title: Hypomethylation of CNG targets induced with dihydroxypropyladenine is rapidly reversed in the course of mitotic cell division in tobacco.
abstract: We followed the mitotic transmission of an experimentally induced hypomethylated state of several tobacco repetitive sequences in callus culture and plants. The initial hypomethylation was induced by a hypomethylation drug, dihydroxypropyladenine (DHPA), the competitive inhibitor of cellular S-adenosylhomocysteine hydrolase, which is known to preferentially inhibit methylation at CNG and non-symmetrical motifs while having a negligible effect on methylation at CG motifs. The deprivation of this drug resulted in an almost immediate remethylation of cytosines at CNG motifs ( MspI and EcoRII sites) leading us to conclude that, the hypomethylation effect of dihydroxypropyladenine is rather transient and differs from that of 5-azacytidine which often induces heritable changes in methylation patterns. The results suggest that de novo methylation of CNG motifs is a rapid and meiotically independent process on DNA sequences with pre-existing CG methylation.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic.
authors.forename: B.
authors.initials: B
authors.lastname: Koukalová
authors.forename: I.
authors.initials: I
authors.lastname: Votruba
authors.forename: M.
authors.initials: M
authors.lastname: Fojtová
authors.forename: A.
authors.initials: A
authors.lastname: Holý
authors.forename: A.
authors.initials: A
authors.lastname: Kovarík