Phytochelatins of Cladophora rupestris in Pb2+ absorption and its detoxification

Abstract

Phytochelatins (PCs) exist widely in plants and are closely related to plant resistance to heavy metals (HMs). Glutathione (GSH) and nonprotein thiols (NPTs) are the major components of PCs. This study investigates the role of the PCs of Cladophora rupestris in Pb 2+ accumulation and detoxification. The distribution of Pb 2+ in the PCs of C. rupestris was studied. FTIR and XPS are used to characterize the chelating power of Pb 2+ with PCs in C. rupestris. The curve fitting of the secondary protein structure is used to identify the functional groups with Pb 2+ . Results showed that the content of Pb 2+ in the PCs of C. rupestris increased with an increase in Pb 2+ stress. Pb content increased to 352 and 314 mg/kg in NPTs and GSH, respectively, when Pb stress concentration reached 7.5 mg/dm 3 . The Pb 2+ fraction of C. rupestris PCs reached a maximum of 10.8 and 9.3% in NPTs and GSH, respectively. The Pb 2+ uptake by GSH and NPTs was 40-48% and 52-60%, respectively. Pb 2+ bound with the PCs of C. rupestris, forming