Cryopreservation of Shoot Tips of Bacopa monnieri (L.) Wettst. by Vitrification Technique

A protocol for cryopreservation of in vitro shoot tips of Bacopa monnieri (L.) Wettst., a medicinal plant of high commercial value was developed. Shoot tips (about 1 mm in length) excised from 4- to 24-week-old proliferating shoot cultures were precultured on MS medium supplemented with various cryoprotectants before dehydration with PVS2 at 0 degrees C. The dehydrated shoot tips were directly immersed in liquid N-2. Following cryopreservation, and after rapid rewarming at 45 degrees C, shoot tips were quickly washed with 1.2 M sucrose solution and then plated on solidified shoot culture medium. Shoot tips were successfully cryopreserved by vitrification, when they were precultured on medium supplemented with 5% DMSO for two days before dehydration. Preculture of shoot tips with sucrose at 25 degrees C significantly improved the survival and shoot regeneration rate of cryopreserved shoot tips. Regenerated plantlets were successfully transferred to pots.