Auxin biosynthesis and metabolism

Abstract

Auxins function at the intersection between environmental and developmental cues and the response pathways that they trigger (Fig. 1). Auxin levels vary dramatically throughout the body and life of the plant, forming gradients that are a central component of its action (4, 5, 14, 20, 34). Accordingly, plants have evolved intricate regulatory networks with considerable redundancy and adaptive plasticity to maintain auxin levels in response to changing environmental and developmental conditions. We refer to this phenomenon as auxin homeostasis; specifically the biosynthesis, inactivation, transport, and inter-conversion pathways that regulate and maintain auxin levels.