高山离子芥试管苗在PEG-6000模拟干旱条件下的生理响应

Physiological responses of Chorispora bungeana seedings in vitro to drought stress simulated by PEG-6000

关键词:  高山离子芥  PEG-6000  干旱胁迫  生理指标  渗透调节

Key words:   Chorispora bungeana  PEG-6000  drought stress  physiological indicators  osmoregulation

摘要:

以高山离子芥(Chorispora bungeana)为试材,采用固液培养法,设置对照(不添加PEG-6000,CK)、5% PEG-6000、10% PEG-6000、20% PEG-6000、40% PEG-6000五个干旱处理水平,研究了不同浓度PEG-6000模拟干旱环境下,对高山离子芥幼苗生理生化特性的影响。结果表明:干旱胁迫下,随着不同的处理时间,脯氨酸含量始终保持上升的趋势且含量显著高于对照; 可溶性蛋白的含量也有波动,呈现先上升后下降的趋势; 丙二醛(MDA)含量,随着时间的延长,呈现先升高再下降的趋势且含量显著高于对照。幼苗叶片叶绿素总含量呈现先升高后下降的趋势,在浓度为40% PEG-6000胁迫下,叶绿素总含量均显著低于对照; 叶绿素a则有显著降低的趋势; 叶绿素b在浓度为5% PEG-6000胁迫下显著升高,在浓度为10%、20%、40%PEG-6000胁迫下也呈现显著升高的趋势; 但其含量总体低于叶绿素a; Chla/Chlb的值经历了先升高后下降的趋势且均高于对照。在各浓度及不同时间处理胁迫下,高山离子芥叶片K⁺、Na⁺、Ca²⁺、Mg²⁺含量有明显波动:K⁺、Ca²在5%和10% PEG-6000胁迫6、12、24、48、72 h后均显著高于对照,而40% PEG-6000胁迫后均显著低于对照。Na⁺在5% PEG-6000各时间段胁迫后含量较对照有所增加,在其它浓度和时间处理下其含量均低于对照; 而Mg²⁺含量在40% PEG-6000胁迫下虽有下降趋势但均显著高于对照。表明在干旱胁迫下,高山离子芥通过改变渗透调节物、光合系统中叶绿素含量及离子含量等,启动应对外界干旱环境的耐旱响应机制,从生理角度揭示了高山离子芥响应耐旱的生理生态机理。

Abstract:

Chorispora bungeana ia a perennial herb,which grows in Qinhai-Tibet Plateau,where has a elevation of 2 600-3 700 m,and has the features of less rain,drought,low temperature,high ambient ultraviolet radiation. The special growing environment gives it the unique molecular and physiological resistance to stress response mechanism. Recently,there are many reports about the molecular and physiological resistance to the low temperature stress response mechanism. However,it has not been reported about what physiological ecology strategies it has in the process of long-term growth to adapt to drought environment. In this study,Taking C. bungeana plantlets in vitro as material,the current study was carried out to investigate the effect of drought stress on a Qinhai-Tibet Plateau plant C. bungeana with solid-liquid culture medium. There were five drought levels being set: the control(without adding PEG-6000,CK),mild drought stress(5% PEG-6000),moderate drought stress(10% and 20% PEG-6000),and severe drought stress(40% PEG-6000)and different stress duration times(6,12,24,48,72). The physiological and biochemical characters were researched. The results showed that,under drought stress and different stress duration times,the contents of proline always kept rising and was significantly higher than control during the experiment; The content of soluble protein showed an initial increase and then subsequent decrease; The content of MDA showed an initial increase and then subsequent decrease but MDA content was significantly higher than control,and chlorophyll also showed an initial increase and then subsequent decrease,and chlorophyll content was significantly lower than control under 40% PEG-6000 stress. Chlorophyll a content showed the trend of decreased significantly. Chlorophyll b content as remarkably increased under 5% PEG-6000 stress and significantely higher than control under 10%,20%,40% PEG-6000. Besides,K⁺、Na⁺、Ca²⁺、Mg²⁺ contents in leaves of C. bungeana had also obvious fluctuation. K⁺ and Ca²⁺ contents were remarkable higher than control under 5% and 10% PEG-6000 during 6 to 72 h. Na⁺ content was higher comparing with control under 5%PEG-6000 and different stress duration times,but the contents were significately decreased under the concentration and time stress. The content of Mg²⁺ showed the declining trend. The study suggested that,under drought stress, C. bungeana started to dealed with drought stress by changing the osmotic regulation substances,photosynthetic system chlorophyll and ion contents. It partly revealed the physiological and ecological mechanism of C. bungeana responding to drought environment.