Cryopreservation and Plant Regeneration from Embryogenic Cultures of Larch (Larix×eurolepis) and Black Spruce (Picea mariana)

A method has been developed for the routine cryopreservation of embryogenic cultures of hybrid larch (Larix×eurolepis) and black spruce (Picea mariana Mill.). The method involves growing the cultures in the presence of sorbitol and then briefly exposing them to DMSO followed by controlled cooling to −40°C. The cultures were then submerged and stored in liquid nitrogen. Growth of the embryogenic cultures was monitored for 14 d after rapid thawing and plating on to media. The highest relative increase in the tissue fresh weight, after storage in liquid nitrogen, was observed when embryogenic cultures of both species were pregrown for 24 h in a medium with 0·4 M sorbitol and then treated with 10% DMSO. This pretreatment also ensured the shortest lag phase in resuming the growth. The post-thaw cultures gave rise to mature somatic embryos which developed into plants