J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (7): 1339-1351.DOI: 10.1111/jipb.13268

• Cell and Developmental Biology • Previous Articles     Next Articles

A feedback regulation between ARF7-mediated auxin signaling and auxin homeostasis involving MES17 affects plant gravitropism

Feng Zhang1, Cuiling Li1, Xingzhen Qu1, Jiajia Liu1, Zipeng Yu1, Junxia Wang1, Jiayong Zhu1, Yongqiang Yu2 and Zhaojun Ding1*   

  1. 1 The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao 266237, China
    2 Horticulture Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China

    *Correspondence: Zhaojun Ding (dingzhaojun@sdu.edu.cn)
  • Received:2021-11-07 Accepted:2022-04-25 Online:2022-04-27 Published:2022-07-01


Gravitropism is an essential adaptive response of land plants. Asymmetric auxin gradients across plant organs, interpreted by multiple auxin signaling components including AUXIN RESPONSE FACTOR7 (ARF7), trigger differential growth and bending response. However, how this fundamental process is strictly maintained in nature remains unclear. Here, we report that gravity stimulates the transcription of METHYL ESTERASE17 (MES17) along the lower side of the hypocotyl via ARF7-dependent auxin signaling. The asymmetric distribution of MES17, a methyltransferase that converts auxin from its inactive form methyl indole-3-acetic acid ester (MeIAA) to its biologically active form free-IAA, enhanced the gradient of active auxin across the hypocotyl, which in turn reversely amplified the asymmetric auxin responses and differential growth that shape gravitropic bending. Taken together, our findings reveal the novel role of MES17-mediated auxin homeostasis in gravitropic responses and identify an ARF7-triggered feedback mechanism that reinforces the asymmetric distribution of active auxin and strictly controls gravitropism in plants.

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