1-aminocyclopropane-1-carboxylic acid enhanced direct somatic embryogenesis from Oncidium leaf cultures

Abstract

Influence of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and two ethylene inhibitors, silver nitrate (AgNO3) and cobalt chloride (CoCl2), on direct somatic embryogenesis were tested in vitro using leaf cultures of Oncidium cv. Gower Ramsey. Leaf cells of tips, adaxial sides and cut ends could directly form somatic embryos on a hormone-free 1/2-strength MS medium. The frequency of embryo-producing explants was 55, 52.5 and 30%, respectively. The embryo numbers per embryo-producing explant was 20.3. ACC at lower concentrations (5 and 10 μM) significantly retarded direct embryo formation from cut ends. However, higher concentrations of ACC (20 and 50 μM) significantly promoted embryogenic response of leaf tips and adaxial sides. All concentrations of AgNO3 and COCl2 significantly retarded direct embryo formation. The best response was found on 20 μM of ACC, and the frequency of embryo-producing explants were 90, 85 and 35% on leaf tips, adaxial sides and cut ends, respectively. The embryo numbers per embryo-producing explant was 32.2.