Abstract:

Reactive oxygen species (ROS) are produced in plant cells during environmental stress, the production rate of ROS and the responses of the antioxidant system are often used to evaluate plant stress tolerance. Two varieties (Spark and Texoka) of buffalograss (Buchloe dactyloides) were subjected to 34 days of 40% (moderate light) and 80% (low light) shading stress, the acclimation of reactive oxygen (superoxide radical O₂^-, hydrogen peroxide H₂O₂), lipid peroxidation (malondlaldehyde MDA), antioxidase (superoxide dismutase SOD, peroxidase POD and catalase CAT) activities, and antioxidant (ascorbic acid, AsA) content in plant leaves were characterized. The results showed that MDA content of buffalograss leaves under low light was higher than those in moderate light, and also were the peak activities of antioxidant enzyme and peak value of antioxidant. The peak activities of SOD and CAT, peak content of AsA in Spark buffloagrass leaves occurred 5 to 10 days later than that in Texoka buffalograss leaves, but peak value was much higher; whereas the peak content of MDA was much lower in Spark buffalograss leaves than in Texoka buffalograss leaves. Compared to antioxidase, there were 2 antioxidant peaks in Spark buffalgrass leaves during the process of shading treatment and the increase of AsA was much greater than in Texoka buffalgrass leaves. These results indicated that Spark buffalograss is more shade tolerant than Texoka buffalograss, and the rapid increase of antioxidant AsA in Spark buffalograss leaves under shading stress may contribute to its better shade tolerance.

Key words: Buffalograss, Shading stress, Lipid peroxidation, Antioxidase, Antioxidant

摘要：

逆境胁迫会诱导植物细胞内活性氧的产生，通过研究同一逆境胁迫下植物活性氧的产生速率和抗氧化系统的响应可衡量植物的抗逆性。以Spark和Texoka野牛草（Buchloe dactyloides）为材料，研究了34天持续的中光（40%遮阴）和低光（80%遮阴）胁迫处理下，两种野牛草叶片活性氧的产生、膜脂过氧化及抗氧化酶活性和抗氧化剂含量的变化规律。结果表明：低光胁迫时植物丙二醛（MDA）的含量更高，抗氧化酶活性和抗氧化剂含量的峰值也更高；Spark野牛草超氧化物歧化酶（SOD）、过氧化氢酶（CAT）的相对活性和抗坏血酸（AsA）的相对含量到达峰值的时间比Texoka野牛草推迟5~10天，但峰值更高，而MDA峰值的相对含量则远远低于Texoka野牛草；与抗氧化酶相比，Spark野牛草叶片中AsA的相对含量出现了两次高峰，峰值远远高于Texoka野牛草，认为Spark野牛草比Texoka野牛草更耐阴的原因与遮阴胁迫下其叶片中AsA含量较高有关。

关键词: 野牛草, 遮阴胁迫, 膜脂过氧化, 抗氧化酶, 抗氧化剂