Assessment of Molecular Genetic Stability Between Long-Term Cryopreserved and Tissue Cultured Wasabi (Wasabia japonica) Plants

BACKGROUND: Maintaining the genetic integrity in long-term tissue cultured and cryopreserved plants is important for the conservation of plant genetic resources. OBJECTIVE: In this study, the genetic stability of cryopreserved wasabi shoot tips stored for 10 years at -150°C was visualized using Amplified Fragment Length Polymorphism (AFLP) and Methylation Sensitive Amplified Polymorphism (MSAP). MATERIALS AND METHODS: The study included plants derived from cryopreserved shoot tips after 10.5 years storage at -150°C (LN10yr), after 2 h storage at -196°C (LN2hr), cryopreservation controls (No LN cooling (TC)) and non-treated controls without LN cooling (LC). The donor plants for LN2hr, TC and LC were also maintained in vitro at 20°C for the same period. RESULTS: Neither technique detected genetic variations in either control or cryopreserved plants. Some mutations were noted in plants maintained in tissue culture for 10 years. Comparison of genome stability for TC and LN2hr plants showed only a minor change in DNA. However, when comparing the LC and Ln10yr, many differences were found. CONCLUSION: We conclude that cryopreservation is a superior conservation method compared to tissue culture in maintaining genetic stability for a long-term storage of wasabi germplasm.