Cryopreservation of Picea sitchensis (Sitka spruce) embryogenic suspensor masses

A cryopreservation method comprising sorbitol pre-growth treatment, DMSO cryoprotection and two-step controlled rate cooling has been optimized for differentiated embryogenic suspensor masses (ESM) of Picea sitchensis. The protocol was applied to clonal cultures from five different half-sibling families each represented by five different genotypes and their responses to cryopreservation assessed over 3 years. Nineteen of the 25 clonal lines tested survived LN and were capable of regrowth and producing stage 2-4 somatic embryos. Following the second subculture cycle of ESM after they had been retrieved from cryogenic storage, post-cryopreservation regrowth was comparable with that of controls. A General Linear Model, multifactorial Main Effects Plot revealed no significant differences between genotypes (P>0.05) in response to cryopreservation, whereas significant differences between families (P<0.05) were detected.