Contributions to the Cytology of Endosperm in Some Angiosperms, III

Abstract

1. The results of the cytological investigations in the endosperm of Amaryllis belladonna L. have been reported.2. The endosperm was free nuclear up to 17-18 days after pollination and then became cellular.3. The endosperm showed, especially at the free nuclear stage, a significant disparity in the size of its nuclei. The ranges in length and breadth of nuclei in 18 day old endosperm were 27.28 to 153.00 microns and 20.40 to 68.00 microns, respectively.4. Endopolyploidy, aneuploidy, multipolarity of spindles, chromosomal bridges and nuclear fusions were responsible for the variation present in the size and shape of endosperm nuclei.5. The normal cytological constitution of the endosperm was determined as triploid with 3n=33 chromosomes.6. A study of the nucleolar numbers and chromosome counts of the endosperm and root tip nuclei has revealed that the number of nucleoli per nucleus cannot be used as an indicator of polyploidy in Amaryllis belladonna.7. Breakdown of the endosperm was possibly caused by the cumulative effect of mitotic aberrations which were apparent in the form of bridges, multipolarity of spindles, polyploidy and aneuploidy. The frequency of the occurrence of mitotic abnormalities was found to be significantly higher in the collapsing endosperm.