Cytogenetic variability of in vitro regenerated Hypericum perforatum L plants and their seed progenies

Fertile plants were regenerated from adventitious shoot cultures of Hypericum perforatum. The plants were maintained under field conditions and after open pollination, two seed generations were obtained. Chromosome counting and flow cytometric analysis of nuclear DNA content revealed a considerable degree of variation in ploidy levels in regenerated plants. While the ploidy level of progenies of diploid regenerants was stable, extensive variation was observed in seed progenies of other regenerants. Crossing experiments made under controlled conditions between tetraploid and diploid plants indicated that this behaviour could be explained by the special mode of reproduction of this species (facultative apomixis). (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.