PLANT REGENERATION FROM CALLUS CULTURE OF AN ENDANGERED ORCHID, GEODORUM DENSIFLORUM

Abstract

An in vitro method was developed to regenerate plantlets from protocorm-derived callus of Geodorum densiflorum (Lam.) Schltr. cultured on half-strength Murashige-Skoog medium with 2,4-dichlorophenoxyacetic acid (2,4-D) at 3 to 5 mg/L and 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (TDZ) at 0.1 to 0.5 mg/L in the dark. The proliferation rate of the pale-yellow embryogenic callus was 3.9 to 4.2 fold in mediums containing 2,4-D 3 mg/L and TDZ 0.1 to 0.5 mg/L after one month of culture in the dark. The callus was regenerated to plantlets via protocorm-like bodies (PLBs) on medium containing 0.5 mg/L TDZ after 6 months of culture, and 644 PLBs and 56 shoot buds per 0.1 g callus were obtained after 12 months of culture. The well-rooted plantlets with pseudobulbs were transferred to sphagnum-containing pots and acclimatized in a greenhouse. The embryogenic callus of the endangered orchid, Geodorum densiflorum has been established.