Micropropagation of buttonwood tree (Conocarpus erectus) through axillary shoot proliferation

Abstract

A method for micropropagation of Conocarpus erectus through axillary shoot proliferation is presented. Shoot tips were excised from adult donor tree and cultured for 4 weeks on Murashige and Skoog’s (MS) medium supplemented with 3 mg·LL1 gibberellic acid (GA3) to induce sprouting of shoots and formation of axillary shoots. Conocarpus erectus shoots were cultured for 6 weeks on MS medium supplemented with different concentrations and combinations of plant growth regulators (PGRs) and proliferation of the shoots was monitored. The type and concentration of cytokinins applied had a significant influence on shoot proliferation responses. Supplementation with 6-benzylaminopurine (BAP) increased the rate of shoot proliferation compared with other cytokinins. The use of BAP in combination with auxins such as indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) resulted in an increased number of shoots per explant compared with treatment with BAP alone. A combination of 2 mg·LL1 BAP and 0.5 mg·LL1 IBA produced the highest number of axillary shoots (7.8 shoots/explant). The best rooting medium was full-strength MS medium supplemented with 1mg·LL1 IBA; this treatment yielded 80%rooting with an average of 3.5 roots per plantlet. All regenerated plantlets were successfully acclimatized to greenhouse conditions.