СВЯЗЬ ЦИТОГЕНЕТИЧЕСКИХ ПОКАЗАТЕЛЕЙ С МОЛЕКУЛЯРНО-ГЕНЕТИЧЕСКИМИ РАЗЛИЧИЯМИ У ВИДОВ РОДА Rhododendron L. ПРИ ИНТРОДУКЦИИ

Currently, woody plants attract special attention given the prospects of their involving in bio- and genomic technologies to address challenges of sustainable environment, biodiversity, food security and production of raw materials. Thence, studies of cytogenetic characteristics of woody plants are increasingly relevant. The change in a number of cytogenetic characteristics, in particular, mitotic activity, which may increase and decrease depending on the intensity of stress loads, an increase in the pathology of mitosis, etc., has been shown. However, attempts to identify the similarities and differences in cytogenetic characteristics in woody plants on the basis of the results of molecular genetic comparison weren’t conducted yet. Sequences of the internal transcribed spacer (ITS) regions of nuclear ribosomal NA were used to generate a phylogenetic hypothesis for disjuncting of wood species of the genus Aralia (J. Wen, 2000), to specify of Rhododendron systematic state (T.V. Baranova et al., 2014) and other genera of the family Ericaceae (O. Schwery et al., 2015). Cluster analysis of nucleotide sequences and construction of the dendrogram were carried out using the ML (Maximum Likelihood, Nearest-Neighbor-Interchange) method in the MEGA software. Germination of Rhododendron seeds was carried out in Petri dishes at room temperature. Roots were stained with acetohe-matoxylin, rinsed with distilled water, and suppressed micro-preparations were prepared using Goyer’s fluid. Nucleotide sequences of the ITS1-ITS2 spacer of the parent plants and cytogenetic parameters (mitotic activity, level and spectrum of pathological mitoses, number of cells with residual nucleoli in the metaphase-telophase mitosis stage) we obtained from seed progeny in four Rhododendron species introduced into the conditions of the Central Black Earth region of Russia. The identity of the nucleotide sequence of the spacer ITS1-ITS2 in species of the genus Rhododendron leads to their greater similarity in the aggregate of cytogenetic indices. However, there is no complete analogy of cytogenetic characteristics in the species studied that have the identical sequence ITS1-ITS2. On the basis of this comparison, it can be assumed that genetic similarity in the studied Rhododendron species causes the similarity of cytogenetic indices. According to mitotic activity in the root meristem of the seedlings, two groups can be distinguished among the seed progeny, i.e. with a high value of mitotic activity, namely Rhododendron dauricum (7.6±0.3 %) and Rh. mucronulatum (7.7±0.7 %), and with low value, namely Rh. sichotense (5.6±0.7 %) and Rh. ledebourii (6.1±0.6%). The greatest cytogenetic instability is noted in Rh. ledebourii (5.2±1.1 %, the level of pathologies of mitosis in this species is maximal), in three other species it was lower (from 3.5±0.5 % for Rh. sichotense to 1.6±0.4 % for Rh. dauricum mitosis pathologies). A higher level of cells with a residual nucleolus at the stage of metaphase—telophase mitosis indicates a greater intensity of synthetic processes associated with adaptation in conditions of introduction. For this indicator, we can distinguish two groups: i) Rh. sichotense (13.3±1.2 %) with a high level of cells with a residual nucleolus at the stage of metaphase—telophase of mitosis, and ii) Rh. mucronulatum (9.1±1.1 %), Rh. dauricum (10.2±1.0 %) and Rh. ledebourii (10.9±1.3 %) with low values. Despite the difference in cytogenetic parameters in the seed offspring of the studied species, a cluster analysis of the totality of the characteristics of the course of mitosis and nucleolar activity made it possible to distinguish two groups: 1) Rh. mucronulatum and Rh. dauricum; 2) Rh. ledebourii and Rh. sichotense. The cytogenetic characteristics of the seed offspring of the species studied are species-specific.