Development of a protocol for the micropropagation of two forest species threatened with extinction in Ecuador

Abstract

Handroanthus chrysanthus Jacq. S. O. Grose and Tabebuia rosea (Bertol.) Bertero ex A.DC are two forest species that grow in the coastal region of Ecuador and are threatened with extinction. A protocol for the mass multiplication of these species was developed using in vitro culture techniques. The cultures were initiated from seeds, and the effect of two culture media: Woody Plant Medium (WPM) and Murashige-Skoog (MS), two concentrations of NaClO (0.5% and 1%), and two disinfection times (3 and 5 min) was studied. During multiplication, the effect of three concentrations of two cytokinins: 6-benzylaminopurine (6-BAP) 4.4, 5.5, or 6.6 μM; kinetin 4.6, 5.75, or 6.9 μM) on the number of shoots, their length, and diameter was analyzed. This phase of the experiment was carried out in two successive multiplications. For rooting, two concentrations of indole-3-butyric acid (IBA) (2.45 and 4.9 μM) were tested, and the number of roots formed and their length were determined. It was demonstrated that the WPM medium is the most suitable for the in vitro culture of both species and that disinfection time and NaClO concentration affect each species differently. For the multiplication of H. chrysanthus, the most suitable cytokinin was 6-BAP 6.6 μM; T. rosea performed better in the absence of cytokinins. IBA 2.45 μM produced the best results for the rooting of H. chrysanthus, while for T. rosea, IBA 4.9 μM was the most suitable. The acclimatized plants showed a high survival rate, demonstrating the feasibility of using this methodology for the accelerated propagation of these endangered species.

Key message

In this research, the culture medium requirements and conditions for the micropropagation of H. chrysanthus and T. rosea were fine-tuned. This technique can be implemented to obtain plants for use in reforestation.