Project description:Some flowering plant and vertebrate genes are expressed primarily or exclusively from either the maternal or paternal allele, a phenomenon called genomic imprinting. Flowering plant imprinted gene expression has been described primarily in endosperm, a terminal nutritive tissue consumed by the embryo during seed development or after germination. Imprinted expression in Arabidopsis thaliana endosperm is orchestrated by differences in cytosine DNA methylation between the paternal and maternal genomes, as well as by Polycomb group (PcG) proteins. Currently only eleven imprinted Arabidopsis genes are known. Here we use extensive sequencing of cDNA libraries to identify many new paternally and maternally imprinted genes in A. thaliana endosperm, including transcription factors, proteins involved in hormone signaling, and epigenetic regulators. The imprinted status of many maternally-expressed genes is not altered by mutations in the DNA-demethylating glycosylase DEMETER, the DNA methyltransferase MET1 or the core PcG protein FIE, indicating that these genes are regulated by novel mechanisms or deposited from maternal tissues. We did not find any imprinted genes in the embryo. Our results demonstrate that imprinted gene expression, particularly from the maternal genome, is an extensive, mechanistically complex phenomenon that likely affects multiple aspects of seed development. Epigenetics Examination of genomic imprinting in Arabidopsis endosperm
Project description:Some flowering plant and vertebrate genes are expressed primarily or exclusively from either the maternal or paternal allele, a phenomenon called genomic imprinting. Flowering plant imprinted gene expression has been described primarily in endosperm, a terminal nutritive tissue consumed by the embryo during seed development or after germination. Imprinted expression in Arabidopsis thaliana endosperm is orchestrated by differences in cytosine DNA methylation between the paternal and maternal genomes, as well as by Polycomb group (PcG) proteins. Currently only eleven imprinted Arabidopsis genes are known. Here we use extensive sequencing of cDNA libraries to identify many new paternally and maternally imprinted genes in A. thaliana endosperm, including transcription factors, proteins involved in hormone signaling, and epigenetic regulators. The imprinted status of many maternally-expressed genes is not altered by mutations in the DNA-demethylating glycosylase DEMETER, the DNA methyltransferase MET1 or the core PcG protein FIE, indicating that these genes are regulated by novel mechanisms or deposited from maternal tissues. We did not find any imprinted genes in the embryo. Our results demonstrate that imprinted gene expression, particularly from the maternal genome, is an extensive, mechanistically complex phenomenon that likely affects multiple aspects of seed development. Epigenetics
Project description:Parent-of-origin-specific (imprinted) gene expression is regulated in Arabidopsis thaliana endosperm by cytosine demethylation of the maternal genome mediated by the DNA glycosylase DEMETER, but the extent of the methylation changes is not known. Here we show that virtually the entire endosperm genome is demethylated, coupled with extensive local non-CG hypermethylation of siRNA-targeted sequences. Mutation of DEMETER partially restores endosperm CG methylation to levels found in other tissues, indicating that CG demethylation is specific to maternal sequences. Endosperm demethylation is accompanied by CHH hypermethylation of embryo transposable elements. Our findings demonstrate extensive reconfiguration of the endosperm methylation landscape that likely reinforces transposon silencing in the embryo. Keywords: Epigenetics; bisulfite sequencing Examination of DNA methylation in four Arabidopsis tissues Description of processed data and raw data file contents can be found in the attached README.txt file
Project description:Parent-of-origin-specific (imprinted) gene expression is regulated in Arabidopsis thaliana endosperm by cytosine demethylation of the maternal genome mediated by the DNA glycosylase DEMETER, but the extent of the methylation changes is not known. Here we show that virtually the entire endosperm genome is demethylated, coupled with extensive local non-CG hypermethylation of siRNA-targeted sequences. Mutation of DEMETER partially restores endosperm CG methylation to levels found in other tissues, indicating that CG demethylation is specific to maternal sequences. Endosperm demethylation is accompanied by CHH hypermethylation of embryo transposable elements. Our findings demonstrate extensive reconfiguration of the endosperm methylation landscape that likely reinforces transposon silencing in the embryo. Keywords: Epigenetics; bisulfite sequencing
Project description:Crossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes (‘paternal excess’) associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes. This is supported by the observation that mutations in imprinted FIS-class genes of Arabidopsis thaliana share many features of the paternal excess phenotype. Here we investigated gene expression underlying parent-of-origin effects in Arabidopsis through transcriptional profiling of siliques generated by interploidy crosses and FIS-class mutants.
Project description:Crossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes (‘paternal excess’) associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes. This is supported by the observation that mutations in imprinted FIS-class genes of Arabidopsis thaliana share many features of the paternal excess phenotype. Here we investigated gene expression underlying parent-of-origin effects in Arabidopsis through transcriptional profiling of siliques generated by interploidy crosses and FIS-class mutants.
Project description:High throughput Illumina sequencing of poly-A selected RNA from Arabidopsis Col and Ler reciprocal F1 hybrid embryo and endosperm tissue isolated at 6-7 days after pollination to identify imprinted genes.
Project description:Crossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes (‘paternal excess’) associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes. This is supported by the observation that mutations in imprinted FIS-class genes of Arabidopsis thaliana share many features of the paternal excess phenotype. Here we investigated gene expression underlying parent-of-origin effects in Arabidopsis through transcriptional profiling of siliques generated by interploidy crosses and FIS-class mutants. Two biological replicate samples each of 2xX2x, 2xX4x, 2xX6x, 6xX2x, 4xX2x and fis1X2x and a single sample of msi1. Each sample was hybridised to a separate array.
Project description:Crossing plants of the same species but different ploidies can have dramatic effects on seed growth, but little is known about the alterations to transcriptional programmes responsible for this. Parental genomic imbalance particularly affects proliferation of the endosperm, with an increased ratio of paternally to maternally contributed genomes (‘paternal excess’) associated with overproliferation, while maternal excess inhibits endosperm growth. One interpretation is that interploidy crosses disrupt the balance in the seed of active copies of parentally imprinted genes. This is supported by the observation that mutations in imprinted FIS-class genes of Arabidopsis thaliana share many features of the paternal excess phenotype. Here we investigated gene expression underlying parent-of-origin effects in Arabidopsis through transcriptional profiling of siliques generated by interploidy crosses and FIS-class mutants. Six biological samples: 2xX2x, 2xX4x, 2xX6x, 6xX2x, 4xX2x and fis1X2x. Each non-2xX2x cross was co-hybridised with 2xX2x to a two-colour array (5 arrays). Dyes were then swapped and the hybridisations repeated using an additional 5 arrays.
Project description:High throughput Illumina sequencing of poly-A selected RNA from Arabidopsis Col and Ler reciprocal F1 hybrid embryo and endosperm tissue isolated at 6-7 days after pollination to identify imprinted genes. Examination of parent-of-origin specific and total gene expression in seed tissues.