[Epigenetic variation of the choriflowered--symflowered character in the symflowered sugar beet line SOAN-14].

The effect of 5-azacytidine on the variation of the choriflowered (CF)-symflowered (SF) character in sugar beet was studied in several generations obtained via seed reproduction. The epimutagen (5-azacytidine) significantly reduced the number of flowers in glomerate inflorescences in the year of seed treatment and in the next generation (Az1), leading to the appearance of plants with single flowers in bract axils of a flower stalk. The CF character resulting from epimutagene treatment of sugar beet seeds (plants with genotype M(Z)M(Z) was inherited as a monohybrid character in both zygotic and apozygotic seed progenies. The proportion of the CF and SF phenotypes in the progenies was affected bythe chromatid number in the chromosomes (mixoploidy of the cell populations). Alleles of the Mm locus were found to affect the variation in phytomere organization of flower stalks.

[Fruit set variation associated with apozygotic reproduction in sugar beet (Beta vulgaris l.)].

Fruit set upon apozygotic reproduction was studied for four years in the msSOAN-5 pollen-sterile inbred sugar beet line. The progenies obtained from pollen-sterile plants by apozygotic reproduction had both fruits with normal seeds and parthenocarpic fruits without seeds, which was not an occasional event. Growth conditions proved to strongly affect the fruit set and seed quality. For instance, water deficiency during early plant development increased the proportion ofparthenocarpic seeds. Waiter deficiency combined with a lower temperature during flowering additionally caused a substantial decrease in the total number of fruits. Under the same growth conditions, related accessions did not differ in seed productivity, but varied in the proportion of normal (with seeds) and parthenocarpic (without seeds) fruits.

[Analysis of serial sequences of seeds in sugar beet plants upon apozygotic reproduction].

Dichotomic serial sequences of fruits of two types (with and without seeds) on shoots were analyzed in sugar beet upon apozygotic reproduction. Serial sequences were analyzed using serial statistical tests. The distribution of fruits of the two types was nonrandom in most cases. The variation of serial sequences is considered in terms of the epigenetic variation of discrete characters in plants.

[Effect of the epimutagen 5-azacytidine on the structure of floral-stalk metameres in sugar beet (Beta vulgaris L)].

This study is dedicated to the effect of the epimutagen 5-azacytidine on the structure of floral-stalk metameres in sugar beet Beta vulgaris L. Simple phytomeres consist of separate flowers (unianthous plants; UA phenotype), while complex metameres occur in synanthous plants (SA phenotype). Treatment of the synanthous line mcSOAN-5 dramatically reduced the number of flowers on phytomeres as early as in generation zero (A0Az0). For the first time, plants with simple phytomeres were found in this line. The proportion of plants with the SA phenotype in generation A0Az0 was 7.7%. In generation A1Az1, the tendency for reduction of the number of flowers on phytomeres persisted. The proportion of plants with simple phytomeres reached 77%; i.e., the frequency of SA phenotypes in the progeny (A1Az1) increased tenfold in comparison with the parents A0Az0. The high frequency of morphogenetic changes in the floral stalk structure under the influence of the epimutagen suggests that the variability of the UA--SA character in beet populations is of epigenetic rather than mutational nature.

[Effect of 5-azacitidine on flower stalk branching in sugar beet (Beta vulgaris L.)].

An influence of epimutagen 5-azacitidine on a flower stalk morphogenesis in sugar beet was studied. After the epimutagene treatment the great number of the first- and the third-order branch formation was observed. A higher level of branching completely modified the flower stalk architectonics (generations A0Az0 and A1Az1). A number of the second-order branches in the control and the experimental plants were not distinguished. A new epiphenotype with higher level of branching (generation A0Az0) inherited in daughter generation A1Az1. A flower stalk architectonics was modified because the third-order branches developed in the bract axil instead of flower primordium. A great number of lateral shoot modified a metamer organization of the flower stalk. The metamers on the third-order branches were single-flowered.

[Structural and transcriptional variation of mitochondrial DNA in pollen-sterile agamospermous sugar beet (Beta vulgaris L.) progeny].

The cytoplasm status according to mitochondrial sequence tags was determined in agamospermous sugar beet progenies characterized by unstable manifestation of cytoplasmic male sterility. The detected variations in the ratios of homologous sequences related to the N and S mtDNA types did not correlate with pollen phenotypes of the plants. Polymerase chain reaction allowed semiquantitative evaluation of these variations and their detection. A cDNA corresponding to a hitherto unknown minor RNA and containing a consensus sequence of dicotyledonous plant promoters was detected by mtRNA display. Probable sources of CMS variability in agamospermous sugar beet progenies are discussed.

[Epiplastome variation of the number of chloroplasts in stomata guard cells of sugar beet (Beta vulgaris L.)]. / Epiplastomnaia izmenchivost' chisla khloroplastov v zamykaiushchikh kletkakh ust'its sakharnoi svekly (Beta vulgaris L.).

