Cryopreservation of Shoot Tips of “Brazilian Ginseng” (Pfaffia glomerata (Spreng.) Pedersen) by Vitrification

Pfaffia glomerata (Amaranthaceae), “Brazilian Ginseng”, is a medicinal plant used in folk medicine. Roots are used as a tonic to restore and enhance wellbeing and for treatment of arthritis, gastritis and rheumatism. Conservation of P. glomerata germplasm is a priority and cryopreservation is the most promising technique for long-term storage of plant genetic resources. Hence, the objective of this work was to develop a cryopreservation protocol for shoot tips of P. glomerata using vitrification techniques. For cryopreservation, shoot tips (ST) from in vitro grown plants were pre-cultured for 19 hr on MS medium containing 0.3 M sucrose, treated with loading and vitrification solutions prior to rapid freezing by direct plunge in liquid nitrogen, rapid thawing on a water bath at 38±2 °C and treatment with a dilution solution. Three vitrification solutions (PVS2, PVS3 and PVS4), three exposure times (20 min., 40 min. and 60 min.) and two temperatures (25 °C and 0 °C) were tested. After cryopreservation, rewarmed shoot tips were inoculated on MS growth medium and the best regeneration percentages were 63%, 42% and 65% for shoot tips treated with PVS2, PVS3 and PVS4, respectively, for 60 min., at 25 °C. The results obtained show that vitrification with PVS2 and PVS4, at 25 °C, for 60 min were the best treatments for successful cryopreservation of shoot tips of in vitro grown plantlets of P. glomerata and that cryopreservation is suitable for ex situ conservation of the germplasm of this medicinal species.