Harnessing Somatic Embryogenesis for Rejuvenation, Sustainable Propagation and Reforestation of Acacia Hybrids in Vietnam
Le Huu Thuong
Nong Lam University HCM, Vietnam.
Pham Hong Diep
International University, VNU-HCM, Vietnam.
Tran Van Minh *
International University, VNU-HCM, Vietnam.
*Author to whom correspondence should be addressed.
Abstract
Introduction: In Vietnam, the Acacia hybrid is one of the most important forestry species. It is planted for forest regeneration and the development of special-use forests and provides raw material for the pulp industry.
Aim: Application of somatic embryogenesis techniques to the rejuvenation, sustainable propagation and reforestation of acacia hybrids in Vietnam.
Experimental Design: The experiment followed a one-factor CBD with four replications. Each replication comprised five 300 mL Erlenmeyer flasks, each containing 65 mL of experimental medium and inoculated with five samples. Data were analysed by ANOVA using MSTAT v1.2 software (α = 0.05).
Methods: In vitro Acacia hybrid material from the selected KL84 clone was used. Healthy, well-developed in vitro seedlings with complete stems, leaves and roots were cultured. Young stems and roots were cut into 1 cm sections, and leaves were cut into 1 cm² pieces.
Results: The WPM (woody plant medium) + TDZ (thidiazuron) (0.2–0.5 mg/L) + BA (6-benzylaminopurine) (1 mg/L) + CW (coconut water) (10%) medium was suitable for somatic-cell induction in all three explant types. WPM + TDZ (0.5 mg/L) + CW (10%) was suitable for differentiating somatic cells into somatic embryos, which were examined by fluorescence microscopy. After 20 days of culture on WPM + TDZ (0.5 mg/L) + CW (10%) agar medium, biomass increased to 1.8 g and 2.1 g from initial biomass levels of 1 and 2 g/65 mL, respectively. In liquid medium, cell density reached 1,650 × 10⁴ cells/mL from an initial biomass of 1 g/65 mL. The somatic-cell suspension was layered and regenerated directly on WPM + TDZ (0.2 mg/L) + CW (10%) medium. Somatic embryonic cells regenerated as shoot clusters, which were continuously multiplied on MS + BA (0.5 mg/L) + K (kinetin) (0.5 mg/L) medium.
Conclusion: Somatic cells were cultured and proliferated in liquid medium, layered on agar medium, differentiated into somatic embryos and regenerated into shoot clusters in vitro. These shoot clusters were rapidly multiplied in vitro and ex vitro.
Keywords: Acacia hybrid, biomass, cloning, differentiation, rejuvenation, KL84, reforestation, regeneration, somatic cells