Mutation of a major CG methylase in rice causes genome-wide hypomethylation, dysregulated genome expression, and seedling lethality

Lanjuan Hu, Ning Li, Chunming Xu, Silin Zhong, Xiuyun Lin, Jingjing Yang, Tianqi Zhou, Anzhi Yuliang, Ying Wu, Yun Ru Chen, Xiaofeng Cao, Assaf Zemach, Sachin Rustgi, Diter Von Wettstein*, Bao Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Cytosine methylation at CG sites (mCG) plays critical roles in development, epigenetic inheritance, and genome stability in mammals and plants. In the dicot model plant Arabidopsis thaliana, methyltransferase 1 (MET1), a principal CG methylase, functions to maintain mCG during DNA replication, with its null mutation resulting in global hypomethylation and pleiotropic developmental defects. Null mutation of a critical CG methylase has not been characterized at a whole-genome level in other higher eukaryotes, leaving the generality of the Arabidopsis findings largely speculative. Rice is a model plant of monocots, to which many of our important crops belong. Here we have characterized a null mutant of OsMet1-2, the major CG methylase in rice. We found that seeds homozygous for OsMet1-2 gene mutation (OsMET1-2 -/-), which directly segregated from normal heterozygote plants (OsMET1-2+/-), were seriously maldeveloped, and all germinated seedlings underwent swift necrotic death. Compared with wild type, genome-wide loss of mCG occurred in the mutant methylome, which was accompanied by a plethora of quantitativemolecular phenotypes including dysregulated expression of diverse protein-coding genes, activation and repression of transposable elements, and altered small RNA profiles. Our results have revealed conservation but also distinct functional differences in CG methylases between rice and Arabidopsis. Oryza sativa L. | monocotyledons.

Original languageEnglish
Pages (from-to)10642-10647
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number29
DOIs
StatePublished - 22 Jul 2014
Externally publishedYes

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