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SHY2 as a node in the regulation of root meristem development by auxin, brassinosteroids, and cytokinin
Author(s) -
Li Taotao,
Kang Xinke,
Lei Wei,
Yao Xiuhong,
Zou Lijuan,
Zhang Dawei,
Lin Honghui
Publication year - 2020
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/jipb.12931
Subject(s) - meristem , cytokinin , auxin , arabidopsis , biology , microbiology and biotechnology , crosstalk , mutant , cell division , brassinosteroid , regulation of gene expression , lateral root , gene , botany , genetics , cell , physics , optics
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.