Project description:DNA methylation is an epigenetic modification that differs between plant organs and tissues, but the extent of variation between cell types is not known. Here, we report single-base resolution whole genome DNA methylomes, mRNA transcriptomes, and small RNA transcriptomes for six cell populations covering the major cell types of the Arabidopsis root meristem. We identify widespread cell type specific patterns of DNA methylation, especially in the CHH sequence context. The genome of the columella root cap is the most highly methylated Arabidopsis cell characterized to date. It is hypermethylated within transposable elements, accompanied by increased abundance of transcripts encoding RNA-directed DNA methylation (RdDM) pathway components and 24 nt small RNAs. Absence of the nucleosome remodeler DECREASED DNA METHYLATION 1, required for maintenance of DNA methylation, and low abundance of histone transcripts involved in heterochromatin formation suggests a loss of heterochromatin may occur in the columella, thus allowing access of RdDM factors to the whole genome, and producing excess 24 nt small RNAs in this tissue. Together, these maps provide new insights into the epigenomic diversity that exists between distinct plant somatic cell types. MethylC-seq from six cell populations covering the major cell types of the Arabidopsis root meristem.
Project description:DNA methylation is an epigenetic modification that differs between plant organs and tissues, but the extent of variation between cell types is not known. Here, we report single-base resolution whole genome DNA methylomes, mRNA transcriptomes, and small RNA transcriptomes for six cell populations covering the major cell types of the Arabidopsis root meristem. We identify widespread cell type specific patterns of DNA methylation, especially in the CHH sequence context. The genome of the columella root cap is the most highly methylated Arabidopsis cell characterized to date. It is hypermethylated within transposable elements, accompanied by increased abundance of transcripts encoding RNA-directed DNA methylation (RdDM) pathway components and 24 nt small RNAs. Absence of the nucleosome remodeler DECREASED DNA METHYLATION 1, required for maintenance of DNA methylation, and low abundance of histone transcripts involved in heterochromatin formation suggests a loss of heterochromatin may occur in the columella, thus allowing access of RdDM factors to the whole genome, and producing excess 24 nt small RNAs in this tissue. Together, these maps provide new insights into the epigenomic diversity that exists between distinct plant somatic cell types. RNA-seq from six cell populations covering the major cell types of the Arabidopsis root meristem.
Project description:Natural epigenetic variation provides a source for the generation of phenotypic diversity, but to understand its contribution to phenotypic diversity, its interaction with genetic variation requires further investigation. MethylC-seq from naturally-occurring Arabidopsis accessions
Project description:In plants, imprinted gene expression occurs in endosperm seed tissue and can be associated with differential DNA methylation between maternal and paternal alleles. Imprinting is theorized to have been selected for because of conflict between parental genomes in offspring, but most studies of imprinting have been conducted in Arabidopsis thaliana, an inbred primarily self-fertilizing species that should have limited parental conflict. We examined embryo and endosperm allele-specific expression and DNA methylation genome-wide in the wild outcrossing species Arabidopsis lyrata. Here we show that the majority of A. lyrata imprinted genes exhibit parentally-biased expression in A. thaliana, suggesting that there is evolutionary conservation in gene imprinting. Surprisingly, we discovered substantial interspecies differences in methylation features associated with paternally expressed imprinted genes (PEGs). Unlike A. thaliana, the maternal allele of many A. lyrata PEGs was hypermethylated in the CHG context. Increased maternal allele CHG methylation was associated with increased expression bias in favor of the paternal allele. We propose that CHG methylation maintains or reinforces repression of maternal alleles of PEGs. These data suggest that while the genes subject to imprinting are largely conserved, there is flexibility in the epigenetic mechanisms employed between closely related species to maintain monoallelic expression. This supports the idea that imprinting of specific genes is a functional phenomenon, and not simply a byproduct of seed epigenomic reprogramming. Examination of total gene expression, parent-of-origin specific allelic bias, or DNA methylation in embryo, endosperm, flower bud or seedcoat tissue from Arabidopsis lyrata accessions MN47 (MN), Karhumaki (Kar or KA), and crosses between them. High-throughput Illumina poly-A-selected mRNA-seq was used to identify imprinted genes in A. lyrata, and high-throughput Illumina whole genome bisulfite-sequencing was used to examine DNA methylation. mRNA-seq samples are designated MMxFF_T# where MM is the mother of the cross (either MN for MN47 or KA for Kar), FF is the father, T is the tissue (E for embryo, N for endosperm, S for seedcoat, b for buds), and # is the replicate numbers. Samples obtained from bisulfite sequencing follow the same naming but have suffix _BS and indicate cytosine methylation context (CpG, CHG, or CHH). For KAxMN bisulfite sequencing, additional files MMxFF_T#_BS_P_C.txt follow the same naming scheme but contain context-specific methylation data (C) from reads that mapped preferentially to one parent strain (P).
