POLYPLOIDIZATION OF STIGMATIC PAPILLAE IN TRIGLOCHIN MARITIMUM L. (JUNCAGINACEAE)

The cytological differentiation of the dry papillate stigma in Trigloc hin maritimum L. Juncaginaceae) was studied. The polyploidization proc ess started soon after the formation of unicellular stigmatic papillae . Later, huge, long papillae with single enlarged nuclei constituted t he receptive surface of the maturing stigma. The nuclear DNA content o f the polyploid papillae and of telophasic (2C) and prophasic (4C) cel ls of the ovule was measured cytophotometrically after Feulgen stainin g. Analysis of nuclear DNA content measurements permitted the degrees of ploidy reached by the papillae to be established. Nuclei with DNA c ontent corresponding to levels of 4C, 8C, 16C, 32C and 64C were found in the mature stigma. The most common were nuclei with DNA content of 16C (29%) and 32C (24%). The absence of mitoses, rhythmical enlargemen t of the DNA content of the nuclei as well as their characteristic end ochromocenters, pointed to endoreduplication as the mechanism of polyp loidization of the stigmatic papillae.