In vitro regeneration through organogenesis in Costus igneus–an important herbal insulin plant

Abstract

Costus igneus is an important high-valued herbal insulin plant. An efficient protocol for in vitro plant regeneration through organogenesis from leaf and nodal explants was standardized. Explants were incubated in Murashige and Skoog (MS) medium amended with diverse levels of plant growth regulators (PGRs). Optimum frequency (68.25%) of adventitious shoot regeneration was obtained from nodal segments cultured onto MS medium containing 2.0 mg/l of 6-benzylaminopurine (BAP) with an average number of 5.0 shoots per explant. Further, MS medium containing 1.5 mg/l 2, 4- dichlorophenoxyacetic acid (2, 4-D) and 1.0 mg/l Thidiazuron (TDZ) produced a higher frequency of callus induction (55.22%) from leaf explants. Optimum shoot regeneration response (66.0%) through indirect organogenesis was observed from leaf-derived callus on MS medium fortified with BAP (2.0 mg/l) and kinetin (0.5 mg/l) with 6 shoots per callus with mean shoot length of 8.0 cm. The shootlets obtained from node and leaf cultures were rooted with a frequency of (63.52%) on MS medium with 1.0 mg/l indole-3-acetic acid (IAA). Plantlets obtained through organogenesis were successfully acclimatized in the greenhouse and field conditions. There were no significant differences among frequency of somatic plants regenerated through either direct or indirect organogenesis. The present study reports on successful plant regeneration through direct and indirect organogenesis in C. igneus. The regeneration protocols discussed here can be used effectively for large-scale multiplication, germplasm survival, pharmacological and genetic manipulation research.