Oxidative stress in plant cell culture: A role in production of β-thujaplicin by Cupresssus lusitanica suspension culture

Oxidative stress is a common physiological stress that often challenges plants. Reactive oxygen species (ROS) are major factors in oxidative stress that significantly affect plant cell growth and secondary metabolism. Here we used β-thujaplicin production by Cupressus lusitanica cell culture as an example to demonstrate the common occurrence of oxidative stress in cultivated plant cells and its effect on multiple aspects of cell culture process. C. lusitanica cells cultivated under Fe ²⁺ stress generate a significant level of ROS, and oxidative stress also occurs at late stages of C. lusitanica cell cultures under normal conditions. ROS production inhibited cell growth, induced lipid peroxidation and cell death, and enhanced ethylene and β-thujaplicin production. It is demonstrated that Fe ²⁺ stress enhances ROS production via the Fenton reaction and promotes β-thujaplicin production via ROS-induced lipid peroxidation that may activate cyclic oxylipin and ethylene pathways. Results further indicate that H ₂O ₂ is a positive signal for β-thujaplicin production, whereas superoxide anion radical (O ₂ ^- negatively affects β-thujaplicin induction and strongly induces cell death. The study suggests that evaluating the oxidative stress and plant responses in a cell culture process is very necessary and important for understanding biochemical processes and for gaining the maximal productivity of target secondary metabolites.