MELATONIN-LOADED ALGINATE BEADS IMPROVE CRYOPRESERVATION OF YAM (Dioscorea alata and D. cayenensis)

BACKGROUND: The cryopreservation of yam is constrained with many challenges. OBJECTIVE: This study tested the effects of melatonin on shoot tips of D. alata and D. cayenensis accessions exposed to water and liquid nitrogen (LN) stresses. MATERIALS AND METHODS: Sucrose pretreatment (0.3 M) was applied for 48 h before cryopreservation. Shoot tips were encapsulated in beads loaded with 0.75 M sucrose, with and without melatonin and desiccated over sterile dry silica gel for 0 - 9 h. RESULTS: The beads moisture content declined from 100% to ∼ 13% after 9 h. The 3 h desiccation period without melatonin produced a significantly higher regeneration compared to 6 h and 9 h. Shoot tips with melatonin had significantly higher regeneration after 3 - 6 h desiccation compared to 9 h and the regeneration of all accessions after 6 h was >80%. Regeneration following 6 h desiccation and LN was significantly greater for melatonin-treated shoot tips compared to non-treated ones. CONCLUSION: The results indicate that melatonin significantly increased regeneration from 15% to 35%.