Both maternally and paternally imprinted genes regulate seed development in rice
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ABSTRACT:
ORGANISM(S): Oryza sativa
PROVIDER: GSE77710 | GEO | 2017/02/04
REPOSITORIES: GEO
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Project description:Imprinting describes the differential expression of alleles based upon their parent of origin. Deep sequencing of RNAs from maize endosperm and embryo tissue 14 days after pollination was used to identify imprinted genes among a set of ~12,000 genes that were expressed and contained sequence polymorphisms between the B73 and Mo17 genotypes. The analysis of parent-of-origin patterns of expression resulted in the identification of 100 putative imprinted genes in maize endosperm including 54 maternally expressed genes (MEGs) and 46 paternally expressed genes (PEGs). Three of these genes have been previously identified as imprinted while the remaining 97 genes represent novel imprinted maize genes. A genome-wide analysis of DNA methylation identified regions with reduced endosperm DNA methylation in, or near, 19 of the 100 imprinted genes. The reduced levels of DNA methylation in endosperm are caused by hypomethylation of the maternal allele for both MEGs and PEGs in all cases tested. Many of the imprinted genes with reduced DNA methylation levels also show endosperm-specific expression patterns. The imprinted maize genes were compared with imprinted genes identified in genome-wide screens of rice and Arabidopsis and at least 10 examples of conserved imprinting between maize and each of the other species were identified. Methylation profiles across endosperm tissue in B73 and Mo17 were assayed for three biological replications using a custom 2.1M gene-focused NimbleGen array.
2011-12-16 | E-GEOD-33730 | biostudies-arrayexpress
Project description:Imprinting describes the differential expression of alleles based upon their parent of origin. Deep sequencing of RNAs from maize endosperm and embryo tissue 14 days after pollination was used to identify imprinted genes among a set of ~12,000 genes that were expressed and contained sequence polymorphisms between the B73 and Mo17 genotypes. The analysis of parent-of-origin patterns of expression resulted in the identification of 100 putative imprinted genes in maize endosperm including 54 maternally expressed genes (MEGs) and 46 paternally expressed genes (PEGs). Three of these genes have been previously identified as imprinted while the remaining 97 genes represent novel imprinted maize genes. A genome-wide analysis of DNA methylation identified regions with reduced endosperm DNA methylation in, or near, 19 of the 100 imprinted genes. The reduced levels of DNA methylation in endosperm are caused by hypomethylation of the maternal allele for both MEGs and PEGs in all cases tested. Many of the imprinted genes with reduced DNA methylation levels also show endosperm-specific expression patterns. The imprinted maize genes were compared with imprinted genes identified in genome-wide screens of rice and Arabidopsis and at least 10 examples of conserved imprinting between maize and each of the other species were identified.
2011-12-16 | GSE33730 | GEO
Project description:The parent-of-origin effect on seed size can result from imprinting or a combinational effect between cytoplasmic and nuclear genomes, but their relative contributions remain unknown. To discern these confounding effects, we generated cytoplasmic-nuclear substitution (CNS) lines using recurrent backcrossing in theArabidopsis thalianaecotypes Col-0 and C24. These CNS lines differ only in the nuclear genome (imprinting) or in the cytoplasm. The CNS reciprocal hybrids with the same cytoplasm display a ∼20% seed size difference as observed in the conventional hybrids. However, seed size is similar between the reciprocal cybrids with fixed imprinting. Transcriptome analyses in the endosperm of CNS hybrids using laser-capture microdissection have identified 104 maternally expressed genes (MEGs) and 90 paternally-expressed genes (PEGs). These imprinted genes are involved in pectin catabolism and cell wall modification in the endosperm.HDG9, an epiallele and one of 11 cross-specific imprinted genes, controls seed size. In the embryo, a handful of imprinted genes is found in the CNS hybrids but only one is expressed higher in the embryo than endosperm.AT4G13495encodes a long-noncoding RNA (lncRNA), but no obvious seed phenotype is observed in the lncRNA knockout lines.NRPD1, encoding the largest subunit of RNA Pol IV, is involved in the biogenesis of small interfering RNAs. Seed size and embryo is larger in the cross usingnrpd1as the maternal parent than in the reciprocal cross. In spite of limited ecotypes tested, these results suggest potential roles of imprinting andNRPD1-mediated small RNA pathway in seed size variation in hybrids.
