REGENERATION OF BIGLEAF MAGNOLIA BY SOMATIC EMBRYOGENESIS

Bigleaf magnolia (Magnolia macrophylla Michx.) cultures were initiated from immature seeds on an induction medium containing 9.0 muM 2,4-D, 1.1 muM BA, and 1 g casein hydrolysate/liter. After 2 months on induction medium, one culture produced adventive embryos. Clumps of embryos transferred to liquid induction medium proliferated as nodules, which grew in diameter, but failed to produce embryos while maintained in induction medium. Nodules transferred to basal medium produced clumps of somatic embryos, which continued to produce repetitive embryos with monthly transfer to fresh basal medium. Individual embryos transferred to basal medium lacking casein hydrolysate germinated and leaves expanded. Plantlets derived from these embryos were transferred to potting mix and acclimatized to greenhouse conditions. Chemical names used: (2,4-dichlorophenoxy)acetic acid (2,4-D); N-(phenylmethyl)-1H-purin-6-amine (BA).