Bioinformatic identification of a putative microRNA-transcription factor network motif in the regulation of laccase genes in peach (Prunus persica)

Laccase proteins are multicopper glycoprotein oxidases expressed in plant tissues under biotic and abiotic stress conditions. They are able to catalyze oxidation of a broad range of substrates including phenols and amines. The regulation of expression of such genes is crucial for proper reaction to stress. At the DNA level, this modulation is mediated by the recruitment of specific transcription factors (TF) to suitable transcription factor binding sites (TFBS), usually located upstream of a gene. At the RNA level, the short microRNAs molecules (miRs) interfere with the translation of target proteins through base‐pairing with messenger RNAs. Complex regulatory circuits combining those interactions fine‐tune protein expression and enhance plant responses to environmental change. In this case study we performed a phylogenetic analysis of peach laccases and characterized specific peach miRs (miR397a and miR408), reported previously as posttranscriptional regulatory elemen ts of laccase genes. Using a bioinformatic approach we identified unique TFBS for abscisic acid (ABA) response elements in promoter regions of both miR and laccase genes. The signaling molecule ABA plays a major role in plant responses to stress. We propose a feed‐forward loop motif in the stress response network involving ABA action in peach by integrating the TF‐mediated regulation of miR and laccase genes at the transcriptional level with the miR regulation of laccase target genes at the post‐transcriptional level.