Abstract: This work is to analyze the response differences of 3 Peltigera specie Peltigera rufescens,Peltigera elisabethae,and Peltigera 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 determine the content of glutathione and the content of intracellular and extracellular copper. The results showed that GSH in 3 lichen species increased gradually at low Cu²⁺ concentrations（1- 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,but 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 adsorbed 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 Peltigera to copper is closely related to their copper adsorption and GSH synthesis ability.

Key words: Peltigera species, Cu^{2 +} stress, glutathione, copper absorption