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Embryo CHH hypermethylation is mediated by RdDM and is autonomously directed in Brassica rapa

Abstract:

Background: RNA-directed DNA methylation (RdDM) initiates cytosine methylation in all contexts and maintains asymmetric CHH methylation. Mature plant embryos show one of the highest levels of CHH methylation, and it has been suggested that RdDM is responsible for this hypermethylation. Because loss of RdDM in Brassica rapa causes seed abortion, embryo methylation might play a role in seed development. RdDM is required in the maternal sporophyte, suggesting that small RNAs from the maternal sporophyte might translocate to the developing embryo, triggering DNA methylation that prevents seed abortion. This raises the question of whether embryo hypermethylation is autonomously regulated by the embryo itself or influenced by the maternal sporophyte.

Results: Here, we demonstrate that B. rapa embryos are hypermethylated in both euchromatin and heterochromatin and that this process requires RdDM. Contrary to the current models, B. rapa embryo hypermethylation is not correlated with demethylation of the endosperm. We also show that maternal somatic RdDM is not sufficient for global embryo hypermethylation, and we find no compelling evidence for maternal somatic influence over embryo methylation at any locus. Decoupling of maternal and zygotic RdDM leads to successful seed development despite the loss of embryo CHH hypermethylation.

Conclusions: We conclude that embryo CHH hypermethylation is conserved, autonomously controlled, and not required for embryo development. Furthermore, maternal somatic RdDM, while required for seed development, does not directly influence embryo methylation patterns.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1186/s13059-021-02358-3

Authors

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Role:
Author
ORCID:
0000-0001-6246-1767
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Institution:
University of Oxford
Division:
MPLS
Department:
Biology
Sub department:
Plant Sciences
Oxford college:
Pembroke College
Role:
Author
ORCID:
0000-0003-2195-0825


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Funder identifier:
https://ror.org/021nxhr62
Grant:
IOS-1546825


Publisher:
BioMed Central
Journal:
Genome Biology More from this journal
Volume:
22
Issue:
1
Article number:
140
Publication date:
2021-05-06
Acceptance date:
2021-04-21
DOI:
EISSN:
1474-760X
Pmid:
33957938


Language:
English
Keywords:
Pubs id:
2054018
Local pid:
pubs:2054018
Deposit date:
2025-01-28
ARK identifier:

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