MiRNAs target conserved motifs of diverse genes encoding NB-LRRs to trigger trans-acting siRNAs in legumes.
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ABSTRACT:
ORGANISM(S): Arachis hypogaea Glycine max Phaseolus vulgaris Medicago truncatula
PROVIDER: GSE31061 | GEO | 2011/10/24
SECONDARY ACCESSION(S): PRJNA146213
REPOSITORIES: GEO
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Project description:Trans-acting siRNAs (tasiRNAs) negatively regulate target transcripts and are characterized by siRNAs spaced in 21-nucleotide 'phased' intervals. TasiRNAs have not been extensively described in many plant species. We identified dozens of new miRNAs in Medicago and soybean and confirmed 119 Medicago targets. A search for phased tasiRNA-like small RNAs ('phasiRNAs') found at least 114 Medicago loci, the majority of which were NB-LRR encoding genes. Notably, conserved domains in NB-LRR-encoding RNAs are targeted by several 22-nt miRNA families to trigger phasiRNA production. DCL2 and SGS3 transcripts were also cleaved by these 22-nt miRNAs, generating phased small RNAs, suggesting synchronization between silencing and pathogen defense pathways. A second example of 'two-hit' phasiRNA processing was identified, utilizing miR156-miR172 sites. Our data illustrate a complex tasiRNA-mediated regulatory circuit that potentially modulates plant-microbe interactions. A few miRNA triggers regulate an extremely large gene family by targeting highly conserved protein motif-encoding sequences, representing a new paradigm for miRNA function. Examination of different tissue types in legumes (Medicago, soybean, common bean, peanut) by high throughput sequencing for small RNA profiling
2011-10-24 | E-GEOD-31061 | biostudies-arrayexpress
Project description:Small RNAs are a class of noncoding RNAs which are of great importance in gene expression regulatory networks. Different families of small RNAs are generated via distinct biogenesis pathways. One such family specific to plants is that of phased, secondary siRNAs (phasiRNAs); these require RDR6, DCL4, and microRNA (miRNA) trigger for their biogenesis. Protein-encoding genes are an important source of phasiRNAs. The model legume Medicago truncatula generates phasiRNAs from many PHAS loci, and we aimed to investigate their biogenesis and mechanism by which miRNAs trigger these molecules. We modulated miRNA abundances in transgenic tissues showing that the abundance of phasiRNAs correlates with the levels of both miRNA triggers and the target, precursor transcripts. We identified sets of phasiRNAs or PHAS loci that predominantly and substantially increase in response to miRNA overexpression. In the process of validating targets from miRNA overexpression tissues, we found that in the miRNA-mRNA target pairing, the 3’ terminal nucleotide (the 22nd position), but not the 10th position, is important for phasiRNA production. Mutating the single 3’ terminal nucleotide dramatically diminishes phasiRNA production. Ectopic expression of Medicago NB-LRR-targeting miRNAs in Arabidopsis showed that only a few NB-LRRs are capable of phasiRNA production; our data indicate that this is due to target inaccessibility determined by sequences flanking target sites. We propose that target accessibility is an important component of miRNA-target interactions that could be utilized in target prediction, and the evolution of mRNA sequences flanking miRNA target sites may be impacted.
