Auxin signaling: Research advances over the past 30 years

Abstract

Auxin, one of the first identified and most widely studied phytohormones, has been and will remain a hot topic in plant biology. After more than a century of passionate exploration, the mysteries of its synthesis, transport, signaling, and metabolism have largely been unlocked. Due to the rapid development of new technologies, new methods, and new genetic materials, the study of auxin has entered the fast lane over the past 30 years. Here, we highlight advances in understanding auxin signaling, including auxin perception, rapid auxin responses, TRANSPORT INHIBITOR RESPONSE 1 and AUXIN SIGNALING F-boxes (TIR1/AFBs)-mediated transcriptional and non-transcriptional branches, and the epigenetic regulation of auxin signaling. We also focus on feedback inhibition mechanisms that prevent the over-amplification of auxin signals.In addition, we cover the TRANSMEMBRANE KINASE-mediated non-canonical signaling, which converges with TIR1/AFBs-mediated transcriptional regulation to coordinate plant growth and development. The identification of additional auxin signaling components and their regulation will continue to open new avenues of research in this field, leading to an increasingly deeper, more comprehensive understanding of how auxin signals are interpreted at the cellular level to regulate plant growth and development.

Modulation of Receptor-like Trans-Membrane Kinase 1 nuclear localisation by DA1 peptidases in Arabidopsis

“…S2B ), this supports the idea that auxin levels modulate DAR1 peptidase activity across the hook region to generate the gradient of TMK1C levels. How auxin is sensed in this system is not yet clear, while a role for TMK1 in direct auxin perception remains unresolved (22, 24, 42).…”

“…S2B), this supports the idea that auxin levels modulate DAR1 peptidase activity across the hook region to generate the gradient of TMK1C levels. How auxin is sensed in this system is not yet clear, while a role for TMK1 in direct auxin perception remains unresolved (22,24,42). DA1 and DAR1 peptidase activities limit the duration of cell proliferation during early stages of organ growth by cleaving and destabilising a variety of proteins that promote cell proliferation (26,27).…”

Testing the polar auxin transport model with a selective plasma membrane H+‐ATPase inhibitor

“…The plant hormone auxin (indole‐3‐acetic acid [IAA]) is transported through plant tissues and demonstrates a polarity of movement from cell to cell (Muday and DeLong, 2001; Yang et al, 2006; Naramoto, 2017; Anfang and Shani, 2021; Yu et al, 2022). Polar auxin transport controls multiple aspects of plant growth and development, such as vascular tissue differentiation, embryogenesis, leaf vein patterning, root patterning, and root gravitropism (Friml and Palme, 2002; Ye, 2002; Möller and Weijers, 2009; Baster et al, 2014; Herrbach et al, 2014; Hu et al, 2021; Kneuper et al, 2021; Ötvös et al, 2021).…”

Divergence of trafficking and polarization mechanisms for PIN auxin transporters during land plant evolution

“…Auxin is a crucial regulator of polarity and morphogenesis in land plants (Mockaitis and Estelle, 2008; Smit and Weijers, 2015; Kato et al, 2018; Leyser, 2018; Yu et al, 2022). The auxin concentration gradient through tissues coordinates a broad spectrum of plant development, ranging from embryogenesis to organ formation and tropic growth (Vanneste and Friml, 2009; Friml, 2021).…”