Chloroplast DNA from three archegoniates

摘要

1. DNA from female and maleSphaerocarpos donnellii(liverwort) plants exhibits at least two species with buoyant densities of 1.703 (main band) and 1.691 (satellite) g cm-3in CsCl equilibrium gradients. At least part, if not all, of the satellite DNA is localized in plastids. It consists of up to 90 of uniformly sized circular molecules of an average circumference of 38.5 μm. Compared to other Chlorophyta, the liverwort's cpDNA is unusually low both in diensity and contour length. — 2. On the hand, cpDNA from the fernsAsplenium nidusandPteris vittataresembles those of higher plants in buoyant density (1.697 g cm-3) and circumference (about 44.8 μm). — 3. Analysis of DNA from the archegoniate chloroplasts with restriction endonucleases indicates chat the cyclic molecules are monomers. — 4. The results show that the circular molecules found in cpDNA of higher plants do not represent the functionally required minimum size of DNA in p