RESUMO
Objective To get a new approach to conserve the germplasm of Platycodon grandiflorum. Methods A method of vitrification was studied to cryopreserve in vitro shoot-tips of P. grandiflorum, and the regenerated plantlets were observed subsequently. Results Shoot-tips, 2—3 mm length, gotten from in vitro shoots of P. grandiflorum precultured on MS medium supplemented with 5% DMSO and 103 g/L sucrose for 3 d, were loaded with the 60% PVS_2 for 20 min at 20 ℃, and incubated in PVS_2 for 90 min at 0 ℃ prior to a direct plunging into liquid nitrogen (LN) and keeping for 1 d. After rapid thawing in water at 40 ℃, the shoot-tips were rinsed in the MS medium supplemented with 410 g/L sucrose for 20 min, and plated on the filter paper sustained by the MS regeneration medium supplemented with 0.6 mg/L KT, 0.2 mg/L BA, and 0.05 mg/L NAA for 1 d in dark and subcultured on the above regeneration medium for one week in dark prior to exposure to the light. The survival of shoot-tips was up to 80%, and they grew normally. Conclusion The method of vitrification to cryopreserve the germplasm of P. grandiflorum is simple in handling with high in survival and normal in regeneration and can be applied in practice.