黄瓜幼苗干旱-低温交叉适应与渗透调节的关系

摘要

[目的]探讨干旱诱导黄瓜幼苗对低温胁迫的交叉适应机理.[方法]以'津优3号'幼苗为试材,用10%聚乙二醇(PEG-6000)溶液模拟干旱预处理黄瓜幼苗2 d,未经预处理的作对照.恢复2 d后在光照培养箱中进行低温(昼/夜温度8℃/5℃)处理.[结果]低温胁迫可使黄瓜幼苗叶片的相对含水量,水势和渗透势显著降低,可溶性糖、脯氨酸和可溶性蛋白的含量明显增加.胁迫前经PEG预处理,黄瓜幼苗叶片的相对含水量、水势和渗透势的降低幅度明显减小,脯氨酸、可洛性糖和可溶性蛋白质含量则显著增加.低温胁迫结束时(7 d)时,PEG处理黄瓜幼苗叶片的相对含水量比对照高24.7个百分点,水势和渗透势分别比对照高0.35 MPa和0.1 3 MPa;脯氨酸、可溶性糖和可溶性蛋白质含量分别比对照高41.4%、80.8%和260.7%.[结论]干旱预处理可诱导黄瓜幼苗对低温胁迫的交叉适应性,这种适应性与渗透调节能力的增强有关.%[Objective] The purpose of this paper is to investigate the mechanism of drought induced cross adaptation to low tempe rature stress in cucumber ( Cucumis sativa L ) seedlings. [Method] ‘Jinyou3’cucumberseedlingswereusedasexperimental materials. Seedlings were pretreated under drought condition, which simulated with 10％ polyethylene glycol (PEG) for 2 d.Recovered 2 d later, the pretreated and non-pretreated seedlings (control) were displaced into growth chambers and treated under low temperature (day/night temperature is 8℃/5℃). [ Result ] The results showed that low temperature stress significantly decreased the relative water content, water potential and osmotic potential, while increased proline, soluble sugar and soluble protein contents.Pretreated with 10％ PEG before exposure to stress condition, cucumber seedlings showed a significant low decreased degree in relative water content, water potential and osmotic potential, while high increased degree in proline, soluble sugar and soluble protein contents, in comparison with non-pretreated seedlings. At the end of the experiment (7 d), the relative water content of seedlings pretreated with PEG increased by 24.7 percentage points, the water potential and osmotic potential increased by 0.35 MPa and 0.13 MPa, respectively, and the proline, soluble sugar and soluble protein contents increased by 41.4 ％, 80.8 ％ and 260.7 ％, respectively,in comparison with non-pretreated seedlings. [Conclusion] Drought pretreatment could induce the cross adaptation to low temperature in cucumber seedlings, and the adaptation might be related to the observed increase in osmoregnlation capability.