Cryopreservation of the Australian species Macropidia fuliginosa (Haemodoraceae) by vitrification

Somatic embryos were used to develop a cryopreservation protocol for Macrop idia fuliginosa, a commercially-important species endemic to the southwest of Western Australia. Somatic embryos were allowed to develop from embryoge nic callus for three weeks on an kinetin medium prior to processing. These were transferred and cultured on a agar solidified basal medium supplemente d with 0 to 0.6 M sorbitol for 2 d prior to incubation in Plant Vitrificati on Solution Two (PVS2). Following this, embryos were then washed in I M suc rose solution (treated controls) or cooled in liquid nitrogen (LN). Cooled embryos were then warmed and washed in sucrose solution. Highest survival f or cooled treatments (67.3%) was achieved by preculture with 0.4 M sorbitol , then incubation in PVS2. Further experimentation varying pre-culture dura tion (2 or 3 d) and incubation on either glycerol (0.8 M) or sorbitol (0.4 M) indicated that very high survival (90.6%) of embryos was achievable by a dopting a 2 d preculture period on 0.8 M glycerol. The phenotype and growth rates of plants obtained using this protocol were similar to those of pare nt plants. This optimised procedure was then applied to tissue culture-deri ved shoot apices of the same clone also resulting in a high survival rate ( 84.4%).