高枝假木贼种子低温萌发与抗氧化酶系统的关系

高枝假木贼具有胎生萌发特性，并且发生在早春。为揭示该植物在早春低温环境中胎生萌发特性，在实验控制条件下，对种子吸胀萌发过程中3种保护酶活性和丙二醛（MDA）含量进行测定，并与野外自然条件下，不同发育阶段幼苗的保护酶活性变化进行对比分析。结果显示：高枝假木贼种子吸水快，在室内5 ℃低温控制下6 h吸水量趋于平稳。种子在低温吸胀过程中，MDA的含量较高（0.02~0.04 μmol?g^-1），过氧化物酶（POD）活性保持在高水平稳定状态，过氧化氢酶（CAT）和超氧化物歧化酶（SOD）活性在吸胀4 h之后快速上升。随着种子萌发，不同幼苗阶段MDA含量急剧下降, 维持在0.004 μmol?g^-1的极低水平，POD活性显著下降，SOD活性先下降后上升至幼苗3 cm时达到最高，CAT活性呈缓慢上升趋势。在野外低温条件下，SOD、CAT和POD活性均显著高于5 ℃恒温控制下的幼苗酶活性水平。表明高枝假木贼快速吸胀萌发特性和3种保护酶在吸胀萌发不同阶段的协同作用，共同为胎生萌发在早春低温的正常生长提供保护。

Relationship between Low temperature Germination and Antioxidant Enzyme Systems of Anabasis elatior Seeds

Anabasis elatiorWTBZ] is a viviparous subshrub that primarily occurs in the Junggar Desert. Vivipary occurs only in early spring. In order to understand how the physiological property of WTBX]A. elatiorWTBZ] adapts the low temperature, the MDA, antioxidant enzyme POD, CAT and SOD activities during imbibition and germination of WTBX]A. elatiorWTBZ] seeds were selected as the physiological indicators to study the physiological response under chilling stress. Moreover, a comparative study between laboratory control and natural environment was conducted to determine the change of activities of antioxidative enzyme POD, CAT and SOD during seed germination under chilling condition. The main results showed that the absolute absorbed water of seeds was stabilized at 5 ℃ after imbibition for 6 hours. MDA content of WTBX]A. elatiorWTBZ] seeds was maintained in a range from 0.02 to 0.04 μmol•g-1. A stable change of POD activity was remained. CAT and SOD activities were increased after 4 hours imbibition. Compared with the imbibition stage, MDA content of seedlings was declined sharply to a very low level (0.002-0.004 μmol•g-1). POD activity was also significantly deceased. SOD activity was low at the early germination stage. Subsequently, SOD activity was gradually increased to the maximum. CAT activity was markedly increased at the first three growth stages (0-3 cm length) of seedlings, then decreased. The activities of antioxidant enzymes of seedlings in natural environment were higher than those at 5 ℃ in laboratory. The results revealed that both rapid water absorption and synergistic effects of three antioxidant enzymes provided a guarantee to form viviparous seedlings, and also a significance to revealing the propagation approach of desert viviparous shrubs.