裸果木对模拟渗透胁迫的生理响应

Physiological responses of Gymnocarpos przewalskii to simulated osmotic stress

【目的】探究裸果木幼苗叶片对PEG渗透胁迫的生理响应规律,为揭示裸果木抗旱生理机制提供理论依据。【方法】以裸果木幼苗为试验材料,采用不同浓度(0%,5%,10%,15%,20%)的PEG-6000分别处理8 h和24 h,测定叶片的部分水分生理指标和抗氧化指标。【结果】在PEG胁迫下,裸果木幼苗叶片的相对含水量显著下降。在胁迫24 h时,随PEG浓度增大,束缚水含量/自由水含量呈现先显著升高后降低的趋势。脯氨酸和可溶性糖含量在PEG胁迫时呈波动变化,但胁迫24 h时达到最大值。丙二醛(MDA)含量随着PEG胁迫程度的增加而上升,胁迫24 h时,所有处理的MDA含量均显著高于对照。过氧化氢含量在PEG胁迫8 h和24 h时均较对照显著升高。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性对8 h和24 h的PEG胁迫响应均达显著水平,过氧化物酶(POD)活性在胁迫24 h时显著增强。【结论】PEG渗透胁迫24 h对裸果木幼苗造成明显的过氧化伤害,增加叶片束缚水比例,主动积累脯氨酸和可溶性糖,增强SOD、CAT、APX和POD酶活性是裸果木适应渗透胁迫的主要方式。

【Objective】 To study the response of Gymnocarpos przewalskii seedlings to PEG stress in order to provide a reference for elucidating the drought resistance mechanism of G.przewalskii.【Method】 Under drought stress,the relative water content of the leaves of G.przewalskii seedlings decreased significantly.The ratio of bound to free water content first increased significantly and then decreased with increasing PEG concentration under 24 h stress.The content of proline and soluble sugars fluctuated under PEG stress and accumulated significantly under 24 h PEG stress.The content of malondialdehyde(MDA) increased with the increase of PEG stress and was significantly higher than that of the control under 24 h stress.Hydrogen peroxide levels increased significantly under PEG stress for 8 h and 24 h compared to the control.The activity of superoxide dismutase(SOD),catalase(CAT) and ascorbic acid peroxidase(APX)reached the significant level compared to the control under PEG stress for 8 h and 24 h,and the activity of peroxidase(POD) increased significantly under 24 h stress.【Conclusion】 PEG stress for 24 h caused significant peroxidative damage to G.przewalskii seedlings.The main adaptation of G.przewalskii seedlings to osmotic stress was to increase the amount of bound water,to actively accumulate proline and dissolved sugars,and to increase the activity of SOD,POD,CAT and APX.