裸果木渗透调节物质和抗氧化酶活性对干旱的响应

裸果木(Gymnocarpos przewalskii)起源于古地中海,为荒漠区少有的第三纪孑遗植物种。本文采用2017年6月、7月和8月采集于甘肃安西自然保护区内的裸果木中龄和老龄植株叶片,分析自然干旱影响下叶片渗透调节物质及抗氧化酶活性的变化。结果表明:随着干旱程度的增加,裸果木叶片的可溶性蛋白(SP)显著积累,发挥着重要的渗透调节作用,中龄植株叶片的可溶性糖(SS)含量和老龄植株叶片的脯氨酸(Pro)含量先增加后显著降低,渗透调节作用有限。干旱加剧时,中龄植株叶片的超氧化物歧化酶(SOD)活性和抗坏血酸过氧化物酶(APX)活性呈明显的先增后降。严重干旱时,过氧化物酶(POD)活性和过氧化氢酶(CAT)活性明显增强,说明其通过4种酶的协同作用清除过剩的活性氧,减轻过氧化伤害;老龄植株叶片的CAT活性持续增强,APX活性明显的先升后降,POD活性在重度干旱时显著增强,主要通过这3种酶减轻膜系统伤害。丙二醛(MDA)含量则随干旱程度增大显著增加,膜脂过氧化程度不断加深。在相同的降雨条件下,裸果木中、老龄植株的Pro、SS、SP含量、POD和CAT活性、MDA含量对干旱的响应程度存在显著差异,隶属度函数评价法表明,老龄植株的抗旱能力大于中龄植株,表明裸果木的抗旱性随年龄的增大而提高。

Response of Osmotic Regulation Substances and Antioxidant Enzyme Activity in Leaves of Gymnocarpos przewalskii to Drought

this study,the leaves of G. przewalskii were collected from the medium-aged and old-aged individuals in the Anxi Nature Reserve in Gansu Province in June,July and August 2017. The samples were used to analyze the change of osmotic regulation substances and antioxidant enzyme activity under natural drought. The results showed that the soluble protein (SP) accumulated significantly with the increase of drought level and played the main osmotic regulation,the soluble sugar (SS) content in leaves of the medium-aged individuals and the proline (Pro) content in those of the old-aged ones increased at first and then decreased obviously,and the osmotic regulation was limited.As for the medium-aged individuals,when the drought level was increased,the superoxide dismutase (SOD) activity and ascorbate peroxidase (APX) activity significantly increased at first and then decreased,and the peroxidase (POD) activity and catalase (CAT) activity were increased significantly under severe drought,which indicated that the four enzymes scavenged the active oxygen by synergistic effect. For the old-aged ones,the CAT activity was continuously increased,the APX activity was obviously increased at first and then decreased,and the POD activity was significantly increased under severe drought,which showed that the damage to membrane system was mainly relieved by the three enzymes. The malondialdehyde (MDA) content in leaves was significantly increased with the increase of drought level and membrane lipid peroxidation. Under the situation with similar rainfall,there were the significant differences between the medium-and the old-aged individuals in the response of Pro,SS and SP content,POD and CAT activity and MDA content in leaves to drought. The result of subordinate function method showed that the drought resistance of the old-aged individuals was higher than that of the medium-aged ones,indicating the drought resistance of G. przewalskii would enhance with the age increase.