Abstract
An efficient in vitro method has been established for the production of whole plantlets of Bauhinia tomentosa using cotyledonary node (CN) explants excised from 15 d-old aseptic seedlings. Proliferating shoot cultures were obtained by placing Cl explants on Murashige and Skoog (MS) medium supplemented with 6-benzyladenine (BA), kinetin (Kn), and 2-isopentenyl adenine (2-iP), singly or in combination, with either of the auxins, indole-3-acetic acid (IAA) or alpha-naphthalene acetic acid (NAA). MS medium augmented with 5.0 mu M BA was found to be most effective in providing the highest frequency (84%) of shoot regeneration, associated with the maximum number of shoots (9.0 +/- 0.6) per explant. The highest efficiency of shoot proliferation was observed using a combination of 5.0 mu M BA and 0.5 mu M NAA, where the number of shoots increased to 16.2 +/- 0.2 per explant after 8 weeks of culture. Improved shoot multiplication and elongation rates were achieved when 20.0 mg l(-1) sulphate (AdS) was added to the combined treatment of 5.0 mu M BA and 0.5 mu M NAA, where an average shoot number of 17.0 +/- 0.6 and an average shoot length of 5.8 +/- 0.3 cm were obtained. The maximum frequency of root formation (70%) and greatest root lengths (2.3 +/- 0.4 cm) were obtained on filter-paper bridges in liquid MS medium augmented with 2.5 mu M IBA and 5.0 mu M chlorogenic acid (a phenolic compound) after 4 weeks of culture. Regenerated plantlets were successfully acclimatised in a growth room and subsequently transferred to a greenhouse. This is the first report on in vitro plantlet regeneration in B. tomentosa using CN explants.