甘蓝型油菜防御酶活性变化与抗病性的关系

对不同抗性油菜品种7～8叶期及盛花期感染油菜菌核病后及对照叶片中几种重要防御酶类活性变化的研究结果表明：7～8叶期叶片SOD活性极显著高于盛花期，而盛花期POD、PPO、PAL活性显著或极显著高于7～8叶期。与对照相比，感病品种处理叶片中SOD、POD活性显著增加，而抗病品种变化较小且因品种而异；7～8叶期及盛花期处理叶片中，各品种(系)PPO活性有不同程度的下降，其中抗(耐)菌核病品种(系)下降达显著水平，并且中R888达极显著水平；7～8叶期各品种(系)处理叶片中PAL活性没有明显变化，盛花期各品种(系)处理叶片中PAL活性均显著地下降，并以抗(耐)菌核病品种(系)下降较多，其中，中R888的PAL活性的下降达极显著水平。酶活与病斑直径的相关性分析也表明，品种抗性主要与7～8叶期对照叶片中SOD、POD活性及盛花期对照SOD、PPO、PAL活性水平较高有关，感病品种处理叶片中防御酶活性与对照相比增加比例较高，说明酶活增加比例与感病性有关。不同时期不同品种(系)防御酶活性的变化不同说明不同抗(耐)菌核病品种(系)在不同的发育时期存在不同的抗病机制。

Activities of Some Defense Enzymes in Brassica napus L.and their Relations with Resistance to Sclerotinia sclerotiorum

The activities of some important defense enzymes were investigated in the leaves of seedling stage (7-8 leaves) and flowering stage in 6 Brassica napus cultivars (lines) with different resistant level of Sclerotinia sclerotiorum. In general, SOD activities in seedling stage were significantly higher than that in flowering stage, but the activities of POD, PPO and PAL in flowering stage were significantly higher than that in 7-8 leaves stage. Comparing with their control, the activities of SOD, POD in susceptible varieties significantly increased in the infected leaves, however, the change was relative small and not consistently in different resistance (tolerance) varieties. The activities of PPO were decreased in the infected leaves in two stages, and the difference was significant for tolerance varieties, especially for the variety of Zhong R888. The activities of PAL were significantly decreased in the infected leaves in flowering stage, and especially for tolerance varieties. The correlation analysis between lesion diameters and enzyme activities and their changes revealed that the tolerance to Sclerotinia sclerotiorum was related to higher level of activities of SOD, POD in seedling stage and SOD, PPO, PAL activities in the flowering stage in uninfected plants, and the increasing rate of these protective enzymes was associated with susceptibility. These results indicated that the resistant mechanisms of these resistant cultivars to Sclerotinia sclerotiorum of rapeseed may be different in different development stage and tolerance varieties.