DNA Methylation Is Critical for Arabidopsis Embryogenesis and Seed Viability

Abstract

DNA methylation (5-methylcytosine) in mammalian genomes predominantly occurs at CpG dinucleotides, is maintained by DNA methyltransferase1 (Dnmt1), and is essential for embryo viability. The plant genome also has 5-methylcytosine at CpG dinucleotides, which is maintained by METHYLTRANSFERASE1 (MET1), a homolog of Dnmt1. In addition, plants have DNA methylation at CpNpG and CpNpN sites, maintained, in part, by the CHROMOMETHYLASE3 (CMT3) DNA methyltransferase. Here, we show that Arabidopsis thaliana embryos with loss-of-function mutations in MET1 and CMT3 develop improperly, display altered planes and numbers of cell division, and have reduced viability. Genes that specify embryo cell identity are misexpressed, and auxin hormone gradients are not properly formed in abnormal met1 embryos. Thus, DNA methylation is critical for the regulation of plant embryogenesis and for seed viability.

Embryo and Endosperm Inherit Distinct Chromatin and Transcriptional States from the Female Gametes in Arabidopsis

“…These observations indicate that maternal CMT3 affects the timing and/or spatial orientation of embryonic divisions. These early phenotypes are strikingly reminiscent of other mutants affecting pattern formation in Arabidopsis, including mutants in DNA methyltransferase MET1 (Xiao et al, 2006) and suggest that cmt3-defective plants similarly uncouple cell division from patterning.…”

“…As reported in numerous papers, cmt3 mutants are fully fertile. Yet, previous reports mentioned that up to 3% abnormal embryo development is observed in cmt3 mutants when including embryo stages from 0 to 6 DAP, which corresponds to the torpedo stage in Arabidopsis (Xiao et al, 2006). We discriminated in our analyses between early (preglobular) and later stages of development (until the heart stage).…”

Mechanisms and evolution of genomic imprinting in plants

“…Parent-oforigin-specific expression of genetically identical alleles is achieved by the application of specific epigenetic modifications in the gametes. In particular, DNA methylation and Polycomb group (PcG)-mediated trimethylation of histone H3 at lysine 27 (H3K27me3) have been widely recognized as important epigenetic marks distinguishing maternally and paternally inherited alleles in mammals (Umlauf et al, 2004;Edwards and Ferguson-Smith, 2007) as well as in plants (Kinoshita et al, 2004;Baroux et al, 2006;Gehring et al, 2006;Xiao et al, 2006;Makarevich et al, 2008;Jullien et al, 2006a, b).…”

Genomic DNA methylation analyses reveal the distinct profiles in castor bean seeds with persistent endosperms

“…Increasing evidence demonstrates that DNA methylation plays crucial roles in the control of seed development and seed size (Xiao et al, 2006a(Xiao et al, , 2006bHu et al, 2014;Xing et al, 2015). In particular, DNA methylation was considered as a major regulator of gene imprinting that mainly manifests itself in the endosperm of angiosperm plants, closely associated with endosperm and seed development, such as the imprinted genes MEA (Grossniklaus et al, 1998;Köhler et al, 2003), FWA (Kinoshita et al, 2004), and FIS2 (Jullien et al, 2006).…”