An Efficient Method for Plant Regeneration from Calli of <i>Swertia mussotii</i>, an Endangered Medicinal Herb

Abstract

Swertia mussotii Franch is an endangered medicinal plant in the Qinghai-Tibet Plateau. Its regeneration from callus culture is very difficult. In this study, an efficient method for plant regeneration was developed from its calli. The calli derived from young stem explants of S. mussotii were cultured at two types of temperature treatments to test their efficiency of shoot regeneration. When the calli were cultured at variable temperature (VT, 20℃ during the day and 10℃ at night) treatment, the adventitious shoots were formed at each combination tested. However, that did not occur when the calli were cultured at constant temperature (CT, 25℃) treatment. The best response (53.7%) of plantlet regeneration was obtained on Murashige and Skoog (MS) medium containing 3 mg·l-1 6-benzylaminopurine with 0.5 mg·l-1 α-naphthaleneacetic acid in the VT treatment. The regenerated plantlets were rooted on half-strength MS medium without growth regulators. They flowered in the following subculture. The results indicate that the treatment of day-night temperature difference is a critical factor to callus differentiation in S. mussotii. This protocol can be used for conservation as well as mass propagation of this medicinal plant.