Abiotic stresses increase plant regeneration ability of rhizome explants of Curcuma caesia Roxb.

Abstract

Curcuma caesia Roxb., commonly called “Black turmeric”, is an important medicinal plant. Normally this plant is micropropagated via rhizome or rhizome bud explant culture. However, the shoot induction from rhizome explants is low and thus, alternate methods could be adopted to induce maximum shoots. In this report, we subjected the rhizome segments to abiotic stresses such as warm water, hot air, cold water and sodium chloride (NaCl) at various time intervals for testing their effect on shoot induction. The best shoot induction medium (control) in terms of percent explants producing shoots (66 %) and number of shoots (11.2 per explant) was Murashige and Skoog medium supplemented with 6-thidiazuron (6.8 µM) and indole-3-butyric acid (1.5 µM). The application of various stresses significantly increased both percent response and number of shoots. Rhizome explants exposed to 1 or 2 h at 30–36 °C warm water significantly improved the response. Optimum response (94 % cultures responding with 22.4 shoots per explants) was observed when rhizomes were exposed at 33 °C for 1 h. In hot air as well as cold water treatments the percent cultures responding and number of shoots showed moderate increase. The increase brought about by 300 and 500 mM NaCl for 1–3 h was significantly higher than control. The rhizomes pretreated with 500 mM NaCl for 3 h showed highest response in contrast to other treatments. Here, 96 % rhizomes responded with an average number of 23.4 shoots per explant. These observations supported the positive role of abiotic stresses in inducing shoots from rhizome segments of C. caesia in cultures.