黄芩(Scutellaria baicalensis)幼苗对干旱胁迫的生理适应性反应

Physiological Responses of Scutellaria baicalensis Seedlings under Drought Stress

采用聚乙二醇(PEG-6000)模拟干旱胁迫处理黄芩幼苗,检测幼苗体内丙二醛(MDA)含量,超氧化物岐化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)保护酶活性,渗透调节物质脯氨酸和可溶性糖含量。结果表明,随着干旱胁迫时间的延长,不同程度的干旱胁迫黄芩幼苗体内MDA含量均不断升高,并且含量均高于对照组。3种不同程度干旱胁迫,SOD活性呈现先升高后降低的趋势,SOD活性表现为:20%PEG胁迫>10%PEG胁迫>30%PEG胁迫。不同程度的干旱胁迫下POD活性表现出不同的动态变化趋势,20%和30%的PEG胁迫后,POD活性先升高后降低,峰值分别出现在处理后第5天和第7天,分别高于对照19.3%和13.3%。CAT活性表现出相似的变化趋势,即干旱胁迫3d后,CAT活性显著升高,均于处理后第5天达到峰值,分别高于对照33.4%、36.8%和29.4%,随后开始下降。10%和20%PEG胁迫第5天,APX活性均急剧升高,30%PEG胁迫第7天,APX活性显著降低,但是干旱胁迫7d后,3种不同干旱胁迫下的APX活性均高于对照组。3种不同程度PEG胁迫处理均于第7天脯氨酸含量达到峰值可溶性糖含量于胁迫3d后大幅升高,并随着胁迫时间的延长增长速率逐渐减小。30%的PEG处理后可溶性糖含量的峰值的出现早于10%和20%的PEG处理。说明在一定干旱胁迫下,黄芩幼苗通过可溶性糖和脯氨酸等渗透调节物质来增强植物保水能力,通过协调各种保护酶的活性来保持一个相对稳定的状态,达到抗旱的目的。

To study the physiological adaptive responses of Scutellaria baicalensis seedlings under drought stress and to provide a theoretical basis for the research of the mechanism of drought resistance,PEG-6000 with three levels（10%,20%,and 30%）was used to simulate drought stress.The contents of MDA,proline,soluble sugar and the activities of SOD,POD,CAT and APX were measured.It was observed that the contents of MDA increased along with time in all stressed groups,and higher than those of the control. The activities of SOD increased and then decreased under stress,and in the order of 20%10%30% treatment.The activities of POD demonstrated different variation patterns：it increased firstly,and then decreased after treated with 20%and 30% PEG,and appeared peak values on day 5and 7,19.3%and 13.3% higher than the control.The activity of CAT showed the same variation tendency under different treatments,i.e.,it significantly increased 3days after the treatment,and reached the peak values on day 5, 33.4%,36.8%,and 29.4% higher than the control.The activities of APX under different treatments werehigher than the control.The content of proline reached a peak on day 7.The peak value of the content of soluble sugar appeared earlier in 30%treatment than in 10% and 20%treatments.The results indicated that seedlings promoted their water conservation capabilities through increasing the contents of osmotic adjustment substances,such as soluble sugars and proline,and coordinated different enzymes in a relative stable levels to resist drought stress.