Polyploidization of stigmatic papillae in Triglochin maritimum L. [Juncaginaceae]

The cytological differentiation of the dry papillate stigma in Triglochin maritimum L. (Juncaginaceae) was studied. The polyploidization process started soon after the formation of unicellular stigmatic papillae. Later, huge, long papillae with single enlarged nuclei constituted the receptive surface of the maturing stigma. The nuclear DNA content of the polyploid papillae and of telophasic (2C) and prophasic (4C) cells of the ovule was measured cytophotometrically after Feulgen staining. Analysis of nuclear DNA content measurements permitted the degrees of ploidy reached by the papillae to be established. Nuclei with DNA content 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 enlargement of the DNA content of the nuclei as well as their characteristic endochromocenters, pointed to endoreduplication as the mechanism of polyploidization of the stigmatic papillae.