低温胁迫对澳洲茶树组培苗生理特性的影响

Effects of low temperature stress on physiological characteristics of Melaleuca alternifolia tissue culture seedlings

关键词:  澳洲茶树, 低温胁迫, 形态特征, 抗氧化物酶, 抗氧化剂, 渗透调节物质

Key words:   Melaleuca alternifolia, low temperature stress, morphology characteristics, antioxidant enzymes, antioxidants, osmotic regulators

摘要:

为探讨澳洲茶树组培苗耐受低温的能力及对低温胁迫的响应机制,该文测定了3月龄澳洲茶树组培苗低温处理过程及恢复培养后叶片叶绿素(Chl)、丙二醛(MDA)、抗氧化物酶(SOD, POD, CAT)、抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性糖(SS)、可溶性蛋白(SP)、游离脯氨酸(Pro)的变化。结果表明:(1)-5 ℃胁迫24 h,保护酶及抗氧化物含量均显著下降,MDA含量显著上升。(2)0 ℃下,AsA和GSH先降后升,POD和CAT相反,SOD持续升高; 胁迫48 h后保护酶活性显著升高,抗氧化剂含量显著降低。(3)10 ℃下,SOD活性先降后升; 胁迫48 h后,渗透调节物质含量均显著升高。因此,3月龄澳洲茶树组培苗在-5 ℃受到致死冻害,幼苗能通过启动抗氧化系统及快速积累渗透调节物质响应0 ℃以上低温胁迫,但对10 ℃和0 ℃两种低温胁迫的应答机制却存在一定的差异。该研究结果将有助于深入了解其对低温的耐受能力及生理响应机制,为合理引种及规模化种植提供理论依据。

Abstract:

To explore the response and adaptive mechanisms of Melaleuca alternifolia tissue culture seedlings to cold stress, 3-month-old tissue culture seedlings were exposed to low temperatures and then recovered at air temperature, the physiological indexes including chlorophyll(Chl), malondialdehyde(MDA), antioxidant enzymes(SOD, POD, CAT), ascorbic acid(AsA), glutathione(GSH), soluble sugar(SS), soluble protein(SP), free proline(Pro)were examined. The results were as follows:(1)The stress at -5 ℃ for 24 h caused a significant decrease in the activities of antioxidant enzymes and the contents of antioxidants, but an increase in the content of MDA.(2)At 0 ℃, the activities of POD and CAT first rose and then descended, while the contents of AsA and GSH showed an opposite pattern; After 48 h of stress, the activities of protective enzymes significantly increased but the contents of antioxidants decreased.(3)At 10 ℃, the activity of SOD first elevated and then declined; All three osmotic regulators manifested a remarkable elevation after the 48 h of stress. Collectively, the 3-month-old tissue cultures seedlings of M. alternifolia could be lethally injured at -5 ℃, but they were able to survive the low temperature above 0 ℃ by rapidly increasing protective enzyme activities and accumulating osmotic regulators. However, there was a certain difference in mechanisms underlying the response to low temperature stress at 10 ℃ and 0 ℃. The results of this study will help to understand its cold resistance ability and physiological response mechanism, and provide the theoretical basis for rational introduction and large scales of planting.