. The inoculated leaves of each cultivar were found to bewith induced resistance alike . Such resistance induced by the alive cells ofCausal agent was stronger and more stable than that by the dead ones. The indu-ced resistance of 74-105 was stronger than that of Jingang 30. The leaf juice ofJingang 30, 74-105 and Nangeng 15 (resistant) inoculated with strain 78-3 in-hibited the growth of strains 76-25 and 78-3 more distinctly than the juice ofthe wounded/normal leaves. N-acetyl-a-glucosamine was the same hapten sugarof embryo/leaf lectins of rice. These two lectins were more agglutinative to theincompatible strains than to the compatible strains. The removal of EPS frombacterial cells increased the agglutination. Lectins of embryo/leaf showed no in-hibition to the causal bacterium. The content of leaf-lectin indicated no differ-ence between the induced leaves and the untreated ones. It was suggested thatthe lectin of rice might play a role in inducing the resistance in the initialrecognization stage and the hapten sugar of lectin be active in inducing the re-sistance to bacterial blight of rice.