Microstructural and histochemical variations during in vitro to in vivo plant developments in Aloe vera (L.) Burm.f (Xanthorrhoeaceae)

•Phytochemicals in tissues showed the adaptability to environmental changes.•In vitro plantlets of Aloe vera had underdeveloped anatomy and histochemicals.•Ex vitro hardening enhanced the structural stability and histochemical deposition.•In vivo plantlets developed micro-morpho-anatomical and histochemical adaptations. Aloe vera (L.) Burm.f (Barbados aloe) is an economically important succulent herb, well accredited for its medicinal properties for centuries. In vitro propagation encouraged the production of identical individuals within a short period. However, there are evidences of in vitro induced disorders in the morphology, anatomy, phytochemistry and physiology of the micropropagated plantlets. These anomalies severely affect the acclimatization process and lead to loss of tissue culture raised plants in the field. This study, therefore, sought to evaluate the foliar micro-morpho-anatomical and histochemical changes during various phases of in vitro plant regeneration of A. vera. These variations were analyzed at three different stages of growth and development of the plantlets from lab to land [in vitro (IV), ex vitro (EV), and field transferred (FT) plants]. The field transferred plantlets showed improved phenotype, foliar micro-structures, leaf pigmentation (chlorophylls and carotenoids), and histochemical depositions in terms of polysaccharides (starch and mucilage), phenolic compounds (tannins, polyphenol, and lignin), and cutin and suberin as compared with in vitro and ex vitro plantlets. The study would allow us to understand the appropriate stage of secondary metabolites accumulation in the tissues and the successful establishment of plantlets in soil. The present findings outline the long-term effort to assess the potential of mass propagation (in vitro) of A. vera for commercial cultivation practices.