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以4个对南方锈病表现不同抗性水平的玉米自交系为材料,5叶期接种后,测定叶片中苯丙氨酸解氨酶、多酚氧化酶、超氧化物歧化酶活性以及脯氨酸、可溶性糖、可溶性蛋白含量的变化,分析其与抗南方锈病的关系。结果表明,自交系抗性水平与苗期发病率呈负相关;除脯氨酸含量外,其他生化指标均在自交系间、处理间和不同检测时间点间存在显著差异。苯丙氨酸解氨酶和多酚氧化酶活性在接菌后明显提高,抗病自交系酶活高峰出现早,酶活性升高幅度大于感病自交系;在抗病自交系中,超氧化歧化酶活性在接种后早期上升快,活性高;在感病自交系中,超氧化歧化酶活性在接种后期表现明显升高。叶片组织中可溶性糖含量与感病程度相关,南方锈病属高糖病害;可溶性蛋白含量下降,抗病自交系中含量降低速度和幅度都大于感病自交系。运用最优曲线回归拟合,接菌后1 d苯丙氨酸解氨酶和多酚氧化酶活性变化量、可溶性糖含量变化量等指标与玉米苗期的发病率呈显著或极显著相关。
Four maize inbred lines with different resistance to southern rust were used as materials. After 5-leaf inoculation, the activities of phenylalanine ammonia-lyase, polyphenol oxidase, superoxide dismutase and proline Acid, soluble sugar, soluble protein content changes, analysis of its relationship with resistance to southern rust. The results showed that there was a negative correlation between the resistance of inbred lines and the incidence of seedling stage. In addition to proline content, other biochemical indexes were significantly different among inbred lines, treatments and different detection time points. Phenylalanine ammonia-lyase (ALA) and polyphenol oxidase (PPO) activity increased significantly after inoculation, and the peak of enzyme activity appeared earlier in resistant disease-resistant inbred lines than in susceptible inbred lines , Superoxide dismutase activity increased rapidly in early stage after inoculation, high activity; in susceptible inbred lines, superoxide dismutase activity was significantly increased in the late inoculation. The content of soluble sugar in leaf tissue was related to the susceptible degree. Southern rust was a high sugar content. The content of soluble protein decreased, and the decreasing speed and range of resistance in inbred lines were higher than that of susceptible inbred lines. Using regression curve fitting of optimal curve, the changes of phenylalanine ammonia-lyase and polyphenol oxidase activity, soluble sugar content and other indicators at 1 d after inoculation were significantly or very significantly correlated with the incidence of maize seedling.