The dual effect of antifreeze protein on cryopreservation of rice (Oryza sativa l.) embryogenic suspension cells.

The effects of fish antifreeze protein AFP-I on cryopreservation of rice suspension cells by three different protocols were investigated. During the two-step method, AFP-I at 0.01 mg/ml significantly lowered the viability of both precultured and non-precultured cells. During the vitrification method, AFP-I at 0.2 mg/ml improved the viability of suboptimally thawed cells; however, much higher doses of this protein (10mg/ml) attenuated the cell viability. During rapid freezing of rice cells in the solutions with relatively high (but non-vitrifying) concentrations of cryoprotectant, AFP-I displayed protective action in the higher concentrated cryoprotectants and detrimental effect in more dilute ones. Taken together, it was concluded that, depending upon a number of factors discussed in the present paper, both positive effect and negative effect could be observed during application of AFP to cryopreservation of rice cells. The possible mechanism of this dual character was discussed.