玉米对南方锈病抗性的生化基础研究

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。

Relationship of Biochemical Parameters of Corn Inbred Lines and Their Resistance to Southern Corn Rust

The changes of the activity of some biochemical parameters, such as phenylalanine ammonia lyase(PAL), polyphenol oxidase(PPO), superoxide dismutase(SOD), soluble sugar, soluble protein and proline, were detectedin four corn inbred lines with different leves of resistance to southern corn rust. The results showed that the resistancelevel was associated with incidence of the disease; except for proline, other biochemical parameters were significantdifferent among inbred lines, test treatments, and testing times after inoculation with Puccinia polysora; the activitiesof PAL and PPO were raised obviously after inoculation with Puccinia polysora. The peak and the increased rateof PAL and PPO were earlier and higher in resistant lines than in susceptible ones. The activity of SOD was higher inresistant lines in the early stage after inoculation, but it was higher in the late stage after inoculation in susceptiblelines. The content of soluble sugar was higher in the susceptible lines than in the resistant lines that means the southerncorn rust is one of high sugar diseases. By means of fitting curve estimation with SPSS software the relationshipbetween the parameters of PAL, PPO and soluble sugar and the incidence of infected plants one day after inoculationwith Puccinia polysora was significant.