Comprehensive investigation of miRNAs enhanced by analysis of sequence variants, expression patterns, AGO loading and target cleavage
ABSTRACT: MicroRNAs (miRNAs) are a class of small RNAs which typically function by guiding cleavage of target messenger RNAs. They have been shown to play major roles in a variety of plant processes including development, and responses to pathogens and environmental stresses. To identify new miRNAs and regulation in Arabidopsis thaliana, 27 small RNA libraries were constructed and sequenced from various tissues, stresses and small RNA biogenesis mutants, resulting in 95 million genome-matched sequences. The use of rdr2 to enrich the miRNA population greatly enhanced this analysis and led to the discovery of 44 new miRNAs arising from both known and new precursors. Parallel Analysis of RNA Ends (PARE) data provide evidence that the majority guide target cleavage. The inclusion of novel stress/tissue conditions, such as submergence-stressed flowers, enabled identification of new stress regulation of both miRNAs and their targets, all of which were validated in wild type plants. By combining small RNA expression analysis with ARGONAUTE (AGO) immunoprecipitation data and global target cleavage data from PARE, a much more complete picture of Arabidopsis miRNAs was obtained. This combinatorial approach led to the discovery of AGO loading and target cleavage biases, which gave important insights into tissue-specific expression patterns, pathogen responses and the role of sequence variation among closely related miRNA family members. Examination of various tissues, stresses and small RNA biogenesis mutants in Arabidopsis by high-throughput sequencing for small RNA profiling. We have used AGO-IP and PARE data from the published data, which were downloaded from NCBI GEO with the following accession number. AGO-IP from GSM253622, GSM707682, GSM642335, GSM642336, GSM512703, GSM512702, GSM707683, GSM707684, GSM707685, GSM149080, GSM253623, GSM304283, GSM642337, GSM642338, GSM253624, GSM415788, GSM707686, GSM707687, GSM707688, GSM707689, GSM415787, GSM149081, GSM253625, GSM415789, GSM415790, GSM304285, GSM415791, GSM415792 PARE sequencing data from xrn4 flowers were obtained from Gene Expression Omnibus with accession number GSM280227.
Project description:The wild grass Brachypodium distachyon has emerged as a model system for temperate grasses and biofuel plants. However, the global analysis of miRNAs, molecules known to be key for eukaryotic gene regulation, has been limited in B. distachyon to studies examining a few samples or that rely on computational predictions. Similarly an in-depth global analysis of miRNA-mediated target cleavage using Parallel Analysis of RNA Ends (PARE) data is lacking in B. distachyon. B. distachyon small RNAs were cloned and deeply sequenced from 17 libraries that represent different tissues and stresses. Using a computational pipeline, we identified 116 miRNAs including not only conserved miRNAs that have not been reported in B. distachyon, but also non-conserved miRNAs that were not found in other plants. To investigate miRNA-mediated cleavage function, four PARE libraries were constructed from key tissues and sequenced to a total depth of approximately 70 million sequences. The roughly 5 million distinct genome-matched sequences that resulted represent an extensive dataset to analyze small RNA-guided cleavage events. Analysis of the PARE and miRNA data provided experimental evidence for miRNA-mediated cleavage of 264 sites in predicted miRNA targets. In addition, PARE analysis revealed that differentially expressed miRNAs in the same family guide specific target RNA cleavage in a correspondingly tissue-preferential manner. B. distachyon miRNAs and target RNAs were experimentally identified and analyzed. Knowledge gained from this study should provide insights into the roles of miRNAs and the regulation of their targets in B. distachyon and related plants. Examination of various tissues and stresses in Brachypodium by high throughput sequencing for small RNA profiling and PARE (Parallel Analysis of RNA Ends)
Project description:Small RNAs have variety of important roles in plant development, stress responses, and other processes. They exert their influence by guiding mRNA cleavage, translational repression, and chromatin modification. To identify novel and regulated rice miRNAs, 62 small RNA libraries were constructed from rice plants and deeply sequenced with Illumina technology. The libraries represent several tissues from control plants and plants subjected to different environmental stress treatments. More than 94 million genome-matched reads were obtained resulting in more than 16 million distinct small RNA sequences. This allowed an evaluation with current criteria of about 400 annotated miRNAs and the finding that among these, about 150 had siRNA-like characteristics. Seventy nine new miRNAs were identified and miRNAs were distinguished that are regulated in response to water stress, nutrient stress, or temperature stress. Among the new examples of miRNA regulation were members of the same miRNA family that were differentially regulated in different organs and had distinct sequences Some of these distinct family members result in differential target cleavage and provide new insight about how an agriculturally important rice phenotype could be controlled in the panicle. This high resolution analysis of rice miRNAs should be relevant to plant miRNAs in general, particularly in the Poaceae. Examination of different tissue types and tissues treated with various environmental and nutrient stresses in rice by high throughput sequencing for small RNA profiling
Project description:To identify senescence-regulation of miRNAs in Arabidopsis thaliana, eight small RNA libraries were constructed and sequenced at four different stages of development and senescence from both leaves and siliques. Parallel Analysis of RNA Ends (PARE) libraries were also constructed and sequenced to enable the large-scale examination of miRNA-guided cleavage products. Genome-wide small RNA profiling was done by Illumina TruSeq sample preparation followed by high-throughput sequencing with Illumina HiSeq 2000 platform.