2015-06-20 | GSE67613 | GEO
Project description:Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs) are negative regulators to target endogenous genes and repetitive sequences in plants. Although miRNAs and trans-acting or phased siRNAs (tasiRNAs or phasiRNAs) were found to target hundreds of disease related genes in Medicago, their role in plant-pathogen interactions in the legumes, particularly the R genes mediated interaction of soybean and the pathogen Phytophthora sojae is poorly understood. A deep sequencing was performed on nine soybean near isogenic lines (NILs) each carrying an Rps (Resistance to Phytophthora sojae) gene and their recurrent parent “Williams”, with sampling performed both pre- and post-inoculation with P. sojae. From these data, 44 known MIRNA loci with new miRNA variants, 78 novel miRNAs corresponding to 108 precursors, and 208 phasiRNA-producing (PHAS) loci were identified. Our data showed that overall the expression levels of miRNAs, phasiRNAs and siRNAs were extensively down-regulated after pathogen-inoculation. Moreover, the down-regulation levels in the nine resistant NILs were significantly higher than that detected in the susceptible Williams, and variations of small RNA expression within the resistant NILs were also observed, suggesting the molecular responses of different Rps lines are distinct. Surprisingly, the expression level changes of 21-nt phasiRNAs were significantly positively correlated with that of the corresponding mRNA level of the PHAS genes, suggesting the cascade effects of miRNA triggers on the downstream PHAS genes and phasiRNAs. Our data provided a comprehensive picture regarding small RNA based regulation of target genes, particularly NB-LRRs, involved in the responses to the pathogen. 20 samples were sequenced, 10 inoculated with P. sojae, the other 10 were mock-inoculated
2015-04-15 | E-GEOD-56859 | biostudies-arrayexpress
Project description:Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs) are negative regulators to target endogenous genes and repetitive sequences in plants. Although miRNAs and trans-acting or phased siRNAs (tasiRNAs or phasiRNAs) were found to target hundreds of disease related genes in Medicago, their role in plant-pathogen interactions in the legumes, particularly the R genes mediated interaction of soybean and the pathogen Phytophthora sojae is poorly understood. A deep sequencing was performed on nine soybean near isogenic lines (NILs) each carrying an Rps (Resistance to Phytophthora sojae) gene and their recurrent parent “Williams”, with sampling performed both pre- and post-inoculation with P. sojae. From these data, 44 known MIRNA loci with new miRNA variants, 78 novel miRNAs corresponding to 108 precursors, and 208 phasiRNA-producing (PHAS) loci were identified. Our data showed that overall the expression levels of miRNAs, phasiRNAs and siRNAs were extensively down-regulated after pathogen-inoculation. Moreover, the down-regulation levels in the nine resistant NILs were significantly higher than that detected in the susceptible Williams, and variations of small RNA expression within the resistant NILs were also observed, suggesting the molecular responses of different Rps lines are distinct. Surprisingly, the expression level changes of 21-nt phasiRNAs were significantly positively correlated with that of the corresponding mRNA level of the PHAS genes, suggesting the cascade effects of miRNA triggers on the downstream PHAS genes and phasiRNAs. Our data provided a comprehensive picture regarding small RNA based regulation of target genes, particularly NB-LRRs, involved in the responses to the pathogen.
2015-04-15 | GSE56859 | GEO
Project description:Maize LEAFBLADELESS1 (LBL1) and Arabidopsis SUPPRESSOR OF GENE SILENCING3 (SGS3) play orthologous roles in the biogenesis of 21 nucleotide trans-acting short-interfering RNAs (tasiRNAs). The phenotypes conditioned by mutation of lbl1 and SGS3 are, however, strikingly different, suggesting that the activities of these small RNA biogenesis components, or the tasiRNAs and their targets might not be entirely conserved. To investigate the basis for this phenotypic variation, we compared the small RNA content between wild-type and lbl1 seedling apices. We show that LBL1 affects all major classes of small RNAs, and reveal unexpected crosstalk between tasiRNA biogenesis and other small RNA pathways regulating miRNAs, retrotransposons, and DNA transposons. We further identified genomic regions generating phased siRNAs, including numerous loci generating 22-nt phased small RNAs from long hairpin RNAs or overlapping antisense transcripts not previously described in other plant species. By combining both analyses, we identified nine TAS loci, all belonging to the conserved TAS3 family. Contrary to other plant species, no TAS loci targeted by a single miRNA were identified. Information from target prediction, RNAseq, and PARE analyses identified the tasiARFs as the major functional tasiRNAs in the maize vegetative apex where they regulate expression of ARF3 homologs. As such, divergence in TAS pathways is unlikely to account for the distinct phenotypes of tasiRNA biogenesis mutants in Arabidopsis and maize. Instead, the data suggests variation in the spatiotemporal regulation of ARF3, or divergence in its function, as a plausible basis for the dramatic phenotypic differences observed upon mutation of SGS3/lbl1 in Arabidopsis and maize. An analysis of tasiRNA biogenesis, activity, and contribution to developmental phenotypes in the maize leaf. Data generated includes small RNA sequencing data and mRNA sequencing data. All data was generated in both wild type and lbl1 mutant maize leaf apices. Three replicates were generated for each genotype for the small RNA data. Two of these replicates were also used for the RNA-seq data.
