MicroRNA-triggered transposon small RNAs mediate genome dosage response (mir845 sRNA-Seq)
Ontology highlight
ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE106115 | GEO | 2017/12/31
SECONDARY ACCESSION(S): PRJNA415635
REPOSITORIES: GEO
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Project description:Chromosome dosage plays a significant role in reproductive isolation and speciation in both plants and animals, but underlying mechanisms are largely obscure. Transposable elements can promote hybridity through maternal small RNA, and have been postulated to regulate dosage response via neighboring imprinted genes. Here, we show that a highly conserved microRNA in plants, miR845, targets the tRNAMet primer-binding site (PBS) of LTR-retrotransposons in Arabidopsis pollen, and triggers the accumulation of 21 to 22-nucleotide small RNA in a dose dependent fashion via RNA polymerase IV. We show that these epigenetically activated small-interfering RNAs (easiRNAs) mediate hybridization barriers between diploid seed parents and tetraploid pollen parents (“the triploid block”), and that natural variation for miR845 may account for “endosperm balance” allowing formation of triploid seeds. Targeting the PBS with small RNA is a common mechanism for transposon control in mammals and plants, and provides a uniquely sensitive means to monitor chromosome dosage and imprinting in the developing seed.
2017-12-31 | GSE106114 | GEO
Project description:Chromosome dosage plays a significant role in reproductive isolation and speciation in both plants and animals, but underlying mechanisms are largely obscure. Transposable elements can promote hybridity through maternal small RNA, and have been postulated to regulate dosage response via neighboring imprinted genes. Here, we show that a highly conserved microRNA in plants, miR845, targets the tRNAMet primer-binding site (PBS) of LTR-retrotransposons in Arabidopsis pollen, and triggers the accumulation of 21 to 22-nucleotide small RNA in a dose dependent fashion via RNA polymerase IV. We show that these epigenetically activated small-interfering RNAs (easiRNAs) mediate hybridization barriers between diploid seed parents and tetraploid pollen parents (“the triploid block”), and that natural variation for miR845 may account for “endosperm balance” allowing formation of triploid seeds. Targeting the PBS with small RNA is a common mechanism for transposon control in mammals and plants, and provides a uniquely sensitive means to monitor chromosome dosage and imprinting in the developing seed.
2017-12-31 | GSE106113 | GEO
Project description:Chromosome dosage plays a significant role in reproductive isolation and speciation in both plants and animals, but underlying mechanisms are largely obscure. Transposable elements can promote hybridity through maternal small RNA, and have been postulated to regulate dosage response via neighboring imprinted genes. Here, we show that a highly conserved microRNA in plants, miR845, targets the tRNAMet primer-binding site (PBS) of LTR-retrotransposons in Arabidopsis pollen, and triggers the accumulation of 21 to 22-nucleotide small RNA in a dose dependent fashion via RNA polymerase IV. We show that these epigenetically activated small-interfering RNAs (easiRNAs) mediate hybridization barriers between diploid seed parents and tetraploid pollen parents (“the triploid block”), and that natural variation for miR845 may account for “endosperm balance” allowing formation of triploid seeds. Targeting the PBS with small RNA is a common mechanism for transposon control in mammals and plants, and provides a uniquely sensitive means to monitor chromosome dosage and imprinting in the developing seed.
2017-12-31 | GSE106112 | GEO
Project description:Epigenetic modifications that arise during plant and animal development, such as DNA and histone modification, are mostly reset during gamete formation, but some are inherited from the germline including those marking imprinted genes. Small RNAs guide these epigenetic modifications, and some are also inherited by the next generation. In C. elegans, inherited small RNA precursors have poly (UG) tails, but how inherited small RNAs are distinguished in other animals and plants is unknown. Pseudouridine (Ψ) is the most abundant RNA modification but has not been explored in small RNAs. Here, we develop novel assays to detect Ψ in short RNA sequences, demonstrating its presence in mouse and Arabidopsis microRNAs and their precursors. We also detect substantial enrichment in germline small RNAs, namely epigenetically activated siRNAs (easiRNAs) in Arabidopsis pollen, and piwi-interacting piRNAs in mouse testis. In pollen, pseudouridylated easiRNAs are localized to sperm cells, and we found that PAUSED/HEN5 (PSD), the plant homolog of Exportin-t, interacts genetically with Ψ and is required for transport of easiRNAs into sperm cells from the vegetative nucleus. We further show that Exportin-t is required for the triploid block: chromosome dosage-dependent seed lethality that is epigenetically inherited from pollen. Thus, Ψ has a conserved role in marking inherited small RNAs in the germline.
