An efficient protocol for in vitro propagation of Trichilia pallida Swartz (Meliaceae): a potential tree for natural insecticide production

Abstract

In vitro and ex vitro germination was successfully achieved for seedling production from monoembryonic and polyembryonic seeds. The seedlings were used as a source of explants for establishing a micropropagation protocol of Trichilia pallida. Cotyledonary node and apical shoot sections were cultured in MS medium supplemented with 6-benzyladenine (BA; 0, 2.0, 4.0, or 8.0 µM) during three subcultures in order to induce new shoots. Polyamines (PAs) were tested to promote shoot elongation and rooting. MS/2 medium supplemented with indole-3-butyric acid (IBA; 0, 1.25, 2.5, 5.0, and 10.0 µM) was used for root induction. The results indicated better responses of shoot regeneration when adding 2.0 µM BA to the culture medium, which promoted shoot regeneration (98% of explants and 5 to 7 shoots per explant), irrespective of the type of explant tested, during three subcultures. PAs showed a positive effect to promote shoot elongation with the supplementation of 0.5 mM spermidine (70%) and rooting of shoots with 2.0 mM putrescine (82%). Rooting was also achieved on MS/2 medium supplemented with 5.0 µM IBA, where 84% of explants showed root development. The commercial substrates tested in combination with vermiculite (1:1 v/v) were efficient for acclimatization, allowing 87.76% and 75.52% of survival rate after 90 and 120 days, respectively, in a greenhouse. In conclusion, a feasible and complete in vitro propagation protocol from seedlings was developed for T. pallida. A complete protocol for germination and micropropagation of Trichilia pallida was established, a species with great potential for conservation and commercial purposes.