2014-11-20 | E-GEOD-50557 | biostudies-arrayexpress
Project description:Maize LEAFBLADELESS1 (LBL1) and Arabidopsis SUPPRESSOR OF GENE SILENCING3 (SGS3) play orthologous roles in the biogenesis of 21 nucleotide trans-acting short-interfering RNAs (tasiRNAs). The phenotypes conditioned by mutation of lbl1 and SGS3 are, however, strikingly different, suggesting that the activities of these small RNA biogenesis components, or the tasiRNAs and their targets might not be entirely conserved. To investigate the basis for this phenotypic variation, we compared the small RNA content between wild-type and lbl1 seedling apices. We show that LBL1 affects all major classes of small RNAs, and reveal unexpected crosstalk between tasiRNA biogenesis and other small RNA pathways regulating miRNAs, retrotransposons, and DNA transposons. We further identified genomic regions generating phased siRNAs, including numerous loci generating 22-nt phased small RNAs from long hairpin RNAs or overlapping antisense transcripts not previously described in other plant species. By combining both analyses, we identified nine TAS loci, all belonging to the conserved TAS3 family. Contrary to other plant species, no TAS loci targeted by a single miRNA were identified. Information from target prediction, RNAseq, and PARE analyses identified the tasiARFs as the major functional tasiRNAs in the maize vegetative apex where they regulate expression of ARF3 homologs. As such, divergence in TAS pathways is unlikely to account for the distinct phenotypes of tasiRNA biogenesis mutants in Arabidopsis and maize. Instead, the data suggests variation in the spatiotemporal regulation of ARF3, or divergence in its function, as a plausible basis for the dramatic phenotypic differences observed upon mutation of SGS3/lbl1 in Arabidopsis and maize.
2014-11-20 | GSE50557 | GEO
Project description:Plants evolved an array of disease resistance genes (R genes) to fight pathogens. In the absence of pathogen infection, NBS-LRR genes, which comprise a major subfamily of R genes, are suppressed by a small RNA cascade involving microRNAs (miRNAs) that trigger the biogenesis of phased siRNAs (phasiRNAs) from R gene transcripts. However, whether or how R genes influence small RNA biogenesis is unknown. In this study, we isolated a mutant with global defects in the biogenesis of miRNAs and phasiRNAs in Arabidopsis thaliana and traced the defects to the over accumulation and nuclear localization of an R protein SNC1. We showed that nuclear SNC1 represses the transcription of miRNA and phasiRNA loci, probably through the transcriptional corepressor TPR1. Intriguingly, nuclear SNC1 reduces the accumulation of phasiRNAs from three source R genes and concomitantly, the expression of a majority of the ~170 R genes was up-regulated. Taken together, this study reveals a new R gene-miRNA-phasiRNA regulatory module that regulates plants' growth-defense trade-off.
