Effects of natural ventilation on leaf ultrastructure of Dianthus caryophyllus L. cultured in vitro

Summary Vessel closure configurations exert direct and indirect control over factors pertaining to the physical boundaries of the mieroenvironment, and induce a typical phenotype in in vitro plant production. Upon modification of the in vitro environment, carnation explants showed a gradation of their ultrastructural characteristics from hyperhydric to normal. A higher degree of development was observed in plants from vessels with higher ventilation compared to ones from vessels with low ventilation rates. The cell walls of epidermal cells from both normal and hyperhydric plants grown in nonventilated vessels were less developed than those from plants grown in ventilated vessels. Cytoplasm of normal plants was dense and generally located in parietal areas. The cytoplasm was even more dense in plants grown in ventilated vessels and acclimated. The degree of thylakoid stacking and distribution were affected by ventilation conditions, being poorly developed with low ventilation. Ultrastructurally, stomata from in vitro plants are ready to carry out their task, although there are significant differences in guard cell size and vacuolar area between acclimated and in vitro plants.