Structural effects on Cattleya xanthina leaves cultivated in vitro and acclimatized ex vitro

Abstract

In vitro orchid micropropagation is efficient biotechnological strategy for conservation and commercial plantlet production. However, micropropagated plantlets generally need to adapt to survive severe changes in humidity, irradiance, and growing medium that accompany the transfer to ex vitro conditions. Such adaptive cellular changes would give insights into the phenotypic plasticity of the model plant Cattleya xanthina (L.) Van den Berg. Therefore, we aimed to evaluate structural changes in the leaves of C. xanthina cultivated in vitro and acclimatized ex vitro using qualitative and quantitative analyses. During acclimatization, we observed a higher accumulation of dry mass, a greater convexity of the outer surface of epidermal cells, an increased deposition of epicuticular waxes, a greater elongation of mesophyll parenchymatic cells, and finally, the presence of chloroplasts with organized thylakoids and well-developed grana. Stomatal density was not changed. Furthermore, a gradual acclimatization allows this species the best adaptation to a new environment.