J Integr Plant Biol ›› 2026, Vol. 68 ›› Issue (3): 568-586.DOI: 10.1111/jipb.70090

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  • 收稿日期:2025-02-21 接受日期:2025-10-22 出版日期:2026-03-08 发布日期:2026-03-10

Collapsed auxin transport by iron inhibits primary root growth under low phosphate stress

Jian‐Feng Zhang1†, Le He1†, Zhao‐Yang Ruan1†, Jing‐Yi Yan1, Kai‐Kai Lu1, Xue Li1, Yan Su1, Wen‐Cheng Liu2* and Feng Ren1*   

  1. 1. Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China

    2. State Key Laboratory of Crop Stress Adaptation and Improvement, State Key Laboratory of Cotton Biology, School of Life Sciences,Henan University, Kaifeng 475004, China

    †These authors contributed equally to this work.

    *Correspondences: Wen‐Cheng Liu (liuwencheng@henu.edu.cn); Feng Ren (renfeng@ccnu.edu.cn, Dr. Ren is fully responsible for the distribution of all materials associated with this article)

  • Received:2025-02-21 Accepted:2025-10-22 Online:2026-03-08 Published:2026-03-10
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (32472036, 31971814,32322010) and the Key Research and Development Program of Hubei Province (ZZCXHZYF2022000535).

Abstract: The inhibited growth of primary roots (PRs) is a typical adaptive response of Arabidopsis to low phosphate (LP) stress. The role of auxin and its relationship with iron (Fe) in this process, however, remains unclear. In this study, we demonstrated that auxin acts as a positive regulator. A high concentration of auxin at the tips of PRs stimulates vigorous PR growth in both LP-arf7 arf19 and LP-yucca mutants. The application of a low dose of exogenous auxin can partially mitigate LP-induced PR growth inhibition. Enhanced auxin signaling, achieved through overexpression of ARF7 or ARF19, also promotes PR growth in LP-transgenic plants. Conversely, LP stress negatively regulates the polar transport of auxin, leading to reduced PIN activity at PRs. Mutations of PINs and application of NPA, therefore, exacerbate the impact of LP stress on PR growth. Consistently, PIN activity remains stable in the PRs of LP-arf7 arf19 mutants, and mutation of PINs normalizes the inhibited growth of these mutants. Furthermore, a correlation is observed between decreased auxin activity and increased Fe at LP-PRs. Fe accumulation triggers a burst of reactive oxygen species (ROS), which inhibits polar auxin transport and distribution at the tips of PRs. Changes in Fe and ROS levels influence auxin activity at LP-PRs, while auxin conversely affects Fe accumulation at these sites. Consequently, Fe levels are low at the PRs of LP-arf7 arf19 mutants, LP-yucca mutants, and auxin-treated LP-WT plants. Conversely, they are high in PRs of LP-pin2 mutant and NPA-treated LP-WT plants. In conclusion, accumulated Fe triggers a burst of ROS, disrupting auxin transport by decreasing PIN activity at LP-PRs. This disruption subsequently inhibits cell division and overall PR growth.

Key words: Arabidopsis, auxin, iron, low phosphate stress, primary root growth, reactive oxygen species

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