In stomata guard cells of sugar beet, variation in the number of chloroplasts was studied in successive generations: (1) hybrid generation; (2) generation yielded by uniparental apozygotic seed reproduction; (3) generation obtained after seed treatment with a colchicine solution; (4) generation obtained after seed treatment with 5-azacytidine. As compared to hybrid generation, uniparental seed reproduction increases the average number of chloroplasts in stomata guard cells (from 13.5 to 15.0) and decreases distribution variance of this trait by a factor of 3 to 4. Colchicine increases both average number of chloroplasts in stomata guard cells (from 13.5 to 18.2) and distribution variance (about twice). 5-Azacytindine reduces the number of chloroplasts in cells (from 15.0 to 12.9) but enhances distribution variance (about 1.5 times). Variation in the number of chromosomes in stomata cells is related to myxoploidy in meristem tissue, on the one hand, and to the rate of cell division, on the other. Uniparental seed reproduction is suggested to enhance the number of organelles per cell due to high myxoploidy in cell populations, which is typical of inbred plants. Colchicine blocks spindle division and sharply increases the level of myxoploidy in cell populations and the number of organelles per cell. 5-Azacytidine hypomethylates chromosome DNA, increases the rate of cell divisions, and reduces the number of organelles per cell. The described changes in the number of chloroplasts are inherited in cell lineage ("cell hereditary memory") and successive sporophyte generations.

[Expression of CMS in zygotic and apozygotic progenies of sugar beet Beta vulgaris L]. / Ekspressiia priznaka TsMS v zigoticheskikh i apozigoticheskikh potomstvakh sakharnoi svekly (Beta Vulgaris L.).

Zygotic and apozygotic progenies of sugar beet exhibit high phenotypic variation with respect to cytoplasmic male sterility (CMS). There are progenies with completely sterile, semisterile, semifertile, and fertile pollen. The proportions of semifertile and fertile plants in zygotic and apozygotic progenies varied from zero to 28% and from zero to 17.8%, respectively. Comparison of the phenotypic distributions in zygotic and apozygotic progenies did not reveal significant differences in the CMS expression, although the latter is determined by the maternal S-plasmotype and both maternal and paternal (pollinator) genotypes in zygotic progenies and only by the maternal S-plasmotype and genotype in apozygotic progenies. It has been hypothesized that the instability of the CMS expression in apozygotic progenies is determined by epigenetic variation in the activities of the genes that control the maintenance of the pollen-grain sterility. Inactivated dominant alleles Rf1(0) and Rf2(0) in homozygous state may function as sterility maintenance genes, whereas activation of these alleles during ontogeny results in a partial or complete restoration of pollen-grain fertility. It was demonstrated that pollen fertility of mother plants with S cytoplasm did not affect the CMS expression in two sib progenies. Conversely, in two other progenies, the proportion of fertile plants was significantly higher in the sib progenies of mother plants with fertile pollen and S cytoplasm (inheritance of epigenetic variation).

[Variability of the number of chloroplasts in a population of stoma guard cells in the sugar beet (Beta vulgaris L.)]. / Izmenchivost' chisla khloroplastov v populiatsiiakh zamykaiushchikh kletok ust'its u sakharnoi svekly (Beta vulgaris L.)

Diploid sugar beet plants demonstrate a broad variability of the number of chloroplasts in stoma guard cells, which is related to myxoploidy of cell populations in leaf apical meristems (epigenomic variability). In addition to random organelle segregation between daughter cells, this variability is affected by factors disrupting the mitotic cycle: (1) plant treatment with a mitotic poison, such as colchicine; (2) duration of the life cycle of a plant; the variability in second-year plants is greater than in first-year ones; (3) the mode of plant reproduction; the variability in inbred plants is greater than in the initial population. Treatment of germinating seeds with a diluted colchicine solution increases the number of organelles in cells in the myxoploid generation (generation C0) and the variance of the distributions in the first vegetation year. The variability in the organelle number in stoma cells correlates with that in maternal meristem cells. It is concluded that the epidermal cell monolayer (including stoma guard cells) keeps record of the epigenomic and epiplastome variability in meristem cells. The variability of the number of chloroplasts in stoma guard cells is approximated by binomials with negative powers.

[The heterogeneity of neurospecific S-100 protein]. / K voprosu o geterogennosti neirospetsificheskogo S-100 belka

A modified method is described of the isolation of neuro-specific S-100 protein from bovine brain tissue by means of thermal denaturation, ammonium sulphate fractionation, chromatography on DEAE-Sephadex A-50 and gel filtration through Sephadex G-100. Considerable heterogeneity of S-100 protein is discovered: it produces 4 fractions (f1--f4) under fractionation on DEAE-Sephadex A-50. The constant elution from the column of the main fraction, eluted with 0.325--0.35 M NaCl, and minor S-100 protein fractions, eluted with more high NaCl concentrations, is registered. At the same time, considerable variation in the quantitative yield of the main component of S-100 protein and in the relative content of main and minor components of S-100 protein is developed. Fast- (in f1 and f4 fractions) and slow-migrating (in f2 and f3 fractions) components are revealed under polyacrylamide gel electrophoresis. The f1 fraction is found to consist mainly of the component with molecular weight of 20 000 while fz, f3 and f4 fractions contain two components having molecular weight of 32 000 and 71 000. Antiserum to S-100 protein produced a positive immunodiffusion reaction with f1 and f2, and not with f3 and f4 fractions.