Interaction between two timing microRNAs controls trichome distribution in Arabidopsis.

The miR156-targeted squamosa promoter binding protein like (SPL) transcription factors function as an endogenous age cue in regulating plant phase transition and phase-dependent morphogenesis, but the control of SPL output remains poorly understood. In Arabidopsis thaliana the spatial pattern of trichome is a hallmark of phase transition and governed by SPLs. Here, by dissecting the regulatory network controlling trichome formation on stem, we show that the miR171-targeted lost meristems 1 (LOM1), LOM2 and LOM3, encoding GRAS family members previously known to maintain meristem cell polarity, are involved in regulating the SPL activity.