In silico identification and characterization of a diverse subset of conserved microRNAs in bioenergy crop Arundo donax L

Identification of Known and Novel Arundo donax L. MicroRNAs and Their Targets Using High-Throughput Sequencing and Degradome Analysis

MicroRNAs (miRNAs) are a class of non-coding molecules involved in the regulation of a variety of biological processes. They have been identified and characterized in several plant species, but only limited data are available for Arundo donax L., one of the most promising bioenergy crops. Here we identified, for the first time, A. donax conserved and novel miRNAs together with their targets, through a combined analysis of high-throughput sequencing of small RNAs, transcriptome and degradome data. A total of 134 conserved miRNAs, belonging to 45 families, and 27 novel miRNA candidates were identified, along with the corresponding primary and precursor miRNA sequences. A total of 96 targets, 69 for known miRNAs and 27 for novel miRNA candidates, were also identified by degradome analysis and selected slice sites were validated by 5′-RACE. The identified set of conserved and novel candidate miRNAs, together with their targets, extends our knowledge about miRNAs in monocots and pave the way to further investigations on miRNAs-mediated regulatory processes in A. donax, Poaceae and other bioenergy crops.

In Silico Investigation of Conserved miRNAs and Their Targets From the Expressed Sequence Tags in Neospora Caninum Genome

Neospora caninum is a protozoan parasite, the etiologic agent of Neosporosis—a common cause of abortion in cattle worldwide. Herd level prevalence of Neosporosis could be as high as 90%. However, there is no approved treatment and vaccines available for Neosporosis. MicroRNA (miRNA) based prophylaxis and therapeutics could be options for Neosporosis in cattle and other animals. The current study aimed to investigate the genome of Neospora caninum to identify and characterize the conserved miRNAs through Expressed Sequence Tags (ESTs) dependent homology search. A total of 1,041 mature miRNAs of reference organisms were employed against 336 non-redundant ESTs available in the genome of Neospora caninum. The study predicted one putative miRNA “nca-miR-9388-5p” of 19 nucleotides with MFEI value -1.51 kcal/mol and (A + U) content% 72.94% corresponding with its pre-miRNA. A comprehensive search for specific gene targets was performed and discovered 16 potential genes associated with different protozoal physiological functions. Significantly, the gene “Protein phosphatase” was found responsible for the virulence of Neospora caninum. The other genes were accounted for gene expression, vesicular transport, cell signaling, cell proliferation, DNA repair mechanism, and different developmental stages of the protozoon. Therefore, this study finding will provide pivotal information to future aspirants upon Bovine Neosporosis. It will also serve as the baseline information for further studies of the bioinformatics approach to identify other protozoal miRNAs.

Computational screening of miRNAs and their targets in saffron (Crocus sativus L.) by transcriptome mining

A robust workflow for the identification of miRNAs and their targets in saffron was developed. MicroRNA-mediated gene regulation in saffron is potentially involved in several biological processes, including the biosynthesis of highly valuable apocarotenoids. Saffron (Crocus sativus L.) is the most expensive spice in the world and a major source of apocarotenoids. Even though miRNAs (20-24 nt non-coding small RNAs) are important regulators of gene expression at transcriptional and post-transcriptional levels, their role in saffron has not been thoroughly investigated. As a result, a workflow for computational identification of miRNAs and their targets can be useful to uncover the regulatory networks underlying biological processes in this valuable plant. The efficiency of several assembly tools such as Trans-ABySS, Trinity, Bridger, rnaSPAdes, and EvidentialGene was evaluated based on both reference-based and reference-free metrics using transcriptome data. A reliable workflow for computational identification of miRNAs and their targets in saffron was described. The EvidentialGene was found to be the most efficient de novo transcriptome assembler for saffron as a complex triploid model, followed by the Trinity. In total, 66 miRNAs from 19 different families that target 2880 genes, including several transcription factors involved in the flowering transition, were identified. Three of the identified targets were involved in the terpenoids backbone biosynthesis. CsCCD and CsUGT genes involved in the apocarotenoids biosynthetic pathway were targeted by csa-miR156g and csa-miR156b-3p, revealing a unique post-transcriptional regulation dynamic in saffron. The identified miRNAs and their targets add to our understanding of the many biological roles of miRNAs in saffron and shed new light on the control of the apocarotenoid biosynthetic pathway in this valuable plant.

