ADAPTIVE VARIABILITY OF SOME WOODY-SHRUB SPECIES LEAF PLATES UNDER OSMOTIC STRESS IN VITRO

The aim of the study is to assess the effect of simulated osmotic stress in vitro culture on the morphophysiological and anatomical parameters of the foliar apparatus of the selected genotypes of woody and shrubby plants. The studies were conducted at the Laboratory of Biotechnology of the FSC of Agroecology of the RAS in 2023–2024. The objects of the study were three species of woody and shrubby plants that are promising in arid climates: Cotinus coggygria Scop. (Cotinus coggygria Scop.), dwarf rootstock for stone fruits Prunus VSL 2, Caragana pygmaea L. (Dwarf caragana). Drought conditions were simulated using a non-ionic osmotic agent polyethylene glycol with a molecular weight of 6000 (PEG). Osmotic stress in the nutrient medium had an inhibitory effect on the growth processes of all studied species. However, the nature of the changes was species-specific. General changes in leaf blades were manifested in a decrease in the size of stomatal cells, complete or partial closure of the stomatal slit and a higher density of stomata. After cultivation on a medium with PEG 60 g/l, the leaf blade area of C. coggygria decreased by 3.8 times, for Prunus VSL 2 leaves – by 1.2 times compared to the control. When cultivating on nutrient media supplemented with PEG 60 g/l, only regenerants of C. pygmaea capable of rhizogenesis survived. One of the criteria for selecting more drought-resistant genotypes is the chlorophyll content in leaf blades, reflecting the stable operation of the photosynthetic apparatus. For C. pygmaea, this indicator was 2.5 times lower than the control. In Prunus VSL 2 and Cotinus coggygria adapted to water deficit, the total chlorophyll content in leaf blades was higher.