Development of Cryopreservation Protocol for Aquilaria malaccensis Lam., a Recalcitrant Seeded Tropical Tree Species.

BACKGROUND: Cryopreservation is the only possible process for long-term germplasm storage of species with recalcitrant behavior. Aquilaria malaccensis is a recalcitrant seeded tropical tree that produces a distinctive fragrance which has high value in the commercial market. OBJECTIVES: In the present study, we aimed to develop possible long-term storage techniques for A. malaccensis germplasm. MATERIALS AND METHODS: We used zygotic embryos and in vitro derived nodal buds as explants. The experiments were performed based on dehydration and encapsulation-dehydration methods. RESULTS: When the dehydration technique was applied, survival (43%) and regeneration (23%) was found to be higher for zygotic embryos than for in vitro derived nodal buds (13% & 10% respectively). In addition to moisture content within the tissue during cryogen exposure, dehydration duration has an important contributory role in post cryo-survival and regeneration. A slight increase in survival (47%) and regeneration (30%) were observed in zygotic embryos with a modification to rehydration after re-warming, while such a change did not improve success with in vitro derived nodal buds. In contrast, the encapsulation-dehydration technique was found to be more effective for in vitro derived nodal buds than zygotic embryos. All the encapsulated nodal buds that survived (27%) regenerated into plantlets while encapsulated zygotic embryos failed to regenerate into plantlets. CONCLUSION: This is the first report on the cryopreservation of A. malaccensis and the developed protocol conveys a comprehensive idea of its reliability for the long-term storage of this desiccation sensitive (recalcitrant) seeded tree species.