Cryopreservation of Plant Cell Suspensions

The cryopreservation of dedifferentiated cells, grown in suspension culture, is one of the portfolio of techniques employedfor the long-term conservation of higher plant germplasm. Suspension cultures are also important in biotechnology, particularlyin transformation studies and for the production of specific metabolites, and, here, there is also a pressing need for geneticallystable, long-term storage of cell lines.
Cryopreservation of suspension cell cultures can be exploited by either slow, or rapid, cooling techniques. During slow coolingthe extracellular solutions are nucleated and the cells cryodehydrate during controlled cooling as a consequence of extracellularice, to the point where their intracellular fluids will vitrify on subsequent transfer to liquid nitrogen. In the rapid coolingprotocols, the cells are prepared by extreme osmotic dehydration, with cryoprotection, before plunging the samples directlyinto liquid nitrogen to achieve vitrification. Extensive success has been achieved with both techniques but rapid coolingis, currently, widely favored because of its simplicity.