肋果沙棘幼苗抗氧化酶系统及总黄酮对UV-B辐射增强的响应

Response of antioxidant enzyme system and total flavonoid of woody plant Hippophae neurocarpa seedlings to enhanced UV-B radiation

该文以青藏高原特有木本植物肋果沙棘为材料,在62μW·cm-2的UV-B辐射强度下,分别测定处理了0~6 d幼苗叶片的氧化损伤程度、抗氧化系统酶活性和总黄酮含量及其抗氧化活性,以探究肋果沙棘对UV-B辐射的生理生态响应机制。结果表明:随UV-B辐射时间的增加,肋果沙棘幼苗过氧化氢含量(H 2 O 2)和膜脂过氧化产物(MDA)显著增加;抗氧化系统酶中过氧化氢酶(CAT)活性显著升高;过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性呈先降后升的趋势,且活性均显著低于对照,超氧化物歧化酶(SOD)活性无明显变化;总黄酮含量随辐射时间的积累显著增加,作为非酶抗氧化物质的总黄酮对1,1-二苯基-2-苦基肼(DPPH)的清除率与其含量变化具有显著正相关关系。综上结果表明,肋果沙棘幼苗在抵御该辐射产生的氧化损伤中,通过提高CAT活性及增加总黄酮含量来抵御辐射造成的氧化损伤。

Hippophae neurocarpa,a woody plant endemic to the Qinghai-Tibet Plateau,were used as materials to determine the degree of oxidative damage,activity of antioxidant system enzyme,content of total flavonoid in leaves and its antioxidant activity under UV-B radiation intensity of 62μW·cm-2 under UV-B radiation treatment for 0-6 d,to explore the physiological and ecological response mechanism of H.neurocarpa to UV-B radiation.The results were as follows:With the increasement of UV-B radiation time,the contents of hydrogen peroxide(H 2 O 2)and membrane lipid peroxidation product(MDA)increase significantly;The activity of catalase(CAT)in antioxidant system enzyme increased significantly;The activities of peroxidase(POD)and ascorbate peroxidase(APX)decreased first and then increased,and the activities were significantly lower than that the control check,while the activity of superoxide dismutase(SOD)has no significant changes;The content of total flavonoid increased significantly with the accumulation of radiation time,the total flavonoid as non-enzymatic antioxidants had a significant positive correlation with clearance rate of 1,1-Diphenyl-2-Picrylhydrazyl(DPPH)and its content changes.The above results indicate that the H.neurocarpa resist the oxidative damage caused by radiation mainly depends on the improvement of the CAT activity and the increase of the content of total flavonoid.The results of the experiment provide a theoretical reference for understanding the countermeasures of woody plants like H.neurocarpa grown on the Qinghai-Tibet Plateau for adapting to UV-B radiation.