Thidiazuron induced high frequency shoot organogenesis in callus from Kigelia pinnata L.

Abstract

An efficient regeneration system was developed for Kigelia pinnata L., a multipurpose tree belonging to the family Bignoniaceae. The nodal segments were cultured in vitro, and the optimum concentrations of plant growth regulators for callus induction were determined. The friable organogenic calli were derived from the basal cut end of the nodal segments. The highest yield of morphogenic callus (100%) was observed when nodal segments were cul- tured on Murashige and Skoog (MS) medium supplemented with 3 µM 2,4 dichlorophenoxyacetic acid (2, 4-D). The morphogenic callus maintained high regeneration during the first four subcultures in the callus induction medium. The maximum shoots (28/culture) were regenerated at the highest frequency of 100% when 3 µM thidiazuron (N-phenyl N' 1,2,3-thidiazol-5-yl urea) (TDZ) and 0.5 µM naphthaleneacetic acid (NAA) were added to MS medium. The emergence of multiple shoots from the calli was histologically documented. The regenerated shoots showed maxi- mum rooting on ½ MS medium containing 4 µM indole-3- butyric acid (IBA). The effect of vesicular arbuscular mycorrhizae (VAM) association in averting the transplantation shock was tested and proved to be highly beneficial, giving a 100% survival rate after 60 d of transplantation. This efficient plant regeneration system provides a founda- tion for generating transgenic plants of this multipurpose tree.