Plants sense a myriad of signals through cell-surface receptors to coordinate their development and environmental response. The Arabidopsis ERECTA receptor kinase regulates diverse developmental processes via perceiving multiple EPIDERMAL PATTERNING FACTOR (EPF)/EPF-LIKE peptide ligands. How the activated ERECTA protein is turned over is unknown. Here we identify two closely related plant U-box ubiquitin E3 ligases, PUB30 and PUB31, as key attenuators of ERECTA signalling for two developmental processes: inflorescence/pedicel growth and stomatal development. Loss-of-function pub30 pub31 mutant plants exhibit extreme inflorescence/pedicel elongation and reduced stomatal numbers owing to excessive ERECTA protein accumulation. Ligand activation of ERECTA leads to phosphorylation of PUB30/31 via BRI1-ASSOCIATED KINASE1 (BAK1), which acts as a coreceptor kinase and a scaffold to promote PUB30/31 to associate with and ubiquitinate ERECTA for eventual degradation. Our work highlights PUB30 and PUB31 as integral components of the ERECTA regulatory circuit that ensure optimal signalling outputs, thereby defining the role for PUB proteins in developmental signalling.

植物通过细胞表面受体感知无数信号，以协调它们的发育和环境反应。拟南芥ERECTA 受体激酶通过感知多种表皮模式因子 (EPF)/EPF-LIKE 肽配体来调节不同的发育过程。激活的 ERECTA 蛋白如何翻转是未知的。在这里，我们确定了两个密切相关的植物 U-box 泛素 E3 连接酶，PUB30 和 PUB31，作为 ERECTA 信号转导的关键衰减因子，用于两个发育过程：花序/花梗生长和气孔发育。功能丧失pub30 pub31由于 ERECTA 蛋白的过度积累，突变植物表现出极端的花序/花梗伸长和气孔数量减少。ERECTA 的配体激活通过 BRI1 相关激酶 1 (BAK1) 导致 PUB30/31 磷酸化，BAK1 作为辅助受体激酶和支架促进 PUB30/31 与 ERECTA 结合并泛素化以最终降解。我们的工作强调 PUB30 和 PUB31 作为 ERECTA 调节电路的组成部分，确保最佳信号输出，从而定义 PUB 蛋白在发育信号中的作用。