GSE171143
ORE15, a PLATZ transcription factor, determines root meristem size by modulating auxin and cytokinin signaling
An optimal size of postembryonic root apical meristem (RAM) is achieved by a balance between cell division and differentiation. Despite extensive research, molecular mechanisms underlying the spatiotemporal coordination of cell division and differentiation remain largely unknown. Here, we report that ORESARA 15 (ORE15), an Arabidopsis PLATZ transcription factor preferentially expressed in the RAM, determines RAM size. The primary root length, RAM size, cell division rate, and stem cell niche activity were reduced in an ore15 loss-of-function mutant but enhanced in an activation-tagged line overexpressing ORE15 compared with the wild type. We further demonstrate that ORE15 regulates auxin transport and distribution, at least partly, by modulating the expression and localization of the auxin importer AUXIN RESISTANT 1 (AUX1). ORE15 forms mutually positive and negative feedback loops with auxin and cytokinin signaling, respectively. Collectively, our findings imply that ORE15 controls the RAM size by mediating the antagonistic interaction between auxin and cytokinin. Overall design: mRNA profiling from ORE15 in root tips in Arabidopsis