Cryopreservation of cocoa (Theobroma cacao L.) somatic embryos for long-term germplasm storage

Fang, J.-Y., Wetten, A.C. and Hadley, P. (2004) Cryopreservation of cocoa (Theobroma cacao L.) somatic embryos for long-term germplasm storage. Plant Science, 166 (3). pp. 669-675. ISSN 0168-9452 doi: 10.1016/j.plantsci.2003.11.002

Abstract/Summary

Cryopreservation using encapsulation-dehydration was developed for the long-term conservation of cocoa (Theobroma cacao L.) germplasm. Survival of individually encapsulated somatic embryos after desiccation and cryopreservation was achieved through optimization of cryoprotectants (abscisic acid (ABA) and sugar), duration of osmotic and evaporative dehydration, and embryo development stage. Up to 63% of the genotype SPA4 early-cotyledonary somatic embryos survived cryopreservation following 7 days preculture with 1 M sucrose and 4 h silica exposure (16% moisture content in bead). This optimized protocol was successfully applied to three other genotypes, e.g. EET272, IMC14 and AMAZ12, with recovery frequencies of 25, 40 and 72%, respectively (but the latter two genotypes using 0.75 M sucrose). Recovered SPA4 somatic embryos converted to plants at a rate of 33% and the regenerated plants were phenotypically comparable to non-cryopreserved somatic embryo-derived plants.