MicroRNAs are important gene regulators controlling almost all biological and metabolic functions. They elicit their regulatory response through modulation of their target gene expression. In this study, we identified eight novel microRNAs (miRNAs) belonging to four miRNA families and one miR* sequence from the French bean genome which responded to high temperature. The precursor miRNAs varied in length and showed conserved signatures of RNA polymerase II transcripts in their upstream regions. Promoter region analysis indicated the prevalence of MYB and WRKY binding sites emphasizing auto-inhibition of miRNA biogenesis. The genomic organization study revealed the presence of 150 putative regulatory motifs of which 41 are unique. Common motifs shared by miRNAs involved in more than one abiotic stresses were also identified. Further, the miRNA validation was carried out by stem-loop real-time PCR, and the results emphasize that the differential expression of miRNAs confers stress tolerance. Functional analysis revealed that most of the targets represent transcription factors. The results obtained would provide new insights to the complex regulatory mechanism employing small non-coding regulatory RNAs toward stress adaptation.

MicroRNAs (miRNAs) are group of small, non-coding RNAs that play important roles in plant growth, development and stress response. There have been an increasing number of investigations aimed at discovering miRNAs and analyzing their functions in model plants. In this study, we constructed high temperature stress induced small RNA libraries and characterized 26 potential miRNAs belonging to 21 families in French bean. A total of 140 annotated potential targets were found, of which majority were transcription factors (MYB, bHLH, GRF1, bZIP, NAC etc.,) which may play an important role in stress resistance. RT-qPCR and Northern blot analysis revealed differential expressions of candidate miRNAs and their target genes. The observed induction of miRNA expression is correlated with the down regulation of their targets. Investigation of gene ontology linked with targets of miRNAs forecasted their involvement in various biological functions. We anticipate the further studies may offer new avenues in developing stress tolerant variety of French bean.

MicroRNAs are endogenous small RNAs regulating intrinsic normal growth and development of plant. Discovering miRNAs, their targets and further inferring their functions had become routine process to comprehend the normal biological processes of miRNAs and their roles in plant development. In this study, we used homology-based analysis with available expressed sequence tag of finger millet (Eleusine coracana) to predict conserved miRNAs. Three potent miRNAs targeting 88 genes were identified. The newly identified miRNAs were found to be homologous with miR166 and miR1310. The targets recognized were transcription factors and enzymes, and GO analysis showed these miRNAs played varied roles in gene regulation. The identification of miRNAs and their targets is anticipated to hasten the pace of key epigenetic regulators in plant development.

French bean (Phaseolus vulgaris L.), a legume grown all over the world, is an important pulse crop of India whose yield is affected by various biotic and abiotic stresses. Micro RNAs (miRNAs) have been shown to play an important role in the regulation of plant responses to several stresses. Boron toxicity is a significant limitation to cereal crop production. In this study, RT-qPCR confirmed seven miRNAs responsive to high concentrations of boron, exhibited differential expression trends compared with the control. Target prediction and their functional analysis showed that most of the miRNA targets represent transcription factors regulating expression of stressrelated genes. GO results supported our hypothesis that miRNAs were involved in diverse cellular processes, including plant circadian cycle, vegetative development, transcription, and cross adaptation. Our research characterized a subset of miRNAs that would facilitate understanding the regulatory mechanisms of small noncoding regulatory RNAs involved in stress tolerance.

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