Regulation of Stomatal Development by Stomatal Lineage miRNAs

Abstract

Stomata in the plant epidermis play a vital role for growth and survival by controlling gas exchange, transpiration, and immunity to pathogens. Plants modulate stomatal cell fate and patterning through key transcriptional factors and signaling cascades. miRNAs are known to contribute to functional and developmental plasticity in multicellular organisms, however, the extent to which miRNAs are involved in stomatal development remains elusive. Here, we reveal highly dynamic, development stage-specific miRNA expression profiles from stomatal lineage. We show that stomatal lineage miRNAs positively and negatively regulate stomatal formation and patterning to avoid clustered and paired stomata. Target prediction of stomatal lineage miRNAs suggests potential cellular processes implicated in stomatal development. We show that dysregulation of stomatal lineage miRNAs and their target mRNAs disclose unexpected genetic pathways modulating stomatal development. We reveal that miRNA399-regulated PHO2, involved in phosphate homeostasis, controls stomatal development. Our study demonstrates that miRNAs constitute a critical component in the regulatory mechanism controlling stomatal development.