Abstract

The effects of lanthanum nitrate (La³⁺) and cerium nitrate (Ce⁴⁺) on Echinaceaangustifolia callus growth and subculture were studied by the measurement of callus fresh weight, dry weight and time-course curve. The effects of La³⁺ on soluble protein content, peroxidase activity and shoot differentiation of callus were also investigated. Low concentrations of La³⁺ and Ce⁴⁺ (0.01, 0.1 and 1 mg/l) showed enhancing action on callus growth while the suppress effect was found at high concentration treatments (10 and 100 mg/l). The result from time-course experiment indicated that La³⁺ or Ce⁴⁺ showed promotion on callus growth after 15 days cultured and Ce⁴⁺ displayed a better effect than La³⁺. Different proportion mixture of La³⁺ and Ce⁴⁺ at 1 mg/l in total showed stimulating action on callus growth and the optimum proportion was the mixture of 40% La³⁺ and 60% Ce⁴⁺. Inhibitory effects were observed when the calli derived from the treatments with La³⁺ and Ce⁴⁺ were subcultured for the first generation. The dose-dependent effects of La³⁺ on soluble protein content, peroxidase activity and shoot differentiation were also noticed. The optimum concentration for callus growth and shoot differentiation was 0.1 mg/l and the green, loose calli with low percentage of brown callus were obtained at this concentration.

Key words: Echinacea angustifolia, rare earth elements, lanthanum, cerium, callus growth, soluble protein, peroxidase activity, shoot differentiation.

Abbreviation

REE, Rare earth elements; MS, Murashige and Skoog basal medium; FW, fresh weight; DW, dry weight; POD, peroxidase