Imprinting of the MEA Polycomb gene is controlled by antagonism between MET1 methyltransferase and DME glycosylase.
The MEA Polycomb gene is imprinted in the Arabidopsis endosperm. DME DNA glycosylase activates maternal MEA allele expression in the central cell of the female gametophyte, the progenitor of the endosperm. Maternal mutant dme or mea alleles result in seed abortion. We identified mutations that suppress dme seed abortion and found that they reside in the MET1 methyltransferase gene, which maintains cytosine methylation. Seeds with maternal dme and met1 alleles survive, indicating that suppression occurs in the female gametophyte. Suppression requires a maternal wild-type MEA allele, suggesting that MET1 functions upstream of, or at, MEA. DME activates whereas MET1 suppresses maternal MEA::GFP allele expression in the central cell. MET1 is required for DNA methylation of three regions in the MEA promoter in seeds. Our data suggest that imprinting is controlled in the female gametophyte by antagonism between the two DNA-modifying enzymes, MET1 methyltransferase and DME DNA glycosylase.
Xiao
Wenyan
W
Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA 94720, USA.
Gehring
Mary
M
Choi
Yeonhee
Y
Margossian
Linda
L
Pu
Hong
H
Harada
John J
JJ
Goldberg
Robert B
RB
Pennell
Roger I
RI
Fischer
Robert L
RL
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D003596:Cytosine / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting / Q000502:physiology*; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012639:Seeds / Q000235:genetics; D013489:Suppression, Genetic; D015534:Trans-Activators / Q000378:metabolism*
D029681:Arabidopsis Proteins; C111712:MEA protein, Arabidopsis; D015534:Trans-Activators; D003596:Cytosine; C499608:MET1 protein, Arabidopsis; D004248:DNA (Cytosine-5-)-Methyltransferases; C463261:DEMETER protein, Arabidopsis; D009699:N-Glycosyl Hydrolases