PLETHORAs: architects of plant development

Plants depend on tight control of development and growth to establish their characteristic architectures. PLETHORA (PLT) transcription factors are among the most widely employed proteins that steer these processes across tissues. Since their discovery in Arabidopsis, it is becoming increasingly clear that their functional role extends to many other species. In this review, we explore how PLTs can act as universal architects of plant development. By integrating recent insights from embryo to shoot and from moss to flowering plants, we propose that they confer meristematic potential to tissues, which is primarily determined by their spatiotemporal expression patterns. We thereby highlight the necessity to study control of PLT transcription rather than to rely solely on orthologous relationships.