Asymmetrical changes of gene expression, small RNAs and chromatin in two resynthesized wheat allotetraploids
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ABSTRACT:
ORGANISM(S): Triticum urartu x Aegilops tauschii Triticum urartu Aegilops longissima Aegilops tauschii Aegilops longissima x Triticum urartu
PROVIDER: GSE98684 | GEO | 2017/12/31
REPOSITORIES: GEO
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Project description:Arabidopsis is a suitable system for testing the hypothesis that duplicate genes accelerate evolution of expression diversity among species diverged from shared whole genome duplications (WGDs) and recurrent events of WGD. In Arabidopsis, at least 9 species split after WGD of the common ancestor and new allotetraploids were formed in nature and can be resynthesized between closely related species. Using genomic and gene expression microarrays, we detected WGD duplicate and single-copy genes preserved in A.thaliana and A.arenosa in addition to change of gene expression levels among those species. We found that even conserved duplicate genes show higher levels of expression divergence between two closely related species than single-copy genes. The proportion of the progenitors’ duplicate genes that were nonadditively expressed in the resynthesized and natural allotetraploids was significantly higher than that of single-copy genes. This results show that WGD duplicate genes provide expression variegation in response to recurring polyploidy as well as among species diverged from common WGD. Duplicate genes related to external stresses tended to be differentially expressed in allopolyploids and among their progenitors. Moreover, multiple-copy duplicate genes are likely to change expression between species and in the resynthesized and natural allotetraploids. Compared to single-copy genes, duplicate genes are less likely to be methylated in the promoter regions, facilitating transcriptional regulation by binding transcription factors and/or cis-and trans- acting proteins. Our results suggest that highly retained duplicate genes are important source for developing species specific expression level and novel expression regulation to adapt to environmental changes including subsequent polyploidy.
2008-11-20 | GSE13468 | GEO
Project description:Polyploidy or whole genome duplication (WGD) provides raw genetic materials for sequence and expression evolution of duplicate genes. However, the mode and tempo of expression divergence between WGD duplicate genes in closely relates species and recurrent allopolyploids are poorly understood. Arabidopsis is a suitable system for testing the hypothesis that duplicate genes increase expression diversity and regulatory networks. In Arabidopsis, WGD occurred more than once prior to the split between Arabidopsis thaliana and Arabidopsis arenosa, and both natural and human-made allotetraploids are available. Comparative genomic hybridization analysis indicated that single-copy and duplicate genes after WGD were well preserved in A. thaliana and A. arenosa. Analysis of gene expression microarrays showed that duplicate genes generally had higher levels of expression divergence between two closely related species than single-copy genes. The proportion of the progenitors' duplicate genes that were nonadditively expressed in the resynthesized and natural allotetraploids was significantly higher than that of single-copy genes. Duplicate genes related to environmental stresses tended to be differentially expressed, and multi-copy duplicate genes were likely to diverge expression between progenitors and in the allotetraploids. Compared to single-copy genes, duplicate genes tend to contain TATA boxes and less DNA methylation in the promoter regions, facilitating transcriptional regulation by binding transcription factors and/or cis-and trans- acting proteins. The data suggest an important role of WGD duplicate genes in modulating diverse and novel gene expression changes in response to external environmental cues as well as internal genetic turmoil such as recurrent polyploidy events.
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Project description:Genome-wide analysis of gene expression has documented differential gene expression between closely related species in plants or animals and nonadditive gene expression in hybrids and allopolyploids compared to the parents. In Arabidopsis, 15-43% of genes are expressed differently between the related species, A. thaliana and A. arenosa, and the majority of them are nonadditvely expressed (differently from mid-parent value) in allotetraploids relative to the parents. The gene expression variation is associated with transcriptional and posttranscriptional mechanisms. Although transcriptional regulation by epigenetic mechanisms plays a role in nonadditive gene expression, the effects of posttranscriptional regulation on nonadditive gene expression is largely unknown. Here we reported a comprehensive genome-wide analysis of mRNA decay in Arabidopsis allotetraploids using oligo gene microarrays. Among ~26,000 annotated genes on the arrays, over 1% of genes showed a rapid decay rate with an estimated half-life of less than 60 min, and these genes are known as genes with unstable transcripts (GUTs). Interestingly, 30% of GUTs matched the nonadditively expressed genes, and their expression levels were significantly negatively correlated. These nonadditively expressed GUTs are highly enriched with a 2-8-fold increase compared to the proportion of all genes in the Gene Ontology (GO) classifications in response to stress, abiotic and biotic stimulus, signal transduction, and transcription. The data are consistent with the enrichment of nonadditvely-expressed genes in those categories in allopolyploids of Arabidopsis, wheat and cotton. Interestingly, the GUTs include some key transcription factors including circadian clock regulators, suggesting a mechanism for rapid response to light signalling and clock regulation in allotetraploids. These data collectively suggest an important role of mRNA stability in nonadditive expression of homoeologous genes in allopolyploids. A total of 8 slides were used for comparison (0 min vs. 120 min), including two biological and four technical replications. Each biological replication consists of two technical replications (four slides) that were hybridized with reverse-labeled probes.
