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Non‐canonical AUX / IAA protein IAA 33 competes with canonical AUX / IAA repressor IAA 5 to negatively regulate auxin signaling
Author(s) -
Lv Bingsheng,
Yu Qianqian,
Liu Jiajia,
Wen Xuejing,
Yan Zhenwei,
Hu Kongqin,
Li Hanbing,
Kong Xiangpei,
Li Cuiling,
Tian Huiyu,
De Smet Ive,
Zhang XianSheng,
Ding Zhaojun
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2019101515
Subject(s) - christian ministry , china , adaptation (eye) , library science , geography , political science , biology , computer science , archaeology , neuroscience , law
The phytohormone auxin controls plant growth and development via TIR 1‐dependent protein degradation of canonical AUX / IAA proteins, which normally repress the activity of auxin response transcription factors ( ARF s). IAA 33 is a non‐canonical AUX / IAA protein lacking a TIR 1‐binding domain, and its role in auxin signaling and plant development is not well understood. Here, we show that IAA 33 maintains root distal stem cell identity and negatively regulates auxin signaling by interacting with ARF 10 and ARF 16. IAA 33 competes with the canonical AUX / IAA repressor IAA 5 for binding to ARF 10/16 to protect them from IAA 5‐mediated inhibition. In contrast to auxin‐dependent degradation of canonical AUX / IAA proteins, auxin stabilizes IAA 33 protein via MITOGEN ‐ ACTIVATED PROTEIN KINASE 14 ( MPK 14) and does not affect IAA 33 gene expression. Taken together, this study provides insight into the molecular functions of non‐canonical AUX / IAA proteins in auxin signaling transduction.