Morpho-anatomical changes and antioxidant enzyme activity during the acclimatization of Genipa americana

The ultimate success of micropropagation and the commercial viability of this technique depend not only on the number of regenerated seedlings but also on the ability to transfer them to an ex vitro environment at a large scale with high survival rates. In this context, the aim of this study was to achieve ex vitro establishment and to evaluate the morpho-anatomical changes and antioxidant enzyme activity that occurred during the acclimatization of Genipa americana L. seedlings. Shoot rooted in vitro were transferred to peat and vermiculite substrate and were maintained in a growth room under a controlled temperature of 25 ± 2 °C and a photosynthetic photon flux density of 67 μmol m−2 s−1. After 14 days of acclimatization in the growth room, the plants were transferred to a greenhouse with 70% shading. At 0 (corresponding to the in vitro phase), 7, 14, 21 and 28 days after the transfer to ex vitro conditions, growth and antioxidant enzyme activity were analyzed. After 30 days of acclimatization, 90% seedling survival was observed. The results reflect the high phenotypic plasticity of this species and morphological and physiological changes such as the emergence of new leaves, the increase in chlorophyll content, the stomata assuming an elliptical shape, the root survival in vitro and the stimulated activity of antioxidant enzymes, which ensured continuous plant growth and acclimatization, leading to continuous growth and a high survival rate (90%) after acclimatization.