High frequency shoot regeneration of <i>Sterculia urens</i> Roxb. an endangered tree species through cotyledonary node cultures

Abstract

A protocol is described for rapid and large scale propagation of an endangered, commercially and medicinally important tree species, Sterculia urens, by in vitro culture of cotyledonary nodes from 15 days
old seedlings. Of the four different cytokinins (thidiazuron, isopentenyladenine, zeatin and adenine sulphate) evaluated as supplements to Murashige and Skoog medium (1962), thidiazuron at an optimal concentration of 2.27 M was most effective in inducing bud break (83.0%). Although, multiple shoot formation was a function of cytokinin activity alone, enhanced frequency of shoot regeneration (93.3%) and number of shoots per explant (19.0) were observed by the addition of ascorbic acid (0.1%). Concentrations of all cytokinins tested above the optimum level reduced the frequency of shoot
regeneration and shoot number. A proliferating shoot culture was established by repeatedly sub-culturing the original cotyledonary node on shoot multiplication medium (0.45 M thidiazuron) after the second
harvest of newly formed shoots. Rooting was best induced (80.0%) in shoots excised from proliferating shoot cultures on a quarter strength MS medium fortified with an optimal concentration of indole-3-butyric
acid (9.80 M).