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Project description:The "triploid block" prevents interploidy hybridizations in flowering plants, and is characterized by failure in endosperm development and function, arrest in embryogenesis, and seed collapse. Many genetic components of triploid seed lethality have been successfully identified in the model plant Arabidopsis thaliana, most notably the paternally expressed imprinted genes (PEGs) that are up-regulated in the tetraploid endosperm with paternal excess. Previous studies have shown that the paternal epigenome is a key determinant of the triploid block response, as the loss of DNA methylation in diploid pollen suppresses the triploid block almost completely. Here, we demonstrate that triploid seed abortion is bypassed in plants treated with the DNA methyltransferase inhibitor 5-Azacytidine during seed germination and early plant growth. We have identified strong suppressor lines showing transgenerational inheritance of hypomethylation in CG context, as well as normalized expression of PEGs. Importantly, differentially methylated loci segregate in the progeny of "epimutagenized" plants, which may allow the identification of epialleles involved in the triploid block response in future studies. Finally, we demonstrate that chemically-induced epimutagenesis allows bypassing interploidy hybridizations in Arabidopsis and interspecific hybridization barriers in crosses between Capsella species, thus potentially emerging as a novel strategy for seed-based breeding of triploids and interspecific hybrids with agronomical interest.
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Project description:The "triploid block" prevents interploidy hybridizations in flowering plants, and is characterized by failure in endosperm development and function, arrest in embryogenesis, and seed collapse. Many genetic components of triploid seed lethality have been successfully identified in the model plant Arabidopsis thaliana, most notably the paternally expressed imprinted genes (PEGs) that are up-regulated in the tetraploid endosperm with paternal excess. Previous studies have shown that the paternal epigenome is a key determinant of the triploid block response, as the loss of DNA methylation in diploid pollen suppresses the triploid block almost completely. Here, we demonstrate that triploid seed abortion is bypassed in plants treated with the DNA methyltransferase inhibitor 5-Azacytidine during seed germination and early plant growth. We have identified strong suppressor lines showing transgenerational inheritance of hypomethylation in CG context, as well as normalized expression of PEGs. Importantly, differentially methylated loci segregate in the progeny of "epimutagenized" plants, which may allow the identification of epialleles involved in the triploid block response in future studies. Finally, we demonstrate that chemically-induced epimutagenesis allows bypassing interploidy hybridizations in Arabidopsis and interspecific hybridization barriers in crosses between Capsella species, thus potentially emerging as a novel strategy for seed-based breeding of triploids and interspecific hybrids with agronomical interest.
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Project description:Heterosis occurs where F1 offspring display superior characteristics to the parents. Heterosis is usually considered to result from crosses of genetically distinct (e.g. homozygous inbred) parents producing heterozygous F1 offspring. Most mechanistic models for heterosis require genetically heterozygous F1 hybrid offspring harbouring allelic diversity. Epigenetic or dosage models for heterosis could allow for heterosis effects in F1 offspring that display no allelic diversity with their parents. Reciprocal inter-ploidy crosses between diploid (2x) and tetraploid (4x) lines in the same genetic background generates genetically identical F1 triploids (3x). Such reciprocal F1 triploids differ according to whether the additional chromosome set is either maternally (maternal excess) or paternally inherited (paternal excess). Biomass accumulation and abiotic stress tolerance between the parental (2x and 4x) and reciprocal F1 triploid (3x) offspring of Arabidopsis thaliana accession C24 reveals a strong parental genome-dosage induced heterosis in the paternal-excess triploid F1 plants. In these F1 triploids, the circadian clock related genes CCA1 and TOC1, and the growth factors PIF4 and PIF5, display different expression levels compared to the non-heterotic maternal excess F1 triploid siblings. Whole transcriptome profiling reveals a paternal genome dosage effect on gene expression levels with strong enrichment for dysregulated abiotic stress-related genes in the paternal excess F1 triploids. This study demonstrates that heterosis can be triggered without allelic diversity in F1 triploid plants. Heterosis without heterozygosity in plants can be induced via an epigenetic “chromosome imprinting” like parental genome dosage effect requiring paternal transmission of an additional chromosome set
