Abstract: Plants induce the metallothioneins (MTs) to regulate metal homeostasis, buffer toxic heavy metals and remove cell-damaging reactive oxygen species (ROS) under metal stress. Building upon functions on plant metallothioneins, the functions and mechanisms of metal ion binding ability and ROS scavenging at home and abroad for the past few years were reviewed. The chemical basis of MTs ability to bind different metal ions based on the characteristics of ligand-to-metal charge transfer (LMCT) was summarized. MTs played important roles in metal homeostasis and heavy metal detoxification. Furthermore, the thiol groups in MTs could be oxidized. MTs interacted with the integral membrane proteins in the outer mitochondrial membrane, and indirectly regulated the activities of antioxidant enzymes or related genes expression to eliminate ROS in plants under heavy metal stress.

Key words: plant metallothioneins, metal detoxification, ROS scavenging, transcriptional regulation