Journal Article

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

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

2014

Overview

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 quantitative molecular 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 .

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Arabidopsis thaliana / Biological Sciences / crops / Cytosine - metabolism / death / DNA / DNA methylation / DNA Methylation - genetics / DNA replication / DNA Transposable Elements - genetics / Enzymes / Epigenetics / Eukaryotes / eukaryotic cells / Gene expression / Gene Expression Profiling / Gene Expression Regulation, Developmental / Gene Expression Regulation, Plant / Genes / Genes, Plant - genetics / Genome, Plant - genetics / Genomes / Genotypes / Heterozygotes / homozygosity / inheritance (genetics) / Liliopsida / mammals / Methylation / methyltransferases / Methyltransferases - genetics / mutants / Mutation / Mutation - genetics / Open Reading Frames - genetics / Oryza - enzymology / Oryza - genetics / Oryza - growth & development / Oryza sativa / phenotype / Phenotypes / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / Ribonucleic acid / Rice / RNA / RNA, Plant - genetics / RNA, Plant - metabolism / Seedlings / Seedlings - genetics / Seedlings - growth & development / Seeds / transposons