Project description:ABSTRACT: Exposure to abiotic stresses triggers global changes in the expression of thousands of eukaryotic genes at the transcriptional 70 and post-transcriptional levels. Small RNA (smRNA) pathways and splicing both function as crucial mechanisms regulating stress-responsive gene expression. However, examples of smRNAs regulating gene expression remain largely limited to effects on mRNA stability, translation, and epigenetic regulation. Also, our understanding of the networks controlling plant gene expression in response to environmental changes, and examples of these regulatory pathways intersecting, remains limited. Here, to investigate the role of smRNAs in stress responses we examined smRNA transcriptomes of Brachypodium distachyon plants subjected to various abiotic stresses. We found that exposure to different abiotic stresses specifically induced a group 75 of novel, endogenous small interfering RNAs (stress-induced, UTR-derived siRNAs, or sutr-siRNAs) that originate from the 3′ UTRs of a subset of coding genes. Our bioinformatics analyses predicted that sutr-siRNAs have potential regulatory functions and that over 90% of sutr-siRNAs target intronic regions of many mRNAs in trans. Importantly, a subgroup of these sutr- siRNAs target the important intron regulatory regions, such as branch point sequences, that could affect splicing. Our study indicates that in Brachypodium, sutr-siRNAs may affect splicing by masking or changing accessibility of specific cis-elements 80 through base-pairing interactions to mediate gene expression in response to stresses. We hypothesize that this mode of regulation of gene expression may also serve as a general mechanism for regulation of gene expression in plants and potentially in other eukaryotes. Analysis of smRNA populations in Brachypodium plants challenged by abiotic stresses: To profile the populations of smRNAs in the model monocot Brachypodium distachyon and examine their regulation in response to abiotic stresses, we conducted high-throughput sequencing of small RNAs from plants exposed to four different abiotic stress conditions, cold, heat (air), heat (water immersion), and salt, in the wild type Brachypodium cultivar Bd21. For our experiments we used information from the literature to select two time-points for stress durations, short and long, which differed for each stress: cold (6 and 24 hours), heat-air (1 and 3 hours), heat-water (1 and 3 hours), and salt (48 hours). We generated small RNA libraries for Illumina sequencing (GAII) from the leaves of Brachypodium plants subjected to stresses and selected smRNAs between 15 and 40 nt in length, which we mapped to the Brachypodium genome.
Project description:Abiotic stress is a major environmental factor that limits cotton growth and yield, moreover, this problem has become more and more serious recently and multiple stresses often occur simultaneously due to the global climate change and environmental pollution. We used microarrays to analyze the crosstalk of responsive genes to multiple abiotic stresses including ABA, cold, drought, salinity and alkalinity in cotton. Cotton seedlings with different abiotic stress treatment were selected at 14-day after germination for RNA extraction and hybridization on Affymetrix microarrays. We sought to identify genes involved in diverse stresses including abscisic acid (A), cold (C), drought (M), salinity (N) and alkalinity (P) by comparative microarray analysis (3 biological replicates for each abiotic stress treatment).
Project description:Purpose: To identify Fusarium wilt and salt-responsive miRNAs at genome wide level in Chickpea. Results: A total of 12,135,571 unique reads were obtained. In addition to 122 conserved miRNAs belonging to 25 different families, 59 novel miRNAs along with their star sequences were identified. Four legume specific miRNAs, miR5213, miR5232, miR2111 and miR2118 were found in all the libraries. The Poly (A) tailing assay based qRT-PCR was used to validate eleven conserved and five novel miRNAs. miR530 was highly up regulated in response to fungal infection and targets zinc knuckle and microtubule-associated proteins. Many miRNAs responded in a similar fashion under both biotic and abiotic stresses indicating a cross talk between the pathways involved in regulating these stresses. The potential target genes for the conserved and novel miRNAs were predicted based on sequence homology. miR166 targets a HD-ZIPIII transcription factor and was validated by 5’ RLM-RACE. Conclusions: The present study has led to identification of several conserved and novel miRNAs in chickpea associated with gene regulation in reference to wilt and salt stress conditions. This study will help in better understanding of how chickpea functions in response to stresses. Total three small RNA libraries from chickpea were prepared and sequenced independently [Control (C), Wilt stress (WS), Salt stress (SS)] on Illumina GAIIx.
