Identification and Characterization of High Temperature Stress Responsive Novel miRNAs in French Bean (Phaseolus...

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.