Plant regeneration in leaf culture of Centaurium erythraea Rafn. Part 1: The role of antioxidant enzymes

Centaurium erythraea Rafn. is a medicinal plant rich in secoiridoids and xanthones and used for gastrointestinal disorders, fever, anemia and many other conditions. C. erythraea is characterized with extraordinary developmental plasticity and manageability in vitro; thus we propose it as an excellent experimental model system for studies in developmental biology. Hereby we describe regeneration of centaury from leaf explants that can proceed via somatic embryogenesis or organogenesis on inductive media containing 2,4-D and CPPU. In the absence of growth regulators, shoots and roots appeared without callusing, on light or in darkness, respectively. Indirect somatic embryogenesis was induced in the presence of growth regulators occurring both on light and in darkness. Light was obligatory for indirect shoot development, where adventitious buds formed simultaneously with somatic embryos. Dynamic changes of antioxidative activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) in response to morphogenetic changes were followed during developmental pathways in vitro. Wounding of centaury leaves immediately induced all SOD and CAT isoforms but caused a decrease in POX activity. In control leaves and leaf explants, three Cu/Zn-SOD activities were detected, which gradually decreased on inductive treatments on light, but remained unchanged during growth in darkness. Morphogenetic paths on all hormonal and light treatments where characterized with dynamic changes of CAT activity (comprised of three major CAT isoforms), but generally CAT was reduced during morphogenesis induction. POX activity was strongly induced during morphogenesis in all treatments.