The phytohormone auxin indole-3-acetic acid (IAA) regulates nearly all aspects of plant growth and development. Despite substantial progress in our understanding of auxin biology, delineating specific auxin response remains a major challenge. Auxin regulates transcriptional response via its receptors, TIR1 and AFB F-box proteins. Here we report an engineered, orthogonal auxin–TIR1 receptor pair, developed through a bump-and-hole strategy, that triggers auxin signaling without interfering with endogenous auxin or TIR1/AFBs. A synthetic, convex IAA (cvxIAA) hijacked the downstream auxin signaling in vivo both at the transcriptomic level and in specific developmental contexts, only in the presence of a complementary, concave TIR1 (ccvTIR1) receptor. Harnessing the cvxIAA–ccvTIR1 system, we provide conclusive evidence for the role of the TIR1-mediated pathway in auxin-induced seedling acid growth. The cvxIAA–ccvTIR1 system serves as a powerful tool for solving outstanding questions in auxin biology and for precise manipulation of auxin-mediated processes as a controllable switch.

植物激素生长素吲哚-3-乙酸 (IAA) 调节植物生长和发育的几乎所有方面。尽管我们对生长素生物学的理解取得了实质性进展，但描述特定的生长素反应仍然是一个重大挑战。生长素通过其受体 TIR1 和 AFB F-box 蛋白调节转录反应。在这里，我们报告了一种工程化的正交生长素-TIR1 受体对，该受体对通过凹凸洞策略开发，可在不干扰内源性生长素或 TIR1/AFB 的情况下触发生长素信号传导。合成的凸 IAA (cvxIAA)在体内劫持了下游生长素信号在转录组水平和特定的发育环境中，仅在存在互补的凹 TIR1 (ccvTIR1) 受体的情况下。利用 cvxIAA–ccvTIR1 系统，我们为 TIR1 介导的途径在生长素诱导的幼苗酸生长中的作用提供了确凿的证据。cvxIAA–ccvTIR1 系统是解决生长素生物学中悬而未决问题以及作为可控开关精确操纵生长素介导过程的强大工具。