Regeneration of Melia volkensii Gu¨rke (Meliaceae) through direct somatic embryogenesis

Abstract

Experiments were conducted to study plant regeneration through direct somatic embryogenesis using mature zygotic embryo and cotyledonary explants from seeds of Melia volkensii stored for <3 and >12 months. Explants were cultured on Murashige and Skoog (MS) medium supplemented with BAP, NAA and 2,4-D (0.5, 1.0 and 2.0 mg l−1) alone, and BAP (0.5, 1.0, 2.0 and 4.0 mg l−1) in combination with 2,4-D or NAA (0.2 and 0.5 mg l−1). After 4 weeks in culture, up to 60% of cotyledonary explants from the seeds stored for <3 months produced direct somatic embryos on BAP (0.5–4.0 mg l−1) in combination with 2,4-D (0.2 mg l−1). The number of somatic embryos ranged from 5 to 14 per explant in BAP (0.5 mg l−1) and 2,4-D (0.2 mg l−1) combination. Only 20% of cotyledonary explants from seeds stored for >12 months produced somatic embryos. Mature zygotic embryos failed to produce any somatic embryos. Subcultures of somatic embryos from cotyledonary explants of seeds stored for <3 months formed clusters of shootlets on semi solid MS and 1/2 MS media. After 6 weeks of subculture on multiplication MS media augmented with BAP (0.5 mg l−1) and IAA (0.2 mg l−1), 70% of the shoot tips formed 4–7 shoots per explant. Up to 33% of the multiplied shoots were rooted in MS medium supplemented with 2.0 mg l−1 IBA. Plantlets developed normally into seedlings in the greenhouse.