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Photoexcited CRY1 and phyB interact directly with ARF6 and ARF8 to regulate their DNA‐binding activity and auxin‐induced hypocotyl elongation in Arabidopsis
Author(s) -
Mao Zhilei,
He Shengbo,
Xu Feng,
Wei Xuxu,
Jiang Lu,
Liu Yao,
Wang Wenxiu,
Li Ting,
Xu Pengbo,
Du Shasha,
Li Ling,
Lian Hongli,
Guo Tongtong,
Yang HongQuan
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16194
Subject(s) - auxin , hypocotyl , arabidopsis , microbiology and biotechnology , chromatin immunoprecipitation , psychological repression , biology , phytochrome , elongation , repressor , transcription factor , biochemistry , gene , gene expression , botany , promoter , mutant , red light , materials science , ultimate tensile strength , metallurgy
SummaryArabidopsis CRY 1 and phyB are the primary blue and red light photoreceptors mediating blue and red light inhibition of hypocotyl elongation, respectively. Auxin is a pivotal phytohormone involved in promoting hypocotyl elongation. CRY 1 and phyB interact with and stabilize auxin/indole acetic acid proteins (Aux/ IAA s) to inhibit auxin signaling. The present study investigated whether photoreceptors might interact directly with Auxin Response Factors ( ARF s) to regulate auxin signaling. Protein–protein interaction studies demonstrated that CRY 1 and phyB interact physically with ARF 6 and ARF 8 through their N‐terminal domains in a blue and red light‐dependent manner, respectively. Moreover, the N‐terminal DNA ‐binding domain of ARF 6 and ARF 8 is involved in mediating their interactions with CRY 1. Genetic studies showed that ARF 6 and ARF 8 act partially downstream from CRY 1 and PHYB to regulate hypocotyl elongation under blue and red light, respectively. Chromatin immunoprecipitation‐ PCR assays demonstrated that CRY 1 and phyB mediate blue and red light repression of the DNA ‐binding activity of ARF 6 and ARF 6‐target gene expression, respectively. Altogether, the results herein suggest that the direct repression of auxin‐responsive gene expression mediated by the interactions of CRY 1 and phyB with ARF s constitutes a new layer of the regulatory mechanisms by which light inhibits auxin‐induced hypocotyl elongation.