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Project description:MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are produced in diverse species and control gene expression and epigenetic regulation. Although physiological and developmental roles of miRNAs and siRNAs have been extensively studied in plants and animals, expression diversity and evolution of miRNAs and siRNAs in closely related species are poorly understood. Here we report comprehensive analyses of miRNA expression and siRNA distribution in two closely related species (Arabidopsis thaliana and A. arenosa), a natural allotetraploid (A. suecica), and two resynthesized allotetraploid lines (F1 and F7) derived from A. thaliana and A. arenosa. The siRNA populations present in A. thaliana were maintained in resynthesized allotetraploids and A. suecica. Although miRNA sequences were highly conserved, their expression patterns were highly variable between the allotetraploids and their progenitors. Significantly, many miRNAs were nonadditively expressed in the allotetraploids relative to the parents and preferentially degraded A. thaliana or A. arenosa targets. Stable inheritance of parental siRNAs in allopolyploids helps maintain genome stability in response to M-bM-^@M-^\genomic shockM-bM-^@M-^], whereas expression diversity of miRNAs and their target preference lead to interspecies variation in gene expression, growth, and development. NOTE: sff files unavailable for Samples AaL and F1L. 10 samples examined: Arabidopsis thaliana leaf, flower, Arabidopsis arenosa leaf and flower, F1 synthetic allopolyploid leaf and flower, F7 synthetic allopolyploid leaf and flower, Arabidopsis suecica leaf and flower. To determine small RNA profiles in Arabidopsis allotetraploids and their progenitors, we made 10 small RNA libraries from rosette leaves (L) and flower buds (F) in five lines, A. thaliana, A. arenosa, Allo(F1), Allo733(F7), and A. suecica. To examine expression of small RNAs among related species and their hybrids, we employed miRNA microarrays and compared small RNA levels.
2009-07-30 | E-GEOD-15443 | biostudies-arrayexpress
Project description:Genome-wide analysis of gene expression has documented differential gene expression between closely related species in plants or animals and nonadditive gene expression in hybrids and allopolyploids compared to the parents. In Arabidopsis, 15-43% of genes are expressed differently between the related species, A. thaliana and A. arenosa, and the majority of them are nonadditvely expressed (differently from mid-parent value) in allotetraploids relative to the parents. The gene expression variation is associated with transcriptional and posttranscriptional mechanisms. Although transcriptional regulation by epigenetic mechanisms plays a role in nonadditive gene expression, the effects of posttranscriptional regulation on nonadditive gene expression is largely unknown. Here we reported a comprehensive genome-wide analysis of mRNA decay in Arabidopsis allotetraploids using oligo gene microarrays. Among ~26,000 annotated genes on the arrays, over 1% of genes showed a rapid decay rate with an estimated half-life of less than 60 min, and these genes are known as genes with unstable transcripts (GUTs). Interestingly, 30% of GUTs matched the nonadditively expressed genes, and their expression levels were significantly negatively correlated. These nonadditively expressed GUTs are highly enriched with a 2-8-fold increase compared to the proportion of all genes in the Gene Ontology (GO) classifications in response to stress, abiotic and biotic stimulus, signal transduction, and transcription. The data are consistent with the enrichment of nonadditvely-expressed genes in those categories in allopolyploids of Arabidopsis, wheat and cotton. Interestingly, the GUTs include some key transcription factors including circadian clock regulators, suggesting a mechanism for rapid response to light signalling and clock regulation in allotetraploids. These data collectively suggest an important role of mRNA stability in nonadditive expression of homoeologous genes in allopolyploids.
