J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (2): 324-342.DOI: 10.1111/jipb.13441

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To curve for survival: Apical hook development

Yichuan Wang, Yang Peng and Hongwei Guo*   

  1. Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Southern University of Science and Technology(SUSTech), Shenzhen 518055, China
    Yichuan Wang and Yang Peng contributed equally to the work.
    *Correspondence: Hongwei Guo (guohw@sustech.edu.cn)
  • Received:2022-11-14 Accepted:2022-12-13 Online:2022-12-23 Published:2023-02-01

Abstract: Apical hook is a simple curved structure formed at the upper part of hypocotyls when dicot seeds germinate in darkness. The hook structure is transient but essential for seedlings' survival during soil emergence due to its efficient protection of the delicate shoot apex from mechanical injury. As a superb model system for studying plant differential growth, apical hook has fascinated botanists as early as the Darwin age, and significant advances have been achieved at both the morphological and molecular levels to understand how apical hook development is regulated. Here, we will mainly summarize the research progress at these two levels. We will also briefly compare the growth dynamics between apical hook and hypocotyl gravitropic bending at early seed germination phase, with the aim to deduce a certain consensus on their connections. Finally, we will outline the remaining questions and future research perspectives for apical hook development.

Key words: apical hook, auxin gradient, differential growth, HOOKLESS1, phytohormones

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