Figure 5.

Effects of Cd on cell wall structure. Cd might affect the cell wall structure in different ways. Cd influences lignification by acting on peroxidase (POX) activity. It further changes the activity of pectin methylesterase (PME), which leads to enhanced content of low‐methylesterified pectin and thereby creates binding sites for Cd within the cell wall. This is also supported by the activity of polygalacturonase (P‐Gal) and polygalacturonase β‐subunit (βP‐Gal). The latter protein is negatively influenced by Cd. Cd directly affects the cell wall structure by changing activity of xyloglucan endotransglucosylase/hydrolase (XTH) and sucrose synthase (SuSy). By degrading sucrose, SuSy provides precursor molecules for cell wall synthesis. Intracellular, Cd indirectly triggers production of ROS, which subsequently activates POX activity and also operates as signalling molecules for downstream processes. Germin‐like proteins (GLP) induce ROS production and therefore influence ROS signalling and trigger POX activity.