RESUMEN
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.
Asunto(s)
Beta vulgaris , Epigénesis Genética/genética , Flores/genética , Azacitidina/farmacología , Beta vulgaris/efectos de los fármacos , Beta vulgaris/genética , Beta vulgaris/crecimiento & desarrollo , Flores/efectos de los fármacos , Flores/crecimiento & desarrollo , Genotipo , Mutagénesis , Fenotipo , Semillas/genéticaRESUMEN
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.
Asunto(s)
Beta vulgaris/crecimiento & desarrollo , Beta vulgaris/genética , Frutas/crecimiento & desarrollo , Frutas/genética , Beta vulgaris/anatomía & histología , Flores/anatomía & histología , Flores/genética , Flores/crecimiento & desarrollo , Frutas/anatomía & histología , Partenogénesis , Polen/genética , Polen/crecimiento & desarrollo , Reproducción , Semillas/genética , Semillas/crecimiento & desarrollo , TemperaturaRESUMEN
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.
Asunto(s)
Beta vulgaris/genética , Epigénesis Genética , Variación Genética , Semillas/genética , ReproducciónRESUMEN
The Weisman's conception of germ track is considered in historical context focusing on fundamental differences among germ tracks in animals and plants. Differentiation of animal germ track cells occurrs once whereas in plant ontogenesis this process is multiply realizing (a concept of recurrent embriony). Fundamental differences in morphogenesis and embryogenesis of animals and plants as well as the differences in the properties of somatic and stem cells provide plants with special and additional modes of variability and evolution which are absent in animals.
Asunto(s)
Plantas , Semillas/citología , Células Madre/citología , Células Vegetales , Desarrollo de la Planta , Plantas/embriologíaRESUMEN
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.
Asunto(s)
Azacitidina/farmacología , Beta vulgaris/efectos de los fármacos , Epigénesis Genética/efectos de los fármacos , Flores/efectos de los fármacos , Mutágenos/farmacología , Beta vulgaris/anatomía & histología , Beta vulgaris/genética , Flores/genética , Flores/crecimiento & desarrollo , Fenotipo , Semillas/efectos de los fármacos , Semillas/genéticaRESUMEN
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.
Asunto(s)
Azacitidina/farmacología , Beta vulgaris , Epigénesis Genética/efectos de los fármacos , Mutágenos/farmacología , Beta vulgaris/efectos de los fármacos , Beta vulgaris/genética , Beta vulgaris/crecimiento & desarrollo , Flores/efectos de los fármacos , Flores/genética , Flores/crecimiento & desarrollo , Fenotipo , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/genética , Brotes de la Planta/crecimiento & desarrolloRESUMEN
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.
Asunto(s)
Beta vulgaris/ultraestructura , Cloroplastos/ultraestructura , Azacitidina/farmacología , Beta vulgaris/citología , Beta vulgaris/efectos de los fármacos , Beta vulgaris/genética , Cromosomas de las Plantas , Metilación de ADNRESUMEN
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).
Asunto(s)
Beta vulgaris/fisiología , Cruzamientos Genéticos , Citoplasma/genética , Fertilidad/genética , CigotoRESUMEN
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.