Non-Protein Thiol Compounds and Antioxidant Responses Involved in Bryophyte Heavy-Metal Tolerance

Heavy-metal pollution represents a problem which has been widely discussed in recentyears. The biological effects of heavy metals have been studied in both animals and plants, rangingfrom oxidative stress to genotoxicity. Plants, above all metal-tolerant species, have evolved a widespectrum of strategies to counteract exposure to toxic metal concentrations. Among these strategies,the chelation and vacuolar sequestration of heavy metals are, after cell-wall immobilization, thefirst line of defence that prevent heavy metals from interacting with cell components. Furthermore,bryophytes activate a series of antioxidant non-enzymatic and enzymatic responses to counteractthe effects of heavy metal in the cellular compartments. In this review, the role of non-protein thiolcompounds and antioxidant molecules in bryophytes will be discussed.