2024-06-05 | GSE249562 | GEO
Project description:In angiosperms, the endosperm provides nutrients for embryogenesis or seed germination and is the primary tissue where gene imprinting occurs. To map the imprintome of the early developing endosperm in maize, we performed high-throughput transcriptome sequencing of the kernels at 0, 3, 5 days after pollination (DAP) and the endosperms at 7, 10, and 15 DAP produced from the B73 and Mo17 reciprocal crosses. We observed a gradual increase of paternal gene mRNAs in the 3- and 5-DAP kernels. In the 7-DAP endosperm, the majority of the tested genes reached a ratio of 2m:1p suggesting that paternal genes were nearly fully activated by 7 DAP. A total of 116, 234 and 63 imprinted genes exhibiting parent-specific expression were identified in the 7-, 10-, and 15-DAP endosperms, respectively. The highest amount of paternally expressed genes (PEGs) was found at 7 DAP mainly due to the significantly deviated parental allele expression ratio of these genes at this stage, while nearly 80% of the maternally expressed genes (MEGs) were specific to 10 DAP which were primarily attributed to the sharply increased expression levels compared to the other stages. GO enrichment analysis of the imprinted genes indicated the 10-DAP-specific MEGs were involved in the nutrient uptake and allocation through auxin signaling pathway in the maize endosperm coincident with the endosperm developmental stage associated with the beginning of starch and storage protein accumulation The unpollinated kernels (0 DAP), the kernels of 3, 5 DAP and endosperms of 7 10, 15 DAP from the B73 and Mo17 reciprocal crosses were used to perform high-throughput sequencing using the Illumina HiSeq2000 platform
2013-06-29 | E-GEOD-48425 | biostudies-arrayexpress
Project description:In angiosperms, the endosperm provides nutrients for embryogenesis or seed germination and is the primary tissue where gene imprinting occurs. To map the imprintome of the early developing endosperm in maize, we performed high-throughput transcriptome sequencing of the kernels at 0, 3, 5 days after pollination (DAP) and the endosperms at 7, 10, and 15 DAP produced from the B73 and Mo17 reciprocal crosses. We observed a gradual increase of paternal gene mRNAs in the 3- and 5-DAP kernels. In the 7-DAP endosperm, the majority of the tested genes reached a ratio of 2m:1p suggesting that paternal genes were nearly fully activated by 7 DAP. A total of 116, 234 and 63 imprinted genes exhibiting parent-specific expression were identified in the 7-, 10-, and 15-DAP endosperms, respectively. The highest amount of paternally expressed genes (PEGs) was found at 7 DAP mainly due to the significantly deviated parental allele expression ratio of these genes at this stage, while nearly 80% of the maternally expressed genes (MEGs) were specific to 10 DAP which were primarily attributed to the sharply increased expression levels compared to the other stages. GO enrichment analysis of the imprinted genes indicated the 10-DAP-specific MEGs were involved in the nutrient uptake and allocation through auxin signaling pathway in the maize endosperm coincident with the endosperm developmental stage associated with the beginning of starch and storage protein accumulation
2013-06-29 | GSE48425 | GEO
Project description:Seed development in angiosperms requires a 2:1 maternal-to-paternal genome ratio (2m:1p) in the endosperm. When the ratio is disrupted, the seed development is impaired. Rice interploidy crosses result in endosperm failures. Here we report that the defective endosperm was associated with nonadditive expression of small RNAs and protein-coding genes. Interestingly, 24-nt siRNAs were enriched in the 5’ and 3’ flanking sequences of nonadditively expressed genes in the interploidy crosses and negatively associated with the expression of imprinted genes. Furthermore, some PRC2 gene family members and the genes for DNA methylation including OsMET1b and OsCMT3a were upregulated in the 2X4 cross but repressed in the reciprocal cross. These different epigenetic effects could lead to precocious or delayed cellularization during endosperm development. Notably, many endosperm-preferred genes including starch metabolic and storage protein genes during grain filling were associated with DNA methylation or H3K27me3 and repressed in both 2X4 and 4X2 crosses. WUSCHEL homeobox2 (WOX2)-like (WOX2L), an endosperm-preferred gene, was expressed specifically in the rice endosperm, on contrary to WOX2 expression in the Arabidopsis embryo. CRISPR/Cas9 editing of WOX2L in transgenic rice blocked starch and protein accumulation, resulting in seed abortion. In addition to gene repression, disrupting epigenetic process in the interploidy crosses also induced expression of stress-responsive genes. Thus, maintaining the 2m:1p genome ratio in the endosperm is essential for normal grain development in rice and other cereal crops.
2018-08-31 | GSE65149 | GEO
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.
2016-09-01 | GSE76076 | GEO
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).
2016-09-01 | E-GEOD-76076 | biostudies-arrayexpress
Project description:Genomic imprinting is an epigenetic phenomenon causing parental alleles to be active depending on their parent-of-origin. In plants, imprinted genes are mainly confined to the endosperm, an ephemeral tissue supporting embryo development. Differential methylation of histone H3 on lysine 27 (H3K27me3) established by the Polycomb Repressive Complex 2 (PRC2) is a major regulatory mechanism determining activity of paternally expressed imprinted genes (PEGs) in animals and plants. Here, we show that the coding region of many PEGs is marked by an epigenetic signature of H3K27me3, H3K9me2 and CHG methylation and that the combination of these three modifications correlates with paternally-biased gene expression in the endosperm. The maternal alleles of PEGs are marked by CHG methylation in the central cell, indicating that the repressive epigenetic signature of PEGs is established before fertilization. We use the presence of the three modifications to predict novel PEGs and propose that genomic imprinting is substantially more common than previously estimated based on expression data.
2019-02-07 | GSE119915 | GEO
Project description:Interspecific hybrids in Arabidopsis result in seed abortion that causes reproductive barrier. To investigate the allelic expression pattern at transcriptome level during early seed abortion stage, we performed RNA-seq analysis in F1 interspecific hybrids with three different ecotypes in A. thaliana as maternal and A. arenosa as paternal and identified MEGs and PEGs. Interestingly, PEGs showed distinct expression pattern in several aspects, compared to MEGs: PEGs showed ecotype-specific expression pattern, suggesting a role for PEGs in ecotype-dependent seed lethality. 35% of previously known MEGs in non-lethal hybrids were found as PEGs in our lethal interspecific hybrids, implying the presence of abnormal paternal allelic upregulation. The correlation test between the upregulation of PEGs and previously reported paternal-excess interploidy cross (2X6) which exhibited seed abortion showed that dosage disruption by abnormal paternal upregulation is correlated with seed abortion. Moreover, epigenetic disruption appears to cause some of abnormal upregulation of paternal alleles in PEGs via mis-regulation of MEA-mediated PcG2 and MET1-mediated DNA methylation. The results provide clue on the critical role of PEGs in seed abortion via disruption of dosage balance and epigenetic regulation.
2015-10-01 | GSE41391 | GEO