J Integr Plant Biol. ›› 2020, Vol. 62 ›› Issue (10): 1500-1517.DOI: 10.1111/jipb.12931

Special Issue: Root development

• Cell and Developmental Biology • Previous Articles     Next Articles

SHY2 as a node in the regulation of root meristem development by auxin, brassinosteroids, and cytokinin

Taotao Li1,2†, Xinke Kang1†, Wei Lei1, Xiuhong Yao1, Lijuan Zou3, Dawei Zhang1* and Honghui Lin1*   

  1. 1Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China.
    2School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China.
    3Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China.

    These authors contributed equally to this work.
    Email: Honghui Lin (hhlin@scu.edu.cn, Dr. Lin is responsible for the distribution of the materials associated with this article); Dawei Zhang (zhdawei@scu.edu.cn)
  • Received:2019-12-16 Accepted:2020-03-02 Online:2020-04-01 Published:2020-10-01

Abstract: In multicellular organisms, the balance between cell division and differentiation determines organ size, and represents a central unknown in developmental biology. In Arabidopsis roots, this balance is mediated between cytokinin and auxin through a regulatory circuit converging on the IAA3/SHORT HYPOCOTYL 2 (SHY2) gene. Here, we show that crosstalk between brassinosteroids (BRs) and auxin occurs in the vascular transition zone to promote root meristem development. We found that BR increases root meristem size by up‐regulating expression of the PINFORMED 7 (PIN7) gene and down‐regulating expression of the SHY2 gene. In addition, BES1 could directly bind to the promoter regions of both PIN7 and SHY2, indicating that PIN7 and SHY2 mediate the BR‐induced growth of the root meristem by serving as direct targets of BES1. Moreover, the PIN7 overexpression and loss‐of‐function SHY2 mutant were sensitive to the effects of BR and could partially suppress the short‐root phenotypes associated with deficient BR signaling. Interestingly, BRs could inhibit the accumulation of SHY2 protein in response to cytokinin. Taken together, these findings suggest that a complex equilibrium model exists in which regulatory interactions among BRs, auxin, and cytokinin regulate optimal root growth.

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