Callus culture and in vitro production of anthraquinone in Gynochthodes umbellata (L.) Razafim. & B. Bremer (Rubiaceae)

Abstract

Gynochthodes umbellata is a rare medicinal plant used in traditional systems of medicine for curing various ailments. It is a woody climber belonging to the family Rubiaceae. Its over collection from the wild population resulted the rapid depletion of this species. There is an urgent need to conserve this species and also establish an alternative system for the production of bioactive compound in vitro without harming the wild population. The present investigation was carried out to analyse secondary metabolite (anthraquinone) production in callus cultures of G. umbellata. In vitro production of anthraquinone through callus cultures of G. umbellata was standardized using in vitro leaves, derived from the nodal explant cultures maintained in Murashige and Skoog solid medium containing 2mg/l 6-benzylaminopurine and 3% sucrose. Leaves were harvested from the healthy shoots of axenic cultures and culture conditions were optimised for the establishment of callus. In vitro derived leaves (1–2cm2) were inoculated onto Murashige and Skoog medium containing different individual concentrations of 2, 4-Dichlorophenoxyacetic acid (0.5–5mg/l), indole-3-butyric acid (0.5–5mg/l), indole-3-acetic acid (0.5–5mg/l) and 1-naphthaleneacetic acid (0.5–5mg/l). Of the different auxins tried for callus induction, 2, 4-Dichlorophenoxyacetic acid was found to be the most suitable auxin with different concentrations for the induction of friable yellow callus. 1-Naphthaleneacetic acid doesn’t show any callus formation while indole-3-butyric acid and indole-3-acetic acid produced greenish white compact callus. A maximum fresh weight (1.7953±0.61g) and dry weight (0.1149±0.04g) of the friable yellow callus and highest amount of anthraquinone content (18.1875±0.58mg/g dw) were recorded in MS medium supplemented with 1mg/l 2, 4-Dichlorophenoxyacetic acid. From the present study it revealed that the callus culture is an effective method for the production of anthraquinone in vitro in G. umbellata. Anthraquinone production through in vitro leaf segment derived callus culture is a viable system for the production of this pharmacologically and industrially important natural plant pigment.