Transcription activator (PubMed:17088607, PubMed:17183265, PubMed:17183267). Together with MYB88 and MYB124, ensures that stomata contain just two guard cells (GCs) by enforcing a single symmetric precursor cell division before stomatal maturity (PubMed:24571519). Together with SPCH and MUTE, regulates the stomata formation. Required to promote differentiation and morphogenesis of stomatal guard cells and to halt proliferative divisions in their immediate precursors. Mediates the formation of stomata (PubMed:17088607, PubMed:17183265, PubMed:17183267). Prevents histone H3K27me3 marks and derepresses stem cell gene expression (PubMed:24654956). Interacts with FAMA through its LxCxE motif (PubMed:25303364). Self-interacts. Interacts also with bHLH071 and bHLH093 (PubMed:17088607). Interacts with RBR1 (PubMed:24571519). Resctricted to stomatal cell lineages (at protein level). Expressed in roots, leaves, stems, and flowers. Not expressed in meristemoids, but strongly expressed in guard mother cells (GMCs) and in young guard cells (at protein level) (PubMed:17088607). Expressed at the transition to terminal stomatal differentiation, just before and after the symmetric division of stomatal differentiation, being confined to late-stage GMC and to young, still differentiating guard cells (PubMed:24571519). Inhibited by low relative humidity (LRH) via epigenetic CG methylation, thus leading to a reduced stomatal index. Excess symmetric divisions during stomata development leading to abnormal guard cells clusters formation. Reduced seeds set and low biomass. These phenotypes are complemented by MYB124. Plants overexpressing FAMA exhibit ectopic stomata.