Induction of somatic embryogenesis from leaf explants of Exacum trinervium (L.) Druce (Binara)

Exacum trinervium, commonly known as Binara, produces dark blue violet flowers with contrasting bright yellow anthers that have a very high potential as commercial flowering, potted, or bedding plants. Lack of planting materials is one of the major constraints for popularizing it and therefore, development of planting materials through in vitro somatic embryogenesis would be a viable solution. The possibility of producing somatic embryos of E. trinervium using in vitro grown leaf explants was investigated. The effect of five concentrations (0, 1, 2, 3 and 5 mg L-1) of 2, 4 -Dichlorophenoxyacetic acid (2,4-D) and 1 - Naphthaleneacetic acid (NAA) on somatic embryogenesis was investigated under dark and light with a photoperiod of 16 hours. The highest percentage of leaf explants (72 %) that produced calli was observed when cultured on the medium supplemented with 1 mg/L 2,4-D. Embryogenic stages could be observed only in calli originating from media supplemented with 1 mg/L and 2 mg/L 2,4-D after transferring to MS medium without growth regulators and incubated both in the light and the complete darkness. Leaf explants cultured on media containing NAA produced heavily rooted calli and did not produce any embryos. The highest number of embryos (15 ± 6 per/mL) was observed in the calli originating from the MS medium containing 1 mg/L 2,4-D. Further development of embryos up to plantlet with 60 % regeneration efficiency could be achieved on MS medium without plant growth regulators.