EVALUATION OF SALINITY AND OSMOTIC STRESS RESISTANCE OF THE GENUS Populus SPECIES AND HYBRIDS IN CULTURE In vitro

The article represents studying the salinity and osmotic stress resistance of regenerants of Populus alba × P. bolleana № 7 and P. tremula F. № 8, and callus culture of P. alba × P. bolleana 7, P. tremula F. № 8, P. koreana and P. pruinosa in vitro. It shows that introducing 50 mM NaCl into the nutrient medium did not affect significantly the growth parameters for P. alba × P. bolleana № 7 and P. tremula F. № 8 plants. NaCl concentration enhancement to 150 mM resulted in a partial plant death, a lamina size decrease more than twice, and leaf chlorosis. 250 mM NaCl concentration was harmful for callus culture of all studied representatives of the genus Populus. 50 mM NaCl applied for the salt-resistant species of P. pruinosa did not affect the calli growth. P. alba × P. bolleana № 7 callus culture showed a regular biomass decrease under NaCl concentration enhancement in the nutrient medium. P. tremula F. № 8 calli were characterized by the lowest biomass growth rates. Analyzing mannitol effect, it was noted that P. pruinosa calli showed rising increment in dry biomass with mannitol concentration enhancement in the nutrient medium. Other poplar species and hybrids demonstrated decrease in growth parameters under mannitol content gain. Callus cultures of the studied poplar species and hybrids on reducing salinity and osmotic stress resistance were distributed as follows: P. pruinosa ‒ P. koreana ‒ P. alba × P. bolleana № 7 ‒ P. tremula F. № 8. The authors have demonstrated that callus cultures of P. alba × P. bolleana № 7 and P. tremula F. № 8 are more sensitive to stressful conditions of drought and salinity than regenerated plants and can act as test systems to evaluate the impact of negative abiotic factors.