三种地卷响应Cu^(2+)胁迫的差异分析

Difference Analysis on the Responses of Three Peltigera Species to Cu^(2+) Stress

基于谷胱甘肽(Glutathione,GSH)含量变化和铜吸附性分析地卷、平盘软地卷和犬地卷响应Cu^(2+)胁迫的差异,以了解谷胱甘肽在低等生物地衣抗重金属胁迫中的作用。分光光度法和火焰原子吸收方法分别测定地衣体的GSH与细胞内、外的铜含量。结果显示,低浓度Cu^(2+)胁迫下,3种地卷GSH均呈上升趋势,4 mmol/L时达最高;5-8 mmol/L时,地卷和犬地卷的GSH逐步下降较明显,但仍显著高于对照组,而平盘软地卷GSH在3-5 mmol/L Cu^(2+)范围差异不显著,Cu^(2+)>5 mmol/L时才出现较明显的下降(P<0.05)。4 mmol/L Cu^(2+)处理时间不同时,犬地卷的GSH变化与处理时间正相关,而地卷和平盘软地卷的GSH出现波动式变化(6 h增加,12 h下降,18-24 h上升)。3种地卷胞外铜与Cu^(2+)浓度和处理时间呈正相关并显著高于胞内铜(P<0.01),而胞内富集的铜与地衣GSH变化相对应呈高-低-高的变化趋势。菌藻共生的特殊生物-地卷类似于高等植物可诱导合成GSH缓解胁迫产生的伤害,3种地卷的铜耐受性差异与其铜吸附性和GSH合成能力密切相关。

This work is to analyze the response differences of 3 Peltigera specie Pehigera rufescens, Pehigera elisabethae, and Pehigera canina to Cu2＋ stress based on the induced glutathione （ GSH ） variation and the copper adsorption, in order to understand the role of glutathione in the resistance of low organism lichen to heavy metals. Spectrophotometry and flame atomic absorption spectrometry were used to delermine the content of glntathione and the content of intracellular and extracellular copper. The results showed that GSH in 3 lichen species increased gradually at low Cu2＋ concentrations （ l- 4 mmol/L ） and reached the highest in the 4 mmol/L. With the increase of the stress （ 5 - 8 mmol/L ）, the GSH contents in both P. rufescens and P. canina decreased significantly, but still higher than that in the control. The GSH content in P. elisabethae varied little under 3 - 5 mmol/L Cu2＋ stress condition, and decreased significantly （ P〈0.05 ） at Cu2＋〉5 mmol/L. Under the highest tolerant concentration 4 mmol/L Cu2＋, the P. canina increased gradually with the prolongation of treated time, hut the GSH contents of the P. rufescens and P. elisabethae fluctuated （ increased in 6 h, decreased in 12 h, and increased gradually in 18 - 24 h ） . The contents of adsm-bed extracellular copper in 3 lichen species were positively correlated with Cu2＋ concentration and treatment time and were significantly higher than that of the adsorbed intracellular copper （ P 〈 0.01 ） . The changes of adsorbed intracellular copper corresponded to the changes of GSH contents in the lichens as an up-down-up pattern. The results of this study indicate that the lichen species may induce the synthesis of GSH to alleviate the toxicity of Cu2＋ on lichen thallus, and the tolerance of 3 Pehigera to copper is closely related to their copper adsorption and GSH synthesis ability.