Auxin is a key hormone in plant development. Although the critical contributions of auxin biosynthesis and polar transport to the auxin maxima formation have been well elucidated, how these processes are regulated and coordinated to generate and maintain the localized auxin accumulation remains elusive.

Recently, the team led by Professor Zhenbiao Yang, Dean of the Institute of Future Agriculture and Chair Professor of the Faculty of Synthetic Biology at Shenzhen University of Advanced Technology (SUAT), published their latest findings in Nature Communications. The study reveals a cell-autonomous self-regulatory auxin flow mechanism in Arabidopsis cotyledons mediated by the auxin transporter PIN2, which spatiotemporally coordinates plant cell expansion and morphogenesis. This work establishes a novel paradigm for understanding organ-scale developmental patterning.

Using the Arabidopsis cotyledon system, the team dissected auxin regulation mechanisms, through which auxin maxima at the cotyledon tip spatially coordinate the expansion of auxin-accumulated region. The study found that at the cotyledon margin, the PIN2 protein polar-localized in the apical membrane of the marginal cells (MCs), forming a tip-oriented polar auxin transport system. This system is dynamically established through self-activating and self-terminating mechanisms, effectively orchestrating the interdigitated patterning of the pavement cells (PCs).

Further analysis revealed that, at the early-stage the auxin precursor indole-3-butyric acid (IBA) is converted into active indole-3-acetic acid (IAA) in marginal cells, promoting PIN2 accumulation and polarized targeting. As auxin levels rise at the cotyledon tip, a TOB1-mediated mediated negative feedback is triggered: vacuolar sequestration of IBAvia TRANSPORTER OF IBA1 (TOB1), terminating PIN2 accumulation and completing this dynamic self-regulatory auxin flux.

This discovery deciphers cell-autonomous self-regulatory mechanism governing auxin gradient homeostasis in plants, while redefining signal transduction pathways during plant development. The researchers suggest that this mechanism likely operates across organ development domains, potentially regulating fundamental developmental programssuch as root elongation and  lateral root initiation.

Professor Zhenbiao Yang, Dean of the Institute of Future Agriculture and Chair Professor at the Faculty of Synthetic Biology at SUAT, is the corresponding author. Dr. Patricio Pérez-Henríquez from the University of California, Riverside, is the first author. The study involved collaboration with multiple institutions, including Fujian Agriculture and Forestry University and the University of California, Riverside, and was supported by the National Natural Science Foundation of China, Fujian Agriculture and Forestry University, SUAT, the Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences (SIAT), the Shenzhen Institute of Synthetic Biology Innovation, the National Institute of General Medical Sciences (USA), and the National Science Foundation (USA).