光叶珙桐根系对PEG模拟干旱胁迫的生理响应及综合评价

Physiological response and comprehensive evaluation of the root system of Davidia involucrata var.vilmoriniana to drought stress simulated by PEG

【目的】光叶珙桐是我国特有珍稀树种珙桐的唯一变种,研究其根系的抗旱性可为其物种保护与研究提供重要参考。【方法】通过盆栽试验,在PEG模拟干旱胁迫处理下,研究光叶珙桐根系中可溶性蛋白、脯氨酸、可溶性糖、还原糖、MDA和SOD的变化,并进行综合评价。【结果】结果表明:15%PEG胁迫处理48 h后可溶性蛋白含量最高(38.534 mg·g^-1);脯氨酸含量随胁迫处理呈先升高后降低的变化趋势,15%PEG胁迫处理下含量最高;可溶性糖、还原糖和MDA含量随干旱胁迫强度的增强和时间的延长而呈升高的变化趋势。PEG干旱胁迫处理24 h后,SOD活性先升高后降低,处理48 h后,呈先降低后升高再降低的变化趋势,随胁迫处理时间的延长,SOD活性显著降低。各生理指标与光叶珙桐根系的抗旱性关联顺序为:可溶性糖(0.731)>MDA(0.702)>可溶性蛋白(0.678)>还原糖(0.646)>脯氨酸(0.609)>SOD(0.587),表明可溶性糖、MDA和可溶性蛋白对光叶珙桐根系的抗旱能力影响最大,还原糖和脯氨酸的影响次之,SOD的影响最小。【结论】光叶珙桐根系在水分胁迫下,可通过积累渗透调节物质,改变保护酶活性等方式来适应干旱胁迫,其适应策略随胁迫程度和时间不同而存在差异。

[Objective]Davidia involucrate var.vilmoriniana is the only variety of D.involucrata a rare and endemic tree species in China.Studying the drought resistance of its root system can provide important reference for species protection and research.[Method]With pot experiment in the treatment of PEG drought stress simulation,the changes of soluble protein,proline,soluble sugar,reducing sugar,MDA and SOD in the root of D.involucrata var.vilmoriniana were studied and evaluated comprehensively.[Result]The results showed that the contents of soluble protein reached the maximam,with 38.534 mg·g^-1,after 48 hours by 15%PEG drought stress treatment,the content of proline increased at first and then decreased,and the content of soluble sugar,inducing sugar and MDA increased with the increase of drought stress intensity and time;SOD activity increased first and then decreased after 24 hours of PEG drought stress treatment,and then decreased after 48 hours of PEG drought stress treatment.SOD activity decreased significantly with the extension of stress treatment time.The order of correlation between the physiological indexes and the drought resistance of the roots of D.involucrata var.vilmoriniana was:soluble sugar(0.731)>MDA(0.702)>soluble protein(0.678)>reducing sugar(0.646)>valine(0.609)>SOD(0.587),indicating soluble sugar,MDA and soluble protein had the greatest influence on the drought resistance of the roots of D.involucrata var.vilmoriniana,followed by the effects of reducing sugar and proline,and the effect of SOD was the least.[Conclusion]Under water stress,the root system of D.involucrata var.vilmoriniana can adapt to drought stress by accumulating osmotic-adjustment-substances and changing the protective enzyme activity.The adaptive strategies vary with the degree and time of drought stress.