In the context of global warming, an important task is to find mechanisms for forest woody plants adaptation to changing environmental conditions. In steppe regions, this issue is particularly acute due to frequent droughts during the growing season. Scots pine is one of the main forest-forming species in Russia and is of great importance. The paper deals with the vital state of Scots pine plantations growing in the pessimal zone of the range in the steppe region, as well as the genotypic structure of the glutamate dehydrogenase locus. The allelic form of Gdh-1 of this enzyme is an embryonic semi-lethal for Scots pine and can act as a molecular marker of adaptation of this species to negative environmental conditions. It is known that organisms with semi-lethal genes in their genotype have a complex of compensatory mechanisms, which causes their increased resistance to adverse factors. The study sample was divided into two groups according to the level of living conditions: strong and weak. It was found that in the group of trees in the best vital condition, the proportion of genotypes containing embryonic half-life ( Gdh-1 ) of scots pine prevails. Also, in the group of strong trees, the allele, which is an embryonic half-fly, is 79%, and in the group of weak trees - 39%, which is 1,9 times less.

In natural conditions of growth, forest woody plants constantly face negative environmental factors. Environmentally unfavorable impacts certainly affect the physiological and biochemical processes occurring in plants and lead to the activation of their own protective mechanisms. In recent years, methods of biotechnology (cell and tissue selection) have been increasingly used in the study of adaptive capabilities, as well as the degree of tolerance of plants to abiotic stress factors. In our work, we evaluated the specifics of the reaction of Betula pendula Roth, Betula pendula Roth var. carelica (Mercklin) L. Hmet-Ahti and Betula pubescens Ehrh. in vitro, in particular the change in the level of free proline to low-temperature stress (+4C) of different duration times. It was found that the highest value of the amino acid content in relation to the control was in the Betula pendula Roth var. carelica Merckl. clones and ranged from 163 to 206%, in the Betula pubescens Ehrh. and Betula pendula Roth clones ranged from 103 to 128% and from 101 to 131%, respectively. Uniformity was noted among the clones of Betula pendula Roth var. carelica Merckl. according to the degree of response to stress. The relationship between the ability of plants to produce more proline and successful adaptation to cold shock was revealed.

A comparative analysis of two Scots pine plantations growing in different ecological conditions of the steppe zone in the south of the Central Black Earth region (Kantemirovsky District of the Voronezh Region) has been carried out. One plantation is located in a relatively ecologically clean area, outside the urban environment, the other one - within the village Kantemirovka. The enzyme system has been studied; it is an important link in the main metabolic pathways in plant organisms influencing the general condition of plants. In the studied stands the genetic structure of the glutamate dehydrogenase locus has been analyzed, one of the alleles of which ( Gdh-1 ) in Scots pine is an embryonic semi-metal. It has been found that in a weakened plantation located in an urban environment and exposed to increased anthropogenic impact, the proportion of this allele and the proportion of genotypes homozygous for it is significantly (p 0,01) higher than in the population from an ecologically clean zone. It is known that organisms with semi-lethal genes in their genotype possess a complex of compensatory genes, which determines their increased resistance to unfavorable factors. An increase in the proportion of semi-lethal alleles in a plantation growing under anthropogenic load can be an adaptive mechanism for increasing resistance at the population level to stress effects of different nature.