Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

MiRNAs target conserved motifs of diverse genes encoding NB-LRRs to trigger trans-acting siRNAs in legumes.

ABSTRACT: 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

ORGANISM(S): Arachis hypogaea

SUBMITTER: Blake Meyers

PROVIDER: E-GEOD-31061 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

MicroRNAs as master regulators of the plant NB-LRR defense gene family via the production of phased, trans-acting siRNAs.

Zhai Jixian J Jeong Dong-Hoon DH De Paoli Emanuele E Park Sunhee S Rosen Benjamin D BD Li Yupeng Y González Alvaro J AJ Yan Zhe Z Kitto Sherry L SL Grusak Michael A MA Jackson Scott A SA Stacey Gary G Cook Douglas R DR Green Pamela J PJ Sherrier D Janine DJ Meyers Blake C BC

Genes & development 20111201 23

Legumes and many nonleguminous plants enter symbiotic interactions with microbes, and it is poorly understood how host plants respond to promote beneficial, symbiotic microbial interactions while suppressing those that are deleterious or pathogenic. Trans-acting siRNAs (tasiRNAs) negatively regulate target transcripts and are characterized by siRNAs spaced in 21-nucleotide (nt) "phased" intervals, a pattern formed by DICER-LIKE 4 (DCL4) processing. A search for phased siRNAs (phasiRNAs) found at ...[more]

PMID: 22156213

Publication: 1/2

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Project description:miRNA levels depend on both biogenesis and turnover. The methyltransferase HEN1 stabilizes plant miRNAs, animal piRNAs, and siRNAs in both kingdoms via 3' terminal methylation. Loss of HEN1 in plants results in non-templated oligo-uridylation and accelerated degradation of miRNAs. In hen1 mutants from Arabidopsis and rice, we found that the patterns of miRNA truncation and uridylation differ substantially among miRNA families, but such patterns for the same miRNA are conserved between species. miR166 and miR163 are truncated predominantly to ~17 and ~16 nt, and subsequently recover via uridylation to approximately their original sizes, 21 and 24 nt, suggesting that in these cases miRNA truncation triggers uridylation. miR171 is untruncated but uridylated to 22 nt in hen1 mutants, gaining the ability to trigger production of phased, secondary siRNAs. Truncated and tailed variants were bound by ARGONAUTE1 (AGO1) in hen1, implying that these events occur while miRNAs are still bound by AGO1. Unexpectedly, a portion of miR158 in wildtype remains unmethylated and thus subject to uridylation and destabilization, suggesting that plants naturally utilize miRNA methylation to modulate miRNA accumulation. Our results suggest that the AGO1-containing RISC complex may undergo programming to reflect each bound miRNA, determining a defined, distinct decay destiny. In this analysis, we sequenced sRNAs from two hen1 mutant alleles in Arabidopsis and three hen1 alleles in rice. In Arabidopsis, the strong hen1-1 allele in the Landsberg erecta (Ler) ecotype is the first hen1 mutant and emerged from an enhancer screen in the hua1-1/hua2-1 background, and hen1-8 in the Columbia (Col) background is a weak allele. In rice, WAVY LEAF1 (WAF1) is the ortholog of Arabidopsis HEN1, and two mutant alleles waf1-1 and waf1-2 each bear a single-base substitution leading to a premature stop codon in the second exon and a non-functional splicing site of the fourth intron, respectively. We identified a third mutant allele of the rice HEN1 gene (Oshen1-3 from the Korean (POSTEC) rice T-DNA mutant population).

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.

Dataset Information

MiRNAs target conserved motifs of diverse genes encoding NB-LRRs to trigger trans-acting siRNAs in legumes.

Publications

MicroRNAs as master regulators of the plant NB-LRR defense gene family via the production of phased, trans-acting siRNAs.

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