DNA METHYLATION IN PLANTS.
Methylation of cytosine residues in DNA provides a mechanism of gene control. There are two classes of methyltransferase in Arabidopsis; one has a carboxy-terminal methyltransferase domain fused to an amino-terminal regulatory domain and is similar to mammalian methyltransferases. The second class apparently lacks an amino-terminal domain and is less well conserved. Methylcytosine can occur at any cytosine residue, but it is likely that clonal transmission of methylation patterns only occurs for cytosines in strand-symmetrical sequences CpG and CpNpG. In plants, as in mammals, DNA methylation has dual roles in defense against invading DNA and transposable elements and in gene regulation. Although originally reported as having no phenotypic consequence, reduced DNA methylation disrupts normal plant development.
Finnegan
E. J.
EJ
1Commonwealth Scientific and Industrial Research Organization, Plant Industry, P.O. Box 1600, Canberra, ACT 2601, Australia, Cooperative Research Centre for Plant Science, P.O. Box 475, Canberra, ACT 2601, Australia; e-mail: jean.finnegan@pican.pi.csiro.au, 2Division of Biochemistry and Molecular Biology, Australian National University, Canberra, ACT 0200, Australia
Genger
R. K.
RK
Peacock
W. J.
WJ
Dennis
E. S.
ES