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【目的】植物外质体是病原入侵的结构和生理性屏障。本文研究外质体反应在镍诱导的、对白叶枯病系统抗性中的作用,以探讨植物对病原和重金属交叉抗性的生理机制。【方法】以0.5、1.0和2.0mmol·L-1硝酸镍喷施三叶期水稻幼苗的第二叶及以下部位,3d后在未处理的第三叶接种稻白叶枯菌(Xanthomonas oryzae pv.oryzae,Xoo),接种后12d调查病情。测定了2.0mmol·L-1镍处理或/和Xoo接种的幼苗第三叶外质体中愈创木酚POD(G-POD)、NADH-POD、二胺氧化酶(DAO)活性、H2O2和木质素含量。【结果】镍诱导了幼苗对白叶枯病的系统抗性,其中2.0mmol·L-1镍的诱导效果最佳。镍处理下,第三叶外质体液(AWF)中和细胞壁结合的G-POD、NADH-POD,以及AWF中DAO的活性和H2O2水平快速上升,木质素含量显著提高;镍诱导且接种组中,上述指标均明显高于未诱导但接种组。另外,产生H2O2的POD的抑制剂NaN3降低了镍诱导的H2O2积累水平和对白叶枯病的系统诱抗效应,而NADPH氧化酶抑制剂(diphenyleneiodonium chloride)预处理则无明显影响。【结论】本研究结果提示,NADH-POD和DAO活性上升是镍诱导外质体H2O2产生的原因;外质体H2O2和木质素在细胞壁中的积累可能参与了镍诱导的水稻对白叶枯病系统抗性的建立。
【Objective】 Plant exoplastics are the structural and physiological barriers to pathogen invasion. In this paper, the effect of exosome reaction on nickel-induced resistance to bacterial blight was studied in order to investigate the physiological mechanism of plant cross resistance to pathogen and heavy metals. 【Method】 The second and the next parts of the three-leaf stage rice seedlings were sprayed with 0.5, 1.0 and 2.0 mmol·L-1 nickel nitrate, and the third untreated leaf was inoculated with Xanthomonas oryzae pv .oryzae, Xoo), investigated 12 days after inoculation. The activities of GOD, NADH-POD and DAO in the third leaf explants treated with 2.0 mmol·L-1 nickel and / or Xoo seedlings were measured. The activities of H2O2 and Lignin content. 【Result】 Nickel induced systemic resistance of seedlings to bacterial blight. Among them, the induction effect of 2.0 mmol·L-1 nickel was the best. Under nickel treatment, the activity of DAO and the level of H2O2 in G-POD, NADH-POD and AWF in the third leaf extravasation body fluid (AWF) increased rapidly and the content of lignin increased significantly. In the nickel-induced and inoculation group , The above indicators were significantly higher than the non-induced but vaccinated group. In addition, NaN3, an inhibitor of POD producing H2O2, reduced the nickel-induced accumulation of H2O2 and its systemic induction effect on bacterial leaf blight. NADPH oxidase inhibitor (diphenyleneiodonium chloride) had no obvious effect on the accumulation of H2O2. 【Conclusion】 The results of this study suggest that the increase of NADH-POD and DAO activity is the cause of nickel-induced H2O2 production. The accumulation of H2O2 and lignin in the cell wall may be involved in the nickel-induced bacterial blight in rice system The establishment of resistance.