MicroRNA858a antagonistically regulates plant response to concurrent biotic and abiotic stresses

Plants face various environmental stresses and have developed sophisticated adaptive mechanisms to cope with constraints. miR858a targets transcription factor (TF) MYB111 and has proven to be a key regulator in modulating plant responses to biotic and abiotic stresses. However, its transcriptional regulation and the underlying mechanisms remain unresolved. To this end, we performed the yeast one-hybrid (Y1H) assay using the miR858a promoter against an Arabidopsis transcription factor library. In this way, we identified 32 TFs that specifically interact with the miR858a promoter. By analysing expression profiles of candidate TFs under different stress conditions, mimicked by flg22, UV-B, and co-treatment of flg22/UV-B treatments, we prioritized candidate TFs, including five flg22-responsive TFs (ERF73, bZIP63, NF-YC6, AL7, and AIN1) and one UV-B-responsive TF, MYBD. Our data show that miR858a is antagonistically regulated by distinct stress-responsive TFs and by their interplay, thus highlighting, for the first time, a crucial role of miRNAs and their expression regulation in plant responses to diverse stress factors. These findings provide deeper insights into the mechanisms by which plants adapt to changing environments and offer valuable traits and approaches for breeding crops resistant to various concurrent stress factors.