Abstract: Two rice cultivars,Yushuinuo and Zhefu 8o2, with high resistance and susceptibility to rice bacterial blight respectively were used as materials. Their second leaves were pre-treated at the two-1eaf stage with paraquat(PQ),a strain of Xanthomonas oryzae pv. oryzae(Xoo )75-1 with weak viru1ence and Tiron (4, 5-dihydroxy-1,3-benzene-disufonic acid)which can specifically react with o2. The challenge inoculation with a strain 76-25 of high viruIence was used at the three-leaf stage. The results showed that pre-treatment with PQ and 75-1 strain induced systematic resistance to strain 76-25, and increased the rate of O2-generation and MDA (malondialdehyde) content in the induced leaves. The change of O2 -generating rate was greatest at 24 h to 72 h after induction with PQ. The changes of MDA content in the induced leaves were later than that of o2-generating rate and the greatest was at 72 h after induction with both PQ and 75-l strain. However the activities of super oxide dismutase (SoD) in the induced leaves decreased after induction with 75-l strain,but increased after induction with PQ. Tiron showed a negative effect on the induced resistance to Xoocaused by 75-l strain and PQ. lt was specially found that the incompatible interaction between 75-1 strain and two rice cultivars turned into a similar compatible interaction when 75-l strain added o2 scavenger Tiron as an inducer.

Key words: active oxygen, Xanthomonas oryzae pv.oryzae, induced resistance, resistance mechanisms, rice

摘要： 以对白叶枯病高抗的水稻品种余水糯和高感的水稻品种浙辐802为材料,于2叶期用Tiron、Paraquat(PQ)和稻白叶枯病菌弱毒株75-1进行诱导处理,测定诱导处理后3、24、48、72 h叶中超氧化物歧化酶(SOD)活性、O2-产生速率及丙二醛(MDA)含量的动态变化,并于3叶期用白叶枯病菌强毒株76-25进行挑战接种,结果表明：75-1和PQ均诱导两品种产生了系统抗性，并使诱导叶中O2-产生速率和MDA含量增加。75-1使O2-产生速率在24 h达峰值，比对照升高30.6%(余水糯)和25.3％(浙辐802);而PQ使O2-产生速率在24～72 h维持较高水平，比对照升高49.4％(余水糯) 和39.7％(浙辐802)。MDA含量的变化晚于O2-产生速率的改变，在72 h达最高值。75-1使SOD活性降低，并在24 h达最大降幅；而PQ使SOD活性升高，并在48 h达峰值。Tiron使PQ和75-1的诱导效果减弱，并使75-1对余水糯和浙辐802的互作由非亲和性互作转变为类似亲和性互作，导致侵染斑的形成。

关键词: 活性氧, 稻白叶枯病, 诱导抗性, 抗性机制, 水稻