2018-10-09 | GSE111239 | GEO
Project description:Plants evolved an array of disease resistance genes (R genes) to fight pathogens. In the absence of pathogen infection, NBS-LRR genes, which comprise a major subfamily of R genes, are suppressed by a small RNA cascade involving microRNAs (miRNAs) that trigger the biogenesis of phased siRNAs (phasiRNAs) from R gene transcripts. However, whether or how R genes influence small RNA biogenesis is unknown. In this study, we isolated a mutant with global defects in the biogenesis of miRNAs and phasiRNAs in Arabidopsis thaliana and traced the defects to the over accumulation and nuclear localization of an R protein SNC1. We showed that nuclear SNC1 represses the transcription of miRNA and phasiRNA loci, probably through the transcriptional corepressor TPR1. Intriguingly, nuclear SNC1 reduces the accumulation of phasiRNAs from three source R genes and concomitantly, the expression of a majority of the ~170 R genes was up-regulated. Taken together, this study reveals a new R gene-miRNA-phasiRNA regulatory module that regulates plants' growth-defense trade-off.
2018-10-09 | GSE111238 | GEO
Project description:The osdcl4-1 mutant exhibits much severer developmental defects than dcl4 in Arabidopsis, suggesting that Os DCL4 may process broader substrates in rice. By deep sequencing of small RNAs from different tissues of wild types and osdcl4-1, we revealed that 21-nucleotide siRNAs were largely dependent on Os DCL4. Besides several tasiRNA loci reported in Arabidopsis and rice, over one thousand 21-nucleotide and several dozen 24-nucleotide phased siRNA (phasiRNA) clusters were identified in panicles but not in seedlings and grains. Further analyses identified two conserved 22-nucleotide motifs among the cleavage sites of the 21- and 24- phasiRNA loci, and the cleavage sites of over 90% of 21- and 24-nucleotide phasing clusters were confirmed by PARE/degradome analysis from 93-11 panicles. MiR2118 and miR2275, expressed specifically in panicles, were predicted to trigger cleavages at 21- and 24-nucleotide phasiRNA clusters, respectively. The triggers of phasiRNAs are more dependent on Os DCL4 than Os DCL1. Furthermore, the processing of 21-nucleotide phasiRNAs was largely Os DCL4-dependent, whereas the processing of 24-nucleotide phasiRNAs was slightly affected by Os DCL4, but not by Os DCL3a and Os DCL1. Our results revealed distinct roles of Os DCL4 in a novel 21- and 24-nucleotide phasiRNA biogenesis pathway in rice. Six small RNA libraries were constructed from seedlings and panicles of 93-11 (a wild-type Indica rice variety) and osdcl4-1, as well as those from Nipponbare panicles and seedlings (a wild-type Japonica rice variety).
2012-03-29 | E-GEOD-22763 | biostudies-arrayexpress
Project description:In plants, tasiRNAs form a class of endogenous secondary siRNAs produced through the action of RNA-DEPENDENT-RNA-POLYMERASE-6 (RDR6) upon microRNA-mediated cleavage of non-coding TAS RNAs. In Arabidopsis thaliana, TAS1, TAS2 and TAS4 tasiRNA production proceeds via a single cleavage event mediated by 22nt-long or/and asymmetric miRNAs in an ARGONAUTE-1 (AGO1)-dependent manner. By contrast, tasiRNA production from TAS3 seems to follow the so-called ‘two-hit’ process, where dual targeting of TAS3, specifically mediated by the 21nt-long, symmetric miR390, initiates AGO7-dependent tasiRNA production. Interestingly, features for TAS3 tasiRNA production differ in other plant species and we show here that such features also enable TAS3 tasiRNA biogenesis in Arabidopsis, and that a single miR390 targeting event is, in fact, sufficient for this process, suggesting that the ‘one-hit’ model underpins all the necessary rudiments of secondary siRNA biogenesis from plant TAS transcripts. Further results suggest that the two-hit configuration likely enhances the fidelity of tasiRNA production and, hence, the accuracy of downstream gene regulation. Finally, we show that a ‘non-cleavable one-hit’ process allows tasiRNA production from both TAS1 and TAS3 transcripts, indicating that RDR6 recruitment does not require miRNA cleavage, nor does the recruitment, as we further show, of SUPRRESSOR-OF-GENE-SILENCING-3, indispensable for tasiRNA generation.
2017-02-16 | GSE89345 | GEO