Appearance of phenotypic plasticity of leaves in psammophyte Corynephorus canescens during flooding

The results of the study of the leaf structure in psammophyte Corynephorus canescens, which grew under controlled conditions and flooding using the methods of light microscopy, scanning electron microscopy, and laser confocal microscopy, are presented. This study revealed common and distinctive signs of morphological and anatomical parameters of C. canescens leaves in the phase of vegetative growth. Among the common features were the shape and size of the leaf laminas, hypostomatic type of the leaf, isolateral structure of the parenchyma, the thick-walled epidermis, and the bilayered hypodermis. Among the distinctive features were the signs of the destruction of cells in the photosynthetic parenchyma, change in their shape with the formation of protuberances at the cells’ poles, and almost doubling area of the aerenchyma in C. canescens leaves under flooding conditions. Scanning electron microscopy showed the similarity of ultrastructure and density of trichomes on the adaxial surface, excepting the formation of cuticular wax structures on the epidermal surface of the leaves in flooded plants. The subcellular localization of silicon inclusions was studied for the first time. The presence of amorphous and small crystalline silicon inclusions in the periclinal walls of the main epidermal cells and amorphous silicon inclusions in leaf trichomes was established. An increase in the relative silicon content along the trichomes in the leaves’ epidermis after flooding was revealed. It was assumed that the phenotypic plasticity of C. canescens, is realized through the increasing area of aerenchyma in leaves and increasing silicon content in trichomes. Such plasticity helps to optimize both the oxygen balance of plants and water balance in flooded plants, thus increasing the species’ resistance to prolonged flooding