低温胁迫对麻竹叶片和根系抗性生理指标的影响

Effects of low temperature stress on resistance physiological indices of leaf and root of Dendrocalamus latiflorus seedlings

采用室内人工低温处理,研究了麻竹(Dendrocalamus latiflorus)叶片及根部质膜透性、丙二醛、可溶性蛋白、可溶性糖含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和膜脂脂肪酸组成的变化,寻找与竹类植物耐寒性关系最密切的抗性生理指标。结果表明:低温预处理(8℃)15d后,麻竹叶片中可溶性糖、可溶性蛋白含量、POD活性显著提高,根部可溶性糖含量、POD活性显著升高;低温胁迫处理(-2℃)72h后,经低温预处理的麻竹叶片可溶性糖、可溶性蛋白质含量、SOD、POD活性显著高于未经低温预处理,而质膜透性显著低于未经低温预处理,但膜脂过氧化程度显著高于-2℃处理前;经低温预处理的麻竹根部SOD、POD活性及膜脂不饱和脂肪酸相对含量显著高于未经低温预处理,而质膜透性、膜脂过氧化程度较-2℃处理前无显著差异。说明剧烈降温对麻竹生理特征造成严重影响,叶片通过提高可溶性蛋白、可溶性糖含量,维持较高的POD活性以减轻低温伤害;根系则通过维持较高的SOD、POD活性以减轻低温下膜脂过氧化水平,并通过提高膜脂不饱和脂肪酸比例降低质膜透性来抵御低温对膜的伤害。

An indoor low temperature experiment was conducted to study the variations of membrane permeability, malondialdehyde, soluble protein and soluble sugar contents, superoxide dismutase （SOD） and peroxidase （POD） activities, and membrane lipid fatty acids composition in Dendrocalamus latiflorus seedling’s leaves and roots under different levels of low temperature stress. The differences in the response characteristics and cold resistance related physiological indices were also analyzed. After low temperature （8 ℃） pretreatment for 15 days, the leaf soluble protein and soluble sugar contents and POD activity and the root soluble sugar contents and POD activity increased significantly. After cold-hardening （-2 ℃） for 72 h, the leaf soluble protein and soluble sugar contents and SOD and POD activities and the root SOD and POD activities and relative content of membrane lipid unsaturated fatty acids with low temperature （8 ℃） pretreatment were significantly higher while the leaf membrane permeability were significantly lower, as compared to those without low temperature （8 ℃） pretreatment. After the cold-hardening with low temperature （8 ℃） pretreatment, the leaf membrane lipid peroxidation was significantly higher, while the root membrane permeability and membrane lipid peroxidation had little difference, as compared to those before cold-hardening （-2 ℃）. Overall, acute low temperature stress had serious impacts on the physiological characteristics of D. latiflorus. D. latiflorus leaves could mitigate low temperature injury via increasing their soluble protein and soluble sugar contents and maintaining higher POD activity, whereas the roots could resist the low temperature injury to their membrane via maintaining higher SOD and POD activities to decrease the membrane lipid peroxidation at low temperature and increasing the relative content of membrane lipid unsaturated fatty acids to decrease membrane permeability.