Abstract
BackgroundMicroRNAs (miRNAs) are ubiquitous components of endogenous plant transcriptome. miRNAs are small, single-stranded and ~21 nt long RNAs which regulate gene expression at the post-transcriptional level and are known to play essential roles in various aspects of plant development and growth. Previously, a number of miRNAs have been identified in potato through in silico analysis and deep sequencing approach. However, identification of miRNAs through deep sequencing approach was limited to a few tissue types and developmental stages. This study reports the identification and characterization of potato miRNAs in three different vegetative tissues and four stages of tuber development by high throughput sequencing.ResultsSmall RNA libraries were constructed from leaf, stem, root and four early developmental stages of tuberization and subjected to deep sequencing, followed by bioinformatics analysis. A total of 89 conserved miRNAs (belonging to 33 families), 147 potato-specific miRNAs (with star sequence) and 112 candidate potato-specific miRNAs (without star sequence) were identified. The digital expression profiling based on TPM (Transcripts Per Million) and qRT-PCR analysis of conserved and potato-specific miRNAs revealed that some of the miRNAs showed tissue specific expression (leaf, stem and root) while a few demonstrated tuberization stage-specific expressions. Targets were predicted for identified conserved and potato-specific miRNAs, and predicted targets of four conserved miRNAs, miR160, miR164, miR172 and miR171, which are ARF16 (Auxin Response Factor 16), NAM (NO APICAL MERISTEM), RAP1 (Relative to APETALA2 1) and HAM (HAIRY MERISTEM) respectively, were experimentally validated using 5′ RLM-RACE (RNA ligase mediated rapid amplification of cDNA ends). Gene ontology (GO) analysis for potato-specific miRNAs was also performed to predict their potential biological functions.ConclusionsWe report a comprehensive study of potato miRNAs at genome-wide level by high-throughput sequencing and demonstrate that these miRNAs have tissue and/or developmental stage-specific expression profile. Also, predicted targets of conserved miRNAs were experimentally confirmed for the first time in potato. Our findings indicate the existence of extensive and complex small RNA population in this crop and suggest their important role in pathways involved in diverse biological processes, including tuber development.
Highlights
MicroRNAs are ubiquitous components of endogenous plant transcriptome. miRNAs are small, single-stranded and ~21 nt long RNAs which regulate gene expression at the post-transcriptional level and are known to play essential roles in various aspects of plant development and growth
There are diverse siRNA species depending on the Dicer-like (DCL) proteins involved in the production, such as natural antisense transcript-derived siRNAs (24 nt), heterochromatic siRNAs (24 nt) and trans-acting siRNAs (21 nt) [1]. miRNAs are small, endogenous, single-stranded and ~21 nt long RNAs that regulate gene expression at the post-transcriptional level by degrading or repressing translation of targeted mRNAs, depending on the extent of complementarity between miRNA and mRNA [1,2]
In summary, we report a comprehensive study of potato miRNAs at genome-wide level using three different vegetative tissues and four early developmental stages of tuberization by high-throughput sequencing and high-end bioinformatics methods
Summary
MicroRNAs (miRNAs) are ubiquitous components of endogenous plant transcriptome. miRNAs are small, single-stranded and ~21 nt long RNAs which regulate gene expression at the post-transcriptional level and are known to play essential roles in various aspects of plant development and growth. MiRNAs are small, single-stranded and ~21 nt long RNAs which regulate gene expression at the post-transcriptional level and are known to play essential roles in various aspects of plant development and growth. There are many classes of small ncRNAs and the two major classes that have been well-studied and defined are miRNAs and siRNAs [1,2] Both are functionally similar, they have different mode of biogenesis. MiRNAs are small, endogenous, single-stranded and ~21 nt long RNAs that regulate gene expression at the post-transcriptional level by degrading or repressing translation of targeted mRNAs, depending on the extent of complementarity between miRNA and mRNA [1,2]. There is increasing evidence which indicates that miRNAs play vital roles in stress responses and various developmental processes, including shoot apical meristem formation, leaf morphogenesis and polarity, floral organ identity, root development, vegetative phase change and vascular development [2,4]
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