Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization

Abstract

The nucleolar activity of Hyacinthus orientalis L. embryo sac cells was investigated. The distributions of nascent pre-rRNA (ITS1), 26S rRNA and of the 5S rRNA and U3 snoRNA were determined using fluorescence in situ hybridization (FISH). Our results indicated the different rRNA metabolism of the H. orientalis female gametophyte cells before and after fertilization. In the target cells for the male gamete, i.e., the egg cell and the central cell whose activity is silenced in the mature embryo sac (Pięciński et al. in Sex Plant Reprod 21:247–257, 2008; Niedojadło et al. in Planta doi:10.1007/s00425-012-1599-9, 2011), rRNA metabolism is directed at the accumulation of rRNPs in the cytoplasm and immature transcripts in the nucleolus. In both cells, fertilization initiates the maturation of the maternal pre-rRNA and the expression of zygotic rDNA. The resumption of rRNA transcription observed in the hyacinth zygote indicates that in plants, there is a different mechanism for the regulation of RNA Pol I activity than in animals. In synergids and antipodal cells, which have somatic functions, the nucleolar activity is correlated with the metabolic activity of these cells and changes in successive stages of embryo sac development.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-012-1618-x) contains supplementary material, which is available to authorized users.

Late progamic phase and fertilization affect calreticulin expression in the Hyacinthus orientalis female gametophyte

“…In turn, in synergids degenerating after fertilization and antipodals, there is a silence of transcriptional activity, including CRT expression in these cells (Niedojadło et al 2012a and this work). The results of our previous studies revealed that in hyacinth, the activation of the zygotic genome and the primary endosperm cell anticipates the first mitotic divisions over time, which confirms the high metabolic activity of a fertilized egg cell and the primary endosperm cell (Niedojadło et al 2012a , b ). In light of the current results, it seems highly likely that soon after karyogamy in the zygote, as well as in the primary endosperm, one also observes the upregulation of CRT expression.…”

“…Commercial cultivars of Hyacinthus orientalis L. were grown at room temperature. The Hyacinthus pistil is composed of a hollow style and a dry stigma, while the female gametophyte develops according to the Polygonum type and consists of two synergids, the egg cell, the central cell containing two polar nuclei, and three antipodals (Pięciński et al 2008 ; Niedojadło et al 2012a , b , 2015 ). For fluorescence and electron microscopy studies, the ovules were mechanically dissected from unpollinated flowers before and during anthesis and from hand-cross-pollinated flowers 8 h after pollination (at the late progamic phase when the pollen tubes have reached approximately three-quarters of the style length and have not entered the ovary) and 96 h after pollination (fertilized ovules).…”

Advances in the study of zygote activation in higher plants

“…Based on those results, it was speculated that the unfertilized egg cell of maize is prepared for selective mRNA translation that is triggered after fertilization (Dresselhaus et al, 1999). In a study on Hyacinthus orientalis, Niedojadło et al (2012) determined the amount of 5 0 -bromouracil, the size of the total RNA polymerase II pool, and the proportions of hypophosphorylated (initiation) and hyperphosphorylated (elongation) forms of RNA Pol II as indicators of transcriptional activity. They also analyzed rRNA metabolism by monitoring the accumulation of ribosomal ribonucleoprotein complexes in the cytoplasm and immature transcripts in the nucleolus.…”

“…They also analyzed rRNA metabolism by monitoring the accumulation of ribosomal ribonucleoprotein complexes in the cytoplasm and immature transcripts in the nucleolus. The results indicated that fertilization was required to initiate the maturation of maternal pre-rRNAs and the expression of zygotic rDNA (Niedojadło et al, 2012). Abiko et al (2013b) studied the gene expression profiles of the egg and zygote of rice using microarray techniques and found that 81% of positive probes in egg cells were also positive in zygotes.…”

An Efficient Method for Quantitative, Single-cell Analysis of Chromatin Modification and Nuclear Architecture in Whole-mount Ovules in <em>Arabidopsis</em>

“…It involves acid hydrolysis (using hypochlorous acid) of the DNA which results in protein denaturation and thus causes destruction of the chromatin structure. Alternatively, chromosome organization in female meiocytes and gametophytic cells can be observed using DAPI staining and immunostaining on semi-thin sections or dissected embryo sacs and MMC (for instance see [14][15][16][17][18] ). Clearly, however, manual dissection and sectioning can be labor intensive and impedes on the qualitative and quantitative analysis of a large number of chromatin epitopes.…”