Cytogenetic variability of apical meristems of oak petiolate

The analysis of the variability of mitotic and nucleolar activity in the apical root meristem of acorn oak seedlings was carried out. Mitotic disorders for oak petiolate, variability of such parameters as: mitotic index, mitotic pathologies, type of nucleolus, surface area of the nucleolus, distribution of dividing cells by stages of mitosis were determined. The most sensitive parameters to the impact of urban environmental factors are identified, which can be used to assess the adaptive potential of tree objects of g. Quercus. The indicators of mitotic activity have a high degree of variation, with a Cv for mitotic parameters from 17 to 65 %, and for nucleolar characteristics from 10 to 150 %, depending on the biotype under study. The mitotic index has the following limits of variation: from 5 to 15 %, mitotic pathology 4 to 24 %. The most sensitive indicator is the mitotic index and pathologies of mitosis. The spectrum of pathologies expands under anthropogenic load. There are deviations in the course of mitotic division, which can be expressed as a delay in division at the prophase stage, and in a violation associated with the chromosomal apparatus. The most common are: lagging chromosomes in metaphase, anaphase, the formation of bridges in anaphase. Less common are agglutinations of chromosomes, multipolar, asynchronous mitoses, and micronuclei. Also, violations are indicated by residual nucleoli, which normally should not be detected at the stages of mitosis. The manifestation of an adaptive response to the influence of factors will be a change in the nucleolar characteristics, a change in the intensity of cell division. The magnitude of mitosis pathologies, i. e. the percentage of dividing cells with division disorders, characterizes the mutability of offspring, which can be used in forest breeding (selection of mutable offspring) and the creation of plantings with a stable genetic apparatus (weakly mutable offspring).