Cryopreservation of adventitious shoot tips of Paraisometrum mileense by droplet vitrification.

ABSTRACT

BACKGROUND: Gesneriaceae family contains numerous species endemic to China, and many of them are listed as endangered species. There is a need for a simple and efficient method for long-term conservation of these species. OBJECTIVE: The study aimed to establish an efficient procedure for cryopreserving Paraisometrum mileense, a critically endangered species endemic to Yunnan, China. METHODS: Effects of sucrose concentration of preculture solution, duration of sucrose preculture, duration of plant vitrification solution 2 (PVS2) treatment, and cold acclimation on regeneration of cryopreserved adventitious shoot tips (ASTs) were assessed. RESULTS AND CONCLUSION: Among different sucrose preculture regimes tested, preculture with 0.3M sucrose for 24h resulted in best regeneration of cryopreserved ASTs. PVS2 treatment also affected regeneration considerably with the maximum survival of ASTs after incubation in PVS2 for 90 min at 0 degrees C. With the optimised parameters, the level of shoot regeneration from cryopreserved ASTs reached 86%. No morphological abnormalities were observed during one year's growth of the plantlets developing from cryopreserved ASTs. Procedure established in this research is a promising technique for the cryopreservation of ASTs of this species.