CRYOPRESERVATION OF TRANSFORMED PAPAVER-SOMNIFERUM CELLS

Different procedures were tested in an attempt to cryopreserve transfo rmed cells of Papaver somniferum in liquid nitrogen. The encapsulation -dehydration process yielded negative results. Cells were encapsulated in alginate beads and precultured for 5 days in 0.75M maltose or sucr ose-enriched medium. They survived a 3-h dehydration, but not freezing to -196 degrees C. The vitrification method, which needed highly conc entrated solutions, also proved ineffective for embedded and non-embed ded cells. In contrast, using the conventional procedure, suspension c ultures resisted to -196 degrees C, when treated with 0.75M sorbitol o r maltose and 5% DMSO, and two-step frozen. Better results after freez ing were achieved using an original method including encapsulation of cells and conventional cryopreservation. This procedure based on trapp ing of cells in calcium-alginate allowed easier handling faster regrow th than for non-encapsulated cells, and successful cryopreservation at -196 degrees C of Papaver suspensions after a cryoprotective treatmen t combined with progressive freezing.