Effects of Moderate Drought on Leaf Bulliform Cells of Aquatic and Coastal Population of Phragmites australis

: Studying leaves of aquatic and terrestrial populations of Phragmites australis grown on the bank of the Venetian strait of the Dnipro River in Kyiv (Ukraine) for establishing the role of bulliform cells in the mechanisms of plant resistance to moderate soil drought were studied. Bulliform (motor) cells participate in the twisting and folding of leaves during drought and strong sunlight. The study of bulliform cells in the leaves of the aquatic and terrestrial populations of P. australis was carried out using the methods of light microscopy, cytochemical methods, laser confocal microscopy, and biochemical methods. The comparative analysis of the structure of bulliform cells of leaves of P. australis has shown significant differences depending on plant growth location. The differences in the number, size, and area of bulliform cells and also polysaccharide content showed clear phenotypical plasticity. Cytochemical and laser confocal microscopic studies of polysaccharides of cell walls in bulliform cells of aquatic and terrestrial ecotypes of P. australis showed that a decrease in soil moisture in a natural moderate drought of soil led to an increase in lignin and syringyl monolignol content in the outer walls of bulliform cells and also to a decrease in cellulose and callose content in outer and inner cell walls. The obtained data shows that the studied signs of bulliform cells can be markers of tolerance for population plants that have the ability to curl leaves for the preservation of optimal water balance in moderate drought.