Sensitivity of CryopreservedLavandula veraCells to Ammonium Ion

Summary We modified the post-thaw culture medium to enhance the survival rate of cryopreserved Lavandula vera cells. Cells on the ammonium-ion-free medium recovered their viability during the first few days of post-thaw culture, whereas the viability of cells on the control medium containing 20 mmol/L ammonium (LS medium) did not increase to as great an extent. This result suggests that ammonium ions accelerate the decrease in viability of freeze-damaged L. vera cells and inhibits recovery from freezing injury. However, ammonium ions were needed for the regrowth of the cells that had recovered from freezing injury. The sensitivity of freeze-injured cells to damage by ammonium ions decreased rapidly after only one day in culture in the absence of ammonium ions, after which ammonium ions promoted cell growth.