In order to confirmation of ploidy level in putative tetraploids, cell nuclei were isolated
from upper young leaves and stained with 4´, 6-diamino-2-phenylindole (DAPI) according
to the manufacturer’s instructions. The relative fluorescence intensity of DAPI-stained
nuclei was measured by a Partec PA-I flow cytometer (Partec GmbH, Münster, Germany),
provided with HBO-lamp, UV-laser; for DNA-content estimations.