Occurrence of DNA Methylation in Chloroplasts of the Suspension Cultured Cells from a Liverwort, Marchantia paleacea var. diptera

Photosynthetically active chloroplasts were formed in Marchantia paleacea var. diptera cells grown under heterotrophic conditions in the dark. To obtain knowledge of a role of DNA methylation inthe expression of chloroplast encoding genes, chloroplast and nuclear DNA were digested with methyl-sensitive and methyl-insensitive isoschizomers of EcoRII/BstNI, HpaII/MspI and MboI/Sau3AI. Digestion patterns showed that cytosine residues of a small amount of 5? CCA(T)GG3? sites of chloroplast DNA were methylated, while cytosine residues of a considerable amount of both 5' CCA(T)GG3' and 5' CCGG3' sites of nuclear DNA were methylated. HPLC analysis of base compositions indicated that 0.2 percent of cytosine was methylated in chloroplast DNA and 17 percent in nuclei. Digestion patterns in chloroplast DNA from photoautotrophically grown cells with those isoschizomer pairs were entirely the same as those from heterotrophically grown cells.