2011-09-16 | GSE26065 | GEO
Project description:MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are produced in diverse species and control gene expression and epigenetic regulation. Although physiological and developmental roles of miRNAs and siRNAs have been extensively studied in plants and animals, expression diversity and evolution of miRNAs and siRNAs in closely related species are poorly understood. Here we report comprehensive analyses of miRNA expression and siRNA distribution in two closely related species (Arabidopsis thaliana and A. arenosa), a natural allotetraploid (A. suecica), and two resynthesized allotetraploid lines (F1 and F7) derived from A. thaliana and A. arenosa. The siRNA populations present in A. thaliana were maintained in resynthesized allotetraploids and A. suecica. Although miRNA sequences were highly conserved, their expression patterns were highly variable between the allotetraploids and their progenitors. Significantly, many miRNAs were nonadditively expressed in the allotetraploids relative to the parents and preferentially degraded A. thaliana or A. arenosa targets. Stable inheritance of parental siRNAs in allopolyploids helps maintain genome stability in response to “genomic shock”, whereas expression diversity of miRNAs and their target preference lead to interspecies variation in gene expression, growth, and development. NOTE: sff files unavailable for Samples AaL and F1L.
2009-07-31 | GSE15443 | GEO
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2013-12-04 | E-GEOD-40674 | biostudies-arrayexpress
Project description:Nascent allohexaploid wheat may represent the initial genetic state for the evolution and domestication of common wheat, which arose by combining the AB genomes of tetraploid Triticum turgidum with the D genome from Aegilops tauschii and out-competed its parents in growth vigor and adaptability. To better understand the molecular basis for this success, we performed mRNA and small RNA expression analyses in three tissues of nascent allohexaploid wheat and its following generations, their progenitors, and Chinese Spring, with the assistance of newly released A and D genome sequences. We found that nonadditive expression was rare among protein-coding genes which exhibited profound parental expression level dominance, with genes of total homoeolog expression level in nascent allohexaploid progeny similar to their expression levels in T. turgidum functionally enriched for development and those to Ae. tauschii distinctively for adaptation. In contrast, miRNAs appeared to be sensitive to polyploidization, with nonadditively expressed miRNAs potentially involved in growth vigor and adaptation. Meanwhile, siRNAs may contribute to biased repression of D homoeolog, possibly due to increased siRNA density on transposable element (TE)-associated D homoeologs. Together, our data provide new insights into homoeolog regulatory mechanisms that may be essential to heterosis in nascent hexaploid wheat. We performed mRNA and small RNA analyses in three tissues of nascent allohexaploid wheat and its following generations, their progenitors, and Chinese Spring.Among these samples, Samples 1-6 and 26-31, tetraploid progenitors; Samples 7-12 and 32-37, diploid progenitors; Samples 13-22 and 38-47, following generations; Samples 23-25 and 48-50, Chinese Spring.
2014-10-20 | E-GEOD-56587 | biostudies-arrayexpress
Project description:DNA methylation and histone H3 lysine 9 dimethylation (H3K9me2) are important epigenetic repression marks for silencing transposons in heterochromatin and regulating gene expression in plant development. However, the mechanistic relationship to other repressive marks, such as histone H3 lysine 27 trimethylation (H3K27me3), is unclear. OsFIE1 (Fertilization Independent Endosperm 1) encodes an Esc-like core component of the Polycomb repressive complex 2 (PRC2), which is involved in H3K27me3-mediated gene repression. Here, we identify a gain-of-function epi-allele (Epi-df) of rice OsFIE1; this allele exhibits a dwarf stature and various floral defects that are inherited in a dominant fashion. We found that Epi-df has no changes in its nucleotide sequence, but is hypo-methylated in the promoter and the 5' region of OsFIE1 and has reduced H3K9me2 and increased H3K4me3. In Epi-df, OsFIE1 was ectopically expressed and its imprinting status was disrupted. OsFIE1 interacted with rice E(z) homologs, consistent with its role in H3K27me3 repression. Ectopic expression of OsFIE1 in Epi-df resulted in alteration of H3K27me3 levels in hundreds of genes. Therefore, this work identifies a novel epi-allele involved in H3K27me3-mediated gene repression, that itself is highly regulated by histone H3K9me2, thereby shedding light on the link between two important epigenetic marks regulating rice development.
2013-12-04 | GSE40674 | GEO