Mani_2022_Plant.Biol.(Stuttg)__

Crinum malabaricum Lekhak & Yadav is a recently discovered and critically endangered aquatic bulbous plant of the family Amaryllidaceae. It gained attention as a wild source of acetylcholinesterase inhibiting alkaloid 'galanthamine' to treat Alzheimer's and Parkinson's disease. The bulbs of this plant contain the highest amount of galanthamine among the Crinum species. The in vitro regeneration systems were developed to produce quality uniform plantlets of C. malabaricum. Bright field light microscope was used to analyze the micro-morpho-anatomical developments taking place in the leaves and roots during in vitro, ex vitro, and in vivo transitions of plantlets. The in vitro raised leaves and roots possessed a higher degree of microscopic structural anomalies such as underdeveloped epicuticular wax deposition, immature and non-functional stomata, more aquiferous parenchyma with the reduced lumen. Roots developed in vitro were characterized by extremely large, uneven cortical cells, and reduced intercellular spaces. The vascular tissues were underdeveloped and only primary vascular tissues observed. As a result of ex vitro acclimatization, a significant acceleration in the improvement of tissue systems in leaves and roots was observed. Such plantlets were capable of having tolerance to elevated temperature and light under in vivo conditions. Thus, the microscopic evaluation of structural trajectory in different stages of plantlet development provides an understanding of the acclimatization process and structural adaptations, which could help in enhanced survival of in vitro raised plantlets under ex vitro and in vivo conditions.