Cell division in the shoot apical meristem is a trigger for miR156 decline and vegetative phase transition in <i>Arabidopsis</i>

Abstract

Significance Why the developmental transitions of multicellular organisms are unidirectional and how the rate of these transitions is determined are biological mysteries. Earlier reports have shown that both animals and plants utilize microRNA (miRNA) as a timer in regulating their developmental transitions. However, how age temporally regulates the abundance of these miRNAs is poorly understood. In plants, the progressive decline in miR156 triggers the appearance of adult traits. Here, we show that cell division in the apical meristem is a trigger for miR156 decline. The transcriptional decline in MIR156C along with cell division in the apical meristem contributes to plant maturation. This simple model explains why the developmental transitions of a plant are unidirectional and inevitable under normal growth conditions.