2014-08-01 | GSE52885 | GEO
Project description:Heterosis occurs where F1 offspring display superior characteristics to the parents. Heterosis is usually considered to result from crosses of genetically distinct (e.g. homozygous inbred) parents producing heterozygous F1 offspring. Most mechanistic models for heterosis require genetically heterozygous F1 hybrid offspring harbouring allelic diversity. Epigenetic or dosage models for heterosis could allow for heterosis effects in F1 offspring that display no allelic diversity with their parents. Reciprocal inter-ploidy crosses between diploid (2x) and tetraploid (4x) lines in the same genetic background generates genetically identical F1 triploids (3x). Such reciprocal F1 triploids differ according to whether the additional chromosome set is either maternally (maternal excess) or paternally inherited (paternal excess). Biomass accumulation and abiotic stress tolerance between the parental (2x and 4x) and reciprocal F1 triploid (3x) offspring of Arabidopsis thaliana accession C24 reveals a strong parental genome-dosage induced heterosis in the paternal-excess triploid F1 plants. In these F1 triploids, the circadian clock related genes CCA1 and TOC1, and the growth factors PIF4 and PIF5, display different expression levels compared to the non-heterotic maternal excess F1 triploid siblings. Whole transcriptome profiling reveals a paternal genome dosage effect on gene expression levels with strong enrichment for dysregulated abiotic stress-related genes in the paternal excess F1 triploids. This study demonstrates that heterosis can be triggered without allelic diversity in F1 triploid plants. Heterosis without heterozygosity in plants can be induced via an epigenetic “chromosome imprinting” like parental genome dosage effect requiring paternal transmission of an additional chromosome set 4 or 5 biological replicates per ploidy level, each replicate being a single two weeks old seedling
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Project description:Epigenetic modifications that arise during plant and animal development, such as DNA and histone modification, are mostly reset during gamete formation, but some are inherited from the germline including those marking imprinted genes. Small RNAs guide these epigenetic modifications, and some are also inherited by the next generation. In C. elegans, these inherited small RNAs have poly (UG) tails, but how inherited small RNAs are distinguished in other animals and plants is unknown. Pseudouridine (Ψ) is the most abundant RNA modification but has not been explored in small RNAs. Here, we developed novel assays to detect Ψ in short RNA sequences, demonstrating its presence in mouse and Arabidopsis microRNAs and their precursors. We also detected substantial enrichment in germline small RNAs, namely epigenetically activated siRNAs (easiRNAs) in Arabidopsis pollen, and PIWI-interacting piRNAs in mouse testis. In pollen, pseudouridylated easiRNAs are produced by RNA polymerase IV and localized to sperm cells. We found that PAUSED/HEN5 (PSD), the plant homolog of Exportin-t, interacts genetically with Ψ synthase and is required for transport of easiRNAs into sperm cells from the vegetative nucleus. We further show that PSD is required for the triploid block: chromosome dosage-dependent seed lethality that is epigenetically inherited from pollen. We propose that Ψ has a conserved role in marking inherited small RNAs in the germline.
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Project description:Pseudouridine (Ψ) is an isomer of uridine found in ribosomal, transfer and other structural RNAs as well as in some mRNAs and non-coding RNAs, but is difficult to detect in short RNA sequences. Using modified techniques we found Ψ in microRNAs (miRNAs) and their precursors from mammalian and plant cells, primarily at the 5ʹ terminus of the mature miRNA. Small RNAs targeting transposons in reproductive cells (piRNA in testis and easiRNA in pollen) were highly enriched for Ψ, indicating a potential role in epigenetic inheritance. In pollen, pseudouridylated small RNAs were produced by RNA polymerase IV and were localized to sperm cells, as were miRNAs with terminal Ψ. We show that pseudouridylated easiRNAs from pollen contribute to imprinting and the triploid block (chromosome dosage-dependent epigenetic lethality) via the activity of PAUSED/HEN5, the plant homolog of Exportin-t. Exportin-t is required for nuclear export of pseudouridylated tRNA, and we found that PSD is required for cell-cell transport of small RNA in the germline.
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