期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 113, 期 52, 页码 15138-15143出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1619047114
关键词
DNA methylation; central cell; egg cell; epigenetics; gene imprinting
资金
- Next-Generation BioGreen 21 Program [PJ011018]
- National Research Foundation of Korea [2014R1A2A2A01004887]
- NSF [IOS-1025890]
- NIH [R01-GM069415]
- Biotechnology and Biological Sciences Research Council (BBSRC) [BB/L025043/1]
- BBSRC [BB/L025043/1, BBS/E/J/000C0675] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/L025043/1, BBS/E/J/000C0675] Funding Source: researchfish
- Direct For Biological Sciences [1025890] Funding Source: National Science Foundation
- Division Of Integrative Organismal Systems [1025890] Funding Source: National Science Foundation
- National Research Foundation of Korea [2014R1A2A2A01004887] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
- Grants-in-Aid for Scientific Research [16K14742] Funding Source: KAKEN
Cytosine methylation is a DNA modification with important regulatory functions in eukaryotes. In flowering plants, sexual reproduction is accompanied by extensive DNA demethylation, which is required for proper gene expression in the endosperm, a nutritive extraembryonic seed tissue. Endosperm arises from a fusion of a sperm cell carried in the pollen and a female central cell. Endosperm DNA demethylation is observed specifically on the chromosomes inherited from the central cell in Arabidopsis thaliana, rice, and maize, and requires the DEMETER DNA demethylase in Arabidopsis. DEMETER is expressed in the central cell before fertilization, suggesting that endosperm demethylation patterns are inherited from the central cell. Down-regulation of the MET1 DNA methyltransferase has also been proposed to contribute to central cell demethylation. However, with the exception of three maize genes, central cell DNA methylation has not been directly measured, leaving the origin and mechanism of endosperm demethylation uncertain. Here, we report genome-wide analysis of DNA methylation in the central cells of Arabidopsis and rice-species that diverged 150 million years agoas well as in rice egg cells. We find that DNA demethylation in both species is initiated in central cells, which requires DEMETER in Arabidopsis. However, we do not observe a global reduction of CG methylation that would be indicative of lowered MET1 activity; on the contrary, CG methylation efficiency is elevated in female gametes compared with nonsexual tissues. Our results demonstrate that locus-specific, active DNA demethylation in the central cell is the origin of maternal chromosome hypomethylation in the endosperm.
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