Clones of Nordmann fir (Abies nordmanniana Stev. Spach) obtained through the somatic embryogenesis process are maintained permanently as embryogenic tissue cultures (ET). For long-term preservation, the clones are cryopreserved, followed by thawing and revitalization. The impact of the length of the ET subcultural stages on the success of cryopreservation was investigated. ETs from six selected cell lines were used at 10, 14, 21 and 28 days after the last transfer to fresh solid medium. For each variant, the fresh and dry weights (FW, DW) were recorded and their increases were calculated. After thawing, the recovery of the clones was evaluated. The clones show very different preferences regarding the subcultural stage, and a correlation between it and the revitalization ratios was not found. In conclusion, the standard parameters regarding the time span after the last subculture prior to cryopreservation should be broadly defined. This data underlines the need to adapt standard parameters to species- and if possible, to genotype-specific requirements.
Eisold et al. (Sat,) studied this question.