Project description:Pi availability is a significant limiting factor for plant growth in both natural and agricultural systems. To cope with such limiting conditions, plants have adapted developmental and biochemical strategies to enhance Pi acquisition and to avoid starvation. A myriad of genes that are involved in the regulation and display of these strategies have been identified. However, the possible epigenetic components regulating the phosphate starvation responses have not been thoroughly investigated. DNA methylation is a major epigenetic mark involved in diverse biological processes and it may play a critical role in Pi starvation stress adaptation, also changes in DNA methylation can lead to a unique gene expression pattern in response to specific developmental and environmental conditions. Here in we demonstrate that non-CpG DNA methylation is required for proper expression of a number of Pi-limitation responsive genes in Arabidopsis thaliana and results in altered morphologic and physiologic phosphate starvation responses.Our data suggest that DNA methylation is involved in the modulation of Pi starvation responses via the transcriptional regulation of a set of phosphate-starvation responsive genes. Analysis of 8 different treatments, 2 different Organs (Root and Shoot), 2 different Phosphate treatments (High Pi, Low Pi), 2 different Times (Short Term, Long Term), 2 biological replicates for treatment
Project description:Whole genome shotgun bisulfite sequencing, small RNA sequencing and transcriptome sequencing of wildtype Arabidopsis plants (Col-0), and met1, drm1 drm2 cmt3, and ros1 dml2 dml3 null mutants using the Illumina Genetic Analyzer. A comparison was performed with regions of the genome containing cytosine DNA methylation identified by methylcytosine immunoprecipitation and whole-genome oligonucleotide tiling microarrays, for wildtype Col-0. Understanding the epigenetic regulatory mechanisms that mediate control of transcription at multiple levels is critical to understanding how plants develop and respond to their environment. We combined next-generation sequencing by synthesis (SBS) technology with novel methods for direct sequencing of the entire cytosine methylome (methylC-seq), transcriptome (RNA-seq), and the small RNA component of the transcriptome (smRNA-seq) to create a set of highly integrated epigenome maps for Arabidopsis thaliana, in conjunction with a set of informative mutants defective in DNA methyltransferase and DNA demethylase activity. At single-base resolution we discovered extensive, previously undetected, DNA methylation, identified the context and level of methylation at each site, and found that local composition has effects upon DNA methylation state. Deep sequencing of the smRNAome exposed a direct relationship between the location and abundance of smRNAs and DNA methylation, perturbation of smRNA biogenesis upon loss of CpG DNA methylation, and a tendency for smRNAs to direct strand-specific DNA methylation in the region of RNA-DNA homology. Finally, strand-specific RNA-seq revealed changes in the transcript abundance of hundreds of genes upon alteration of the DNA methylation state, and enabled the identification of numerous previously unidentified genes regulated by DNA methylation. Keywords: Whole genome shotgun bisulfite sequencing, small RNA sequencing, transcriptome sequencing, methylcytosine immunoprecipitation, whole-genome oligonucleotide tiling microarrays Whole genome shotgun bisulfite sequencing, small RNA sequencing and transcriptome sequencing of wildtype Arabidopsis plants (Col-0), and met1, drm1 drm2 cmt3, and ros1 dml2 dml3 null mutants using the Illumina Genetic Analyzer. A comparison was performed with regions of the genome containing cytosine DNA methylation identified by methylcytosine immunoprecipitation and whole-genome oligonucleotide tiling microarrays, for wildtype Col-0.
Project description:Most transgenic crops are produced through tissue culture. The impact of utilizing such methods on the plant epigenome is poorly understood. Here we generated whole-genome, single-nucleotide resolution maps of DNA methylation in several transgenic rice lines. We found that all tested transgenic plants had significant losses of methylation compared to untransformed plants. Loss of methylation was largely stable across generations, and certain sites in the genome were particularly susceptible to loss of methylation. Loss of methylation at promoters was associated with deregulated expression of protein-coding genes. Analyses of callus and untransformed plants regenerated from callus indicated that loss of methylation is stochastically induced at the tissue culture step. These changes in methylation may explain a component of somaclonal variation, a phenomenon in which plants derived from tissue culture manifest phenotypic variability. Whole genome methylation maps of rice were generated using BS-seq (Hume Stroud, Suhua Feng, Steve Jacobsen at UCLA). Whole genome expression maps of rice were generated using mRNA-seq and smRNA (Stacey Simon, Blake Meyers at Univ of Delaware).
Project description:Short-read NGS technology (SOLIDTM, Life Technologies) was used to establish a comprehensive repertoire of miRNA expressed in either equine cartilage or subchondral bone. Undamaged cartilage and subchondral bone samples from 10-month Anglo-Arabian foals affected by osteochondrosis (OC) were analyzed and compared with samples from healthy foals. Samples were also subjected or not to an experimental mechanical loading to evaluate the role of miRNAs in the regulation of mechano-transduction pathways. Epiphyseal cartilage and subchondral bone miRNome were defined, including about 300 new miRNAs. Differentially expressed miRNAs were identified between bone and cartilage from healthy and OC foals, as well as after the experimental mechanical loading, suggesting that miRNAs play a role in equine OC physiopathology and in the cellular response to biomechanical stress in cartilage and bone.
Project description:The complexity of the maize (Zea mays) genome makes it an ideal system for the study of both genetics and epigenetics. Here, we generated the integrated maps of transcriptomes and epigenomes of shoots and roots of two maize inbred lines and their reciprocal hybrids, and globally surveyed the epigenetic variations and their relationships with transcriptional divergence between different tissues and different genotypes. We observed that whereas histone modifications vary both between tissues and between genotypes, DNA methylation patterns are more distinguishable between genotypes than between tissues. Histone modifications were associated with transcriptomic divergence between tissues and between hybrids and parents. Further, we show that genes up-regulated in both shoots and roots of hybrids were significantly enriched in the nucleosome assembly pathway. Interestingly, 22- and 24-nt siRNAs were shown to be derived from distinct transposable elements (TEs), and for different TEs in both shoots and roots, the differences in siRNA activity between hybrids and patents were primarily driven by different siRNA species. Together, our results suggest that despite of the variations in specific genes or genomic loci, similar mechanisms may account for the genome-wide epigenetic regulation of gene activity and transposon stability in different tissues of maize hybrids. Genome-wide integrated maps of mRNA and small RNA (sRNA) transcriptomes, DNA methylomes and genome-wide distribution of three representative histone modifications (H3K4me3, H3K9ac and H3K36me3) in the shoots and roots of 14 day old seedlings of two maize inbred lines (B73 and Mo17) and their reciprocal hybrids (B73 x Mo17 and Mo17 x B73).