Chromatin diminution during endosperm development in Allium atroviolaceum Boiss. (Alliaceae).

Bulletin of the Georgian National Academy of Sciences ISSN - 0132 - 1447 01/2002; 166(3):537-540.

ABSTRACT On the base of these data one should be suggested that the genome of the chalazal polar nucleus of A. atroviolaceum undergoes complete or partially inactivation already at the megagametogenesis by transforming into facultative heterochromatin. During endosperm formation, genome of the chalazal polar nucleus should not play any essential role in the functioning of the endosperm nuclei and proceeds its elimination from the triploid endosperm genome originated by the triple fusion. Although, participation of the chalazal polar nucleus in the formation of the primary endosperm nucleus supports earlier hypothesis (Gvaladze, 1976) that a role of the chalazal polar nucleus of A. atroviolaceum in a triple fusion is restricted only to the initiation of earlier development of the endosperm in comparison with the embryo. Beginning with the 8-nucleate stage, in spite of the elimination of the chalazal polar nucleus genome from the endosperm nuclei, the development of diploid endosperm proceeds similar to the triploid endosperm of the other Allium species that do not possess pycnotic chalazal polar nucleus and are not characterized by DNA elimination from the endosperm nuclei.

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    Botanicheskii Zhurnal St.Petersburg. 07/1992; 77(7):71-75.
  • Nature 05/1949; 163(4148):676. · 38.60 Impact Factor
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    ABSTRACT: Pentaploid endosperm nuclei in certain Gagea species exhibit large masses of sticky and dense chromatin, not observed in somatic nuclei. These heterochromatin masses most probably stem from the triploid chalasal polar nucleus of the embryo sac, thus representing an example of facultative heterochromatinisation in plants. In the present investigation, we studied the nuclei in Gagea lutea (L.) Ker-Gawl, endosperm tissue. The position of the heterochromatin in interphase nuclei was observed by confocal laser scanning microscopy (CLSM) and the DNA methylation status of the euchromatin and heterochromatin was analysed by immunolabelling with an antibody raised against 5-methylcytosine (anti-5-mC). In young endosperms, heterochromatin was relatively dispersed, occupying some peripheral and inner parts of the nuclei. In a later endosperm development, the nuclei became smaller and more pycnotic, and the heterochromatin masses were placed predominantly near the nuclear periphery. The distribution of anti-5-mC labelling on the heterochromatic regions was unequal: some parts appeared hypermethylated while other parts were, like the euchromatin, not labelled. During mitosis, the labelling intensity of all the chromosomes was approximately the same, thus indicating that there are no cytologically detectable methylation differences among the individual sets of chromosomes. However, differences in the anti-5-mC signal intensity along individual chromosomes were observed, resulting in banding patterns with highly positive bands apparently representing constitutive heterochromatic regions. From these results it is obvious that facultative heterochromatinisation, in contrast to constitutive heterochromatinisation, need not be strictly accompanied by a prominent DNA hypermethylation.
    Planta 05/1998; 204(4):506-14. · 3.35 Impact Factor


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