A three media transfer system for direct somatic embryogenesis from leaves ofSenecio x hybridus Hyl. (Asteraceae)

Abstract

Bisected leaves were cultured on semi-solid Murashige & Skoog medium amended with 13.5 IxM 2,4-D and 4.5 ixM BA for 7-14 days, transferred to 0.5% activated charcoal medium (without growth regulators) for three days, then transferred to MS basal medium. Control explants remained on initiation medium for comparison to transferred explants. Twenty-eight days after initiation of cultures, explants exposed to 11-14 days on induction medium yielded the largest number and most developmentally advanced embryos. Mature, white somatic embryos from transferred explants were visible after 35 days. Conversely, somatic embryos on control explants were not morphologically mature until 2-4 months. Mature embryos from transferred explants germinated without a resting stage, whereas embryos from control explants appeared quiescent. Histological examination confirmed embryo anatomy, however embryos, regardless of treatment, had abnormal cotyledons and regenerated plants had multiple stems.