Plant regeneration of sweet acacia (Vachellia farnesiana [L.] Wight & Arn.) via somatic embryogenesis

Vachellia farnesiana (L.) Wight & Arn. is a leguminous tree of ecological and economic value, yet its propagation is limited by seed dormancy and inefficient vegetative methods. This study establishes a somatic embryogenesis (SE) protocol using cotyledons from immature zygotic embryos. Among the basal media tested, Murashige and Skoog (MS) medium ensured the highest explant viability by minimizing browning and contamination. Embryogenic callus formation was optimized with 1.0 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D) in liquid MS medium under darkness. During maturation, polyethylene glycol 4000 (PEG 4000; 3%) and sucrose (5%) increased the number of somatic embryos, while abscisic acid (ABA; 1.0 mg L−1) produced the highest maturation frequency. PEG also enhanced callus dry weight and reduced moisture content. Histological analysis confirmed the origin and developmental stages of somatic embryos. For germination, gibberellic acid (GA3; 0.5–1.0 mg L−1) promoted radicle emergence, whereas 6-benzylaminopurine (BAP; 0.5–1.0 mg L−1) alone or combined with GA3 reduced normal development and increased abnormalities. This protocol establishes a reproducible framework for SE in V. farnesiana, with potential applications in clonal propagation, conservation, and biotechnology pending further optimization.