Since the early days of plant biology, small molecule hormones have held a central place in our understanding of development. A key feature of plant hormone action is the ability to regulate multiple developmental processes. Despite this pleiotropy, decades of genetic and molecular studies have shown that plant hormone signaling is often canalized through a core pathway. This raises the difficult question of how one signaling pathway produces different outputs in different tissues. Drawing on examples from gibberellin and strigolactone signaling pathways, we propose this conceptual problem arises from an upside-down perspective of hormone signaling. Recent studies have revealed hormone and core pathway–independent mechanisms of regulating downstream signaling components, which could explain multiple developmental responses to the same hormone.

从植物生物学的早期开始，小分子激素在我们对发育的理解中就占据了中心位置。植物激素作用的一个关键特征是调节多个发育过程的能力。尽管具有这种多效性，但数十年的遗传和分子研究表明，植物激素信号传导通常是通过核心途径进行的。这提出了一个信号通路如何在不同组织中产生不同输出的难题。借鉴赤霉素和独脚金内酯信号通路的例子，我们提出这个概念问题源于激素信号的颠倒视角。最近的研究揭示了调节下游信号成分的独立于激素和核心通路的机制，这可以解释对同一激素的多种发育反应。