Cryopreservation of an embryogenic suspension culture of Picea sitchensis and subsequent plant regeneration

Embryogenic suspension cultures of sitka spruce (Picea sitchensis) were successfully cryopreserved. The best method for cyropreservation as demonstrated by regrowth tests was: 1) preculture in medium containing 0.4 M sorbitol and pretreatment with 5% (v/v) DMSO (dimethylsulfoxide), 2) freezing the cultures at a cooling rate of 0.5°Cmin‐1 to —40°C followed by transfer to LN (liquid nitrogen). After thawing in a waterbath at 45°C the growth rates of cell cultures cryopreserved by this method were equal to growth rates of untreated unfrozen cultures. The cryopreserved cultures gave rise to mature somatic embryos which developed cotyledons, roots and shoots 3–4 months after thawing.