Endoreduplication in the suspensor of Gagea lutea [L.] Ker Gawl. [Liliaceae]

Karyological processes of differentiation of the suspensor of Gagea lutea (L.) Ker Gawl. were compared with the development of the embryo proper. The zygote divides into the smaller apical cell and the bigger basal cell, which becomes the basal cell of the suspensor. The mature suspensor consists of a huge basal cell and a few chalazal cells. The nuclear DNA content of the suspensor basal cell attains a high degree of ploidy, up to 128C. Nuclei with the highest ploidy level of 128C were found only in fully differentiated basal cells of more than 20-celled embryos. During polyploidization, the volume of the nuclei increased, and changes in the chromatin structure of polyploid nuclei were noted. With increasing levels of ploidy, polytene chromosomes were observed in the suspensor nucleus. Changes in DNA content, nucleus size and chromatin structure point to endoreduplication as the mechanism of polyploidization of the suspensor in Gagea lutea.