Morphoanatomy and changes in antioxidant defense associated with the natural ventilation system of micropropagated Lippia dulcis plantlets

Abstract

Micropropagation is a plant tissue culture technique widely used for the production of medicinal plants. Lippia dulcis is an aromatic species that has potential therapeutic use. The objective of this study was to evaluate the effects of a natural ventilation system (NVS) on the vegetative growth, anatomical characteristics, production of photosynthetic pigments, and antioxidant defense of Lippia dulcis plantlets grown in vitro. Nodal segments pre-established in vitro were inoculated in flasks with 50 mL of MS culture medium and sealed using lids with one (NVS1), two (NVS2), or four (NVS4) membranes or no membrane (NM). After 45 days, vegetative growth parameters, anatomical characteristics, accumulation of photosynthetic pigments and phenolic compounds, and antioxidant defense responses by nonenzymatic mechanisms were evaluated. The NVS4 group had the highest growth rates, greatest accumulation of photosynthetic pigments, and the most anatomically organized tissues, in addition to the best antioxidant defense response. This natural ventilation system with four membranes offered the best conditions for the growth and development of Lippia dulcis plantlets.