In Silico Identification and Functional Characterization of Conserved miRNAs in the Genome of Cryptosporidium parvum

Cryptosporidium parvum, a predominant causal agent of a fatal zoonotic protozoan diarrhoeal disease called cryptosporidiosis, bears a worldwide public health concern for childhood mortality and poses a key threat to the dairy and water industries. MicroRNAs (miRNAs), small but powerful posttranscriptional gene silencing RNA molecules, regulate a variety of molecular, biological, and cellular processes in animals and plants. As to the present date, there is a paucity of information regarding miRNAs of C. parvum; hence, this study was used to identify miRNAs in the organism using a comprehensible expressed sequence tag-based homology search approach consisting of a series of computational screening process from the identification of putative miRNA candidates to the functional annotation of the important gene targets in C. parvum. The results revealed a conserved miRNA that targeted 487 genes in the model organism (Drosophila melanogaster) and 85 genes in C. parvum, of which 11 genes had direct involvements in several crucial virulence factors such as environmental oocyst protection, excystation, locomotion, adhesion, invasion, stress protection, intracellular growth, and survival. Besides, 20 genes showed their association with various major pathways dedicated for the ribosomal biosynthesis, DNA repair, transportation, protein production, gene expression, cell cycle, cell proliferation, development, immune response, differentiation, and nutrient metabolism of the organism in the host. Thus, this study provides a strong evidence of great impact of identified miRNA on the biology, virulence, and pathogenesis of C. parvum. Furthermore, the study suggests that the detected miRNA could be a potential epigenomic tool for controlling the protozoon through silencing those virulent and pathway-related target genes.

In silico identification of conserved miRNAs in the genome of fibre biogenesis crop Corchorus capsularis

Corchorus capsularis, commonly known as jute occupies the leading position in the production of natural fibre alongside lower environmental threat. Small noncoding ~21 to 24 nucleotides long microRNAs play significant roles in regulating the gene expression as well as different functions in cellular growth and development. Here, the study adopted a comprehensive in silico approach to identify and characterize the conserved miRNAs in the genome of C. capsularis including functional annotation of specific gene targets. Expressed Sequence Tags (ESTs) based homology search of 3350 known miRNAs of dicotyledons were allowed against 763 non-redundant ESTs of jute genome, resulted in the prediction of 5 potential miRNA candidates belonging five different miRNA families (miR1536, miR9567-3p, miR4391, miR11300, and miR8689). The putative miRNAs were composed of 18 nucleotides having a range of -0.49 to -1.56 MFEI values and 55%–61% of (A + U) content in their pre-miRNAs. A total of 1052 gene targets of putative miRNAs were identified and their functions were extensively analyzed. Most of the gene targets were involved in plant growth, cell cycle regulation, organelle synthesis, developmental process and environmental responses. Five gene targets, namely, NAC Domain Containing Protein, WRKY DNA binding protein, 3-dehydroquinate synthase, S-adenosyl-L-Met–dependent methyl transferase and Vascular-related NAC-Domain were found to be involved in the lignin biosynthesis, phenylpropanoid pathways and secondary wall formation. The present study might accelerate the more miRNA discovery, strengthening the complete understanding of miRNAs association in the cellular basis of lignin biosynthesis towards the production of high standard jute products.

In silico determination of transposon-derived miRNAs and targets in Aegilops species

Transposable elements (TEs) are found almost in all living organism, shaping organisms' genomes. miRNAs are noncoding RNA types which are especially important in gene expression regulations. Many previously determined plant miRNAs are identical/homologous to transposons (TE-MIR). The aim of this study was computational characterization of novel TE-related miRNAs and their targets in Aegilops genome by using stringent criteria. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed by BLAST2GO. Seventeen novel TE-related miRNAs in Aegilops genome were identified for the first time. GO analyses indicated that 40 targets played different roles in biological processes, cellular components and molecular functions. Moreover, these genes were involved in 10 metabolic pathways such as purine metabolism, nitrogen metabolism, oxidative phosphorylation, etc. as a result of KEGG analyses. Identification of miRNAs and their targets are significant to understand miRNA-TEs relationships and even how TEs affect plant growth and development. Obtaining results of this study are expected to provide possible new insight into Aegilops and its related species, wheat, with respect to miRNAs evolution and domestication.Communicated by Ramaswamy H. Sarma.