Abstract
The plastid DNA contents of egg, sperm, sporophyte, and gametophyte cells were measured to clarify the relative changes in plastid DNA content during the life cycle of the hornwort Anthoceros punctatus. Samples stained with DAPI were observed using epifluorescence microscopy and CHIAS. The plastid DNA content of unfertilized egg cells did not change before and the fertilization because of preferential digestion of organelle DNA in sperm cells. In the 2n-generation, plastids multiplied by binary fission, with DNA duplication. It is thought that plastid DNA content is halved in spore mother cells, but recovers before, or immediately after, spore germination. In the ngeneration, plastids multiplied by binary fission, with DNA duplication, and the plastid DNA content was maintained at the same level as that of the 2n-generation.
