Micropropagation of Cypripedium formosanum Hayata through Axillary Buds from Mature Plants

Abstract

A micropropagation protocol for an endangered slipper orchid species, Cypripedium formosanum Hayata, through axillary buds from adult plants has been developed. The season of explant collection is crucial for the initial success of an aseptic culture. Explants collected in the middle of January gave the highest percentage of explant survival (54.2%) and shoot-forming percentage (41.7%). Of the two cytokinins tested, N6-benzyladenine (BA) was found to be superior to thidiazuron for normal shoot formation. The optimum result was obtained in quarter-strength Murashige and Skoog medium containing 22.2 or 44.4 μM BA in which the cultures produced 6.3 and 7.1 shoots per explant with 10.6 to 11.7 mm average length after 90 d of culture. Regenerated shoots rooted for 60 d in the basal medium with 1 g·L−1 activated charcoal and 20 g·L−1 potato homogenate were ready for growth in pots. This is the first report on shoot multiplication in vitro from mature plants of Cypripedium that provides a reliable method for propagating the selected elites.