Different availabilities of reduced nitrogen: Effects on oxidative stress in chicory plants

The aim of this work was to study the induction of the synthesis of ROSscavenging molecules and the evolution of enzymatic activities such as ascorbate peroxidase (APX) and polyphenoloxidase (PPO) as a function of different availabilities of reduced nitrogen. Chicory seedlings were grown in nutritive solution for 35 days in controlled conditions. On the 14th day, one third of the plants was transferred into a nutritive solution containing (NH4)2SO4 60 mM, one third was transferred into a medium containing Urea 60 mM, and the remaining was let grow in the nutrition solution, as a control. Three samplings of leaves were performed, respectively after 21, 28 and 35 days of growth. The urea and ammonium sulphate-treated samples showed higher ascorbic acid and polyphenol contents than the control, together with a lower anthocyanins content. APX showed the highest activity in the urea-treated samples, while the highest PPO activity was to refer to samples treated with ammonium sulphate. The variations in organic components suggest an effect of the supply of reduced nitrogen on the cell redox potential, confirming the importance of fertilization for obtaining high amounts of antioxidant molecules.