Structural organization and evolution of the plastid genome of Vaucheria sessilis (Xanthophyceae).

The plastid DNAs of 18 Vaucheria sessilis strains from various habitats in western Europe were digested with the restriction endonucleases Eco RI, Sal I, Bam HI and Pvu II. Their restriction patterns showed variable fragment divergencies. Two main groups of plastid genomes were recognized, which were substantiated by morphological features. The differences among the restriction patterns could be attributed to the loss or appearance of restriction sites and to minor size variations caused by deletions/insertions. The Sal I and Bam HI restriction sites which together discriminate six different plastid genomes were mapped on the circular molecule of 124 kilobase paris (kbp). The plastid genomes of several Vaucheria sessilis strains were shown to exist in two inversion isomers caused by intramolecular recombination within the inverted repeat segments.