Analysis of epigenomic and epiplastome variability in the haploid and dihaploid sugar beet ( Beta vulgaris L.) plants

Reproduction of cells, individuals, populations is a principal concept of biology. This process is characterized by two properties: heredity and variation. The concept of inheritance indicates the identity of the parents and the offspring’s; the concept of variability indicates the incompleteness of this identity. There is a direct proportional relationship between the genome level ploidy, the cy-toplasm volume and the cell size (nuclear-plasma ratio). Variation of chromosome or chromatid numbers in the cell nuclei determines the epigenomic variability and variation of intracellular organelle numbers in the cell (for example chloroplasts) determines epiplastome variability in plants. Relationship of the chloroplast number in stomata guard cells and nucleus ploidy level in sugar beet is well known that permit to compare an epiplastome variability in plants and different ploidy of genomes. Chloroplast number in the cells varies, partly due to the asymmetric organelle distribution during cytokinesis. However the epiplastomic variability is related not only with a random organelle distribution during cytokinesis, but also with a genome number variation per cell nucleus (epige-nomic variability). An endohaploidy, i.e. an appearance of haploid cells in cell population, is one of the variant of epigenetic variability display. Sugar beet may form the haploid seeds spontaneously both by biparental and uniparental reproduction. In the work the diploid (control, generation A 0), dihaploid and haploid (generation A 1) seed progeny were used. Dihaploids and haploids were obtained by the parthenogenetic reproduction mode (pollen less condition). In the paper we considered a variability of chloroplast number in stomata guard cells and integral tissue characteristic which are compared with harmonious proportions (Fibonacci number, golden ratio). It was studied following parameters: a) a chloroplast number in stomata the guard cells; b) a plastotype number in the epidermal tissue. And it was determined the average value of chloroplast (M) and plastotypes (Pt) number in stomatal guard cells of haploid, diploid and dihaploid plants. On the base of obtained data the ratios of epigenetic stability (D-ratio) in haploid, diploid and dihaploid (control) sugar beet plants were estimated. D is logarithmic ratio of the chloroplast number to plastotypes and indicates the physiological and epiplastome stability of cell populations. It was shown the differences between the experiment simples: D-ratio in dihaploids is always above than one in the haploids. It was established for the first time that integral tissue characteristic (D-ratio) corresponds to harmonious proportions (bio-logical invariants), i.e. Fibonacci numbers (golden ratio). In diploids and dihaploids this ratio corresponds to the first terms of the harmonious series (from first to fifth), in haploids D-ratio corresponds to eighth and higher terms of the harmonious sequence.