Genome-Wide Demethylation of Arabidopsis Endosperm
Tzung-Fu Hsieh,*
Christian A. Ibarra,*
Pedro Silva,*
Assaf Zemach,
Leor Eshed-Williams,
Robert L. Fischer,
Daniel Zilberman
Parent-of-origin-specific (imprinted) gene expression is regulated
in
Arabidopsis thaliana endosperm by cytosine demethylation
of the maternal genome mediated by the DNA glycosylase
DEMETER,
but the extent of the methylation changes is not known. Here,
we show that virtually the entire endosperm genome is demethylated,
coupled with extensive local non-CG hypermethylation of small
interfering RNA–targeted sequences. Mutation of
DEMETER partially restores endosperm CG methylation to levels found
in other tissues, indicating that CG demethylation is specific
to maternal sequences. Endosperm demethylation is accompanied
by CHH hypermethylation of embryo transposable elements. Our
findings demonstrate extensive reconfiguration of the endosperm
methylation landscape that likely reinforces transposon silencing
in the embryo.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: rfischer{at}berkeley.edu (R.L.F.), daniel.zilberman{at}nature.berkeley.edu (D.Z.)
