High frequency plant regeneration through rhizome derived callus in Curculigo orchioides Gaertn – An endangered Medicinal herb
Nagesh KS and Shanthamma C
Curculigo orchioides Gaertn is an important medicinal plant with anticancer properties. The rhizome and tuberous roots of the plant have been used extensively in India in indigenous medicine. Due to its multiple uses, the demand for Curculigo orchioides is constantly on the rise; however, the supply is rather erratic and inadequate. Destructive harvesting, combined with habitat destruction in the form of deforestation has aggravated the problem. The plant is now considered ‘endangered’ in its natural habitat. Therefore, the need for in vitro propagation of this plant is crucial. Here, we describe a successful protocol for effective plant regeneration through shoot regeneration was achieved using rhizome derived callus in Curculigo orchioides. Three weeks old nodular callus from medium containing NAA (0.5-2.5 mg/l) and BAP (0.5-4 mg/l), or NAA (0.5-2.5 mg/l) and Kn (0.5-4 mg/l), when sub cultured on MS medium with low levels of NAA (0.1-0.5 mg/l) and high levels of BAP (1-5mg/l) or Kn (1-5 mg/l) the regeneration of shoot buds were observed. Among different concentrations and combinations tried, maximum number of shoot buds induction were noticed in the presence of BAP (3 mg/l) and combined with 0.3 mg/l of NAA and 90% response within 4 weeks of incubation. Effect of different levels of sucrose (0, 2, 3, 4, 5%, w/v) for shoot bud regeneration was tested, medium fortified with 3% sucrose was found to be optimum concentration resulting in maximum number of shoot buds regeneration. Half strength MS liquid medium with IBA or NAA (0.5-2 mg/l) tested for root induction. Maximum of 18 - 19 roots were produced at 1 mg/l of IBA on MS half -strength liquid medium with an average root length of 6 - 8 cm after 20 days. The rooted plantlets were successfully transferred to soil with 85-90% survival, and the plants showed normal morphological characteristics.