Mechanistic study of programmed cell death of root border cells of cucumber (Cucumber sativus L.) induced by copper

Programmed cell death (PCD) in root border cells (RBCs) induced by Copper (Cu) has been little studied. This study explored whether Cu induced PCD in RBCs of cucumber or not and investigated the possible mechanisms. The results showed that the percentage of apoptotic and necrotic RBCs increased with increasing concentration of Cu treatment. A quick burst of ROS in RBCs was detected, while mitochondrial membrane potential (ΔΨm) decreased sharply with Cu treatment. Caspase-3 like protease activity showed a tendency of increase with Cu treatment. The potential of Cu to induce PCD in RBCs of cucumber was first proved. Our results showed that ROS generation and mitochondrial membrane potential loss played important roles in Cu-induced caspase-3-like activation and PCD in RBCs of cucumber, which provided new insight into the signaling cascades that modulate Cu phytotoxicity mechanism.