多歧苏铁对高温和聚乙二醇处理的生理响应

Physiological Response of Cycas multipinnata to High Temperature and PEG Treatments

以多歧苏铁离体叶片为试材,研究了高温(25、35、45、55℃)和聚乙二醇(PEG)处理(0、0.05、0.10、0.15、0.20g·mL^(-1))对多歧苏铁生理指标的影响,以期了解多歧苏铁的抗逆机理及生态适应策略。结果表明:各温度处理间丙二醛含量无显著差异;45℃处理后的过氧化氢酶(CAT)活性显著高于其它温度处理;与25℃处理相比较,35、45、55℃处理后的过氧化物酶(POD)活性显著下降,超氧化物歧化酶(SOD)活性显著升高;45℃和55℃处理后可溶性糖含量显著升高,但各温度处理间脯氨酸含量无显著差异。各浓度PEG处理间,色素含量及组成、Fv/Fm、丙二醛和脯氨酸含量及抗氧化酶(CAT、POD、SOD)活性均无显著差异,但0.10g·mL^(-1)和0.15g·mL^(-1) PEG处理后的可溶性糖含量较其它浓度PEG处理后的显著提高。综上所述,多歧苏铁对高温具有一定耐受性,其中,可溶性糖和抗氧化酶(CAT、SOD)在渗透调节和抗氧化胁迫中起了一定作用。同时,所试PEG浓度并未引起多歧苏铁明显生理变化,该种可能具有较强的耐旱性。

To understand the ecological adaptive mechanisms of Cycas multipinnata under stress conditions,leaves collected from adult trees were used to determine the effects of different temperatures （25,35,45,55 ℃） and different concentrations of PEG （0.00,0.05,0.10,0.15,0.20 g？mL-1） on physiological characteristics of C.multipinnata.The results showed that MDA content did not vary significantly among different temperatures;CAT activity of leaves subjected to 45 ℃ was significantly higher than that of leaves subjected to other temperatures;compared to those of leaves subjected to 25 ℃,POD activity decreased and SOD activity increased significantly for leaves that were treated at 35,45,55 ℃;the soluble sugar content of leaves treated at 45 ℃ and 55 ℃ increased significantly,but the proline content of leaves did not vary significantly among temperature treatments.The pigment content and composition,Fv/Fm,MDA content,proline content and antioxidant enzyme （CAT,POD and SOD） activities did not vary significantly among leaves treated at various concentrations of PEG,but the soluble sugar contents of leaves treated at 0.10,0.15 g？mL-1 of PEG were significantly higher than that of leaves treated at other concentrations of PEG.In conclusion,C.multipinnata possessed relatively high tolerance to heat,and soluble sugar and antioxidant enzymes such as CAT and SOD played roles in osmotic adjustment and resistence of oxidative stress under high temperatures.The physiological process of C.multipinnata was not significantly affected by the tested concentrations of PEG which might suggest the relatively high tolerance of the species to drought.