Li Lanxin, Gallei Michelle, Friml Jiří
Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
Trends Plant Sci. 2022 May;27(5):440-449. doi: 10.1016/j.tplants.2021.11.006. Epub 2021 Nov 27.
The phytohormone auxin is the major growth regulator governing tropic responses including gravitropism. Auxin build-up at the lower side of stimulated shoots promotes cell expansion, whereas in roots it inhibits growth, leading to upward shoot bending and downward root bending, respectively. Yet it remains an enigma how the same signal can trigger such opposite cellular responses. In this review, we discuss several recent unexpected insights into the mechanisms underlying auxin regulation of growth, challenging several existing models. We focus on the divergent mechanisms of apoplastic pH regulation in shoots and roots revisiting the classical Acid Growth Theory and discuss coordinated involvement of multiple auxin signaling pathways. From this emerges a more comprehensive, updated picture how auxin regulates growth.
植物激素生长素是控制向性反应（包括向重力性）的主要生长调节因子。受刺激茎的下侧生长素积累促进细胞扩张，而在根中则抑制生长，分别导致茎向上弯曲和根向下弯曲。然而，相同的信号如何触发如此相反的细胞反应仍是一个谜。在本综述中，我们讨论了最近对生长素调节生长机制的一些意外见解，对几个现有模型提出了挑战。我们重点关注茎和根中质外体pH调节的不同机制，重新审视经典的酸生长理论，并讨论多种生长素信号通路的协同作用。由此浮现出一幅关于生长素如何调节生长的更全面、更新的图景。
