Direct shoot organogenesis and plant regeneration from cotyledonary node of kenaf (<i>Hibiscus cannabinus</i> L.)

Abstract

Using the whole cotyledonary node as explants, a rapid and efficient regeneration protocol was established for kenaf (Hibiscus cannabinus L.) on Murashige and Skoog (MS) basal medium. The effects of the plant growth regulators: N6-benzyladenine (BA), indole-3-aceticacid (IAA) and the non-ironic surfactant pluronic F-68 (F-68) on shoot regeneration were evaluated by the orthogonal design L16 (4⁵). The best combination for shoot regeneration was MS medium supplemented with 5.0 mg l^-1 BA, 0.3 mg l^- 1 IAA and 0.2% (m/v) F-68. The maximum number of shoots per explant and the frequency of shoot regeneration were 12.97 and 100%, respectively, after cultivation for 21 days. The results indicated that BA had the greatest contribution on shoot inducing, followed by F-68, and IAA showed no significant effect on shoot formation. Furthermore, 0.5 ~ 2.0 mgl^-1 of IAA and 1-naphthyleneacetic acid (NAA) were used respectively for root induction. More than 13 roots were obtained on MS medium supplemented with 2.0 mgl^-1 of IAA after culturing for 14 days. IAA was more effective than NAA on root induction.
According to this method, the plantlets could be obtained within 2 months and showed no morphological difference from those naturally grown plants. This protocol could be used for kenaf genetic improvement by Agrobacterium mediated transformation.

Keywords: Kenaf, Hibiscus cannabinus L., cotyledonary node, shoot regeneration, rooting