Micropropagation, Mexican oregano, phenolization, multiplication coefficient, plant growth regulators.
Objective: The objective of this study was to establish the method of propagation of Oryganum vulgare and Lippia graveolens employing a plant tissue culture technique that decreased the phenolization percentages and increased the multiplication coefficients.
Design/ methodology/ approach: The in vitro germination percentage was evaluated in both MS and MS medium + activated carbon. Microcuttings (small shoots) of both species were established in base medium added with different antioxidant agents to decrease the phenolization of explants; the treatments were arranged in a completely randomized block design. For the propagation phase, a completely randomized factorial design was used, where the auxin/cytokinin phytoregulators, type of explants (axillary buds and leaves), and the species (Lippia graveolens and Oryganum vulgare) were considered as factors.
Results: maximum germination (63.3% ±12.5) was obtained on day 15 in both culture media for L. graveolens and O. vulgare. The use of antioxidant agents mainly activated carbon, increased the in vitro establishment and activation of vegetative buds in both species by up to 90%. There were significant differences in the variables evaluated regarding the treatments, the explant, and the species in the multiplication phase. The combination 1.0/ 0.5 mg L-1 BA/AIB induces callus formation for both species. When used as leaf explants, callus formation was potentiated.
Study Limitations / Implications: The results presented are advances from a long-term experiment.
Findings/conclusions: The germination of L. graveolens seeds can be achieved in MS medium after 15 days. Microcuttings of both L. graveolens and O. vulgare were successfully established in MS basal medium enriched with 1 g L-1 charcoal that showed low oxidation percentages and induced up to 90% the production of shoots in the explants. The mixture of 1.0/0.5 mg L-1 BA/AIB induces callus formation for both species; when this medium is in contact with leaves as an explant, its formation is potentiated, achieving diameters up to 15 mm. In order to achieve the induction of shoots and roots, buds should be established in MS medium enriched with 0.5 mg L-1 IBA for both species; this mixture encreased the multiplication coefficients