Results and discussion
The seeds of C. ternatea cultured on MS basal medium
exhibited germination within 4 days in responding seeds
(Fig. 1a). Seed germination rate was comparatively low
and 14 % of the seeds germinated and produced healthy
cotyledons measuring a size of about 0.8 cm in length
(Fig. 1b). Such cotyledons were excised from the germinating
seedlings after 14 days and cultured on MS medium
supplemented with various concentrations of 2, 4- D
(1.0–4.0 mg/l; Fig. 1c). The cotyledons were cultured with
the abaxial side facing the medium. The initial sign of
callusing was observed 1 week after culture (Fig. 1d). Only
the cut end of the cotyledon responded (Fig. 1e) by producing
profuse embryogenic friable callus. After 45 days
the cut end of the cotyledon was fully surrounded by
proliferating embryogenic callus and these calli turned
green in certain localized areas (Fig. 1e). The callus later
produced somatic embryos after subculture on a suitable
medium. Cotyledons are excellent explants for induction of
somatic embryogenesis. Somatic embryos were induced
directly or indirectly from cotyledon explants in various
systems like Fraxinus mandshurica (Kong et al. 2012),
Brassica oleracea (Yang et al. 2010), Apium graveolens
(Song et al. 2007) and Protea cynaroides (Wu et al. 2007).