Project description:Purpose: To identify abiotic stress responsive and tissue specific miRNAs at genome wide level in wheat (Triticum aestivum) Results: Small RNA libraries were constructed from four tissues (root, shoot, mature leaf and spikelets) and three stress treatments of wheat seedlings (control, high temperature, salinity and water-deficit). A total of 59.5 million reads were obtained by high throughput sequencing of eight wheat libraries, of which 32.5 million reads were found to be unique. Using UEA sRNA workbench we identified 47 conserved miRNAs belonging to 20 families, 1030 candidate novel and 51 true novel miRNAs. Several of these miRNAs displayed tissue specific expression whereas few were found to be responsive to abiotic stress treatments. Target genes were predicted for miRNAs identified in this study and their grouping into functional categories revealed that the putative targets were involved in diverse biological processes. RLM-RACE of predicted targets of three conserved miRNAs (miR156, miR160 and miR164) confirmed their mRNA cleavage, thus indicating their regulation at post-transcriptional level by corresponding miRNAs. Expression profiling of confirmed target genes of these miRNAs was also performed. Conclusions: This is the first comprehensive study on profiling of miRNAs in a variety of tissues and in response to several abiotic stresses in wheat. Our findings provide valuable resource for better understanding on the role of miRNAs in stress tolerance as well as plant development. Additionally, this information could be utilized for designing wheat plants for enhanced abiotic stress tolerance and higher productivity. Total eight (three stress, one control and four tissue specific small RNA libraries were pepared and sequenced independently [wheat control (WC), wheat high temperature stressed (WHTS), wheat salinity stressed (WSS) and wheat drought stressed (WDS), wheat shoot(WSH), wheat leaf (WLF), wheat flower(WFL), wheat root(WRT)] on Illumina GAIIx
Project description:microRNAs (miRNAs) are small non-coding RNAs that function in literally all cellular processes. miRNAs interact with Argonaute (Ago) proteins and guide them to specific target sites located in the 3’ untranslated region (UTR) of target mRNAs leading to translational repression and deadenylation-induced mRNA degradation. Most miRNAs are processed from hairpin-structured precursors by the consecutive action of the RNase III enzymes Drosha and Dicer. However, processing of miR-451 is Dicer-independent and cleavage is mediated by the endonuclease Ago2. Here we have characterized miR-451 sequence and structure requirements for processing as well as sorting of miRNAs into different Ago proteins. Pre-miR-451 appears to be optimized for Ago2 cleavage and changes result in reduced processing. In addition, we show that the mature miR-451 only associates with Ago2 suggesting that mature miRNAs are not exchanged between different members of the Ago protein family. Based on cloning and deep sequencing of endogenous miRNAs associated with Ago1-3, we do not find evidence for miRNA sorting in human cells. However, Ago identity appears to influence the length of some miRNAs, while others remain unaffected. Examination of miRNAs associated with endogenous human Ago1-4 in HeLa cells
Project description:Abiotic environmental stresses cause serious economic losses in agriculture. These stresses include temperature extremes, high salinity and drought. To isolate drought-responsive novel coding and noncoding genes, we used the next generation sequencing method from three rice cultivars (wild type nipponbare, nipponbare AP2 transgenic plants, wild type vandana). 36 NGS data of mRNA-seq, small RNA-seq, riboZero-seq were analyzed. For the analyses of these data we constructed a TF-TG (Transcription Factor-Target Gene) network and an ap2 rooted cascading tree. Using these networks and tress we isolated lincRNAs, differentially expressed miRNAs and their targets. We identified several drought stress-related novel/function unknown coding transcripts (transcription factors and functional genes) and non-coding transcripts (small noncoding transcripts such as microRNA and long noncoding transcripts) from these database analyses and have constructed databases of drought stress-related coding and noncoding transcripts Identification of drought-responsive Regulatory Coding and Non-coding Transcripts from rice by deep RNA sequencing
Project description:Salt stress is a primary cause of crop losses worldwide, and it has been the subject of intense investigation to unravel the complex mechanisms responsible for salinity tolerance. MicroRNA is implicated in many developmental processes and in responses to various abiotic stresses, playing pivotal roles in plant adaptation. Deep sequencing technology was chosen to determine the small RNA transcriptome of Saccharum sp cultivars grown on saline conditions. We constructed four small RNAs libraries prepared from plants grown on hydroponic culture submitted to 170mM NaCl and harvested after 1h, 6hs and 24hs. Each library was sequenced individually and together generated more than 50 million short reads. Ninety-eight conserved miRNAs and 33 miRNAs* were identified by bioinformatics. Several of the microRNA showed considerable differences of expression in the four libraries. To confirm the results of the bioinformatics-based analysis, we studied the expression of the 10 most abundant miRNAs and 1 miRNA* in plants treated with 170mM and with a severe treatment of 340mM NaCl. The results showed that 11 selected miRNAs had higher expression in samples treated with severe salt treatment compared to the mild one. We also investigated the regulation of the same miRNAs in shoots of four cultivars grown on soil treated with 170mM NaCl. Cultivars could be grouped according to miRNAs expression in response to salt stress. Furthermore, the majority of the predicted target genes had an inverse regulation with their correspondent microRNAs. The targets encode a wide range of proteins, including transcription factors, metabolic enzymes and genes involved in hormone signaling pathways of, probably assisting the plants to develop tolerance. Our work provides insights into the regulatory functions of miRNAs, thereby expanding our knowledge on potential salt-stressed regulated genes. Screenning of sRNA transcriptome of sugarcane plants infected with Acidovorax avenae subsp avenae after seven days