A simple cryopreservation protocol for in vitro-grown shoot tips of Chinese genuine red bud taro (Colocasia esculenta L. Schott Var. Cormosus CV. Hongyayu) by encapsulation-dehydration

This study reports on the first use of an encapsulation dehydration procedure for the successful cryopreservation of in vitro-grown shoot tips of Chinese genuine red bud taro (Colocasia esculenta L. Schott var. cormosus CV. Hongyayu). After stock shoots were preconditioned on hormone-free MS medium with 0.29 M sucrose for 8 weeks, shoot tips were excised and then encapsulated into alginate-gel beads. Encapsulated shoot tips were precultured in liquid MS medium supplemented with 3.5 mg L−1 6-BA, 0.5 mg L−1 IBA, 0.1 mg L−1 GA3 and 0.75 M sucrose for 2 days. Precultured beads were dehydrated to 18-19% moisture content (fresh weight basis) with silica gel or by laminar airflow prior to directly immersion in LN for 1 day. After rapidly rewarming in a 40 °C water bath for 3 min, cryopreserved shoot-tips was post-cultured in the dark for 3 days and then transferred to a 16 h photoperiod. The average regeneration rate amounted to about 65%. Regrowth of cryopreserved shoot tips was not affected by the period of cryopreservation. Plants regenerated from cryopreserved shoot tips were morphologically normal. This encapsulation dehydration procedure will facilitate the routine use of the cryopreservation for shoot tips of Chinese genuine red bud taro.