Restriction endonuclease cleavage site map of chloroplast DNA from Oenothera parviflora (Euoenothera plastome IV).

1. More than 50 cleavage sites produced by the restriction endonucleases Sal I, Pst I, Kpn I, Sma I and Eco RI have been physically mapped on the 47 μm circular DNA molecule of the Euoenothera plastome IV. This plastome (= plastid genome) is considered to be the phylogenetically oldest of the subsection. 2) The DNA molecule is segmentally organized into four regions represented by a large duplicated sequence in inverted orientation whose copies are separated by two single-copy segments. The single-copy regions comprise about 14 and 57 Md in size, respectively. 3) The size of the inverted repeat, about 15 Md, was determined by restriction site mapping, by mapping of genes for ribosomal RNAs and by hybridization of a cRNA transcribed from a homologous part of Spinacia oleracea chloroplast DNA which appears to be phylogenetically conserved. 4) Hybridization of radio-iodinated spinach 16S, 23S and 5S chloroplast rRNA species to Southern blots of restricted plastome IV DNA has localized the rDNA to the inverted repeat regions, in the order given. The genes for 16S and 23S rRNA are separated by a 2.4 kbp spacer. 5) The physical map of the plastome IV DNA serves as basis for comparison with the DNA from the four other, closely related Euoenothera plastomes.